Correct combo? Doesn't feel fast

V8_Kind_Of_Guy · Sep 1, 2008

Hey everyone, new guy here. I have an '88 GT 302 5 speed but don't know if I am using the right engine combo. There is very little torque below 3000 rpm, but when 3000 comes around, it really takes off. I have raced against my friends '86 gt that only has an aluminum flywheel, gears and full exhaust. The problem is we seem to be dead even in a race. I bought this car with an Explorer upper and lower intake and Explorer heads (GT40P), 1.7 rockers, I believe a 2040 crane cam, CAI, MAF conversion, 24# injectors and a claimed '93 cobra computer. I have done a lot of other mods like smog pump and a/c delete, electric fan, aluminum flywheel and driveshaft, and 3.73 gears, 75mm TB and spacer. I also have shorty headers and full 2.5" exhaust w/cats and many more mods. I thought for sure I would just waste him in a race. I am really stumped. Any Ideas?

lang williams · Sep 1, 2008

I'd try to get it on a dyno an tuned. Also do a check for vacuum leaks.

fivespeedsteed · Sep 1, 2008

dyno tuner should be of help. my friend had a 89 with stuff and it was the other way around, fast to 3k then slow, he said his injectors were wacked out, and it fixed it. try getting a tune.

LiquidGT · Sep 1, 2008

Does the claimed Cobra computer have the Cobra MAF unit? The '93 Cobra's cpu was calibrated for the injectors (24#) and not the actual MAF housing computer like on 89-93 Mustangs. A Cobra cpu and Mustang mass air doesnt mix.

2000xp8 · Sep 1, 2008

Post the computer part number.
If it is a cobra computer, lose it, the cobra computer and meter do more harm than good.
The sale of those parts should fund a PMAS meter and stock 5 speed computer.

Also, you may be expecting too much, that's probably only about a 245rwhp or so setup, should be enough to show up on a timeslip, but it doesn't give a ton of SOTP feel.

Not sure of the specs on the 2040, but i'd also assume that a cam coupled with 1.7 rockers, are too much for stock valve springs.

TomCat · Sep 1, 2008

Hmm... my gt40p setup feels pretty nice compared to a nearly stock GT. When you say you bought it with those mods, did you actually verify that the parts are there?
I've seen people claiming cobra motors and inspection shows E7s and orange-top injectors =\ Just wondering.
Hope you find what the issue is!

Jack's95gt · Sep 1, 2008

The Comp Cams 2040 is the same as a E cam. With 1.7 rockers your going to see .528 lift and the GT40p heads had valve springs rated for .480, that spells out valve float and lost of power. If you have the the stock valve springs then look into upgrading them.

V8_Kind_Of_Guy · Sep 1, 2008

I know the upper intake should be the Explorer as the runners are offset from one another. I have to look to check the computer part number. The heads are stamped with "GTP" and the injectors are blue top. I had checked for vacuum leaks earlier and vacuum is good.

Mr. Rustypwnz · Sep 1, 2008

I say go back to the 19's with a stock computer, and a maf off of a 94-95 gt, if its not tuned the 24's could be holding you back, Ive ran 3 different combos with these heads all with the exploder intake and either a b or e cam, and all of them we had 19's in it with no tuning and they hauled pretty well enough to waste a stocker...

V8_Kind_Of_Guy · Sep 1, 2008

I just checked the computer out, it's got "A9L" in large black letters and looks brand new. The MAF says "Granatelli" on it too, just not sure of the size of it.

Mr. Rustypwnz · Sep 1, 2008

the a9l is not the "cobra" computer its just a stock computer, make sure the maf is calibrated for 24's if not get one and it should pick up alot of pep..

whats the vin on the maf ill run it for you...

V8_Kind_Of_Guy · Sep 1, 2008

On the MAF, the Model, Serial, and Calib are all blank. There is something scratched in on the side really small reading "00A2275". Measuring the MAF with a tape measurer, it measures abut 3 3/8" in and 3" out. Looking online at a conversion calc, it showed 85.725mm in and 76.2mm out.

Mr. Rustypwnz · Sep 1, 2008

im finding nothing man, sorry bud..

V8_Kind_Of_Guy · Sep 1, 2008

Thanks for looking. Any ideas on how to check to see if its calibrated?

LiquidGT · Sep 1, 2008

I would try to call or e-mail Granatelli to see what the maf is calibrated for.

I have nearly the same combo and its way quicker than stock, mine doesnt pick up to about 3k rpm also, but I blame that on the 273 rear end. First gear is nearly useless and second can and I can get sideways in second still.

stykthyn · Sep 2, 2008

I would also look into changing the aluminum flywheel back to a stock steel one. tha luminum wheel is going to suck all the low end grunt out of your car. go with an SFI steel one.

2000xp8 · Sep 2, 2008

The granitelli meter is more than likely an old pro m bullet.
And if it was miscalibrated, there would likely be more problems than a lack of power feel.

I'll agree with styklyn, an aluminum flywheel is not the best for a fairly low hp setup.
The car needs the weight to get it moving.
Removing it may make the car easier to drive too.

wtpLXfox · Sep 2, 2008

I just installed the TFS top end kit with longtubes, 24# injectors, etc. and you will lose a lot of your low end grunt from the new heads and intakes. However, you gain more top end so it's a trade off. My car doesn't really start pulling until 3k and then hauls ass from 4k to 6k which is the highest I'll take it. My car is still un tuned so I wish I had the 19# back in there, but I figured I'll eventually get a dyno tune anyways.

LiquidGT · Sep 2, 2008

stykthyn said:
I would also look into changing the aluminum flywheel back to a stock steel one. tha luminum wheel is going to suck all the low end grunt out of your car. go with an SFI steel one.

His buddys car is the one with the aluminum flywheel.

Now I spotted that you have a 75mm tb and spacer, thats way too big for that combo. A 65mm is perfect for a mildly modded 5.0; I would go with a 65mm tb (no bigger than 70) and that should give you a little more low end.

V8_Kind_Of_Guy · Sep 2, 2008

ok, I just started looking more at my car. I found that the distributor cap is in bad shape. across the terminals where the rotor swings around and makes contact to each wire, has a lot of carbon build up or whatever it is. I ordered new cap and rotor, wires and coil from summit along with a MSD 6AL, that should be in on thursday. I will deffenetly look it to a smaller TB and spacer and think about the steel flywheel again. I do like that the car feels easier to drive and a little more responsive after I had the flywheel installed.

Correct combo? Doesn't feel fast

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I want to measure mine. It doesn't look that tall.

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I want to measure mine. It doesn't look that tall.

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