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Car Forum / Pontiac / Pontiac Firebird / February 2004Reducing weight
Dear all: I have been thinking about how reducing weight can improve performance. Let's say you bought a performance car and looked for all the things you can do to reduce weight, wouldn't you save about 100 pounds if you took out the empty front seat and also left the spare tire at home? How much performance do you think you will gain by doing that? Also, I heard that some people cut the belt for the AC in the winter. I was wondering if that really helps? Do the AC still spin if you don't turn it on? What is the thinking behind that? sincerely. Thx in advance. > I have been thinking about how reducing weight can improve > performance. Let's say you bought a performance car and looked for [quoted text clipped - 6 lines] > winter. I was wondering if that really helps? Do the AC still spin > if you don't turn it on? What is the thinking behind that? Wouldn't it be slightly easier to by a more powerful car? ;-)) I mean if you want power, buy power. Otherwise, I'd take the unused seats out, strip the paint off of the bodywork, take the rear window out :-)) I wouldn't listen to _heavy_ metal on the radio Any other ideas? Matthew/Poland -- If you want to e-mail me click below: http://www.cerbermail.com/?YX7je5fgrY "What an ongelofelijk f.ck-up by the BAR!!!!" - Dutch commentary "Basically, sh.t happens!" - JPM and what will you gain by this? you can race at the stop lights? > Dear all: > [quoted text clipped - 10 lines] > > sincerely. Thx in advance. > I have been thinking about how reducing weight can improve > performance. Shaving any weight is always a good thing. Shaving unspung weight is the best. Do a Google for unsprung weight. Or better yet, find the Carrol Smith book on tuning for performance. You'll get an education on race car dynamics. > Dear all: > [quoted text clipped - 10 lines] > > sincerely. Thx in advance. Reducing weight in straight line terms. For every 100 pounds you remove you will gain .10 (one tenth of a second) lower ET's in the 1/4 mile. So basically lose 1000 pounds go a second faster. So unless your a dedicated racer, tearing apart your daily driver is a waste of time. Charles "Charles Bendig" <rarepartshunter@yahoo.com> wrote in message news:hg8Xb.4166 > Reducing weight in straight line terms. For every 100 pounds you remove > you will gain .10 (one tenth of a second) lower ET's in the 1/4 mile. So > basically lose 1000 pounds go a second faster. So unless your a dedicated > racer, tearing apart your daily driver is a waste of time. Where did you get this formula? Regards, Noddy. > "Charles Bendig" <rarepartshunter@yahoo.com> wrote in message > news:hg8Xb.4166 [quoted text clipped - 9 lines] > Regards, > Noddy. That Formula has been around long then me. It has been proven at countless Drag Strips across the USA. It has been in Car Craft, Hot Rod, and a few other magazines before as well. As for where I got it, I don't recall. Charles > > Where did you get this formula? > That Formula has been around long then me. It has been proven at > countless Drag Strips across the USA. It has been in Car Craft, Hot > Rod, and a few other magazines before as well. It's a "rule of thumb" not a formula, and it is certainly not accurate or applicable to all cars. Man, there was a great article in Hot Rod magazine back about 20 years ago.... I think the article was called "Caddy-Hack". They took a 1970 Cadillac with a stock worn-out 472 I think it was, and ran it in the quarter. It was pretty slow, maybe ran a 17 second e.t., something like that. They then removed the hood, doors, seats, etc, shaving off say a few hundred pounds, then ran it again... results were much better. They kept on shaving off weight until they were down to the bare frame with engine... it was very funny. They put a racing bucket and simple roll bar for the driver... other than that, it was a frame with an engine... and it ran surprisingly fast! I think it might have been in the high 12s or so... can't remember. I wish I still had this article. It gave good insight into the benefits of weight reduction. But ultimately, they had to totally cut the car apart to make it go fast. They literately took off several thousand pounds in order to go several seconds faster. Reducing just 100 pounds is not worth it unless it is very easy and convenient to do. Removing your front seat or spare tire in a daily driver does not make any sense. Hey... how much do YOU