whitebro

iTrader: (4)

I am involved in an offroad race called KingoftheHammers. Right now I have a supercharged LS1, which is great - however there are too many variables for 65-80 mph passes through 2-3ft whoop-dee-doo's, 20ft watefall climbs, and general rock racing.

I made the decision to get rid of the that combo, and will be posting it up soon. The new combo is interesting, being that I am a general fabrication guy, and not necessarily a motor guy.

Questions for the experienced - With this combo, will I have cooling issues? Can I run 91 octane safely at 4500 ft above sea level? Will it live and be reliable? Hp and Tq numbers based on experience (rough estimate - I'll post actuals later)

I've discussed with some pretty serious engine builders, and want the national input from this board.

Project -
LQ cast 6.0 block
bored .065
LS3 pistons and standard MLS gaskets
Scat 4340 forged internals (balanced of course)
L92 heads (70cc - stock valves) port matched and flashing smoothed
Crane dual springs and a Patrick G designed cam (custom)
11:1 compression
L76 intake and NW 90mm TB
ARP head bolts
1 7/8" custom stepped headers to 3" y-pipe to 3.5 moroso spiral flow dumped
Tuned - of course
Big Aluminum radiator with Mark VIII fan

So... do you think I am playing with fire here, or will I be safe? Let me have it...

Thanks in advance all

JakeFusion

iTrader: (7)

You'll need to sonic the block to see if it can accept such a large overbore. I assume you already have the LS3 pistons (which is why you want to do this). If not, it's interesting that you'd go Scat forged crank/rods and stock cast pistons.

My advice would be to run no more than 30 thou over for the LQ4/9 block (you can run the L92 heads on anything with 4"+ bore). Then run a set of 2618 alloy pistons from Wiseco setup for the LS3/L92 heads. If this is going to be raced, I'd want a tough piston in there to take any detonation that might strike.

Also, I'd be inclined to run an aluminum block so the thermal expansion between the heads and block remain fairly consistent in a race application that could see prolonged WOT. Generally, you can run more timing on an all aluminum setup as well vs the iron block, so that might be another advantage if you're looking for a little extra power combined with around 80lbs less weight.

1CAMWNDR

iTrader: (21)

I agree with what Jake said. Get the L92 block. It is aluminum and the stock bore is 4.065", also go ahead and get some top quality foirged pistons.

dug

iTrader: (10)

supercharger will work better at that altitude.

whitebro

iTrader: (4)

**** hell fire damnation... a supercharger on that thing with all the mods would be NUTS.

The torque multiplier would just be insane. 32:1 ratio on a waterfall + 600+ lb/tq would be a axlesnappin' no so fun time! ha!

I appreciate the feedback. Some LQ4/9 blocks have been taken .125 over, and are fine. I am sure that there are limits, but I'll have this thing tuned good at the local "dyno shop". I have closed loop on the MSD that'll keep things inline for the most part, and it'll run a bit fatter than others due to the altitude and detonation issues.

The pistons are Mahle forged 4.065 "LS3 type". The walls of the block are good, however will be sonic'd at "total performance". A friend has a lQ9/4 block with .060 over and twin turbo's I should be good at .065 N/A.

There was another guy on this board (taken with a grain of salt) that went .080 over and ran a dirt modified car with no issues.

We shall see...

dug

iTrader: (10)

**** it, just put a ls9 in there. Checkout the dyno section for the insane dyno numbers theyre pushing out.

whitebro

iTrader: (4)

I'll have $4500 into this motor... not bad, and not even close to an LS9.