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Car Forum / UK Car Forums / Car Maintenance (UK group) / September 2006General engine questions
Hi all, I've some fuel injection related questions for you, experts. Here we go: Imagine a hypotetical engine which at 5000rpm and 90% open throttle, manages to have the fuel injectors saturated (continously on...underrated injectors), to achieve the correct mixture for lambda 1. 1. Since the fuel injectors cannot deliver more fuel at this point, the engine speed will not be possible to increase, is this correct? 2. What happens when the throttle is 100% open (still 5000rpm), in other words, even more air is being sucked into the engine, while the injectors still cannot provide more fuel. This results in a lean mixture with risk of damaging valveseats, but: What happens to the engine speed at this point? Will a lean mixture tend to decrease the engine speed? Reason for asking all this, (sorry if I describe it strange...) is if a fuel injector is setting a limit of the maximum rpm or power and when you reach this point when the injector saturates, will this result in some kind of rpm-limitation, since the fuel-flow isn't sufficent? Thanks, Regards, Stefan > Hi all, > I've some fuel injection related questions for you, experts. [quoted text clipped - 7 lines] > 1. Since the fuel injectors cannot deliver more fuel at this point, the > engine speed will not be possible to increase, is this correct? In short, engine speed will continue to rise, but as the speed increases, the engine will start to run lean and cause damage if run for a prolonged time with a lean burn situation. Also performance will decrease. The speed it will rev to will depend on the particular engine. > 2. What happens when the throttle is 100% open (still 5000rpm), in > other words, even more air is being sucked into the engine, while the > injectors still cannot provide more fuel. > This results in a lean mixture with risk of damaging valveseats, but: > What happens to the engine speed at this point? Will a lean mixture > tend to decrease the engine speed? The amount of air increase will only be marginal as the engine is still pumping the same amount of air, albeit with a slightly lower vacuum in the inlet manifold. The engine speed will still rise, but once again performance will reduce. > Reason for asking all this, (sorry if I describe it strange...) is if a > fuel injector is setting a limit of the maximum rpm or power and when > you reach this point when the injector saturates, will this result in > some kind of rpm-limitation, since the fuel-flow isn't sufficent? It will create a slight rpm limitation, but it would be quite erratic in what speed it would rev to (it would vary greatly depending on engine load)  SignaturePosted via a free Usenet account from http://www.teranews.com M Cuthill skrev: > > Hi all, > > I've some fuel injection related questions for you, experts. [quoted text clipped - 32 lines] > It will create a slight rpm limitation, but it would be quite erratic in > what speed it would rev to (it would vary greatly depending on engine load) Thanks for your reply, let me tell you the background of my questions... I've designed an electronic blackbox which measures injector pulsetimes and adds about 30% extra time to allow use of alcohol (ethanol) in order to have the lambda correct. And at about 4000rpm and maximum throttle I get the "injector saturated" warning light turn on. This results in, as you tell, a lean burn condition, which worries me. I then thought that when reaching this critical limit, the engine wouldn't have the chance of increasing rpm, thus some form of automatic rpm limitation. But you tell that, though the engine runs lean, it will still increase rpm. That's not good. I would rather see the engine more or less rpm limited at this point the burn turns lean. But you also tell that performance during a lean burn will be bad, so actually the output power from the engine will drop, which would tend to decreasing the engine speed, right? > Thanks for your reply, let me tell you the background of my > questions... > > I've designed an electronic blackbox which measures injector > pulsetimes and adds about 30% extra time to allow use of alcohol > (ethanol) in order to have the lambda correct. This might be a silly question, but why would you reinvent the wheel, when there's programmable ECUs like Megasquirt about already? Adrian skrev: > > Thanks for your reply, let me tell you the background of my > > questions... [quoted text clipped - 5 lines] > This might be a silly question, but why would you reinvent the wheel, when > there's programmable ECUs like Megasquirt about already? There are no silly questions...and I know of Megasquirt indeed. Though, the price of my box compared to MS is very low, and my box is much easier to install than a complete MS system. Besides, it suits to a big number of brands. "Anyone" could install it , with very little engine knowledge. This is not true for a MS system. In news:1157711348.906032.275060@d34g2000cwd.googlegroups.com, powerampfreak <powerampfreak@hotmail.com> wittered on forthwith; > Adrian skrev: > [quoted text clipped - 14 lines] > "Anyone" could install it , with very little engine knowledge. This is > not true for a MS system. Thing that worries me is it appears to be designed by someone with very little engine knowledge. SignaturePete M - Using the Scouse Side of the Force - Range Rover Vogue EFI x 2 OMF#9 "This is not 'Nam, this is bowling. There are rules" Pete M (pete.murray@bogoffwithzepressedmeatblueyonder.co.uk) gurgled happily, sounding much like they were saying : >>> This might be a silly question, but why would you reinvent the >>> wheel, when there's programmable ECUs like Megasquirt about already? >> There are no silly questions...and I know of Megasquirt indeed. >> Though, the price of my box compared to MS is very low, and my box is >> much easier to install than a complete MS system. Besides, it suits to >> a big number of brands. >> "Anyone" could install it , with very little engine knowledge. This is >> not true for a MS system. > Thing that worries me is it appears to be designed by someone with very > little engine knowledge. Quite. Particularly when an MS ECU kit is about a hundred quid, yet his is "very low" price compared... I can't possibly imagine how anybody could replace a factory ECU and put a viable map together with "very little engine knowledge". > > Thing that worries me is it appears to be designed by someone with very > > little engine knowledge. [quoted text clipped - 3 lines] > Particularly when an MS ECU kit is about a hundred quid, yet his is "very > low" price compared... Wow. £100 sounds cheap so I hate to think what a sub £50 one would be like. Hell, it costs more than that to convert my car from points to electronic ignition. > I can't possibly imagine how anybody could replace a factory ECU and put a > viable map together with "very little engine knowledge". Badly? Obviously no idea what 3D mapping is. SignatureConor