weigh? Maybe you need to go on a diet! And forget taking your girlfriend for any rides, she must weigh at least 110 lbs. Never fill up your gas tank either because a full tank will be another 100 pounds more than a near empty tank. This gets really silly after a while, so it's best to just forget about it. As for the AC compressor belt... I'd leave it on. You should use the AC/defogger occasionally throughout the winter to keep the compressor seals in shape... not good to let it sit unnused for 8 solid months. When the AC is not "on", I'd say the extra drag from the pulley is so minimal that you'd never ever notice it. Leave well enough alone, you will be happier in the long run, and your car will be in better shape and will retain it's value. > Man, there was a great article in Hot Rod magazine back about 20 years > ago.... I think the article was called "Caddy-Hack". They took a 1970 [quoted text clipped - 28 lines] > you will be happier in the long run, and your car will be in better > shape and will retain it's value. I remember that article, it was funny as heck! One other thing to remember about weight, were is it, can it be removed, or is it better to move? Moving the battery to the left rear for instance will remove some weight from the front end which will help handling, and add it to the left rear to help with traction during acceleration. Lighter rims/tires/rotors/drums will reduce unsprung weight helping handling. There are a few sway bars out made of hollow tubing. Lighter weight but still does the job. Fiberglass or carbon fiber hood can shave a few more pounds off of the front end, once again benefiting handling. As has been mentioned, any mods need to be looked at in the light of what you personally want to do with the car. >> Man, there was a great article in Hot Rod magazine back about 20 >> years ago.... I think the article was called "Caddy-Hack". They [quoted text clipped - 41 lines] > As has been mentioned, any mods need to be looked at in the light of > what you personally want to do with the car. Another note; adding weight in the form of frame connectors or strut tower braces etc are more than worth the extra weight due to the added handling and traction increases. saylo1234@aol.com (LovingPerson) wrote in news:fed77941.0402130815.64c2a012 @posting.google.com: > Dear all: > > I have been thinking about how reducing weight can improve > performance. Let's say you bought a performance car and looked for Try the Atkins diet If you dont already have an electric fan, you can gain some hp that way. A K&N filter, and a free flowing muffler are some other cheap ways to gain a little bit of power. As someone mentioned before getting rid of unsprung weight will help alot. > If you dont already have an electric fan, you can gain some hp that > way. A K&N filter, and a free flowing muffler are some other cheap > ways to gain a little bit of power. As someone mentioned before > getting rid of unsprung weight will help alot. Good idea on the electric fan. Something that might add a bit of weight, but shave off a power robber would be to put in an electric water pump as well. >> If you dont already have an electric fan, you can gain some hp that >> way. A K&N filter, and a free flowing muffler are some other cheap [quoted text clipped - 4 lines] >but shave off a power robber would be to put in an electric water pump as >well. The problem with an electric water pump is it runs at a constant speed and is no good for the street unless you devise some kind of bypass that will keep the flow to a minimum at idle yet allow full flow at the top end all the while keeping the correct load on the electric motor that it was designed for. ...Ron -- 68' RS Camaro 88' Formula Bird http://www.frontiernet.net/~rscamero Some are wise and some are otherwise > The problem with an electric water pump is it runs at a constant speed > and is no good for the street unless you devise some kind of bypass [quoted text clipped - 3 lines] > > ...Ron Easy peasy these days. There are little pulsed signals everywhere. So the pump output could be varied by all or some of those signals. Some for road speed, some for engine speed, some for fuel flow. So the electric water pump isn't so bad an idea, just like the electric power steering pumps, which really are speed sensitive. But I wonder whether a 12 Volt motor would do the job well enough. I remember a car I was hill climbing popping a heater hose off at near 7000RPM (not a rotary, either), and dumping the entire contents of the cooling system through a that rather small hose *before* I'd finished soiling my nappie. BIG flow rate there, and I reckon the engine needed it, too.  