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Help with Fiero Dyno results. Pics inside. by IcantDo55
Started on: 12-06-2005 03:40 PM
Replies: 7
Last post by: IcantDo55 on 12-06-2005 05:26 PM
IcantDo55
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Report this Post12-06-2005 03:40 PM Click Here to See the Profile for IcantDo55Click Here to visit IcantDo55's HomePageSend a Private Message to IcantDo55Direct Link to This Post
Well below is the dyno runs for my 85 gt. It has a stroked 2.8 with a cam. I bought the car with 1K on the motor and don't know much else about it. I'm sure I have the cam specs home somewhere.

I have put about 2K hard miles on it including countless Auto-x's. The car always ran a little rough but not bad. It pulled hard but fell off at about 4K RPM. The previous owner told me there was a custom chip in it made by a guy in Canada just for the car. I can see from the A/F graph that thet chip is lacking FUEL, and alot of it.

I guess help meout here. Who can make a custom chip to complement the displacement motor and the problems shown in the dyno graph.

All pull were at 65* and the base timeing set at 10*

http://img.photobucket.com/albums/v88/icantdo55/fieroTQ500.jpg
http://img.photobucket.com/albums/v88/icantdo55/fieroAF500.jpg
Thanks

------------------
Mike

85GT 4-Spd 3.4 Stroker, cam, ported intake exhaust and TB. Natural weight reduction in progress(rust).
My other toy:
WWW.IcantDo55.com

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goatnipples2002
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Report this Post12-06-2005 04:11 PM Click Here to See the Profile for goatnipples2002Click Here to visit goatnipples2002's HomePageSend a Private Message to goatnipples2002Direct Link to This Post
was the motor stroked and bored because if it was only stroked then you aren't going to get more then a 3.1 for displacement.

Darth fiero can make a custom chip for you. You should really find those cam specs so you don't get a chip that hurts that.

May I suggest an adjustable fuel pressure regulator instead of a chip.

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IcantDo55
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Report this Post12-06-2005 04:37 PM Click Here to See the Profile for IcantDo55Click Here to visit IcantDo55's HomePageSend a Private Message to IcantDo55Direct Link to This Post
 
quote
Originally posted by goatnipples2002:

was the motor stroked and bored because if it was only stroked then you aren't going to get more then a 3.1 for displacement.

Darth fiero can make a custom chip for you. You should really find those cam specs so you don't get a chip that hurts that.

May I suggest an adjustable fuel pressure regulator instead of a chip.

Yes it was bored.

The fpr is a good idea but see at the end of the run where it richer. I don't know but I can only guess it would just move the entire graph down. Making the begining lean and the high rpm's fat.

Darth Fiero....good info there. Hope he chimes in.

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Alex4mula
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Report this Post12-06-2005 04:54 PM Click Here to See the Profile for Alex4mulaSend a Private Message to Alex4mulaDirect Link to This Post
Wow! That's a lot of rwHP for a bore and a cam. Please share your cam specs. The AFR does seems lean all the way to 5300. Does it pings? The correct way to address it is burning a PROM. Everything else is a band aid. The guy in Canada may be Wester's garage. He has lifetime warranty. Check if the guy who sold it to you can get e free re-burn with that dyno chart. But mail order tunning is shooting with one eye at best.

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http://pbfieros.tripod.com

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Arns85GT
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Report this Post12-06-2005 05:02 PM Click Here to See the Profile for Arns85GTSend a Private Message to Arns85GTDirect Link to This Post
Sounds to me like you need more fuel mixture all way round for a much better breathing engine.

You might want to look at a ported intake plenum too, or look at the Truelco.

Congrats on your results. You will just keep getting better as you refine it.

Arn

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Fierobsessed
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Report this Post12-06-2005 05:11 PM Click Here to See the Profile for FierobsessedSend a Private Message to FierobsessedDirect Link to This Post
WOW. that's a pretty bad lean. But on the bright side, for a 3.1 those are exceptionally good numbers from a RWHP dyno. A good running 2.8 will put out 120 at the wheels. a good running 3.4 doesn't usually quite hit 140. Even 14.7:1 AFR will hurt you on the dyno. Given that... I'd say get that chip fixed, or the fuel injectors? Fuel pressure regulator? Fuel filter? Could be a lot of things. But for sure you are making good power.

Notice that you have a second peak after 5400 or so RPMS. This is HIGHLY uncharacteristic for your engine, but then again it does coinside with your AFR's coming back down to earth.
heres my old 2.8's dyno chart, this is pretty typical of a stock 2.8, even though it had a 2030 compucam (piece of crap cam)

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fieroguru
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Report this Post12-06-2005 05:24 PM Click Here to See the Profile for fieroguruSend a Private Message to fieroguruDirect Link to This Post
It needs more fuel under 4500 RPM and an adjustable fuel pressure regulator will help.

As far as it going rich at the upper end that is most likely the restriction of air causing a mismatch in the assumed fuel need (Gotta love Speed Density). The stock intake is restrictive for a 2.8 and it just happens sooner with it bored and stroked. Focusing on getting more airflow through the engine will help a bunch, or you could get a new chip to take some fuel away at the upper end.

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IcantDo55
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Report this Post12-06-2005 05:26 PM Click Here to See the Profile for IcantDo55Click Here to visit IcantDo55's HomePageSend a Private Message to IcantDo55Direct Link to This Post
Thanks for the replys!

I don't think its bad injectors it fuel pump because its richer in the higher RPM than anywhere else on the graph. If it were a problem I can only guess it would be more proniunced the higher the RPM went.

Wester's garage, thanks. I bought the car from a guy I no longer can get in touch with so I'm alone on this one.

So these are "Good" rwhp #'s? I guess I did not know what to expect.

I know nobody that can do a tune locally so mail order is all I got. Whos recomended for this?

I'll see if I can find the cam specs tonight.

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