How about taking the safety labels off everything, and let the stupidity-problem solve itself? > I can't possibly imagine how anybody could replace a factory ECU and put a > viable map together with "very little engine knowledge". He didn't say he did that. He said he designed a box which would extend the fuel injector pulse by ~30%. So there's a box that sits between the ECU and the injectors, increasing the duty cycle of each pulse... SignatureDavid Taylor >> I can't possibly imagine how anybody could replace a factory ECU and >> put a viable map together with "very little engine knowledge". > He didn't say he did that. > > He said he designed a box which would extend the fuel injector pulse > by ~30%. So there's a box that sits between the ECU and the > injectors, increasing the duty cycle of each pulse... Even when it's inappropriate... So the engine will use 30% more fuel at all times, and run massively rich. Except it won't, because the lambda will knock the overfuelling back... > Except it won't, because the lambda will knock the overfuelling > back... <thinks> Of course it bloody won't, because the lambda will be right because of the effect of the Ethanol... <thinks a bit further> Would your average narrowband Lambda do that automagically anyway? Possibly not. > <thinks a bit further> > Would your average narrowband Lambda do that automagically anyway? Possibly > not. No, probably not - average fuel trim allowable is normally <15% and only occurs at cruise conditions anyway so off-cruise it would go to pot again if no ~34% correction were applied. > Except it won't, because the lambda will knock the overfuelling back... It will be relatively correct in most locations as the lambda sensor reads oxy content so wont know what fuel its running on, but as you say, its not as simple as that. For a start the o2 sensor only works between certain rpms and not at WOT. If this tuner hopes to gain massive power increases by using ethanol, he will be doing it at WOT, where the stock ECU cant keep control of itself. IF the injectors are near 100% they can float and either run lean or rich. The poster clearly doesnt understand the depths of control required to tune an engine, but im sure he/she is learning so lets not be too harsh. > He said he designed a box which would extend the fuel injector pulse > by ~30%. So there's a box that sits between the ECU and the injectors, > increasing the duty cycle of each pulse... Sounds an incredibly arse about face way of doing it. Injectors need a fair bit of power, and the drivers are already present in the ECU. Easier therefore to modify the ECU. Signature*Make it idiot-proof and someone will make a better idiot. Dave Plowman dave@davenoise.co.uk London SW To e-mail, change noise into sound. >> He said he designed a box which would extend the fuel injector pulse >> by ~30%. So there's a box that sits between the ECU and the injectors, >> increasing the duty cycle of each pulse... > Sounds an incredibly arse about face way of doing it. Injectors need a > fair bit of power, and the drivers are already present in the ECU. Easier > therefore to modify the ECU. Dunno about that... If it really WAS as simple as "+30% across the range", then it's a decent way to do it - no need to do umpty-seven-thousand maps for everything. I'm just not sure it is. But Matey thinks he's got a big payslip, so he MUST be right. > Sounds an incredibly arse about face way of doing it. Injectors need a > fair bit of power, and the drivers are already present in the ECU. Easier > therefore to modify the ECU. The other problem is that not all injectors are plain high impedence ones and can just be PWMd - many OEM injector driver circuits are far from just a switch, instead providing current control and adjustments at varying rpms/duty cycles etc. The OPs solution is indeed cheap, but it has many flaws due to him apparently not investigating in depth the existing setups possible in OEM ECUs. Its about an A-level electronics project level, and summer homework is due in soon for the new term....? I'm being mean lol but in all honesty it would could work fairly well with a very basic early 90s EFI system on an un-stressed engine, its WAY lacking on a modern car EFI system and could cause some damage on a high power vehicle if not set up correctly. IMO of course. >> He said he designed a box which would extend the fuel injector pulse >> by ~30%. So there's a box that sits between the ECU and the injectors, [quoted text clipped - 3 lines] > fair bit of power, and the drivers are already present in the ECU. Easier > therefore to modify the ECU. No it isn't. Modifying ecu's takes a lot of effort and will be a different solution for every vehicle. Piggy back boxes that intercept ecu signals and modify them are a well established tuning principle except that the OP is trying to take it beyond the limits of most standard injectors. SignatureDave Baker www.pumaracing.co.uk "Why," said Ford squatting down beside him and shivering, "are you lying face down in the dust?" "It's a very effective way of being wretched," said Marvin. > > Sounds an incredibly arse about face way of doing it. Injectors need a > > fair bit of power, and the drivers are already present in the ECU. > > Easier therefore to modify the ECU. > No it isn't. Modifying ecu's takes a lot of effort and will be a > different solution for every vehicle. Piggy back boxes that intercept > ecu signals and modify them are a well established tuning principle > except that the OP is trying to take it beyond the limits of most > standard injectors. They might well be commercially expedient. Doesn't stop them being a bodge, though. Signature*I never drink anything stronger than gin before breakfast * Dave Plowman dave@davenoise.co.uk London SW To e-mail, change noise into sound. >> > Sounds an incredibly arse about face way of doing it. Injectors >> > need a fair bit of power, and the drivers are already present in [quoted text clipped - 8 lines] > They might well be commercially expedient. Doesn't stop them being a > bodge, though. Want to buy a Universal Perfromance Modification? http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=280023738107 A commercially expedient bodge if ever I saw one. >>> > Sounds an incredibly arse about face way of doing it. Injectors >>> > need a fair bit of power, and the drivers are already present in [quoted text clipped - 14 lines] > > A commercially expedient bodge if ever I saw one. I'm almost tempted to buy one at that price just to confirm what I think it is. And having just looked back at the negative feedback, looks like it is what I thought it was. I wonder how many people actually think it makes a difference? It'll make a difference until the ECU enters closed loop operation, then the ECU will adapt to the new parameters dropping back to it's original power level. And it won't alter the timing on any engine that has a knock sensor fitted (that'll be most then!) SignaturePosted via a free Usenet account from http://www.teranews.com > > A commercially expedient