SignatureToby quidquid latine dictum sit, altum viditur Warning: All posts to be treated with a grain of salt. By Order K.K. Toby Ponsenby spilled my beer when they jumped on the table and proclaimed in <14hqq9x8s14s1.1lsky3onvaxu4$.dlg@40tude.net> >> The problem with an electric water pump is it runs at a constant speed >> and is no good for the street unless you devise some kind of bypass [quoted text clipped - 17 lines] > soiling my nappie. > BIG flow rate there, and I reckon the engine needed it, too. The problem is that in order to control the motor, you will have to lower the voltage. In doing this, the electric motor then can not push as hard, and runs the risk of stalling. The bypass idea Ron said is, IMO, the best way to go in such a situation, but I haven't figured out a rudimentary way to control it yet. :) (I don't trust computers. Shush Glk :) ) NOI > The problem is that in order to control the motor, you will have to > lower > the voltage. In doing this, the electric motor then can not push as > hard, and runs the risk of stalling. Do you honestly believe that the only factors that can possibly affect the speed of an electric motor is load and voltage? You poor, uninformed person! Marvin spilled my beer when they jumped on the table and proclaimed in <402e5226.0@news1.mweb.co.za> > >> The problem is that in order to control the motor, you will have to [quoted text clipped - 6 lines] > > You poor, uninformed person! That was off the top of my head, but hey, if you want to discuss it, then start listing them. NOI >> The problem is that in order to control the motor, you will have to >> lower [quoted text clipped - 5 lines] > >You poor, uninformed person! Like NOI says. Instead of calling us uninformed, why not use the knowledge in you head and give us some reasons. I see that someone brought up pulse control of the motor. That is a fine idea, but it sounds rather expensive and how do the electronics in such a unit fare with changing ambient conditions? What else can you bring to the table? ...Ron -- 68' RS Camaro 88' Formula Bird http://www.frontiernet.net/~rscamero Some are wise and some are otherwise > Toby Ponsenby spilled my beer when they jumped on the table and proclaimed > in <14hqq9x8s14s1.1lsky3onvaxu4$.dlg@40tude.net> [quoted text clipped - 4 lines] > >> the top end all the while keeping the correct load on the electric > >> motor that it was designed for. no , run an ac motor and an scr , simple , sensor varies current and voltage as required , although a belt is much simpler and I expect a lot cheaper. > >> ...Ron > > [quoted text clipped - 19 lines] > > NOI atec77 spilled my beer when they jumped on the table and proclaimed in <402E5E2C.D7EC2D29@hotmail.com> > no , run an ac motor and an scr , simple , sensor varies current and > voltage as required , although a belt is much simpler and I expect a lot > cheaper. But you still can run into the electric motor stalling. NOI We have a bit more technology available today. Use pulse width modulation(full voltage) instead of a dropping resistor. Great torque and low speed control. > Toby Ponsenby spilled my beer when they jumped on the table and proclaimed > in <14hqq9x8s14s1.1lsky3onvaxu4$.dlg@40tude.net> [quoted text clipped - 28 lines] > > NOI > The problem is that in order to control the motor, you will have to lower >the voltage. In doing this, the electric motor then can not push as hard, [quoted text clipped - 3 lines] > > NOI Davies Craig make one in a kit! Oz1...of the 3 twins. I welcome you to crackerbox palace,We've been expecting you. [followups set] >Toby Ponsenby spilled my beer when they jumped on the table and proclaimed >in <14hqq9x8s14s1.1lsky3onvaxu4$.dlg@40tude.net> >>> The problem with an electric water pump is it runs at a constant >>> speed and is no good for the street unless you devise some kind >>> of bypass that will keep the flow to a minimum at idle yet allow >>> full flow at the top end all the while keeping the correct load >>> on the electric motor that it was designed for. >> Easy peasy these days. >> There are little pulsed signals everywhere. >> So the pump output could be varied by all or some of those signals. >> Some for road speed, some for engine speed, some for fuel flow. >The problem is that in order to control the motor, you will have to >lower the voltage. In doing this, the electric motor then can