632C2

bams12: I would definitely pick up horsepower and torque with a set of headers but I was trying for a stock look with this motor. The last thread that I started had a picture of the engine compartment. It blows peoples minds when I pop the hood and they see the exhaust manifolds. I know when I was younger(the 70's and 80's) the first thing we did was remove the exhaust manifolds and throw them away. Headers were a given.

ML67: Mark, as always I appreciate your comments and insight. Have you given any more thoughts to moving out here so we can share this DynoJet?

jpatrick636: Thank you as well! I am always a little apprehensive before I make these posts because I am sure there are forum members out there that are real tired of listening to me blow my own horn. It is good to know that there are others that aren't. As far as getting a set of headers, I have no plans to do so. I like the novelty of running exhaust manifolds.

73jst4fun: You are welcome and I hope this helps a little.

big_G: Max horsepower occurred at 5900 rpm but was relatively flat from 5500 to 6200.

MotorHead: Thanks! A friend of mine has a set of the large case Super Turbos on his Monte Carlo that we tested when it had a late model LS6 in it. We ran the car with open headers and closed. With closed exhaust he only lost 4 rwhp as compared to the open exhaust. The mufflers were a complete surprise. He has an interesting exhaust system. He made his own 1-3/4" to 1-7/8" stepped headers with a 3-1/2" merge collector. From there he ran a 3-1/2" 'X' pipe. After the 'X' pipe he went with the 3" Super Turbos and then 3" tailpipes. His name is John Bzdel. He designed the 2-3/8" headers I fabricated for my 632" motor in my '67 coupe. In my mind, he is the exhaust Meister.

The heads are not ported. I did port match the intake ports to the intake manifold and clean up the combustion chambers and pockets. They are the Platinum version.

The cam I am running is the ZZ383.

When I bought my DynoJet, they told me to make all of my runs in a gear as close to 1:1 as possible. They said it had to do with putting the right load on the motor. On my stock 327 that came with this car, I picked up rwhp when I made runs in 3rd gear as opposed to 4th gear. John Bzdel's Monte Carlo has a T56 6 speed that we tested in 4th(1:1), 3rd, and 5th. The most power was made in 4th, it lost 14 rwhp in 5th gear, and lost 19 rwhp in 3rd gear. His rear gear ratio is 4.10:1 while at the time mine was 3.36:1.

Steve

Little Mouse

You probably don't want to hear this being a ford product, my
fathers 63 Lincoln conv. has resonators well before the muflers.
guess they wanted to make sure a luxury car was stone quiet.

632C2

That doesn't bother me at all. The thing I am most impressed with about these DynoMax Race Bullets is that they killed the noise but didn't hurt the power.

Steve

CoolKars

Steve,

Thanks for posting your results. About the Dynomax Super Turbo, was the model a 17733 2 1/2" ID inlet 2 1/2" ID outlet. I thought the pipe going inside is 2 1/2" OD on this model. Which model did you measure.


Regards,


Kevin

vettfixr

Just as a point of reference my 74, which was the last year for true dual exhaust with no cats, had stock resonators positioned right about under the seats. I still have the insulating pads mounted to the body on my car.

632C2

The part number I measured was indeed the #17733.

That is good to know. I just got back from another drive in the car and the exhaust now sounds phenomenal! No more embarassment. It's all good.

Steve

SLVRSHRK

As always, thanks for the post. Your methodical approach and detailed postings are always welcome.

neoh77

I have in fact been to John's web page and I think he has one of the BEST sounding exhaust systems I've ever heard, g-body or any body style for that matter. I see he no longer has this engine combo..the new one looks like a heck of a setup.

http://www.montecarloss.com/ls1montecarloss/July02.html

Anyhow...this is a great post! I'm not tired of it either
-Matt

632C2

You are welcome as well. Thanks!

Thanks for the comments! I was with John at Pacific Raceways when he got warned about the 11.50 ET barrier. His car flat flies!

