SIR

opinions please <img border="0" title="" alt="[Big Grin]" src="gr_grin.gif" />

A 4.125 bore LS1 with forged pistons, Oliver rods, Lunati 4.125 forged crank, ARP studs, Jessel J2k rockers for the roller...Lq9 heads that have been fully ported and polished AND thermal coated <img border="0" title="" alt="[Big Grin]" src="gr_grin.gif" /> <img border="0" title="" alt="[Eek!]" src="gr_eek2.gif" />

What do you think my MAX boost is ???? 10 psi???

MelloYellow

The Z06 Turbo and Supercharger kits are going with 6psi boost at their 10.5:1 with stock pistons.

Black LS1 T/A

I wouldn't put 10 PSI on a motor with 10.5:1 static compression. 5 to 7 and the most.

gogogadgetcar

I guess it realy depends on what kind of fuel you want to use.

<small>[ December 11, 2002, 03:23 AM: Message edited by: gogogadgetcar ]</small>

SIR

I guess 7psi would be OK for street use with my forged pistons (the pistons will also be themal coated on and ploy coated on the skirts)and then splash some 100 octane in the tank for track use and 10psi???

Pro Stock John

iTrader: (34)

Splash?

I think you might have to run straight 100 to run 10psi but I guess it depends on the max timing you can run.

SIR

The reason I am thiking 10 psi is because Halltech just ran their TT on a STOCK Z06 and at 14psi it cracked a couple pistons. So I am thinking with FORGED pistons and 10 psi MAX I should be OK. I think I would just run 5-6psi on the street. <img border="0" title="" alt="[Big Grin]" src="gr_grin.gif" />

SIR

bump

Mark C

Is this a trick question? If you are already going into the motor, why would you not just buy low compression pistons? 9.0:1 or thereabouts.

Stock Z06 and 14 psi. I doubt forged pistons would have made any difference.

SIR

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by Mark C:
<strong>Is this a trick question? If you are already going into the motor, why would you not just buy low compression pistons? 9.0:1 or thereabouts.

Stock Z06 and 14 psi. I doubt forged pistons would have made any difference.</strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif"><img border="0" title="" alt="[Big Grin]" src="gr_grin.gif" /> no trick question. THe bore is 4.125, so I recently found out that the dish to bring down the compression would be so big that the dome would be to thin. I think with a -15cc dish I can get it down to about a 10.2:1 or a lil higher.

I agree with the 14psi on stock pistons, I think they were just trying to find the limts. I am betting I can still run 10psi. <img border="0" alt="[devil]" title="" src="graemlins/gr_devil.gif" />

JimmyKash

its more of a timing and detonation issue, i had a friend that had a 383sbc that went high 10s with a vortech s-trim, 12psi, and 10.5:1

no knock. He had a DFI to control the timing though which you can do through LS1edit anyhow

Pro Stock John

iTrader: (34)

Well you can run 10psi for sure but the question will be with what timing and what octane...

Let's throw a parameter out there, you will never run more than 100 octane. If that's the case then you'd have to see how far you can get with that octane. Who knows, the motor might want 17 degrees of timing, heck maybe 22 at peak HP, it's all going to be in the tune. Also will depend on cam shaft L/S too.

SIR

Yeah the cam can give me grief. Probably want one to bleed off compression faster. I guess I would dial up to 10 psi and 15* of timing and then work my way up using 100 octane until it detonates.

I guess it will take a few weeks of trial and error <img border="0" title="" alt="[Big Grin]" src="gr_grin.gif" />

Pro Stock John

iTrader: (34)

Supercharger?

Perhaps start out with 20 degrees of timing.

I'd dyno with a sponsor and then assume that you want to run a bit phatter AF since on the street you might see more boost and more load.

SIR

I will probably dyno over at Izzo's <img border="0" title="" alt="[Big Grin]" src="gr_grin.gif" /> <img border="0" title="" alt="[Big Grin]" src="gr_grin.gif" />
He has run some turbos huh ahahha <img border="0" title="" alt="[Big Grin]" src="gr_grin.gif" /> <img border="0" title="" alt="[Big Grin]" src="gr_grin.gif" />

BIGBOS

I am going to be constantly running 7psi on the street and most of the time at the track, with 93 octane, my heads are 10.3:1 compression, I might run a straight tank of 100 and up it to 9lbs if I'm in the mood... <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" /> I just don't want to blow up until I can afford some rods/pistons... <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" />

Rpm2800

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by JimmyKash:
<strong>its more of a timing and detonation issue, i had a friend that had a 383sbc that went high 10s with a vortech s-trim, 12psi, and 10.5:1

no knock. He had a DFI to control the timing though which you can do through LS1edit anyhow</strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">With an Ls1 the situation is a little different than a conventional sbc or Lt1 because of the head lifting issue. Quite a few guys run compression in the 10's with 10-12 psi of boost on Lt1 and other SBC's. But, they have more meat,around the cylnders and 17 head bolts.

You could proabably find a way to do it, but Im just saying it's not going to be like when conventional sbc guys do it. (They usually have to have detonation to blow a gaskest or lift heads). Even if the Ls1 does not detonate, many have had problems "lifting heads." Even with decent fuel and the proper timming.

Rpm2800

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by SIR:
<strong>The reason I am thiking 10 psi is because Halltech just ran their TT on a STOCK Z06 and at 14psi it cracked a couple pistons. <img border="0" title="" alt="[Big Grin]" src="gr_grin.gif" /> </strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">With forged pistons, the pistons might have been ok, but if it had stock type head bolts, the pressure probably would have just come out the other end. (Head surface) Which could kinda be like a "safety" fuse if you would call it that. Better to change head gaskest that pistons though.

With an Lt1 or another sbc, compression in the 10's and 10psi of intercooled boost wouldn't have me very parinoid, but with an LS1, I would wait and see a little longer. I'd watch more cars like Harlans and others that are running more boost. (Even though some of them use race gas.)

SIR

was going to use ARP studs. Don't know about o-ringing the heads for use with te resleeve.

chasgiv3

iTrader: (1)

I ran 10PSI at 10.5:1 CR with a mix of 93 and 104. Bout half and half.

I know it can be done. But...this was relatively cool weather. At higher temps I'd REALLY be concerned.

Also after running my motor with not enough fuel I had a head starting to weap coolant to the outside.