Tuning problems
11-19-2007, 12:38 AM
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Tuning problems
I have a 1991 camaro Z28 with a 350 TPI engine and i recently did alot of work on it and am now having alot of problems getting the car to run right. Also sometime the car's exhaust smokes a blueish smoke. I don't know a ton about cars but i know alot more than the average person. I have the engine rebuild and the Mods i did to the engine internally are it's bored .30 over, it has a slighty bigger cam, and ported heads. On the intake side i bought TPIS mini ram intake, and a 58mm holley throttle body. For the exhaust i bought shorty hooker comp headers, and a high flow magnaflow cat and muffler. Also I bought all new injects and a holley fuel pump, and i had a chip burned by TPIS to match the cam specs. I attached a copy of the dyno sheet, and just by looking at it you can clearly see there is something wrong going on. If you have any ideas what the problem might be let me know.
Thanks,
Jonathan
Thanks,
Jonathan
Last edited by visionpb16; 11-19-2007 at 02:57 PM.
11-19-2007, 03:03 PM
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Re: Tuning problems
here is the dyno sheet. I dont remember exactly how we seated the rings but the guy that rebuilt my engine gave us a sheet with directions to follow. I think we just had to run the engine dry for about 30 minutes, at a certain rpm. But also we did a compression test on all the cylinders and they were all around 150psi. Does that see about right?
11-19-2007, 03:54 PM
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Re: Tuning problems
alright, somethings definetely wrong. But I think it's in the upper RPM range, because the motor's making plenty of torque. If something was wrong in the actual internals, it wouldn't be making power anywhere. What are the specs of the cam you put in the motor? It could also be a bad prom setup, have you tried running your stock one at all?
11-19-2007, 10:56 PM
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Re: Tuning problems
During the dyno i did not have a wideband hooked up, but i did adjust the fuel pressure the see if that effected anything, but it one changed the peak horsepower by 1 or 2 horse and the graph was similar in shape. Also here is a link to the cam i put in the motor.
http://store.summitracing.com/partde...4&autoview=sku
I didn't try to run the stock computer with that cam because i wasnt sure if it would even run.
http://store.summitracing.com/partde...4&autoview=sku
I didn't try to run the stock computer with that cam because i wasnt sure if it would even run.
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11-20-2007, 12:24 PM
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Re: Tuning problems
yes, if you look at the applications tab, it says "recommended for TPI engines with modified computer" also the car has 1.6 roller rockers, which i forgot to mention earlier. I know that the originally the motor had a roller cam, do you think that could be the problem switching from a roller to flat tappet, even though i put roller rockers?
11-21-2007, 07:03 AM
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Car: 1989 Camaro Iroc-Z
Engine: 5.7L TPI
Transmission: TCI 700R-4
Axle/Gears: 3.24
Re: Tuning problems
The dyno graph shows some issues for sure. The power curve should be much smoother then it is. (FYI) You should always run with a wide band 02.
If you are running a flat tappet cam you need to use flat tappet lifters. There is a big difference in the design of a roller cam vs a flat tappet cam. The rockers have nothing to do with the cam type but you still have to check your push rod length seletion.
Other things to note (after you double check you lifters and do more research on roller cam vs flat tappet cams):
You really need to know where you fuel is at to start with. We seen dyno graphs like these that indicate extreme rich or lean conditions that cause ignition to brake up.
Your Compression seems low, but as long as you are with in 5 PSI on each cylinder, it most likely is not the cause of the lack of power and overall poor performance.
Be sure to go back and check the basics. Ensure your ignition system is in good working order. Plugs are OK and with the correct gap. Also go back and check you valve lash once now that you have run the car and did a basic brake in.
We don't usually do a WOT run on the dyno until the car has seen around 500 miles and a fresh oil change.
Once you know you ignition is OK...get back on a dyno and check low to mid power with a wide band 02.
Good luck...
If you are running a flat tappet cam you need to use flat tappet lifters. There is a big difference in the design of a roller cam vs a flat tappet cam. The rockers have nothing to do with the cam type but you still have to check your push rod length seletion.
Other things to note (after you double check you lifters and do more research on roller cam vs flat tappet cams):
You really need to know where you fuel is at to start with. We seen dyno graphs like these that indicate extreme rich or lean conditions that cause ignition to brake up.
Your Compression seems low, but as long as you are with in 5 PSI on each cylinder, it most likely is not the cause of the lack of power and overall poor performance.
Be sure to go back and check the basics. Ensure your ignition system is in good working order. Plugs are OK and with the correct gap. Also go back and check you valve lash once now that you have run the car and did a basic brake in.
We don't usually do a WOT run on the dyno until the car has seen around 500 miles and a fresh oil change.
Once you know you ignition is OK...get back on a dyno and check low to mid power with a wide band 02.
Good luck...
Last edited by cgtms; 11-21-2007 at 07:16 AM.
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