not The voltage isn't lowered. The motor is driven by pulse width modulation (PWM) which means that the full voltage is available for a fraction of the time. The modulation frequency is typically in the 10's of kilohertz. >push as hard, and runs the risk of stalling. The bypass idea Ron >said is, IMO, the best way to go in such a situation, but I haven't >figured out a rudimentary way to control it yet. :) (I don't trust >computers. Shush Glk :) ) What are you doing here then? :-) It doesn't have to be a _computer_. And it certainly wouldn't be Windows anyway. Signature/"\ Bernd Felsche - Innovative Reckoning, Perth, Western Australia \ / ASCII ribbon campaign | I'm a .signature virus! X against HTML mail | Copy me into your ~/.signature / \ and postings | to help me spread! Bernd Felsche spilled my beer when they jumped on the table and proclaimed in <f1v2g1xco4.ln2@innovative.iinet.net.au> First off, thanks for the thoughtful reply. > The voltage isn't lowered. The motor is driven by pulse width > modulation (PWM) which means that the full voltage is available for > a fraction of the time. The modulation frequency is typically in the > 10's of kilohertz. Good idea. Unfortunately, I have been out of the Electronics field too long to have thought of that. :) >>push as hard, and runs the risk of stalling. The bypass idea Ron >>said is, IMO, the best way to go in such a situation, but I haven't >>figured out a rudimentary way to control it yet. :) (I don't trust >>computers. Shush Glk :) ) > > What are you doing here then? :-) Not all cars have computers. :) Seriously, that was a tongue-in-cheek comment poking fun at my present career. > It doesn't have to be a _computer_. And it certainly wouldn't be > Windows anyway. True. For instance a lot of cars today don't have to be reprogrammed everyday... NOI On or about Sat, 14 Feb 2004 11:31:52 -0500, Thund3rstruck_N0i <Thund3rstruck_N0i@hotmail.comREMOVE> wrote or did cause to be written: >Toby Ponsenby spilled my beer when they jumped on the table and proclaimed >in <14hqq9x8s14s1.1lsky3onvaxu4$.dlg@40tude.net> [quoted text clipped - 19 lines] > > NOI Excuse me but isn't it called a thermostat? I seem to recall that most cars have had those for a few years now? The thermostat closes blocking the flow when the temperature goes down (the only reason you need to restrict flow) and opens when the temperature gets hot. There is no need to maintain a constant load on the motor. The only potential problem is windage in the pump causing the water to boil if all flow is stopped but that isn't a problem because, if you recall, we have a thermostat near the pump outlet that allows flow when the water gets warm. If you insist on controlling the motor then you use discharge pressure. Maintain a constant pressure at the pump outlet by decreasing voltage. If the motor starts to stall the pressure falls and the voltage goes back up. Same thing happens if the thermostat opens and the flow increases. Now if you want a real problem, that electric motor is rather large and draws a hefty current. Where is that coming from? Now you need a BIG alternator. With a BIG belt or, better yet, gear drive. Because of losses converting mechanical motion to electricity and electricity back to mechanical motion, the electric pump is going to take more power from the engine than the simple mechanical pumps we have now. Now you need an automatic full throttle cut out just like we already have on the A/C compressors. But do you just cut off the pump risking overheating or do you cut off the alternator risking loss of all electrical power when the battery can't handle the load? P.S. As an engineer I've seen more nonsense in this thread than most. Weight reduction can make a significant improvement in acceleration or it may never be noticed. The improvement is in direct proportion to the percentage of weight change. I have a 36HP motorcycle that weights 350 pounds with me aboard. It's FAST!!! Much faster than my Corvette. Put a 100 pound passenger on the back and it seems like it has trouble outrunning a Geo. But add 100 pounds to a Hummer and you would never notice. A lot of people will waste good money on the latest "electro-magnetic vortex storm" gizmo that promises to add "up to 10hp" when they could get a guaranteed 10hp equivalent by a simple weight reduction that would also yield better handling. 