Steve

C3 Stroker

632C2 - Thanks for the info on jetting. I think there is some headroom for improvement on my 825 Demon, and I see I'm not the only one with larger secondary jets compared to primaries.

lebvette

I'm running a similar engine, but with a Holley. The big jump in the secondaries sounds interesting. Isn't this something that Lars does also? Great job on your RWH. I wish you were a neighbor. You could teach me a few things. Larry

MotorHead

Just a note about the rear end thing, from a purely psysics point of view if the higher gear say 4.10 makes more heat than a 3.08 when doing a dyno pull then yes you will lose a few HP

This wide spread on the secondary is catching on I changed to 76 pri and 92 secondary on my 825 Race Demon a while back

632C2

It's a little unusual to have 76/93's but as someone once said, the motor wants what the motor wants. With the stock jetting that came in the 825 Mighty Demon, the A/F during the run was between 15:1 and 16:1. Terrible.

Thanks for the kind words. You could always move out here....

That is an interesting observation on the gear gear issue. I wonder if Barry Grant is aware of the jetting issues with thier carburetors. My 825 Mighty Demon actually came with 71/79 jets. Their website says it should have had 76/84.

Steve

comp

good reading

enkeivette

Wow, 344 to 401 I wish I had taken my car to a shop that actually tuned the engine when they did my dyno run!

So just by adding the x pipe, adjusting the jets and timing you picked up 55hp? Or did I miss something?

Also, the BG website fooled me too. They list the jet sizes for their downleg carbs. The annular carbs come with significantly smaller jets. Is your 825 an annular carb?

632C2

comp: Thanks!

Actually, I started with a Holley 770 Street Avenger then switched to the 750 Speed Demon and finally the 825 Mighty Demon. I also started with 1.52 roller rockers and ended up with 1.8 roller rockers.

The 825 Mighty Demon has a downleg booster.

As far as taking the car to a shop that can do some tuning I can only say that doing so is a very time consuming process.

To illustrate this point I have 82 dyno runs on this combination!! I can't imagine how much a dyno shop would charge for that.

Steve

enkeivette

Woah, who makes 1.8 rockers for a SBC? I thought that the biggest available were the 1.6 rockers. Does anyone make a 1.7?

C3 Stroker

.....Yes, 1.7s are available
see this link:http://www.powerandperformancenews.c...Category_Code=

632C2

I bought my 1.8 rockers from Crower back in the mid '90s. I would be surprised if they no longer offer them. Also, they made 1.7's as well.

BTW, I just got back from Pacific Raceways. It was a good news / bad news type of night. My best ET was 12.15 and my best mph was 114.11. I only made 3 runs before they called the race due to continued rain. It was sprinkling off and on all night and the temp was in the mid 70's. The problems with my runs were pathetic launchs, hitting the rev-limiter badly prior to every shift, and extremely slow shifting.

My driving was far worse than last time. The only way that I am going to get any better is with more practice but I am done racing this car.

Steve

ajrothm

Steve, you can't give it up.. You GOT TO get an 11.90 outta that car. Just the high humidity and crappy DA probably killed 1-2mph. What the times on your slip? Your car gives us guys that want a stock looking, 11 sec street car hope without a million dollars tied into the motor. Your car is by far my favorite vette on this board.

My buddy has a 66', 388" with Accel/TPIs fuel injection. Its a solid roller with AFR 195cc that makes 407rwhp. He has a Richmond 5 spd(3.37 1st gear) and runs a 3.08 in the rearend. So far his best is an 11.80@114 on ET Street radials with a 1.62 60'.

Your car makes around the same power and runs so close to his except he is probably 60' ing better.. He has all this high dollar BS in the motor and yours is a plain old hyd roller, carbed, stock manifolds and making the same power. Your car will run the numbers, especially when you get some good air. Atleast you have ***** enough to run an old vette, not just sit around and talk about wax, spring decals and what you used to run back in the 60's