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Car Forum / Saab Cars / November 2006Cold Air Intake
Does anyone know of a good cold air intake that I can purchase and install easliy with out too much modification and that will actually improve the speed of my already "fast"stock 1995 900se turbo five speed coupe saab? (non convertible) Also, with out upgrading my exhaust, (which is after market, yet stock) am I wasting my money! I am tired of hearing my friend (who drives a cobra) says it will improve my horse power and increase my speed! > Does anyone know of a good cold air intake that I can purchase and > install easliy with out too much modification and that will actually [quoted text clipped - 4 lines] > am I wasting my money! I am tired of hearing my friend (who drives a > cobra) says it will improve my horse power and increase my speed! Cold Air Intakes are a waste of time and money. Your cobra driving friend is a goof. You will not increase the engine power because the engine is not limited by the intake flow. If you want more power there is only one thing that you need to do: increase the boost.  Signature-Fred W > Does anyone know of a good cold air intake that I can purchase and > install easliy with out too much modification and that will actually > improve the speed of my already "fast"stock 1995 900se turbo five speed > coupe saab? (non convertible) With a turbo car, any cold air is going to get very warm once it has gone through the charger. To that end, a better intercooler is always going to be a good purchase, but IIRC the NG900 has a pretty good intercooler anyway. You could always look at putting a more open air filter into your intake and perhaps ensure that air is ducted up towards it. > Also, with out upgrading my exhaust, (which is after market, yet stock) > am I wasting my money! I am tired of hearing my friend (who drives a > cobra) says it will improve my horse power and increase my speed! Doubtful! I'm not sure what the stock size is for the NG900, but the C900 is 2.25". 2.5" is good for around 300 BHP and 3" is for serious power nuts ... Or people who want a noisy exhaust :) I think yours will be about 2.5". If you do want to gain a little power in the exhaust, spend your money on a free-flow catalyser, or "Sports cat". Maybe 5 BHP? I'm sure they'll quote 10 BHP, but I wouldn't be too swayed by that. Increasing the boost is the way to more power. Reckon on 5 BHP per 1 PSI of boost increase. You can get good software maps from Maptun for your ECU. They're costly, but people do rate them. Paul 1989 900 Turbo S http://saab.go.dyndns.org/ > .... that will actually improve the speed If you want more speed you need more power. For more power you need to burn more fuel: - increase displacement - increase boost - increase RPM Anything else will only be marginal... SignatureMH '72 97 '77 96 '78 95 '79 96 '91 900i '95 900SE >If you want more speed you need more power. For more power you need to burn more >fuel: [quoted text clipped - 3 lines] > >Anything else will only be marginal... I disagree somewhat. You left off "increase flow and effective charge" First, the charge: the difference in boost as the outside temps change from season to season by 30 degrees or so is fairly substantial and measurable by the butt dyno. This crude testing demonstrates that due to the exponential effect of the forced induction that a cold charge makes a big difference vs a warm charge. So, a CAI will help with HP. But, I did say "disagree somewhat". You likely won't notice a CAI upgrade alone when driving. If you want to add some response to this motor, do a CAI, add a sport exhaust, remove the turbo silencer, port the cast intake pipes and port/match the castings at the throttle body, and add an MBC or ECU update. To the OP - most of us have done our own CAI on these cars. Most of the other mods are IY or advanced DIY. I can supply more details if you care. > I disagree somewhat. You left off "increase flow and effective charge" > [quoted text clipped - 3 lines] > to the exponential effect of the forced induction that a cold charge > makes a big difference vs a warm charge. So, a CAI will help with HP. I fail to see how the boost would vary with temperature, considering that the ECU can run the charge up as high as it can until it begins to detonate. That would be the "hard limit" on boost. When you have that musch intake pressure going on, it isn't going to make a diddly bit of difference how free flowing the intake is UNTIL you reach massive flow rates, at which point you could lose pressure due to the restriction. I don't have any specs or scientific evidence, but considering how small the engine displacemnet is, and how low rps these things spin, I still say any cold air intake, or other fiddling with the intake to "improve flow" would not net any tangible difference. Y boost MV Signature-Fred W >I fail to see how the boost would vary with temperature, considering >that the ECU can run the charge up as high as it can until it begins to >detonate. That would be the "hard limit" on boost. When you have that >musch intake pressure going on, it isn't going to make a diddly bit of >difference how free flowing the intake is UNTIL you reach massive flow >rates, at which point you could lose pressure due to the restriction. I have to say, I disagree a bit here too. Like you say, the boost *pressure* won't change, but if the air is cooler, then the mass will be greater for the same pressure. I agree though, that any increase in peak power due to just fitting a CAI will be pretty marginal. >I don't have any specs or scientific evidence, but considering how small >the engine displacemnet is, and how low rps these things spin, I still >say any cold air intake, or other fiddling with the intake to "improve >flow" would not net any tangible difference. If you can do something to the intake that genuinely increases flow, then it's still worthwhile, even though the boost pressure is limited. It might not increase peak power, but IME, it really can help off-boost where the boost limit doesn't apply. I've got no figures, but I recently changed my air filter for a new standard one. The old one had done 60K miles. My bum tells me that the 9-3 is now slightly faster off boost, has a slightly lower boost threshold and shows a bit less lag. It could all be in my mind, I suppose... Cheers, Colin. >I have to say, I disagree a bit here too. Like you say, the boost >*pressure* won't change, but if the air is cooler, then the mass will >be greater for the same pressure. Yes... exactly. I have some semi-scientific testing done. I use an MBC on my engine. Using an MBC eliminates the computer's ability to adjust boost (the very intent). However, the computer still maintains final authority and if it detects "too much" boost, it will cut the fuel, a rather radical, but effective way, to prevent overboost as set by the factory. I have the MBC set up to run well in the Summer. It boosts very nicely into the red and holds there - but never hits fuel cut. Recently temps dropped around here, by about 30 degrees average over Summer. First, I do notice a substantial increase in power, both seat of the pants as well as watching the boost gauge. In addition, I managed to hit boost cut accidentally the other day. I was not running WOT, just accelerating hard. Still, I hit it. So, how much of an effective boost increase do I get? One lb? Two? I don't know... but I know it's there, no question about it, and it's reliably detectable with the temperature change from the seasons. >I agree though, that any increase in >peak power due to just fitting a CAI will be pretty marginal. Yep, still agree. >>I have to say, I disagree a bit here too. Like you say, the boost >>*pressure* won't change, but if the air is cooler, then the mass will [quoted text clipped - 17 lines] > no question about it, and it's reliably detectable with the > temperature change from the seasons. OK, so you're saying that in the cooler weather, your manual boost control allows higher boost pressure which results in more power? Well, wasn't that my whole point all along? Yes, in a normally aspirated engine colder (denser) air results in more power. But we aren't talking about NA engines here... I said the way to increased power is increased boost all along. I was just advocating doing it with an improved software map in the APC (Automatic Performance Control) instead of a MBC and colder temps. The bigger advantage to sticking with an APC being that the APC can back down the performance marginally if / when you have to run lower octane fuel or as weather conditions & altitude vary. It does that by monitoring the ignition performance through the direct ignition cassette. In that way, with the right software, you can run the boost right up to the point of preignition. With a MBC you need to leave some margin so you don't get detonation, or risk blowing the engine. But I'm not saying the stock APC program will do all of that. Just that the potential is there with remapped software. Signature-Fred W Install water injection >Install water injection Don't need it unless you increase boost and fuel substantially. |
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