bodge if ever I saw one. > I'm almost tempted to buy one at that price just to confirm what I think > it is. It's a penny resistor. Signature*OK, who stopped payment on my reality check? Dave Plowman dave@davenoise.co.uk London SW To e-mail, change noise into sound. > Adrian skrev: > [quoted text clipped - 4 lines] > "Anyone" could install it , with very little engine knowledge. This is > not true for a MS system. But the MS is very simple to install for anyone with basic electronics knowledge and a good level of engine/control/tuning knowledge. To convert a car to run on ethanol you do not just need to adjust fuel injection ratios across the board by a fixed %, and you should know an aweful lot more about engine tuning than just the relative AFRs. And considering lambda 1 isnt ideal for max power your X% adjustments will be wrong at high load situations and doesnt take into account cyl temps and the adjustment of mixture to cool the cyl walls. Re-mapping on a different fuel with different calorific content and different knock supression abilities takes a LOT of time and effort and a good 'tuning head', time on a dyno etc. The engine will react differently to the fuel and you will need to monitor exhaust gas temps to ensure you dont end up with total meltdown. The cost of all the extra knowledge and equipment needed to do it safely totally negates the cost of your product. I have built and installed a fully working MS system in my car for £300. IT needs mapping (say another couple of hundred). If you make a product that drops into any vehicle without the correct adjustments for other possible mods etc (Which are unique to an engine/car combination) you will end up with no engine, very quickly. IF you sell this product to others you will end up with lawsuits, very quickly too. > I have built and installed a fully working MS system in my car for £300. What in? Something on factory injection or as a conversion from carb? > IT needs mapping (say another couple of hundred). Get it broadly there so it runs cleanly across the rev range, then log it, run the log and map through MegaTweak, repeat until right. S'wot I'm planning to do if I ever get round to doing anything with this collection of bits... > Get it broadly there so it runs cleanly across the rev range, then log it, > run the log and map through MegaTweak, repeat until right. Its not quite that simple unless youre running a low power, non-turbocharged, fueling only setup. I'm running full spark control and fuelling to 300bhp which is 50% increase on stock with 100% higher boost levels - at this point you're not just worrying about your fuelling, despite having wideband AFR monitoring and AFR targetting set up - you're still only 3 seconds worth of too much advance away from total meltdown, holey pistons and a big rebuild cost. If I was doing a lower power setup on a normal runaround or converting a carbd car I wouldnt have an issue with giving it a rough setup. But then i wouldnt bother fitting an MS to a normal car, except if i were doing a gas conversion. > S'wot I'm planning to do if I ever get round to doing anything with this > collection of bits... Its worth it, and i am road-mapping but it is a big risk enginewise. What car/engine you doing it on, out of interest? Are you a member on msefi? J >> Get it broadly there so it runs cleanly across the rev range, then >> log it, run the log and map through MegaTweak, repeat until right. > Its not quite that simple unless youre running a low power, > non-turbocharged, fueling only setup. Which is exactly what I'm planning to do... > What car/engine you doing it on, out of interest? Look at the email address... > Are you a member on msefi? Megasquirt-UK on Y!Groups, yes, but I've not looked at the web fora for ages. > Look at the email address... > > Are you a member on msefi? > Megasquirt-UK on Y!Groups, yes, but I've not looked at the web fora for > ages. Ahah, excellent - classic motors, be interesting to see how you get on with those! I have a friend who is planning the do a beetle and that has some interesting unique areas to work around. If you need to bounce any problems off someone just drop me an email - i enjoy musing on peoples problems! > Coyoteboy (coyoteboyuk@hotmail.com) gurgled happily, sounding much like > What in? Something on factory injection or as a conversion from carb? Oops, missed that bit. Its a '91 Celica GT4, turbocharged 2 litre 4 cyl, using all stock sensors except for wideband oxy sensor and fast response intake temp sensor. All mounted in a stock ECU case and connectors so i can plug n play if i have a fault. Was working great until my nearside front caliper seized the other day and since then its been sat in the drive looking forlorn lol. Look, my box is a microcontroller with injector drivers connected between ecu and injectors. It simply adds 30% extra injector time since ETHANOL HAS LOWER ENERGY CONTENT AND THEREFORE ENGINE NEEDS 30% EXTRA FUEL TO KEEP THE CORRECT MIXTURE AND ACHIEVE LAMBDA 1. IT'S NOT TO INCREASE POWER. I would wish that all posters did READ THE ORIGINAL POSTINGS BEFORE JUMPING ON UNRELEVANT FACTS, thank you. > Look, my box is a microcontroller with injector drivers connected > between ecu and injectors. It simply adds 30% extra injector time since Should be 34% apparently. > ETHANOL HAS LOWER ENERGY CONTENT AND THEREFORE ENGINE NEEDS 30% > FUEL TO KEEP THE CORRECT MIXTURE AND ACHIEVE LAMBDA 1. Well done, we read that in the first one. My point, about not always running at lambda 1, was nothing to do with that if you read my post, and linked to the reason the change of fuel is being considered, which you never stated. > IT'S NOT TO INCREASE POWER. I would wish that all posters did READ THE > ORIGINAL POSTINGS BEFORE JUMPING ON UNRELEVANT FACTS, thank you. That would be "irrelevant" but.... your question raises questions that need clarification - i.e. what is the intended work environment/point of the product. Life isnt black and white. Why would you want to run ethanol, other than "green" reasons? Its harder to get hold of, more expensive (currently). Your question was answered, well and truly, by the first replies. Others were simply adding thoughts that you might want to consider in your design. If you give very little information and sound like you dont know what you are doing (which im sorry but you do sound that way) then people will warn you about the problems you MAY face to try to save you from failure. Provide more information and you will get less of what you consider irrelevant. Otherwise dont be so ungrateful when you came asking for help. Coyoteboy skrev: > > Look, my box is a microcontroller with injector drivers connected > > between ecu and injectors. It simply adds 30% extra injector time since [quoted text clipped - 26 lines] > of what you consider irrelevant. Otherwise dont be so ungrateful when > you came asking for help. bla bla bla.... ethanol costs much less than unleaded, also counting in the 30% increase in consumption. > Coyoteboy skrev: >> [quoted text clipped - 10 