SS125

iTrader: (1)

Now that winter is here and I have to pull the engine anyways, I need some advice as to where to head with this thing. Here is what I have now:

434 CI LS1 with MID sleeves. I've had a problem with these sleeves and and pulling the engine to send the block to Darton to have them look at the sleeves and see if the sleeves and block are salvageable.

C5R Heads

Comp cam 773 lift 340 duration at .020

Mast Motorsports manifold with holley dominator 1150 car

MSD Distributor, front mounted

MSD 7AL Ignition

Callies 4" Crank

CP 4.155" -5cc dish pistons

GRP Aluminum Rods

MDS Crank Trigger

This motor has 15:1 compression so it runs on C16 race fuel. I've decided to make this engine a little more streetable and reduce the compression to run some sort of pump gas. Horsepower was quoted to me to be 800 or better. My goal is to reduce the compression to be able to run a high octane pump gas and still try to get a streetable 600-650 hp motor that will run low 10's high 9's. Does anybody think this is possible? I know it depends on the car and I've completely redone a 2001 SS Camaro to reduce the weight, new rear end with right now 4:10 gears in a DTS 12 bolt rear end. I have a set of Patriot LS6 heads with the 59 cc chambers. What I was thinking was if the block is salvageable, to use the pistons in there now, change to an H-beam rod, I would have to talk with Comp about the cam, use the same crank, same manifold with probably a different carb, have the patriot heads worked on and use these heads.

Anybody have any comments about this setup or any other suggestions? I would greatly appreciate any input anybody could give me. This car and engine will see limited street time and mostly track time, but I still want to drive it on occasion on the street. Right now the way it is at the compression that it has and the price of C16 fuel, its not streetable. Plus with the problems I've had with the sleeves, I now can redo the entire engine and put it how I want it. Any comments or suggestions will be greatly appreciated.

wildcamaro

iTrader: (15)

Why wouldn't you run those c5r heads? Those are Mack daddy of GMs stock gen 3 heads!

bww3588

iTrader: (49)

They have small chambers, driving the compression thru the roof. This being a carb/distributer engine, your going to need to get the compression down to about 11:1 to run good on pump gas. I'd look into a totally different top end to suit your needs. An ls7 top end would work well.

bww3588

iTrader: (49)

Your going to need a Much larger chamber than 59cc's to get compression down.

mark21742

Before buying parts or swapping heads I'd look at cam options to get your compression under control and see when that would put you. I'm running a 408 with 12.5:1 compression, but my 255/271 cam drops the dcr down to a street friendly 8.22:1 and the motor pulls hard as hell from 4,000 to my 8,000 rpm fuel cutoff.

SS125

iTrader: (1)

I know that cam won't work and the springs are huge so I'm not too sure how the springs would even work with a smaller cam. He's right about the chambers on those heads, that is the majority of the problem, 35cc chambers. Would I be able to get down to say, 12.5:1 by going to a shorter deeper dished piston and still be able to maintain that horsepower level that I'm looking for? The piston in it currently is -5cc.

bww3588

iTrader: (49)

The problem with a dished piston is, you lose your quench area, making it even harder to run pump has on a given compression. Quench is what you need to look at. The closer to optimum quench you get, the better and more projected the flame front will be, resisting detonation.

SS125

iTrader: (1)

How do you look at quench? I mean is there quench number as a factor, like the higher the better or lower the better. How do I determine what to use to result in an optimum quench?

mark21742

I've always shot for as close to .035" quench....parts expand, move and stretch so you need some space to keep things safe and not have the piston crash into the head

mark21742

On street I would definately not go any less than .030"

bww3588

iTrader: (49)

Agreed.

Quench is the distance between the top of the piston and the quench pad of the head. Things like deck clearance, and gasket thickness determines this.