542” Tri-Power motor, cast iron exh.manifolds – 671.05 rwhp through mufflers!
 

The car is a 1967 Corvette convertible.

All of the runs were made with the factory 1967 tri-power intake manifold, factory cast iron exhaust manifolds, a custom fabricated 3” exhaust system, all accessories connected (including clutch fan), and power steering.

Here are the numbers from the DynoJet:
STD: 671.05 rwhp / 633.45 rwtq
SAE: 652.77 rwhp / 616.20 rwtq
Uncorrected: 671.87 rwhp / 634.23 rwtq

Some of my friends want to know what that equates to in flywheel horsepower. I hear a lot of people talk about 15%-20% for manual transmission cars.

If you take 15% the numbers become the following:
STD: 789.47 flywheel hp / 745.24 flywheel tq
SAE: 767.96 flywheel hp / 724.94 flywheel tq
Uncorrected: 790.43 flywheel hp / 746.15 flywheel tq

If you take 20% the numbers become the following:
STD: 838.81 flywheel hp / 791.81 flywheel tq
SAE: 815.96 flywheel hp / 770.25 flywheel tq
Uncorrected: 839.84 flywheel hp / 792.79 flywheel tq

There are some people on this forum that insist Corvettes eat up well over 20% due to the independent rear axle.

For any purists out there, I am not trying to pass the car off as an original 435 hp 427 Corvette. It is a 327 car pure and simple. I will freely admit this to anyone who asks. The more I thought about trying to make a tri-power setup produce big numbers, the more I wanted the challenge. Making this combination run with factory exhaust manifolds just added to the challenge.

My goal with this combination is to have it appear factory correct under the hood. I also happen to have a 1967 Corvette coupe with a 632" motor that looks nothing like stock under the hood. I wanted to do something different this time. I have taken a great deal of time trying to make things appear stock. Most everything for this conversion was purchased from Paragon Corvette Reproductions.

This car originally came with a 350 hp 327. I put a 383” motor in it around January of 2006. With cast iron exhaust manifolds and 2-1/2” exhaust, that motor made 416.47 rwhp / 430.4 rwtq and went 11.93 at 114.99 mph in the quarter. (BTW, the 383” motor is for sale.)

The gold color you see on the top of the exhaust manifolds are a result of the exhaust manifold paint I purchased from Paragon. I painted the entire exhaust manifold with this product. It starts out gold and then as they heat up they change to a cast iron color. Since the temperature of the exhaust manifold is lower the closer you are to the exhaust flange of the head, the longer it will take to change colors.

The motor consists of the following: Chevrolet Bowtie block, Dart *highly disguised* 335 CNC heads, Jesel valvetrain, Mike Jones solid roller cam, Isky EZX roller lifters and valve springs, BRC crank, Howards I-Beam rods, J&E pistons, Total Seal rings, Clevite 77 bearings, Dan Olson oil pan, Holley fuel pump, and a trio of *SPECIAL* Holley 2-barrel carburetors.

I have made 52 DynoJet runs to get to this point. My first run was on October 20th, 2011 and the final run was on November 20th, 2011. I have tried everything within reason including moving the cam timing 4 separate times. I am not talking about ignition timing here. Anyone who has moved the cam timing on a motor that doesn’t have a belt drive while the motor is in the car can attest to the amount of work it requires. The entire front end of the motor has to come off every time.

I'm sure I left a bunch of stuff out but this is a start. I have a friend that owns a machine shop that bored, torque plate honed, align-honed, and decked the block to my specifications. He also balanced the rotating assembly. Everything else was done by me. This includes the assembly and necessary massaging of the components in the motor. For instance, since I now have a mill and a lathe, I was able to flycut the pistons and machine my own pushrods. I also made significant modifications to the oil pan and fabricated the 3" exhaust system including making my own 'X' pipe. The exhaust system consists of (2) DynoMax bullet mufflers and (2) DynoMax Ultra Flo oval mufflers run in series.

One last thing. I will be drag racing this car this spring. (Sorry for the long-winded post.)

Steve
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awesome! Very nice. I like the sleeper look

All I can say is AWESOME, can you post some pic's of the exhaust system and maybe the rest of the car?

Very impressive! Big power from a stock looking motor. Well done. :thumbs:

Thats all? :rofl: Cant hide money!!

As always, you do fascinating builds and get numbers I never thought possible. :cool:

So did you modify the exhaust manifolds? Extrude hone? How about the intake?

Looks like there is a 'bog' at about 3200 rpm. Is that something that may be a "tri-power setup" issue? (transition from center carb to all three?)

P.S. This isn't a 'criticism'...just an observation. Your car and the whole engine setup is terrific!!

Steve, you are so talented, lucky, blessed. Happy Thanks Giving:D

I have 20 pounder going in the smoker later on. It might sprinkle snow later through tomorrow.

I've always wondered where you road test these fantastic machines of yours

WOW.....

Thats all I can say....



Congrats Steve.... Awesome build as usual man..... That engine makes INSANE power and through stock manifolds at that...:crazy:

Love the stock valve covers and plug wires. I was expecting a tri-power on top of a race motor, this is better

Thanks guys!

Steve

It's what they call a "budget build".

Steve

I will post some pics of the exhaust shortly. Thanks!

Steve

Thanks for the kudos, Markus.

I modified the exhaust manifolds and intake manifold the old-fashioned way - hand porting.

Steve

thats a BEAST!!!!!!. yea i'm jelous:thumbs:

WOW...NICE!!!! We want more pics....

You need to stamp "MATCHING NUMBERS" on the block pad to finish it off!!!

And for those newbies that haven't seen Steve's "other" car- check these out-


Richard

http://i51.photobucket.com/albums/f3...4/DSCN2048.jpg

http://i51.photobucket.com/albums/f3...4/DSCN2042.jpg

http://i51.photobucket.com/albums/f3...4/DSCN1980.jpg

http://i51.photobucket.com/albums/f3...4/DSCN1971.jpg

http://i51.photobucket.com/albums/f3...4/DSCN2036.jpg

No criticism taken. I have worked extensively on this problem. When I first started, the A/F ratio was off the chart lean - over 18:1. After much work I have gotten it down to hair over 15:1. In fact, when I first started you could feel an enormous hesitation. Now, it is imperceptible.

Thanks for the comments.

Steve

WOW Steve....that's incredible! I knew it was going to be a good one...but that is just insane!

BTW- got your message. Yep..was traveling to Denver to visit. Just got here and had to ck on this post!

This will be fanatastic to read about as all the details sneak out!

Fantastic job as usual!

JIM

George, thank you very much. Happy Thanksgiving to you as well.

My wife is also preparing a 20 pounder but not smoked. To say that I am cooking challenged is an understatement! I'm jealous!

Road testing these cars is always a challenge.

Thanks again.

Steve

Alan, the thing I like about your car so much is that it just flat gets with the program. No BS or hype - just great ET's. I realize that your car is an automatic but I've purchased the same M/T tires that you use in order to try to maximize the car's traction.

If I can only match your ET's I will be ecstatic!! Thanks.

Steve