lines] > ethanol costs much less than unleaded, also counting in the 30% > increase in consumption. And there endeth the helpful replies... Still, back to school now so it should quieten down a bit. >> Coyoteboy skrev: >>> [quoted text clipped - 14 lines] > > Still, back to school now so it should quieten down a bit. As a parting thought, if you're going to do it in a cack handed way then why not just increase the fuel pressure 34% instead? PC Paul skrev: > >> Coyoteboy skrev: > > As a parting thought, if you're going to do it in a cack handed way then why > not just increase the fuel pressure 34% instead? Increasing fuel pressure by 34% will NOT result in a 34% extra fuel flow through the injector. The flow increases by the squareroot of the increase in flow. Say, ethanol needs 34% extra flow, this comes out to be 1.34 X 1.34 = 1.79, so the fuel pressure has to be increased by 79% to achieve 34% extra fuel. Unfortunately, many fuel pumps doesn't like this. > PC Paul skrev: > [quoted text clipped - 9 lines] > so the fuel pressure has to be increased by 79% to achieve 34% extra > fuel. Unfortunately, many fuel pumps doesn't like this. No, you'd need a bigger pump. You can't always get by with turning it up to 11, Mr Freak. In news:psOdnewoXK_xdpzYnZ2dnUVZ8qGdnZ2d@brightview.com, PC Paul <urd@munge.org.uk> wittered on forthwith; >> PC Paul skrev: >> [quoted text clipped - 12 lines] > No, you'd need a bigger pump. You can't always get by with turning it > up to 11, Mr Freak. Surely Marshall do a fuel pump regulator? SignaturePete M - Using the Scouse Side of the Force - Range Rover Vogue EFI Citroen Xantia SX TD OMF#9 "This is not 'Nam, this is bowling. There are rules" >> PC Paul skrev: >> [quoted text clipped - 12 lines] > No, you'd need a bigger pump. You can't always get by with turning it up > to 11, Mr Freak. The size of the pump doesn't make a rat's arse of difference to the flow at a given pressure drop. You still need the required pressure to get the desired flow. Most standard FI pumps can supply enough fuel at 3 bar to handle 300 bhp even when the engine puts out less than half that. What they can't do is run at much higher pressures than standard for long periods. It's the injector that limits the fuel supply at a given pressure drop, not the pump. Please stop pontificating about things you don't understand. SignatureDave Baker www.pumaracing.co.uk "Why," said Ford squatting down beside him and shivering, "are you lying face down in the dust?" "It's a very effective way of being wretched," said Marvin. >>> PC Paul skrev: >>> [quoted text clipped - 15 lines] > The size of the pump doesn't make a rat's arse of difference to the > flow at a given pressure drop. Who said I was talking about physical size? It's quite common when talking about pumps for a 'bigger' pump to mean it can give a greater head - which is exactly what you would need here, barring replacing injectors, reprogramming ECUs etc. > You still need the required pressure > to get the desired flow. Most standard FI pumps can supply enough > fuel at 3 bar to handle 300 bhp even when the engine puts out less > than half that. What they can't do is run at much higher pressures > than standard for long periods. It's the injector that limits the > fuel supply at a given pressure drop, not the pump. Tell you what, put a bigger pump in to increase the pressure and give a higher fuel supply for the same injectors. Why didn't I say that in the first place. > Please stop pontificating about things you don't understand. Please stop making assumptions then saying I'm wrong based on them. Maybe I don't build engines for a living, but I know enough not to try and simplistically extend the injector duty cycle 30% across the entire range and expect it to work smoothly. So that makes me amply qualified to comment. And anyway, it's Usenet, so nurr. >> You still need the required pressure >> to get the desired flow. Most standard FI pumps can supply enough [quoted text clipped - 6 lines] > higher fuel supply for the same injectors. Why didn't I say that in the > first place. Nice try but whether you really meant bigger pump or higher pressure pump makes no odds. Injectors are designed to work over a given range of pressures. 35 to 45 psi is the normal range and you might get away with 60 psi. Much more than that and they won't seal when shut and start dribbling fuel into the manifold. That's a common enough fault even at 40 psi when they're getting old or fuel deposits are building up on the pintle. SignatureDave Baker www.pumaracing.co.uk "Why," said Ford squatting down beside him and shivering, "are you lying face down in the dust?" "It's a very effective way of being wretched," said Marvin. >>> You still need the required pressure >>> to get the desired flow. Most standard FI pumps can supply enough [quoted text clipped - 14 lines] > even at 40 psi when they're getting old or fuel deposits are building > up on the pintle. Fair enough. I never said it would work anyway, but a combination of running the injectors at a higher pressure and for longer *might* just give enough extra to actually run on ethanol. Allowing for a more sophisticated control system then the one being proposed, anyway. ;-) Just as an aside, is ethanol the same density/viscosity as petrol? Does that make a difference to how well the injector seals etc.? > PC Paul skrev: > [quoted text clipped - 10 lines] > so the fuel pressure has to be increased by 79% to achieve 34% extra > fuel. Unfortunately, many fuel pumps doesn't like this. Ah. Well at least you know some basic physics if not much about engine operation. SignatureDave Baker www.pumaracing.co.uk "Why," said Ford squatting down beside him and shivering, "are you lying face down in the dust?" "It's a very effective way of being wretched," said Marvin. >>> Coyoteboy skrev: >>>> [quoted text clipped - 17 lines] > As a parting thought, if you're going to do it in a cack handed way then > why not just increase the fuel pressure 34% instead? Silly boy. Fluid flow is proportional to the square root of pressure drop rather than to pressure drop itself. With an average FI system running at about 3 bar (43.5 psi) you'd need to up that to 5.4 bar (78 psi) to get the required flow increase. Possible in some situations if the pump is up to it but not recommended for a long and happy pump life. SignatureDave Baker www.pumaracing.co.uk "Why," said Ford squatting down beside him and shivering, "are you lying face down in the dust?" "It's a very effective way of being wretched," said Marvin. >> Look, my box is a microcontroller with injector drivers connected >> between ecu and injectors. It simply adds 30% extra injector time since [quoted text clipped - 3 lines] >> ETHANOL HAS LOWER ENERGY CONTENT AND THEREFORE ENGINE NEEDS 30% >> FUEL TO KEEP THE CORRECT MIXTURE AND ACHIEVE LAMBDA 1. Where did you get 30-34% from? You can't use Higher Calorific Value (or Gross Calorific Value or Higher Heating Value) as the water from combustion doesn't condense and yield it's energy to the engine. You