Chicago Crew UnderBoss

iTrader: (1)

Crazy question I know, but just wondering what the most someone has milled LS6 heads down to and what the most boost they ran in a cent. supercharged application.

I know not many would do this or probably have done this, but interested in finding out how many have done this if any (and only intereted to find out in a boosted application not N20).

SonofaBish

iTrader: (5)

I have 61.5cc 5.3L heads on my motor from when it was N/A... However, i used a large dish piston to bring the CR down... If you did the same, I wouldnt see a problem with it... but if you're using a flat top piston, i'd imagine that would make for a really high CR

Ed @ Late Model Speed

iTrader: (4)

I agree, and really short engine life at 14 PSI

Ed

Chicago Crew UnderBoss

iTrader: (1)

GUYS, let me add that this is on a very stout FORGED, forced induction, 347 LS6 motor, built specifically for boost levels higher than the 14 lbs I plan on running. Just trying to get to my desired compression of 10:1 to 1, and it's not easy given the choice of off the shelf blower pistons on the market, most of which are -8cc by Diamond or -11cc by Wiseco.

Pro Stock John

iTrader: (34)

You can do that if you want, head CC is only part of the equation.

Chicago Crew UnderBoss

iTrader: (1)

JOHN,

What is the most you have known somebody run successfully withhout blowing heads gaskets, passing water, etc., etc., on a milled LS6 head when running from 10:0 to 10:5 to 1 compression, and up to 14lbs of boost, on a purpose built 346/7 forced inducton LS1/6 shortblock?

Anybody,

59cc, 60 cc, 61cc, 62cc, 63cc,, etc., etc.

I know the deck thickness on a stock LS6 casting is thin to begin with but need to know how far I can get them milled b/c I am looking to run more compression then less and need at least 10:0 to 1 for my set-up to make max power on and off the boost (at 14 lbs).

Pro Stock John

iTrader: (34)

I would think that 10:1 compression and 14/15 is doable with some sort of intercooling/aftercooling/knock suppression. Are you going to run the ATI stock intercoolers?

Chicago Crew UnderBoss

iTrader: (1)

JOHN that compression and 14 to 15 bls of boost is a walk in the park and ECS has done this on hundreds of boosted C5s, etc., and I am running ECS D1SC complete set-up with their huge intercooler. Running 1o to 1 compression and 14 lbs of boost is a no brainer on my set-up as proven time in and time again by East Coast Supercharging.

The point of this thread is can I run that boost and compression on LS6 heads that have been milled to 59 or 60 cc and if not, what it is the most I can mill the heads to? I don't want the heads to lift or have water leakage b/c they are to thin/weak from the extra milling from 64cc, down to 59 or 60cc!

Pro Stock John

iTrader: (34)

LS6 heads are 62cc stock right?

SonofaBish

iTrader: (5)

64 i think....?

ls1 - 66.66667
ls6 - 64
5.3 - 61.5
6.0 - 72

Pro Stock John

iTrader: (34)

Oh thanks I have forgotten the numbers. I would run some AFR 205's then.

Chicago Crew UnderBoss

iTrader: (1)

Not the question bro, already bought Stage II TEA LS6 heads which are at 64cc and not switching now. I realize that they have a lot less thinner deck than the aftermarket heads thus my post.

I also know that on unmilled 64CC heads East Coat Supercharging (ECS) has run LS6 head no problem at 14 to 15 lbs of boost and over 750rwhp, without having any issues with the LS6 heads blowing off, or blowing head gaskets, etc.

I most likely therefore will go with the exact same manley pistons that ECS runs, to get the same results, but would not mind a lil more compression for on and off the boost and that is why I posted this thread.

Pro Stock John

iTrader: (34)

Well with 64cc heads and say a 10:1 shortblock, you are at 10.5:1 or so. I'm running 10:1 flattops in the Camaro and 59cc (milled) TFS heads.

stevieturbo

When I started out, I ran a 346, ported 853 castings which had been milled to 62cc. I got some Mahle -16cc pistons to drop my CR. These were off the shelf.
I think I was making about 15psi at that time and a tad under 9.0:1 CR with my YSi
IIRC I ran 11.5 @ 132 or so on pump fuel, although that was at an airfield, not a proper strip.

I had occasion to use those pistons again recently, when I threw together a temp 346 engine to get me to a race at end of July, albeit with diff heads this time.
I ran 10.49 @ 138 that time. ( major valve spring issues )

the Mahles seemed to hold together great for me.

If only I could say the same about the Ross and JE pistons Ive wrecked recently lol.

Chicago Crew UnderBoss

iTrader: (1)

Stevie Turbo,

Did you boost those 853 heads that were milled to 62 cc and if yes, how much boost did you run and for how long and did you have any problems with the heads blowing head gaskets, lifting heads, etc., etc, before you dropped in the -16cc Mahles?

stevieturbo

I dont recall exactly, but I think I ran the 346, with 853 castings AND -16cc Mahles for a little under a year.
I never had any problems with that engine at all during that time.

This engine was 346, Callies rods, Mahle pistons, FFHP stg1 853's, ARP studs, GM MLS gaskets, 230/236 on 112LSA cam, YSi Blower. As far as I recall, this did make about 15-16psi at the top end.
I think this was from around May 05-May06 then I built a new 382 using the same block, which has now turned into a 383 ( and now again for a 2nd time lol )

The only engine I used before this, was a totally stock 2001 346, which I only ran n/a for about a week when I first fitted an Ls1 to my car, then strapped my blower onto it, and ran it like that for a few weeks, before fitting the forged 346.
i was making about 10psi on the totally stock engine ( + exhaust etc )

BLNLS1/RX7

iTrader: (2)

You need to check with Bob at Exotic Performance Plus.com. He is the expert in North America.

Chicago Crew UnderBoss

iTrader: (1)

I did and he told me to stay at 9:5 to 1 compression and not mill my heads past 64cc given 15 lbs of boost i plan and that is my final decision as to my set-up.

Thanks everyone who helped out here and thank you ANDY/LAST LS1 for your advice when i talked to you yesterday on the phone convinced me to stay pat at 9:5 to 1 compression (and no more)! 750rwhp here we come!