[slowbird]

Dad took his GTO to a Mustang chassis dyno yesterday to do some tuning. I dont have all the info right now but the best run was with 28 degrees of timing and it made 493.5hp @ 6250rpm and was torque 443.3 @ 5500rpm. He was told that would be close to 680hp on an engine dyno. Not to bad for a tri-power and hyd cam, in my opinion.

[Keith Seymore]

I agree; very impressive.

Is the car an auto or a stick? 680 hp estimated at the flywheel seems a bit optimistic. Even if you use a 20% loss for an automatic trans that's 493.5 at the wheels x 120% = 592.2 at the flywheel, unless I'm missing something. I have also heard of a "straight add" of 120 hp for a TH400, which would put you at roughly 613 hp.

What does the car weight? The 10.08 ET in your signature is the number that really counts (IMO), and it takes 625 hp at the wheels of my bulbous Chevelle to hit that same number. (lol)

K

[slowbird]

Car weighs 3450lbs. I do know that the chassis dyno he took it reads low. My brother took his car there and it showed it had 310hp to the wheels, he also dynoed it on an engine dyno it showed it at 495hp, his car has ran 119mph in a 3600lbs car so I am pretty sure there is more than 310hp to the wheels on his. They are just numbers and the only thing that matters is getting into the 9s. The best it has ran so far is 10.01 at 131mph. The reason he took it is because it is going back the 1/4 in a couple weeks and he really wants his 9 so he just wanted to make sure he had everything tuned up.

[gearbanger]

That is really cool man. Dyno time is the best money you can spend I think. I took mine to the chassis dyno once and I thought it was tuned to perfection. I mean it ran great, plugs always looked good, no hesitations, no smoke or rich smells. We picked up 60 hp at the wheels with timing and leaning out the holley. I was blown away. For $295 I picked up 60 hp. And it was a blast!

[Keith Seymore]

Originally Posted by slowbird

Car weighs 3450lbs. I do know that the chassis dyno he took it reads low. My brother took his car there and it showed it had 310hp to the wheels, he also dynoed it on an engine dyno it showed it at 495hp, his car has ran 119mph in a 3600lbs car so I am pretty sure there is more than 310hp to the wheels on his. They are just numbers and the only thing that matters is getting into the 9s. The best it has ran so far is 10.01 at 131mph. The reason he took it is because it is going back the 1/4 in a couple weeks and he really wants his 9 so he just wanted to make sure he had everything tuned up.

That is excellent!

I understand about getting into the 9's: My best so far is 10.001 but I just can't seem to break that barrier! (lol)

K

[guidos]

Excellent numbers, mine made 471HP and 491ftlbs on a Mustang Chassis dyno.

What is the total package, engine cubes, mods to the intake, carbs?

Tripower in the 9's that would be awesome!!!!!

Rich

[slowbird]

Its 478cid, the intake and carbs have had quite a bit of work done to them. The intake flows 306cfm when bolted to the heads. The thing that surprised me more than anything is that it liked 28 degrees of timing. He tried everything from 26 to 34 and there wasnt more than about 10hp difference between all of them but the 28 degrees was a couple hp up on the other settings.

[guidos]

What kind of heads?

[slowbird]

e-heads

[T Syron]

I am pretty sure I seen this car years ago at Cordova running in the higher 10s. Is it blue with multi color strip going down side? Very cool car, I was very impressed.

What rear gear is he running?

Tom

[guidos]

That is interesting, mine made the most power at 44 degrees, we moved it around and it was repeatable at 44 degree......wonder what the difference is. Mine are 72 cc version with dished pistons, 10.5 to 1 compression. Which are his?

[J.C.you]

a big difference in timing can be something as simple as timing marks being off from one balancer or timing tape to the next.

[slowbird]

T Syron, yep that is the car, and he has 4.11 gears

Guidos our heads start out at 72cc they have been milled to about 65cc now and the compression is about 13.5:1 now.

[Don Chapman]

Hope it gets in the 9s. Thats a real nice car. I think your Dad said he owned it since 1975?

[Cliff R]

One of our customers runs into the 9's at that weight, and his engine makes around 730hp, and the car is set up very well to use it. Low gear set TH350, 5000 stall converter, 4.56 gears (nearly as I can remember). He shifts around 6800 and goes thru at 7200rpm's. The engine isn't all that dramatic, 325cfm E-heads and a basic 455 shortblock with a forged cranks, aluminum rods and light pistons......Cliff

[slowbird]

Ya he has it since 1975. It has been part of the family longer than I have.

[tjwelter]

I Know that car---Keep up the good work,JW

[harry k]

Originally Posted by slowbird

Not to bad for a tri-power and hyd cam, in my opinion.

.[/quote]Guidos our heads start out at 72cc they have been milled to about 65cc now and the compression is about 13.5:1 now.[/quote]

just curious , why hyd cam with 13.5 compression ?or is that a typo error.

[slowbird]

No typo. Just set it and forget. All dad does is change the oil. Then about every 2 years or 3 years he goes through the engine but the valve covers never come off until it is time for a rebuild. It is about as trouble free as you can get.

[CraigG.]

Hey Slowbird, Very cool! I am excited to go see your dad get his 9 in Cordova. Is he zero decked with a flat top - type of head gasket to get 13.5 to 1? Thanks Again, CraigG.