have to use Lower Calorific Value (or Net Calorific Value or Lower Heating Value). http://www.ec.gc.ca/cleanair-airpur/CAOL/transport/publications/ethgas/ethgas4.htm Ethanol 21.1MJ/L, Petrol 31.8MJ/L. You need 31.8/21.1 = 1.507 times the volume flow rate (51% increase). The above site says 53%, no doubt the LHV was rounded. Or you need 2.34x the fuel pressure. >Well done, we read that in the first one. My point, about not always >running at lambda 1, was nothing to do with that if you read my post, >and linked to the reason the change of fuel is being considered, which >you never stated. It's possible to run very lean at light cruise load without doing engine damage. Reduce engine rpm, open throttle to restore power to cruise requirement and then move mixture lever lean. It's safe because the head temperature drops a lot from Lambda=1 temperature. This was used to increase operational duration of a WWII fighter bomber from 5 hours to 8 hours and still have more fuel in the tank on landing than before. It's how the B29 Superfortress did the long range missions it did and how the Lockheed Constellation crossed the Atlantic direct New York to London with 100 passengers without a splash and dash in Ireland or St Johns. -- Peter Hill Spamtrap reply domain as per NNTP-Posting-Host in header Can of worms - what every fisherman wants. Can of worms - what every PC owner gets! > Look, my box is a microcontroller with injector drivers connected > between ecu and injectors. It simply adds 30% extra injector time So it's sh.t, then. > since ETHANOL HAS LOWER ENERGY CONTENT AND THEREFORE ENGINE NEEDS 30% > EXTRA FUEL TO KEEP THE CORRECT MIXTURE AND ACHIEVE LAMBDA 1. And you don't have a clue. > IT'S NOT TO INCREASE POWER. I would wish that all posters did READ THE > ORIGINAL POSTINGS BEFORE JUMPING ON UNRELEVANT FACTS, thank you. <sigh> The thread moved on from there. Get over it. Adrian skrev: > > Look, my box is a microcontroller with injector drivers connected > > between ecu and injectors. It simply adds 30% extra injector time [quoted text clipped - 11 lines] > <sigh> > The thread moved on from there. Get over it. Adrian, I think I earn the same amount of money in a week as you do in a month. Or possibly two months.... :-)) You seem to have very low skills in reading, since you fail to read (or understand...) the original postings....... >> <sigh> >> The thread moved on from there. Get over it. > Adrian, I think I earn the same amount of money in a week as you do in > a month. > Or possibly two months.... :-)) <rolls eyes> Firthy and Huge do that "Con-sid-erably richer than YOW" line far better than you. > You seem to have very low skills in reading, since you fail to read (or > understand...) the original postings....... Yes, yes, we did that already. Remember? > >> <sigh> > >> The thread moved on from there. Get over it. [quoted text clipped - 5 lines] > <rolls eyes> Firthy and Huge do that "Con-sid-erably richer than YOW" line > far better than you. That's because, at least with Firthy, it's actually believeable. SignatureSteve H 'You're not a real petrolhead unless you've owned an Alfa Romeo' www.italiancar.co.uk - Honda VFR800 - Hongdou GY200 - Alfa 75 TSpark Alfa 156 2.0 TSpark - B6 Passat 2.0TDI - COSOC KOTL BoTAFOT #87 - BoTAFOF #18 - MRO # - UKRMSBC #7 - Apostle #2 - YTC # > Adrian, I think I earn the same amount of money in a week as you do in > a month. > Or possibly two months.... :-)) > You seem to have very low skills in reading, since you fail to read (or > understand...) the original postings....... Oh dear - you lost your credibility right there freak. > Look, my box is a microcontroller with injector drivers connected > between ecu and injectors. It simply adds 30% extra injector time since > ETHANOL HAS LOWER ENERGY CONTENT AND THEREFORE ENGINE NEEDS 30% EXTRA > FUEL TO KEEP THE CORRECT MIXTURE AND ACHIEVE LAMBDA 1. > IT'S NOT TO INCREASE POWER. I would wish that all posters did READ THE > ORIGINAL POSTINGS BEFORE JUMPING ON UNRELEVANT FACTS, thank you. Then let's try and find you a workable solution. However you've posted your query on a forum where very few people are going to have the technical knowledge to solve your problem. Few injector systems are going to have 30% extra capacity in the duty cycle as you've found out. However if you achieve part of the enrichment from increased fuel pressure and part from increased duty cycle you have a solution. Assuming the fuel system runs at 3 bar and it can be safely increased to 4 bar you gain 15.4% extra fuel from the pressure increase. You then require 1.3 / 1.154 = 12.6% extra from the duty cycle. Most systems can cope with 15% to 20% extra duty cycle so you now have a viable solution if you fit a different, or adjustable, pressure regulator. The pump output should not be a limitation because they often have 50% or more spare capacity to cope with wear and tear. There are however some cars which run the injectors at very close to maximum duty cycle so if you intend this to be a universal panacea it might not always work. In those situations, as I said previously, your solution is to fit larger injectors. SignatureDave Baker www.pumaracing.co.uk "Why," said Ford squatting down beside him and shivering, "are you lying face down in the dust?" "It's a very effective way of being wretched," said Marvin. >> Look, my box is a microcontroller with injector drivers connected >> between ecu and injectors. It simply adds 30% extra injector time since [quoted text clipped - 17 lines] > be a limitation because they often have 50% or more spare capacity to cope > with wear and tear. Another thought is, can a normal fuel pump designed to be run on petrol, withstand running on ethanol? SignaturePosted via a free Usenet account from http://www.teranews.com > Look, my box is a microcontroller with injector drivers connected > between ecu and injectors. It simply adds 30% extra injector time since > ETHANOL HAS LOWER ENERGY CONTENT AND THEREFORE ENGINE NEEDS 30% EXTRA > FUEL TO KEEP THE CORRECT MIXTURE AND ACHIEVE LAMBDA 1. > IT'S NOT TO INCREASE POWER. I would wish that all posters did READ THE > ORIGINAL POSTINGS BEFORE JUMPING ON UNRELEVANT FACTS, thank you. I'd assumed you were only trying to run an ethanol/petrol blend but now I'm not so sure. In fact I think you may be horribly confused about all sorts of things. The heating value (calorific value) of ethanol is indeed about 33% lower than that of petrol but that has absolutely nothing to do with the stoichiometric air/fuel ratio. Firstly, even if the 'energy content' was relevant, simple maths tells you you'd want 50% extra fuel not 33% to compensate for a 33% drop in calorific value. Secondly the stoichiometric A/F ratio for ethanol is 9 as opposed to 14.7 for petrol. That means you actually need 63% more fuel by weight for a given amount of air. As ethanol has a slightly higher specific gravity than petrol the increase required by volume (which is what the injectors will meter at any given pressure) is somewhat lower than this, around 53% extra. If you