10Hp in a 400Hp machine is the same as a 2.5% change in weight. You do the math. By the way, a gallon of gas weighs about 8 pounds. Dale 85 Silver > The problem with an electric water pump is it runs at a constant speed > and is no good for the street unless you devise some kind of bypass [quoted text clipped - 3 lines] > > ...Ron Best of all to run it with a temperature switch, so it works most when it's most needed. Cheers, Steve > I have been thinking about how reducing weight can improve >performance. Let's say you bought a performance car and looked for >all the things you can do to reduce weight, wouldn't you save about >100 pounds if you took out the empty front seat and also left the >spare tire at home? How much performance do you think you will gain >by doing that? Reducing weight will *definitely* increase your performance. One of the most important indicators of performance is weight per horsepower. For example, assume you have a 3000 lb car with 250 horsepower. This works out to 12 lbs per hp. All else being equal this car will be quicker in a straight line than a car with a higher lbs/hp number, and slower than one with a lower lbs/hp number. Obviously there are two ways to improve this ratio - either raise the hp or lower the weight. I know in my car that the spare tire and jack weigh 28 lbs, and the electrically adjustable seats weigh 52 lbs apiece. Lets say you remove the spare and the passenger seat thus saving 80 lbs. Replace the driver's seat with a nice Recaro or the like and you'll easily save another 20 lbs, getting you to an even 100 lbs of weight reduction. On the hypothetical car above this improves your lbs/hp ratio to 11.6 (2,900/250). You can now work backwards to see that you could have achieved the same lbs/hp ratio by adding 8.6 hp and leaving the weight the same (3,000/11.6 = 258.6). Thus, on this car 100 lbs of weight reduction is equivalent to a gain of 8.6 hp. Weight also has a big impact on braking and handling. All else being equal a lighter car will always handle and brake better than a heavier car. Minimizing weight is extremely important if you're thinking about racing your car, but I agree with some of the other posters who've said that its kind of pointless to gut your daily driver in search of increased performance. Jim C. >Dear all: > I have been thinking about how reducing weight can improve [quoted text clipped - 3 lines] >spare tire at home? How much performance do you think you will gain >by doing that? SEE Porsche 911 RS 2.7, BMW 3.0CSL, Corvette Z06(?), Ferrari 360 Challenge Stradale... > Also, I heard that some people cut the belt for the AC in the >winter. I was wondering if that really helps? Do the AC still spin >if you don't turn it on? What is the thinking behind that? Little: A/c compressors have electromangnetic clutches, and only draw significant power when engaged; cutting the belt will yield little power gain and might send the alternator output to zero as well. > >Dear all: > > I have been thinking about how reducing weight can improve [quoted text clipped - 14 lines] > significant power when engaged; cutting the belt will yield little > power gain and might send the alternator output to zero as well. Well, cleared up your head then, huh? (hopefully that isn't going to be "Bush for second term" anytime soon) mace One of the best way to reduce weight for straight line performance is to reduce flywheel mass. Depending on the engine torque curve....up to 5-7% extra power can be gain. the effect of flywheel mass reduction compare to body weight is about 1:10. which means every lb you reduce flywheel weigh is equal to shving 10lbs of body weight. The only draw back is, cruising at speed is more difficult, and rev drop occur alot quicker and engine needs to rev a bit higher to take off to provent stall. > Dear all: > [quoted text clipped - 10 lines] > > sincerely. Thx in advance. > One of the best way to reduce weight for straight line performance is to > reduce flywheel mass. Depending on the engine torque curve....up to 5-7% [quoted text clipped - 5 lines] > occur alot quicker and engine needs to rev a bit higher to take off to > provent stall. Aside from the driveability issues you mention and the fact that rotational mass mostly affects acceleration/deceleration and doesn't have a hell of a lot to do with power output of an engine......... Often wondered how one would go about lightening the flywheel on one of those execrable Yankee 'externally balanced' V8's. Gouge little chunks out if it here and there? Oh, hang on, I get it - go buy a special one as used in NASCAR from the corner store. >> Dear all: >> [quoted text clipped - 8 lines] >> winter. I