Dyno'd my 86, what do you think?
08-29-2011, 08:36 AM
#1
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Dyno'd my 86, what do you think?
I went ahead and put my car on the dyno at Carlisle just to see what it had. I wasn't expecting anything radical, but thought for sure I would be over 200hp and 300ft/lbs. Found out I was running very rich, how do I fix this? Any comments on the numbers or what I can do to improve them are welcome. Also, if you can tell a difference in the curve on mine with an modified TPI versus a stock TPI let me know, as I don't really know what to compare it to. All I've done so far is ported edelbrock runners, ported plenum and base, open air lid with k&n filter and underdrive pulleys. It also still has the stock cast iron heads.
08-29-2011, 09:15 AM
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Due to possibly the tq converter clutch engaging at 3400 RPM your peak tq number spiked and is reading higher then it should, probably actually around 280 tq. Yes you are running way to rich that could be corrected with a custom chip, you could pick up approx 10-20 TQ and HP it you could get WOT A/F around 12.8. The dyno is using the proper SAE correction and smoothing factor so your numbers could be approx 5-10% lower then some of the dyno numbers posted that do not. Your numbers are typical for a stock 86 so if you were to lean it out you will probably be where you want to be.
08-29-2011, 09:23 AM
#3
Melting Slicks
The rich probably needs to be fixed with some sort of tune assuming injectors are in good working condition.The curve - not that I've spent a lot of time looking at dyno results, I think it's interesting that with ported intake you peaked at 4100rpm, seems low.
I did the Carlisle dyno thing back when I had stock upper end, stock bottom with a cam and aftermarket exhaust (stock manifolds) and hit 230 to the rear wheels I believe closer to 4500 rpm.
08-29-2011, 09:39 AM
#6
Melting Slicks
About normal, I think, except for the rich condition.
A freer flowing exhaust is about the best help for an otherwise mostly stock TPI.
I bet that would wake it up some. It did mine.
A freer flowing exhaust is about the best help for an otherwise mostly stock TPI.
I bet that would wake it up some. It did mine.
08-29-2011, 10:11 AM
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Is the only way to correct the richness a tune? If so does anyone have recommendations in Va, I know its getting harder and harder to find people to tune OBD1. I've also seen adjustable fuel pressure regulators, would that be an option? I plan on doing heads/cam in a few years and would prefer not to spend the money to get it tuned twice. The curve peaking so low is what I think is the weirdest, I know the intake has been opened up more than stock but I did that with the intention to increase the RPM's, not sure what went wrong there.
08-29-2011, 10:22 AM
#8
Race Director
Decrease the fuel pressure with an adjustable pressure regulator. Decrease it approx 10%. It'll help at wot.
08-29-2011, 10:47 AM
#9
Le Mans Master
Whoa! Did the 86 have less HP than the 88 (I can't remember)?
I had an 88 auto theat I put on the dyno with 100+K miles and IIRC it was 214 rwhp and 300+ tq. If the rated HP is the same you have a sick puppy. Do a compression and leak down test first. Your STOCK tune should be real close on AF ratio - remember it had to pass emissions when it was built. If its running rich you have an air leak thats causing the O2 sensors to tell the computer to send more fuel.
I had an 88 auto theat I put on the dyno with 100+K miles and IIRC it was 214 rwhp and 300+ tq. If the rated HP is the same you have a sick puppy. Do a compression and leak down test first. Your STOCK tune should be real close on AF ratio - remember it had to pass emissions when it was built. If its running rich you have an air leak thats causing the O2 sensors to tell the computer to send more fuel.
08-29-2011, 03:38 PM
#13
Burning Brakes
08-29-2011, 03:50 PM
#14
Melting Slicks
Used to have an 86 myself. Best think you can do is headers with true duals and heads. The cast iron heads are boat anchors.
Custom chip will fix rich condition.
Eddie
Custom chip will fix rich condition.
Eddie
08-29-2011, 06:39 PM
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Is the only way to correct the richness a tune? If so does anyone have recommendations in Va, I know its getting harder and harder to find people to tune OBD1. I've also seen adjustable fuel pressure regulators, would that be an option? I plan on doing heads/cam in a few years and would prefer not to spend the money to get it tuned twice. The curve peaking so low is what I think is the weirdest, I know the intake has been opened up more than stock but I did that with the intention to increase the RPM's, not sure what went wrong there.
08-29-2011, 06:53 PM
#16
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^None of that is true^ If it were true, then why doesn't it correct the overly rich condition that currently exists? According to your theory, the thing must be "self tunning". It's not.
No. You can do something as simple as lowering your fuel pressure. I know, because I've done it.
When you need to tune in the ECM or chip, is when you have localized spots in the RPM range that are out of whack. Making a "global" change such as injector size or fuel pressure may fix the issue in one of the localized spots...but hurt it elsewhere. If you'll notice, your A/F ratio went FAT, the second you mashed the gas, and stayed virtually flat, the entire time. That means there isn't a "curve" that needs localized tuning (ECM/Chip); the WHOLE THING is fat. You can fix that easily (and for FREE) by lowering your fuel pressure.
And the "reduced atomization" you'll see from lowering FP won't mean squat.
No. You can do something as simple as lowering your fuel pressure. I know, because I've done it.
When you need to tune in the ECM or chip, is when you have localized spots in the RPM range that are out of whack. Making a "global" change such as injector size or fuel pressure may fix the issue in one of the localized spots...but hurt it elsewhere. If you'll notice, your A/F ratio went FAT, the second you mashed the gas, and stayed virtually flat, the entire time. That means there isn't a "curve" that needs localized tuning (ECM/Chip); the WHOLE THING is fat. You can fix that easily (and for FREE) by lowering your fuel pressure.
And the "reduced atomization" you'll see from lowering FP won't mean squat.
Last edited by Tom400CFI; 08-29-2011 at 07:00 PM.
08-29-2011, 07:41 PM
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^None of that is true^ If it were true, then why doesn't it correct the overly rich condition that currently exists? According to your theory, the thing must be "self tunning". It's not.
No. You can do something as simple as lowering your fuel pressure. I know, because I've done it.
When you need to tune in the ECM or chip, is when you have localized spots in the RPM range that are out of whack. Making a "global" change such as injector size or fuel pressure may fix the issue in one of the localized spots...but hurt it elsewhere. If you'll notice, your A/F ratio went FAT, the second you mashed the gas, and stayed virtually flat, the entire time. That means there isn't a "curve" that needs localized tuning (ECM/Chip); the WHOLE THING is fat. You can fix that easily (and for FREE) by lowering your fuel pressure.
And the "reduced atomization" you'll see from lowering FP won't mean squat.
No. You can do something as simple as lowering your fuel pressure. I know, because I've done it.
When you need to tune in the ECM or chip, is when you have localized spots in the RPM range that are out of whack. Making a "global" change such as injector size or fuel pressure may fix the issue in one of the localized spots...but hurt it elsewhere. If you'll notice, your A/F ratio went FAT, the second you mashed the gas, and stayed virtually flat, the entire time. That means there isn't a "curve" that needs localized tuning (ECM/Chip); the WHOLE THING is fat. You can fix that easily (and for FREE) by lowering your fuel pressure.
And the "reduced atomization" you'll see from lowering FP won't mean squat.
08-29-2011, 08:05 PM
#20
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It was $80 for two pulls, I know there are better prices than that out there but it was worth the experience. To all those saying their 87's-91's have more power. I know this is true as horsepower increased each year, thus I specified I have an auto and cast iron heads, the lowest powered tpi cars. Thanks for all the replies, and continue enlightening me on what I can do to.