are indeed trying to run pure ethanol in your car, or even worse trying to develop a system to sell to others then you're an accident waiting to happen because you appear neither to understand the stoichiometry or even the basic maths of the situation. SignatureDave Baker www.pumaracing.co.uk "Why," said Ford squatting down beside him and shivering, "are you lying face down in the dust?" "It's a very effective way of being wretched," said Marvin. > Adrian skrev: > [quoted text clipped - 15 lines] > "Anyone" could install it , with very little engine knowledge. This is > not true for a MS system. The small fly in the ointment is it isn't going to work for any vehicle that has less than 30% spare capacity in the injector duty cycle. The way to do this properly is fit injectors with 30% more flow capacity at the same pressure drop. That way the ecu doesn't know anything has changed, no need for electronics, the closed loop lambda will keep mixture at stoichiometric at part throttle and at full throttle the engine will revert to the OE mixture setting. SignatureDave Baker www.pumaracing.co.uk "Why," said Ford squatting down beside him and shivering, "are you lying face down in the dust?" "It's a very effective way of being wretched," said Marvin. > M Cuthill skrev: > [quoted text clipped - 46 lines] > order to have the lambda correct. And at about 4000rpm and maximum > throttle I get the "injector saturated" warning light turn on. Hardly surprising. Most fuel injection systems don't have an extra 30% spare capacity in the duty cycle and the critical point is going to be at peak torque rpm when duty cycle is highest. This > results in, as you tell, a lean burn condition, which worries me. I > then thought that when reaching this critical limit, the engine > wouldn't have the chance of increasing rpm, thus some form of automatic > rpm limitation. That's a very silly hypothesis. If you accelerate at part throttle you still accelerate. Why would rpm become limited to a dead stop just because the mixture started to go a bit weak and some power is lost? > But you tell that, though the engine runs lean, it will still increase > rpm. That's not good. [quoted text clipped - 3 lines] > actually the output power from the engine will drop, which would tend > to decreasing the engine speed, right? Again don't be silly. The engine will continue to increase rpm if the load on the car is less than the power output. Depending on circumstances that could well be the case until the mixture is so weak the engine blows up. The only way to rev limit an engine via fuel supply is a complete cut off until the rpm drops backs below the critical point. SignatureDave Baker www.pumaracing.co.uk "Why," said Ford squatting down beside him and shivering, "are you lying face down in the dust?" "It's a very effective way of being wretched," said Marvin. Hi again, everyone! Looks like my posting started a hurricane... Anyways, I'M GREATFUL FOR ALL POSTINGS, though some of them were not what I expected. No hard feeling from my side. Let's shake hands and enjoy. I apologize if I were unkind to someone. Coyoteboy, adrian and who else... But some of you aren't very kind either.... Anyways........ Actually, I've run my car on ethanol over one year, and it performs very well. I'm no engine expert (the reason for posting here) and some advice are always welcome. I'm working as an electronic designer for the audio industry (power amplifiers and switchmode power supplies) but engines has always been an interesting area, especially efi. Thank you. > Actually, I've run my car on ethanol over one year OK - would you care to answer the question about where the hell you get it from, because I've never once seen Ethanol fuel for sale in any country. >> Actually, I've run my car on ethanol over one year > > OK - would you care to answer the question about where the hell you get it > from, because I've never once seen Ethanol fuel for sale in any country. Slipping slightly off topic, does anyone remember if it was Ethanol fuel that a BTCC team said they were using at Knockhill last Sunday? SignatureDavid Taylor Ethanol is widely used in Sweden. It's costs less than petrol and with its 104 octance it's a good fuel for turbo engines. > Ethanol is widely used in Sweden. It's costs less than petrol and with > its 104 octance it's a good fuel for turbo engines. I assume its a hybrid mix then, as fairly pure ethanol is meant to be 129 octane and 34% less calorific value. In most of the developed world this costs more than petrol and is only available from industrial chemical outlets, and at around 3x the price of petrol (maybe even under licence IIRC, it being toxic in small quantities). Hence many people questioning why you would want to bother unless it were for high-performance reasons. No-one wanted to be nasty in the first place - we were just offering advice - clearly you know something about electronics but you asked about engines and got told about it and then warned that engines arent as simple as just using X% increase. We were only trying to help you not damage your (or other peoples) vehicles without good understanding first. Sorry if that came across badly or unpleasant but I feel i have to warn people - ive had several undergraduate students approach me with ideas - only to come back with damage done because i expected them to research the area properly but they failed to spot simple problems they should have seen coming. J The fuel is called E85, it's a mix of 85% ethanol and 15% petrol. Many cars in Sweden are sold as FFV-cars, flexible fuel vehicles, they accept ANY mix of E85 and petrol, so the engines have no problem with it. > The fuel is called E85, it's a mix of 85% ethanol and 15% petrol. Not available here in the UK. > Many cars in Sweden are sold as FFV-cars, flexible fuel vehicles, they > accept ANY mix of E85 and petrol, so the engines have no problem with > it. How will your box know which fuel is in the car? > How will your box know which fuel is in the car? He could use a fuel grade sensor, but these are hundreds so i assume he wont. He could use a flick of the switch but if you switch between fuels (tankfulls) with any regularity it is irrelevant as the mixture will be some unknown quantity of each, leaving both settings running like shite. I would assume he is talking about switching solely to ethanol based, which would be simpler. >> How will your box know which fuel is in the car? > He could use a fuel grade sensor, but these are hundreds so i assume he > wont. He could use a flick of the switch but if you switch between > fuels (tankfulls) with any regularity it is irrelevant as the mixture > will be some unknown quantity of each, leaving both settings running > like shite. I would assume he is talking about switching solely to > ethanol based, which would be simpler. If somewhat restricting when it comes to foreign travel... > The fuel is called E85, it's a mix of 85% ethanol and 15% petrol. > Many cars in Sweden are sold as FFV-cars, flexible fuel vehicles, they > accept