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Max boost through alum LS block?

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Old Jun 4, 2013 | 01:25 PM
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Default Max boost through alum LS block?

Bores are at 3.907, ARP hardware throughout, Callies rods, Wiseco pistons, 10.5:1 CR, plenty of valve spring to support the cyl pressures, plenty of fuel system, AIS meth kit onboard, IATs <100, current boost @ ~19psi.

How far have the aluminum blocks been pushed without imminent failure?
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Old Jun 4, 2013 | 01:30 PM
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I see 0* KR right now. But just because KR isn't happening doesn't mean I can just keep pushing up the boost... right?

Last edited by Eagle02; Jun 4, 2013 at 01:42 PM.
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Old Jun 4, 2013 | 02:53 PM
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Fireball made some where around 1700 hp enough to run 7.99 with his Aluminum ls2 granted it had pinned mains and was a filled block. but that was when he lost a stock sleeve.
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Old Jun 6, 2013 | 06:46 AM
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I've been 8.7@157 at 3450lb with a stock ls1 block
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Old Jun 6, 2013 | 07:19 AM
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Originally Posted by ls1curt
I've been 8.7@157 at 3450lb with a stock ls1 block
he asked max boost.... comprehension ftw.

Last edited by Fireball; Jun 6, 2013 at 01:17 PM.
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Old Jun 6, 2013 | 07:48 AM
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28lbs on a few combos
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Old Jun 6, 2013 | 01:15 PM
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IIRC I was generally pushing about 34psi on my LS2...about 1700 hp give or take....sleeve finally cracked.
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Old Jun 6, 2013 | 01:18 PM
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Originally Posted by Camper
he asked max boost.... comprehension ftw.
Easy there cowboy!

FYI, max boost = meaningless LOL. 20psi with killer heads makes WAAAYYYY more power than 20 psi with stock heads

power is what breaks stuff....mph indicates hp.
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Old Jun 6, 2013 | 03:58 PM
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Originally Posted by Eagle02
Bores are at 3.907, ARP hardware throughout, Callies rods, Wiseco pistons, 10.5:1 CR, plenty of valve spring to support the cyl pressures, plenty of fuel system, AIS meth kit onboard, IATs <100, current boost @ ~19psi.

How far have the aluminum blocks been pushed without imminent failure?
How fast other alloy blocks have been pushed mean little as to how much you're bored to the limit LS1/6 block are pushed.

There are several block/liner combos and each will have different strengths. But from the bore size you mention I assume you have either LS1/6
And you also dont say how much power you are making, boost is irrelevant other than the potential for detonation.

But the simple fact your liners will now be very thin, isnt a good starting point.
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Old Jun 6, 2013 | 04:14 PM
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Originally Posted by ls1curt
I've been 8.7@157 at 3450lb with a stock ls1 block
Thats good news...

Originally Posted by skinnies
28lbs on a few combos
Yeah, I've heard 25 is a good #, 28 sounds even better.

Originally Posted by Fireball
Easy there cowboy!

FYI, max boost = meaningless LOL. 20psi with killer heads makes WAAAYYYY more power than 20 psi with stock heads

power is what breaks stuff....mph indicates hp.
I'm just below 20psi right now, 16* timing, zero KR.

Originally Posted by stevieturbo
How fast other alloy blocks have been pushed mean little as to how much you're bored to the limit LS1/6 block are pushed.

There are several block/liner combos and each will have different strengths. But from the bore size you mention I assume you have either LS1/6
And you also dont say how much power you are making, boost is irrelevant other than the potential for detonation.

But the simple fact your liners will now be very thin, isnt a good starting point.
Yep, LS6 block. Haven't dyno'd the car, but it trapped 170mph in a 1/2mi drag last weekend. I know that doesn't help much... lol

I need to get the car back on the dyno, but the local shops are busy as hell. Next appointment isn't until July.

Finally, I wasn't under the impression that a fresh 3.907 bore was all that far out there. Other threads are saying 3.915, 3.910, even 3.908 ok as max bore sizes.

Quite simply, I'd thought about pushing out to ~25psi to achieve the best ET this combo has in it, then detune it a bit. I don't want to kill it this early in the year!
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Old Jun 6, 2013 | 04:23 PM
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I would say very few push a stock LS1/6 block past 3.905", especially with boost.

All you can do is take your chances. People have bust them with less power and boost. Or all it might take is some detonation

If you absolutely trust your knock sensors then all good and well in that respect.
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Old Jun 6, 2013 | 04:25 PM
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Yep, my knock sensors have not lied to me in the past. I keep em around just for that reason!
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Old Jun 11, 2013 | 11:27 AM
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Originally Posted by ls1curt
I've been 8.7@157 at 3450lb with a stock ls1 block
Impressive, that calculates to over 1000hp. Any other details on the combo?
  • Type of power adder
  • Fuel used
  • Compression ratio
  • Stock block, or stock block, crank, rods, etc.
  • Stock heads and head bolts

I'm currently at 20 psi and almost 900rw on a cam only 85k mile LS1 with twin turbos. I'm trying to figure out how much more it will take.
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Old Jun 11, 2013 | 12:00 PM
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That's exactly what I was looking to determine myself. Going to take her to the track and just start working my way up and checking the tune each and every pass.

* PT88
* 100 + 50/50 meth
* 10.5:1
* stock block & crank, forged rods & pistons
* reworked 317s, ARP studs throughout
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Old Jun 11, 2013 | 12:11 PM
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Originally Posted by R_trim 93GT
Impressive, that calculates to over 1000hp. Any other details on the combo?
  • Type of power adder
  • Fuel used
  • Compression ratio
  • Stock block, or stock block, crank, rods, etc.
  • Stock heads and head bolts

I'm currently at 20 psi and almost 900rw on a cam only 85k mile LS1 with twin turbos. I'm trying to figure out how much more it will take.
Thanks. s400-hp88 turbo, 93+meth, 10.4:1, stock ls1 block, forged crank, rods, pistons, 317 heads w/ studs
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Old Jun 11, 2013 | 12:27 PM
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Thanks, man. I found one of your threads where it lists the setup. Very good numbers with a lot of stock parts. This looks like a good indication of what is possible. What kind of air fuel ratios were you seeing? I made 3 test passes on 20 psi at 10.6:1 AFR. I typically run 11:1 AFR on 18 psi.
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Old Jun 11, 2013 | 06:11 PM
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Didn't Harlan run a 346ci to 8s at 170mph years ago????
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Old Jun 11, 2013 | 09:17 PM
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he had a 6.0 iron right? (harlan)
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Old Jun 12, 2013 | 11:09 AM
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I think Harlan went 8.3 on an aluminum ls1 block, not sure of his weight though.
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Old Jun 12, 2013 | 05:20 PM
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With your 317 heads, more than likely you're going to start pushing water at 20+ psi. Bob
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