Ok so i have a 2003 cavalier Ls Sport Coupe w/ a 5 speed and 80k on the odometer. I was just wondering whats a good way to gain some top end power. So far the only performance parts on the car are a AEM CAI, RK Sport 4-2-1 Header and a Custom 2.25" cat-back. Other misc parts include lowering springs, iridium plugs, minor weight reduction and a grounding kit. As of now the car feels very strong 1st and 2nd gear but once it gets going it feels like it hits a flat spot..... I was thinking of getting a high flow cat and a lightened crank pulley. Not really looking into doing internal work seeing as how i am purchasing a EVO again and would be keeping this car sort of like my daily driver. Thanks
I would get a big bore throttle body.
I would also match port it to the manifold.
You can also get the 2.4 manifold.
I would get that car tuned, your flat spot may just require tuning to bring balance to your mods.
2003 Sunfire with 2 1/4 inch turbo muffler, 2 1/4 piping, 2 1/2 inch resonator, a 2 1/4 inch catalytic converter, 2 1/2 inch down-pipe, a 4:2:1 RK Sports 'clone' header, E-bay strut brace, ground wire kit and an AEM true cold air intake NOPI edition.
Mike85220 wrote:I would get a big bore throttle body.
I would also match port it to the manifold.
You can also get the 2.4 manifold.
I would get that car tuned, your flat spot may just require tuning to bring balance to your mods.
big throttle body? no, wont give any top end and will take away from the low end at the stage he's at now. you wont notice any real gains without doing any major bits (cams, portng, internals etc...) bolt-ons wont do much for you.
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Thanks for the input guys.. I guess i will just leave it as is.
The velocity of air coming into a larger TB is supposedly slowed if all other components remain the same.
But the intake runners are where the velocity of the air is manipulated the most.
If the runners are stock, I doubt the big bore TB will affect it much.
This TB on a car with a lot of flow on the exhaust side 'should' benefit from more air coming in as on the top end it requires more. It is letting more exhaust gases leave and in turn requires a little more to come in.
The TB is just letting in more air.
The throttle plate regulates the intake, and if it is a WOT on the high end, it 'should' benefit.
The intake manifold could probably also benefit from more volume.
The runners are the point where it starts shifting the band drastically.
If it is larger ports on the runners, it shifts the power upwards.
That is what I have experienced with other cars I have modded.
I do see the internals such as the valves, cam profile and port size being key to achieving more flow.
There is of course a point where too much will not help.
But, I can't imagine the larger TB with just max bolt ons will not help and in fact rob power.
You're probably right, as I have not done a big bore TB on an Ecotec 2.2, I cannot say it as a fact.
But, I do have to ask... "why wont it help"?
I also feel that the type of port is part of what does and what doesn't work.
I have seen 62mm ported fronts and untouched back ends of the TB.
Some have small porting on the back and 60mm on the front.
Some have large porting on the back to match the front 60/60 or 60/62.
Some by a manufacturer and some by shadetree mechanics.
If the front is 62mm stepped down to a lightly ported rear, I can't imagine that it wouldn't help a max bolt on motor.
Not trying to argue, just trying to understand.
2003 Sunfire with 2 1/4 inch turbo muffler, 2 1/4 piping, 2 1/2 inch resonator, a 2 1/4 inch catalytic converter, 2 1/2 inch down-pipe, a 4:2:1 RK Sports 'clone' header, E-bay strut brace, ground wire kit and an AEM true cold air intake NOPI edition.