ANY mix of E85 and petrol, so the engines have no problem with > it. In that case a back of a fag packet calculation shows that the extra fuel by volume required to achieve stoichiometry is about 42% not the 30% you have been trying. SignatureDave Baker www.pumaracing.co.uk "Why," said Ford squatting down beside him and shivering, "are you lying face down in the dust?" "It's a very effective way of being wretched," said Marvin. > The fuel is called E85, it's a mix of 85% ethanol and 15% petrol. > Many cars in Sweden are sold as FFV-cars, flexible fuel vehicles, they > accept ANY mix of E85 and petrol, so the engines have no problem with > it. So through the whole discussion about how you need to pump more Ethanol in because of it's lower energy density, you're actually talking about between 94-104 octane variation, i.e. Petrol or better. I'm confused now... PC Paul skrev: > > The fuel is called E85, it's a mix of 85% ethanol and 15% petrol. > > Many cars in Sweden are sold as FFV-cars, flexible fuel vehicles, they [quoted text clipped - 6 lines] > > I'm confused now... Don't be confused. Normally, you fill up either petrol or E85. Some gasstations doesn't have E85 yet. If you have 100% E85 in your tank, you need to add around 33% to the injector-duration. This demand decreases as you mix petrol with E85. If you keep 50/50 you'll need only a 15% additional duration. The finetuning is done by the ecu, so it achieves lambda 1. Actually, some 2.0 GM engines has a very wide lambda area, so extra electronics isn't necessary. It achieves lambda 1 still, with 100% E85. > PC Paul skrev: > [quoted text clipped - 19 lines] > electronics isn't necessary. It achieves lambda 1 still, with 100% > E85. But... isn't 104 octane *more* energetic than petrol? Or is octane just concerned with ignitability and flame front speed, so ethanol explodes quicker but doesn't have the 'oomph' that petrol would have? >But... isn't 104 octane *more* energetic than petrol? Or is octane just >concerned with ignitability and flame front speed, so ethanol explodes >quicker but doesn't have the 'oomph' that petrol would have? No. The "energetic" value you seek is the lower calorific value LCV. Yes. Ethanol has lower LCV than petrol which is why he needs more to run the same power. Octane is measure of the anti knock properties, the resistance of the fuel to detonation and pre ignition. Ethanol has higher AKI than petrol. Only way to take advantage of it is to increase compression or boost. Ethanol is slower burning and needs more ignition advance. An E85/Petrol bi-fuel vehicle will advance the timing and use the knock sensor to detect the best ignition timing for the fuel mix in use. So the ECU has to both adjust the mixture for Lambda =1 and move the ignition timing. -- Peter Hill Spamtrap reply domain as per NNTP-Posting-Host in header Can of worms - what every fisherman wants. Can of worms - what every PC owner gets! >>But... isn't 104 octane *more* energetic than petrol? Or is octane >>just concerned with ignitability and flame front speed, so ethanol [quoted text clipped - 15 lines] > So the ECU has to both adjust the mixture for Lambda =1 and move the > ignition timing. Doh. Yes, I remember now. Octane works like viscosity - the opposite to what you'd expect. Less is more and all that. Carry on... ;-) > PC Paul skrev: > Normally, you fill up either petrol or E85. Some gasstations doesn't [quoted text clipped - 5 lines] > Actually, some 2.0 GM engines has a very wide lambda area, so extra > electronics isn't necessary. It achieves lambda 1 still, with 100% E85 It is rare for engines to have more than about 15% trim on a narrowband (1,2,3 or 4 wire oxygen sensor), and generally they have a long and a short term 'trim'. The long term trim is set when the ECU is reset and takes car of big variations, the short term trim is a much smaller % variation and is designed to make smaller modifications so the controller doesnt swing through large variations when correcting creating driveablilty issues. A wideband lambda car (5+ wire) should be able to deal with it but may still need an ECU reset between tanks as they arent generally meant to correct for such massive variations in AFR between tankfuls. J Is there any other discussion forum which may answer questions, that you consider to be silly? I like to get some information from time to time, and don't know where to turn to. > Is there any other discussion forum which may answer questions, that > you consider to be silly? > I like to get some information from time to time, and don't know where > to turn to. No-one considered your questions silly. Your questions were answered. Extra help was offered, admittedly some was with a slight sneer about your apparently over-simple approach. You decided not to listen to it and proceeded to shout at us about how you didnt care - WITH CAPITALS - an action guaranteed to piss people off. Think about it this way - if you shouted what you wrote while talking to someones face how long would you expect to last before he smacked you in the face for being ignorant and shouting at him? I'd give you a few seconds. You can get all the information you like here, just try not to tell people who are answering your questions that you dont want to hear what *they spent time writing for you*. If you want answers from professional engineering forums (of which im also a member) then I can give you a list but you'd have to be a qualified, accredited mech engineer to join. Trust me, if you think this is an elitist group that hand out "irrelevant" information wait until you stick your nose into a proper engineering/tuning technical forum, you will soon decide this place was better for the "head in the sand" approach you wish to persue ;-) J Maybe you people are a bit later than us in Sweden technically... :) E85 has been around for about 5 years, originally it has been used for 25 years in Brazil, in another shape E22 I guess. Nowadays they have E85 also. They have very good experience with ethanol for cars and so do I. I think you guys believe that ethanol takes more modifications than it actually does to a car engine. Remember, there are similair "dumb boxes" around in Brazil, which only extend the injection pulse to a degree suitable for ethanol. You could watch http://www.flextek.com and see for yourselves!! These boxes do have the same problem as mine, with the injectors limiting the maximum fuel. For 9 months I used an variable fuelpressure regulator trimmed to around 4bar, this worked equally well. 3 months ago I'm using my own "black box" which works good. The injector extend time can be set anywhere between 10-100%. The only thing is that around 4000rpm and full throttle, the duty-cycle goes to 100% and my red warning led illuminates. But it's very rare for me going up to 4000 so it's generally no problem. The engine have perfect values in emission tests and achieves lambda 1 with no problem. > Maybe you people are a bit later than us in Sweden technically... :) > E85 has been around for about 5 years I don't