jhelms

iTrader: (2)

A local non-internet enabled LS1 buddy of mine is deciding soon about his engine package.

He's got a Vortech kit but has ordered pistons/rods from ARE (they were back-orderd which has him rethinking the compression). He's running a 224/228 cam and ported heads, headers, etc.

His problem is, he originally ordered pistons to put him at 9:1 compression and was going to run 12psi of boost, HOWEVER now he is thinking it would be safer to run 9.5:1 cr and a tad less boost (10psi?) and get the same rwhp without the possibility of lifting the heads.

Is that the right school of thought there or is that on the limits of destruction either way?

He has a decent intank pump, some 42# injectors, but stock fuel system other than that. I'll pass along any help, and it would be greatly appreciated, thanks!

MelloYellow

Hard to know, eh?
The dual intercooled ATI chart says 9.5:1 is plenty with full timing if you believe that.. Actually they say up to 13psi if I recall. Hard to believe.

I'm going to try ATI with 9# and 9.6:1. Will see how it works out. I'd focus on an MLS gasket. Either the new 2002 GM or the LPE style Cometic one.

VINCE

iTrader: (1)

I hear you on the boost. I would run 9.5:1 and 10lbs of boost just to be safe.. I am sure they will come out with something soon for the heads lifting issue.. Then he can up the boost and still be safe with 9.5:1. If guys are running 10.1:1 and 10 to 12 psi of boost I do not see why a car built for boost cant run more, but we are finding out the ls1 is not the most boost friend engines.. Another thing that kills me is people are already trying to push the limits before R&D has even reached the limits.. I would be safe and up the boost later..

smokinHawk

iTrader: (48)

I'd say run 9:1 and go with 12psi
2lbs of boost shouldnt be much harder on the engine, but the half of point might be for more knock.

Black LS1 T/A

Static Compression is tougher on an engine than the dynamic compression imposed by FI. FI is a softer hit.

You can run more boost relative to a set static compression, than more compression relative to a certain amount of boost. <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" />

2bseen

first of all he is never going to get 12# on a heads and cam car even with a 2.75 pulley you might get 10 before you go over the rpm limit on the v-9 I just started my car on sat. I put the small pulley on it with ported heads and cam I hope to get 8# out of it. I will let you know in about 3 weeks when it is tuned and dynos. Check out vortechs web site it will tell you what rpms the charger can run with the rpms the car is going to run.

CHRISPY

I would run the 9:1 comp with that setup on pump gas. Would be tuning friendly and give him more leeway. That with 9#'s boost, good fuel system and a decent cam would be sick.
Cheers,
Chris

MIGHTYMOUSE

iTrader: (59)

yea the lower compression is just better. might want to do some math though, if you cant run more than 9psi then might as well get 9.5 since that will also be safe.

VINCE

iTrader: (1)

I would be safe..

2bseen

My compression is 9.6-9.7 and hoping with small pulley to run 8-9# if I am lucky.

VINCE

iTrader: (1)

With the limited R&D on ls1 FI cars I would think we would try and play it safe. I want to know who is running this crazy amount of boost and they are not having problems.. Hello!!! We all come up with these awesome setups on paper, but reality is the ls1 has issues with FI.. I say show proof that we can run 12lbs safely by giving me more than one example of a daily driver that runs that amount of boost daily and has minimal issues. I am talking about 93 to 94 octane as a fuel requirement.

MelloYellow

Ya, I think 12# is pushing it.

2bseen

I think 12# is posible to run daily maybe with alky injection and good pistons and rods.

VINCE

iTrader: (1)

Check out the with... Alky... I personally would play it safe until more R&D is done. We could always upgrade later. I would love to run 15psi.. Could I? Who knows.. Until I see someone do it w/out any issues I will stick to the norm.. Besides, who can beat a ls1 with a blower on the highway anyway? With 9lbs of boost a Supra is wondering what happened..

cablebandit

iTrader: (37)

I'm gonna try somwhere around 12 psi. I am going with roughly 8.9-9:1 compression...the "boost ready" gaskets and arp head studs. Harlan has run 12psi..tho on 100 octane but i think it can be done with alky and 93 on lower compression. FWIW, lets not get hung up on psi again as it is just backpressure. I blew up on probably only 7 psi due to detonation. I have lifted a head and pressurised the coolant system with 8 and 10 psi due to detonation. Its all in the tune.

jhelms

iTrader: (2)

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by cablebandit:
<strong>the "boost ready" gaskets and arp head studs..</strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">Where did you end up getting the gaskets and studs from?

cablebandit

iTrader: (37)

i got the gaskets from Cometic.com for 200.00 the arp studs from katech for 187.00

VINCE

iTrader: (1)

I agree with it is all in the tune.. I am going to research the hell out of it and play it by ear this time. Watching the people ahead of me as well.. I do not plan on any alky.. I just want a nice daily driver setup that has supercar performance..

2bseen

since cablebandit is tuning both his and my car who do you think will have the best tune!

VINCE

iTrader: (1)

Who is running 12psi on a daily basis?