ok so it seems like my car is slower than it should be i think it might be the exhaust and header. i have the obx 4-2-1 header and megan racing cat back its 2.5 inch tubing i think. and i think that im not haveing enought backpressure. um if i got a p&p head would it make the exhaust not so bad? or should i sell mine and get something else? thanks
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crap i thought i was in the performance zone. wtf. well if a moderator stumbles across this id apreciate the move. i wouldnt want to repost.
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well bernoulli says that a large diameter pipe will increase flow but decrease velocity. you have a 2.5" pipe, this means that at low RPM's the exhaust is flowing slower--giving you backpressure.
backpressure robs the engine's power, the reason that small diameter pipe increases low end (low RPM) power is because the exhaust has high velocity, it is leaving the pipe faster- giving you a more efficient engine at low RPM's. however at higher RPM's there isn't enough pipe diameter for the exhuast to flow freely so you have backpressure.
with a bigger diameter exhaust you simply changed it's powerband. i'll bet that you have more power after say 4,000 RPM's.
if you want a broader powerband, go with a higher lift/duration cam and/or rocker arms, ported head, exct. all the things that help the engine breathe.
i have 1.6 roller tip rockers, so i should get a dif cam and a ported head?
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slowgreenfire wrote:ok so it seems like my car is slower than it should be
Butt-dyno or track numbers? The only time my car ever feels fast is for a day or two after a new mod.
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Quote:
Originally posted by MSD
I have an 03 5-speed Cavy, and when I race.. I shift at 6300-6500. That method (coupled with the fact that the guy probably couldn't drive for @!#$) allowed me to keep up with/have a slight lead on an 04 Mustang GT.
yeah , i got my exhaust and i didnt feel faster, and i got my header and i felt about the same too, didnt notice any real diferrence cept the loudness.
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i may get a p&p had an intake manifold, ill need all new gaskets i assume. anything else?
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Do your own p/p. It's alot cheaper. I did mine on my first time. Not too hard to do. Just patience! My exhaust ports are like mirrors most of the way through and my valve/combustion area, you can actually see yourself in them. I used felt pads and metal polish when I was done doing some cutting. NICE!
little known thing. is when you Open your car up that much.. pulling all the air & Pushing it out so freely.. it doesnt have enough fuel for all the air it's pulling in & pushing out... so thus loss of HP. MY friend w/ his Del Sol had the same prob. I'd look into upgrading yoru fuel delivery system. Injectors, fuel pump, fuel rail.. all that good stuff. It's about prolly a lil cheaper than P&P a head... but it's something worth looking into at least.
btw.. i didnt even know this. But Magnaflow actuall has a chart online for the diameter of your exhaust for the HP you're pushing. My Z24 has about 145 WHP (estimated) stock as it sits so i'll be putting a dual 2 1/4" exhaust on my car... So i dont have the problems tha tyou are having. Then i'm adding more bolt ons for more HP as well as a 50 shot of Nitrous. here's tha tinformation on Magnaflow's website.
http://www.magnaflow.com/07techtips/faq/question10.asp
Faith is to believe what you do not see; the reward of this faith is to see what you believe.
-Saint Augustine
never thought of that.i dont think my car has a fuel rail. but i could be wrong. where is a place that sells higher flowing injectors for the 97 2.2? would a higher flowing pump be all i need? would the fuel pressure riser from A+ do the trick? thanks
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you cant get new injectors for your 97 2.2 the only company that makes them are crappy they leak.... have fun...
would the fuel pressure riser from a+ need a higher flowing pump to work with it, or would it be fine by itself. also would it defeat the purpose of a higher flowing pump? and yeah i prolly should get my injectors cleaned.
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An adjustable pressure regulator on the stock pump will raise the pressure. Not sure how far it will go. More fuel on your stock setup will only give you gas leaking past the rings into your oil. I know because it happened to me. (But I have a high flow fuel pump). I drained the oil and it really smelled like gas. I threw the filter into our wood stove and it ingulfed into flames as soon as it went in there. I don't have any leak-down in cylinder pressure, just lots of soot on the outer part of the plugs and lots of soot around my side skirt where the exhaust pipe comes out. Just something to think about. Waiting on the Wideband commander to arrive so I can adjust evrything with my s-afc2.
uhmm.. for a 2.2 go to cavalierconnection.com and maybe shoot them an email to help you out. They do alot w/ the 2200 motors.. and i mean ALOT! I believe Venom made injectors for a 2.2, but i'm not sure i dont remember anymore. LOL Chemothearaphy cooked my brain in '01 haha, As for fuel rails.. Rksport makes them for a 2.4, mayeb a 2.2 i dont think so. You might be able to adapt one for your 2.2, but that's only if you go w/ larger injectors. Venom as well makes a fuel rail too. So it's worth check out.. What i do for all Cavy parts.. I go to yahoo.com or google.com and type in "1997 Chevrolet Cavalier Fuel injectors" or "Fuel rail" stuff like that.. that's actually how i find alot of my stuff. Good source the internet is.
