LS Engine Conversion Info

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wildcatjason

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Looks like a lot of guys use efi live or hp tuners.
 

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would anyone be wary of using a high mileage engine or ya figure screw it, its gettin rebuilt anyway..? also i really like the idea of using a cummins turbo, they're quite plentiful and i never would have though of that, thanks!
 

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This all depends on which engine model, and what you consider high mileage. An LS is just broke in good at 100,000. If it was well maintained, 250,000 isn't much to ask of one. And Old school 350, well maintained should do over 150,000 and closer to 200,000. Also depends on how they've driven, if they towed alot etc. I know of a 350 motor that's real close to 400,000 with nothing but a valve job and new valve seals and no head resurface. He didn't resurface them for a reason, #1, it had never been overheated and what tiny bit it was out of flat, the head gasket absorbed, but he didn't want to raise the compression ratio on the tired rings. He may be over 400,000 by now. It did use 1 - 1 1/2 quarts of oil between oil changes of 3000-5000 miles after 300,000.
 

wildcatjason

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An ls1 running twins depending on what two you pick could easily hit 60 psi. I'd rebuild it. Thast a lot of extra compression on a tired motor. How strong is the bottom end on these engines? I mean the turbo I mentioned was designed for an engine running 17:1. Realisitically I would thing you'd want dished forged pistons and stronger connecting rods.
 

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EFI live or HP Tuners. 2 main LS tuning programs.

With twin turbos or even a single turbo Id take it somewhere and have it tuned. Especially if you have no experience with tuning software. Ive seen a guy work with tuning software for an Evo before and it can get confusing.
 

wildcatjason

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Here are some specs on cummins/holset turbos that might help.
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Just an FYI the new 6.7 turbo has a variable exhaust housing. They call it a he351ve.
 

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An ls1 running twins depending on what two you pick could easily hit 60 psi. I'd rebuild it. Thast a lot of extra compression on a tired motor. How strong is the bottom end on these engines? I mean the turbo I mentioned was designed for an engine running 17:1. Realisitically I would thing you'd want dished forged pistons and stronger connecting rods.

You defintely wouldn't be running 60 lbs of boost on a gasser, that's diesel only territory, unless you are talking majorly built race motors. 8-20 lbs is a more realistic range. That would put you somewhere between 350-600whp range dependin on the specific turbo.
 

wildcatjason

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You defintely wouldn't be running 60 lbs of boost on a gasser, that's diesel only territory, unless you are talking majorly built race motors. 8-20 lbs is a more realistic range. That would put you somewhere between 350-600whp range dependin on the specific turbo.

Will one turbo be enough for 8-20 on a gasser. I've rebuilt a few sbc. Never with boost. My 4bt will hit a hair over 30 if I lay into it with an he341. I am not comparing. Just curious.
 

wildcatjason

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I would assume a diesel can spin a turbo due to the amount of exhaust that comes out, but I am talking about a 4 cyl. Not an 8.
 

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Will one turbo be enough for 8-20 on a gasser. I've rebuilt a few sbc. Never with boost. My 4bt will hit a hair over 30 if I lay into it with an he341. I am not comparing. Just curious.

Oh yeah, 20psi isn't a problem as long as the turbo is reasonably sized to the engine. There is a lot of math to sizing it. I actually wrote a small app to calculate the values so you can pick a proper turbo for your application.
 

wildcatjason

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You should post it to help the dude out.
 

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That is one thing I never got into. I can make motors go fast, but it's all in natural aspiration and doing it the hard way. Someday, I hope to learn about Turbo's and Supercharges. And I think I'm even going to play with a little giggly juice on the Olds 455. Just a little 100 shot for the occasional Ricer shutting up show down.
 

wildcatjason

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That is one thing I never got into. I can make motors go fast, but it's all in natural aspiration and doing it the hard way. Someday, I hope to learn about Turbo's and Supercharges. And I think I'm even going to play with a little giggly juice on the Olds 455. Just a little 100 shot for the occasional Ricer shutting up show down.

I like the idea of raising compression as you lay your foot into it. You have a fuel sipper with normal cruising and hear that ****** whistle when you want to spin it.
 

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I have been tossing this idea around for when I get everything ironed out perfectly on my TBI.
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