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Going Back on the Dyno for More HP!


Well-known member
Feb 15, 2003
In my workshop bar in Denver
64 Black Roadster; 85 Coupe; 09 G8 GT 4-door Vette
HELP! I’m a dyno addict!! We need more horsepower!!!
You remember my earlier thread regarding the dyno results of a mild 383 roller engine that I build for a friend and Vette enthusiast: We got 407 horsepower and 444 ft/lbs of torque:


Here’s the engine in the original configuration. Note the stock-type Edelbrock “EPS” manifold which seemed to limit our performance:


407 hp is not enough. We're going for 420.

I just finished installing a Performer RPM Airgap on the 383, and just got a fantastic set of Stainless Steel 1-7/8" headers for a smokin' deal by promising the builder that we'd give him dyno data (these headers look AWESOME - see photos - check out the flanges on those headers...!). I’ll give him a plug here once I have results:



I also had Henry out at Ole’s Carbs send me some Wilson Tapered Spacers (these things look SOOOOO cool), and he gave me an HP750 Holley to run against the BG750 currently on the engine.

So here's the plan:

First, I'm putting my old 1-5/8" headers back on the engine and running it with the new Airgap RPM manifold and the BG750 - this will give me good comparison data to the first run using the EPS manifold and the small headers, with only a manifold change.

Then, I'm swapping over to the sweet stainless 1-7/8 headers. This should be interesting...

Once dialed in, I'm sliding in a Wilson 1-1/2" Tapered Spacer on top of the Airgap and re-setting mixtures for best performance - I don't care if this fits under the poor guy’s hood - he can cut it. I can show him how.

Then, the Holley HP goes on and gets optimized for A/F ratio. We'll see if the Holley can kick butt...

For the final blow-out shot (using whichever carb is the best), I’m retarding the cam 4 degrees to get the max top-end power and running this thing until the HP curve drops off the back side at over 6,000 rpm (or until the valves float or rods break - whichever comes first).

This stuff makes my nipples hard.

Stay tuned for results and back-to-back comparison data that you always wish you could afford to get.

You might end up with more HP than anticipated if the intake truly restricted flow as much as suspected. Not that there's anything wrong with that.


:eek:hnoes I think I have a new hero..............anticipating the header info as well:cool
I think you have it wrong-- you're not a dyno addict, you're a HORSEPOWER addict.....;LOL
Try installing an LT-5 instead. You START at 375hp and go up from there very easily.:chuckle:_rock
Yeah, with starting prices for the entire conversion starting at $10,000. Right now, I have 407 hp for $3,000, and it bolts right in.
Let's poll this one! :happyanim:
My money's on the air gap and Demon.
All winnings and losses to be traded at the bar! :beer

Hey, who's bad azz black Midyear is that in the background photo there?! What a shine!!
The Airgap is on there to stay, so the betting would be on the BG versus Holley, the 1-5/8" headers versus 1-7/8, and on the various carb spacer combos. If we have time to retard the cam, we're doing that, too, so bets are fair on the cam timing as well.

The black midyear would be my '64:

The black midyear would be my '64:

I knew that, just paying compliment! Actually, black with a red stinger hood is my fav combo on a C2!

If you feel up to it, I'd like to read an update to your C2 resto thread as to your final comments on how everything turned out. How was the test drive, happy with engine output. What you would or would not do again, etc..:beer

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