remember seeing it widely available when I was over there a couple of years ago. I'll look out next summer. > They have very good experience with ethanol for cars and so do I. > I think you guys believe that ethanol takes more modifications than it > actually does to a car engine. The thing to bear in mind is that you're asking questions in a UK group (you'll note the name...) about something which is semi-widely-available in a couple of countries around the world only - excluding here. If you wanted answers with Ethanol experience, perhaps you'd have done better to ask a Swedish or Brazilian group... > The thing to bear in mind is that you're asking questions in a UK group > (you'll note the name...) about something which is semi-widely-available in > a couple of countries around the world only - excluding here. http://www.morrisons.co.uk/1424.asp >> The thing to bear in mind is that you're asking questions in a UK group >> (you'll note the name...) about something which is semi-widely-available >> in a couple of countries around the world only - excluding here. > http://www.morrisons.co.uk/1424.asp Exactly. The first pump in the UK, in March this year, with plans for a whole 9 more. > Exactly. > > The first pump in the UK, in March this year, with plans for a whole 9 > more. And at a whopping saving of 2p/litre - who would care considering to get the same power you need 30% more?! False economy. >Maybe you people are a bit later than us in Sweden technically... :) >E85 has been around for about 5 years, originally it has been used for >25 years in Brazil, in another shape E22 I guess. Nowadays they have >E85 also. Brazil originally used 100% ethanol. Brazillian Honda 125 had a very small petrol tank for starting and main tank for ethanol. Engine was started on petrol and switched to ethanol when warm. This prevented carb icing problems on cold engine without having to use a hot air induction system of manifold hot spot. -- Peter Hill Spamtrap reply domain as per NNTP-Posting-Host in header Can of worms - what every fisherman wants. Can of worms - what every PC owner gets! The message <e16bg2h1c10teq46jrgo8mrt4r74il0kan@4ax.com> from Peter Hill <peter.usenet1@nospam.demon.co.uk> contains these words: > Brazil originally used 100% ethanol. Brazillian Honda 125 had a very > small petrol tank for starting and main tank for ethanol. Engine was > started on petrol and switched to ethanol when warm. This prevented > carb icing problems on cold engine without having to use a hot air > induction system of manifold hot spot. I guess that'd be 'cos at best you can get around 95% pure ethanol, the rest being water which won't come out by distillation, needing dessicants to nobble the remainder. I don't suppose it was even that pure at the pump - and all that water would make inlet icing a real menace. SignatureSkipweasel Pay no attention to that man behind the curtain. > Maybe you people are a bit later than us in Sweden technically... :) > E85 has been around for about 5 years, originally it has been used for > 25 years in Brazil, in another shape E22 I guess. Nowadays they have > E85 also. Yes, and no. We only tend to take on the sort of fuels that are worth trying. Morrisons (hardly a large % of the market share lol) plan to have 10 pumps of the stuff and sell it at 2p a litre cheaper than normal. Assuming your modded box uses 30% longer DCs at the same revs thats a significantly more expensive fuel. Pointless. If you were to make it pure ethanol I'd re-map one of my fueling/timing tables and run big boost with it but at that rating and cost its just not worth while. > They have very good experience with ethanol for cars and so do I. > I think you guys believe that ethanol takes more modifications than it > actually does to a car engine. I think you may be happy to run a daily driving shopping cart on an alternative fuel - im fine with that too. But on my performance engine i'd not bother. I dont think it takes many modifications to the engine, very few in fact, but the tuning of it *properly* in a highly stressed modern engine is critical. If youre putting it in a normal late 90s car then fine, shove an extra 30% through, run your injectors at a DC they arent meant to (which can damage them) and have shorter range on a tankful - be my guest! >Remember, there are similair "dumb > boxes" around in Brazil, which only extend the injection pulse to a > degree suitable for ethanol. Yeah, theres lots of things in brazil that are hacked together and done in a bodge fashion as in 90% of cases it works fine. I know my luck and id be in the 10% that get problems. Hence i wouldnt bother. The thing is youre asking a group in the UK where we have no experience and no interest in using an expensive fuel. Those of us who have the knowledge to tune for the fuel are likely to be running high performance motors and dont want to put an unknown quantity through it. > For 9 months I used an variable fuelpressure regulator trimmed to > around 4bar, this worked equally well. 3 months ago I'm using my own > "black box" which works good. FPRs at higher pressure put undue stress and wear on injectors. And running lean at 4Krpm and high load is BAD for an engine. It can be very bad. > The injector extend time can be set anywhere between 10-100%. You dont want to run injectors past 90% if you can help it, they can "float" and deliver unknown quantities and running extended periods at 90%+ can lead to burnout and rapid shortening of the life of the. There is a reason why car tuners drop in bigger injectors and higher flowrate pumps and then spend ages struggling to tune idle due to the larger fuel delivery per DC - thats because it is well known that if you push your injectors too far you will end up in tears, not just because its fun to spend £500 on new parts! > The only thing is that around 4000rpm and full throttle, the duty-cycle > goes to 100% and my red warning led illuminates. But it's very rare for > me going up to 4000 so it's generally no problem. But in an emergency, when you desperately need to accelerate out of the way of an accident you'll floor it and run lean, the engine will cough and splutter, hesitate and leave you in danger. Just another reason not to bother IMO. >e engine have > perfect values in emission tests and achieves lambda 1 with no problem. Its very easy to pass emissions tests - in all honesty, they arent that strict. As ive said from the start, on a normal runabout car you are fine doing this, apart from over-stressing your injectors and causing a possible danger due to not being able to give the full rev range without serious stumbling. However if you consider that unimportant then sure, see how it goes and enjoy the cheap fuel :) All anyone was trying to point out was that you havent thought of all the problems that are possible, as a vehicle manufacturer would, so you are risking problems. Older engines are far less difficult to break than newer ones so beware if you switch the box to a newer one. J |
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