was wondering if that really helps? Do the AC still spin >> if you don't turn it on? What is the thinking behind that? Troll thinking? Hint. Turning the Air Conditioning off with the thoughtfully provided 'switch' is what people who have a clue get up to in the more tolerable weather. >> sincerely. Thx in advance. SignatureToby quidquid latine dictum sit, altum viditur Warning: All posts to be treated with a grain of salt. By Order K.K. In aus.cars Toby Ponsenby <Toby@privacy.net> wrote: > Hint. Turning the Air Conditioning off with the thoughtfully provided > 'switch' is what people who have a clue get up to in the more tolerable > weather. Or add a cutout switch under the throttle pedal, which turns off the A/C whenever the pedal is pressed past say 7/8 throttle... First fitted standard to Corvettes AFAIK. SignatureAthol <http://cust.idl.com.au/athol> Linux Registered User # 254000 I'm a Libran Engineer. I don't argue, I discuss. > Or add a cutout switch under the throttle pedal, which turns off the > A/C whenever the pedal is pressed past say 7/8 throttle... First > fitted standard to Corvettes AFAIK. And do two auto cars here. I reckon it helps the compressors lifespan too. I recall a I rented HJ60 Cruiser once - didn't have a lot of K's under its belt, but the paint near the sill under the air conditioner switch was worn clean away. I figured out why the first time I asked it to do an overtake with the AC on:-( SignatureToby quidquid latine dictum sit, altum viditur Warning: All posts to be treated with a grain of salt. By Order K.K. > Or add a cutout switch under the throttle pedal, which turns off the > A/C whenever the pedal is pressed past say 7/8 throttle... First > fitted standard to Corvettes AFAIK. And do two auto cars here. I reckon it helps the compressors lifespan too. I recall a I rented manual HJ60 Cruiser once - didn't have a lot of K's under its belt, but the paint near the sill under the air conditioner switch was worn clean away. I figured out why the first time I asked it to do an overtake with the AC on:-( SignatureToby quidquid latine dictum sit, altum viditur Warning: All posts to be treated with a grain of salt. By Order K.K. > Or add a cutout switch under the throttle pedal, which turns off the > A/C whenever the pedal is pressed past say 7/8 throttle... First > fitted standard to Corvettes AFAIK. I need one of them that determines when I'm trying to do a hill start... I love my rotar ;) Charlie In aus.cars Thomas McMechan <zeabow@yahoo.com.au.nospamer> wrote: > One of the best way to reduce weight for straight line performance is to > reduce flywheel mass. Yes. > Depending on the engine torque curve....up to 5-7% > extra power can be gain. No. The reduction in rotational inertia can achieve acceleration equivalent to a power increase of 5 to 7%, but changing the rotational inertia does not increase power. > the effect of flywheel mass reduction compare > to body weight is about 1:10. which means every lb you reduce flywheel > weigh is equal to shving 10lbs of body weight. > The only draw back is, cruising at speed is more difficult, and rev drop > occur alot quicker and engine needs to rev a bit higher to take off to > provent stall. The fewer power strokes per engine rev, the worse this effect will be. SignatureAthol <http://cust.idl.com.au/athol> Linux Registered User # 254000 I'm a Libran Engineer. I don't argue, I discuss. >Dear all: > [quoted text clipped - 3 lines] >100 pounds if you took out the empty front seat and also left the >spare tire at home? How much performance do you think you will gain spare tire is weight from the rear, not exactly what you want to remove in a mustang unless you can remove the same amount of weight from the front. Will only increase traction problems if not. >by doing that? > [quoted text clipped - 3 lines] > >sincerely. Thx in advance. Remove NO-SPAM from email address when replying > Dear all: > > I have been thinking about how reducing weight can improve > performance. I've heard Xenical works... -- regards PeterD >Dear all: > I have been thinking about how reducing weight can improve [quoted text clipped - 3 lines] >spare tire at home? How much performance do you think you will gain >by doing that? I've just read that the Ferrari Challenge Stradale is some 3.5 seconds faster around Fiorano than the 360 Modena; but in addition to being 110kg lighter it has greatly improved aerodynamics (+50% downforce) and an additional 25hp. |
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