Ok, here is the story. I have aftermarket pushrods and rockers on a 1998 Cavalier with a 2200. Now i have a few otehr mods, but i finally got my car dyno'd. I was making 144 ft lbs of torque @3600 rpm and 107hp @4700 rpm at the wheels. Since it was an automatic, the dyno guy gave an equation of estimated engine power of 170ish ft.lbs of torque and 135ish hp. The problem is that the hp curve tops at only 4700rpm.
At 5700rpm the hp is down to 87 hp at the wheels. Now my problem is that the fuel mixtures are good (via wideband), spark is good, and the engine runs just fine at those rpms. The hptuner tunes are good, no spark retardation, and good compression tests.
The guy had saw my rocker installation, and said it looked odd. The rockers are adjusted fine, but they have side to side movement. No very much, dont come off the valves or anything. The guiding tabs on the tips of the rockers are in good shape. You cant see the rockers move side to side while turning the engine over by hand, at an idle or 1500rpm with the valve cover off. He said "Yeah they look ok here, but waht about 5000rpm?"
Am i looking at a possiblity of this being the problem, has anyone else had any problems? Or am i looking at the mid-ranged cam that came stock with a 2200.
For info, I have bigger injectors (plans for turbo), did the quad4 tb swap, a full exhaust, the pushrods and rockers, and of course a tune. I dont have the money to put the stock rockers back on and dyno test, but i could put them back on and do a test drive. Im afraid i'll lose my good torque numbers. But liek i said i might be over reacting, and this is normal from a stock cam.
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What was the air/fuel readings? Are you on a stock cam?
FU Tuning
If you're running the stock cam profile and stock flowing head, that is actually about right. The 2200OHV is not a screamer...it's used in the S10 pick up truck and is more of a low rpm grunt than a 6500rpm HP monster. Actually, the numbers you put down are very respectable for that engine.
If you want to see power build above 4500 rpm, think about cams and increasing head flow.
Yes, the studs are ARP. If i remember correctly...you had to replace the studs.
Also, air\fuel ratios were steady at around 12.45 to 1. Yes, I am on stock camshaft.
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Isn't that a little on the rich side for an N/A motor? Espcially a relatively low compression OHV? Maybe try to shoot for 13.5:1.
Did you find that this was the best ratio for power on the dyno?
I would lean the motor out some to like 13.0-13.2, but with a stock cam you are doing pretty good. Remember toprque is what moves a car. What kind of timing advance you got? In the ECU tuning?
FU Tuning
Nowhere in my timing is it ever more than 3degrees more advance. I usually run higher octane because of it, and the richer mixture helps make sure that it doesnt detonate. Actually, i smoothed the table out.. so some spots have up to negative (.8) or something.
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A/F should definitely be mid-high 13's on that motor.
fortune cookie say: better a delay than a disaster
you didnt mention weather you changed the exhaust mani ....
these cars have a verry restrictive mani and down pipe and if that is still stock then thas prolly your prob
as far as the stock cam goes .... i have a 93 cavi with nothing more than a header and exhaust with a wai and i build power up to 6g
(yes it was on a dyno)
but p and p the head and change the exh mani and exhaust and i bet youl do fine ....
What about valve springs...stock, stiffer??
Stock valve springs, stock valves, stock lifters. I have a pacesetter header, a high flow cat, and a monza catback. Im not happy with the exhaust sound, but performance wise it does good. The cylinder head has not been ported\or polished. Its completely stock. Soon as i get the courage... i have a head i ported and polished in my closet to put on.
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