Faith is to believe what you do not see; the reward of this faith is to see what you believe.
-Saint Augustine
so jfk, your saying i dont need more fuel with my current set up? or what? and i saw some venom injectors, are they any good? thanks
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You don't really need more fuel right now. You can still go with bigger injectors but use the s-afc to turn them down until you get boosted. But you'll need a wideband to check it properly. The more vacuum you're pushing, the more the fuel regulator will increase fuel pressure to a certain extent. There's give and take on certain bolt-ons. To actually get somewhere you need to do all the motor work with the bolt-ons. Just a p/p will increase your air flow and increase vacuum and raise your fuel pressure just a little. The more you make the engine breath, the more fuel you will automatically dump in. It's hard to try and explain it all, you just need to do some more homework before you decide what you really want next. Like mine is now ready for boost, just waiting on a turbo kit. Everything is done to the motor.
Something to think about!!!
The fuel rail on the '97 and older 2.2s is cast into the intake runner assembly(lower intake), they can't be changed. The injectors are side feed and do not interchange with the other motors. The Venom injectors, if you can get them, had a bad reputation for leaking and locking up. You can get a FPR(both Accel and areomotive have one that will work from the 92-96 Corvette LT1) and raise the pressure. Be careful how far you go, only a few extra psi, or they freeze up. Anyways the stock injectors will work with all but the most extreme N/A appplications.
As far as the 2 1/2" exhaust, thats too big for the 2.2. Youre losing the velocity that builds the low eng torque. 2 1/4" is about right,even with a cam and P&P head, for a daily driver that may see track time, or just driven hard.
Ive done most everything listed by everyone that posted above and the last thing I've got to do is regear my auto transaxle(3sp,3T40/TH125C). Crane Cams reground my cam and they recomend a cruse RPM @ 60mph of 2400 to 3200RPM. My effective gearing is a 2.84:1ratio(2290RPM @ 60), going to change it to a 3.18:1(2568RPM @ 60) by changing the drive chain gears. Event changed his to a 3.06:1 and said his pulls really hard, but I dont know where his power band falls, mine falls right where Crane's Dave Maxwell said it would. You can change the gears in your 5 spd, but you would have to research that you self, it took alot of work to find mine.
What I'm saying here(before all my ramblings) is, that the whole car is a system in which all the parts must work together and at the same RPM band. GM designed them to work at one range and any performance mods will change that. Most bolt ons will keep you within that range as long as you don't go to extremes.
ok thanks a ton for your answers guys. they are quite helpful. but now i have a few more questions. since ill be getting the head, im thinking about waiting to install it and build it up with some ss valves and harder springsfirst, then i could use the s-afc and make my rev limiter a little higher.would that work, and in that case, would i be safe if i raised it slighty to say 62/6300 and used stock pistons etc. and would i need more fuel then? thanks again.
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The s-afc WILL NOT do anything for the rev limiter. It only controls the signal from the pressure sensor. You can hook it up to see the rpm's on the screen but not control it. The only thing it will control is the injectors through the pressure sensor signal. It's not a stand-alone, it's a piggy-back system. I would recomend going with another head and get it all ready to go. You'll just be one step ahead. Then you could do the work to the other head and use it as a spare on down the road or sell it for a little profit. Just doing the p/p will increase your flow a little. Not enough to upgrade your fuel system yet. Your stock set-up will handle it just fine.
ok thanks.
in the performance faq there was a post i read about the apexi afc that it changed the redline. maybe it made it lower? on the second page is the post about it and it quote
"I have mine set at:
Pr: 1.0kg/cm2 (1 bar MAP)
Ne: 8000rpm (My new redline is 7400 - )
Cr: +/- 30% "
yeah, idk about that though, or if it would work for the 2.2.
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