LT1-LT4 Modifications 1993-97 Gen II Small Block V8

How Much Boost?

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Old 11-23-2012, 07:43 PM
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Default How Much Boost?

How many pounds of boost will a stock lt1 handle before something gives? Will it handle 7lbs reliably? 8lbs? Has anyone tried running bost on a stock engine? The boost will be supplied by a garret t3 turbo.
Old 11-23-2012, 08:32 PM
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Nope, you will be the first. I say run all of it.
Old 11-23-2012, 09:36 PM
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If I were to try 8psi it would definitely be intercooled as well as possible and I would consider alky too.

I would also have a plan for how to deal with the carnage should something go wrong.

You do understand boost is more or less a measure of how much air is NOT getting into the engine right, bit of an oversimplification but........? You put a cam in it to free up the induction and the boost number can go down while the power number goes up. Not saying that will make it more reliable.

I would at least give it some LT4 springs to keep the valves under control.

You understand a decent heads/cam car will hand you your *** if you are just putting boost to an otherwise completely stock engine on pumpgas right? I am not saying don't do it, if you want the extra power with perfectly stock manners this will get you a boost in power without the raised idle, higher peak rpm, stall and gearing etc a heads/cam setup would need.
Old 11-23-2012, 11:08 PM
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I did 9 effectively on a bone stock setup.
Old 11-24-2012, 12:28 AM
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Make sure fueling is good and your timings not to high. Itd be alittle safer running e85 too if youd like to go that route.
Old 11-24-2012, 01:51 AM
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MY donor car (1993 Camaro, STOCK) that the blower set up came from ....let go under 7 lbs of boost......
Old 11-24-2012, 05:12 AM
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I have a question at what hp level are larger fuel lines and fuel rails required? I know dual intank 255lph pumps will help with volume but how much power can the stock stuff handle?
Old 11-24-2012, 07:38 AM
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Originally Posted by 97Z28SS
I have a question at what hp level are larger fuel lines and fuel rails required? I know dual intank 255lph pumps will help with volume but how much power can the stock stuff handle?
For a well tuned setup that runs efficiently NA, plus a moderate ~200 shot on top of it, the stock lines and rails will support at least 850 crank hp, from the setups I've been around. Some say more, but I can't vouch for that.
For 99% of LT1 NA setups, you won't find the limits.
For a boosted application, I don't know, out of my experience. You just have to consider you're running a richer A/F ratio AND sucking up power you don't even see just to drive the blower, so it won't be as high as an NA or nitrous setup. I'd expect somewhere in the 700's net crank.
Old 11-24-2012, 12:33 PM
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Originally Posted by bowtienut
For a well tuned setup that runs efficiently NA, plus a moderate ~200 shot on top of it, the stock lines and rails will support at least 850 crank hp, from the setups I've been around. Some say more, but I can't vouch for that.
For 99% of LT1 NA setups, you won't find the limits.
For a boosted application, I don't know, out of my experience. You just have to consider you're running a richer A/F ratio AND sucking up power you don't even see just to drive the blower, so it won't be as high as an NA or nitrous setup. I'd expect somewhere in the 700's net crank.
Friend makes 709rwhp through stock lines without an issue.
Old 11-24-2012, 02:44 PM
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i think that pounds of boost that a stock engine will take is kind of vague statement now as a supercharger guy i personally have seen a alot of guys run 8# w either a p600 or a p1 but guys that have tryed wiith a d1 have have failed within a month but u are not talking apples to apples so i dont know much abt the volume sizes of turbos but i would b curious to know the size of the turbo used where 7# caused faused failure was there fuel issues were they running a rich (safer) tune or were they pushing it. i know in the FI section they have a failure chart maybe look at that and make a informed decision that i personallly think wo knowing the individual tune ur just guessing.
Old 11-24-2012, 03:45 PM
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Thanks Guys, helps alot. I guess where I go from here is to get the build started. If it lets go ill just have an excuse to upgrade . Ill make sure to run a safe tune and timing will be kept under control aswell. If it holds for a long time then its just a testament to these engines and when i have a replacement ready to go ill throw more t it till it goes. Thanks again
Old 11-24-2012, 03:55 PM
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One difference between boost from a turbo vs a blower is a turbo is backing up the exhaust building heat, where the nice headers and free exhaust of a supercharger let the heat escape more easily.

The heat held in the chamber by a turbo could easily be the deciding factor far as why say a blower gets away with 8psi but a turbo might only be OK at 6psi
Old 11-24-2012, 05:13 PM
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Originally Posted by 96capricemgr
One difference between boost from a turbo vs a blower is a turbo is backing up the exhaust building heat, where the nice headers and free exhaust of a supercharger let the heat escape more easily.

The heat held in the chamber by a turbo could easily be the deciding factor far as why say a blower gets away with 8psi but a turbo might only be OK at 6psi
That's a good point. More energy is retained in the exhaust of a turbo motor until after it exits the turbine. But to counteract that, logic dicatates that you run less boost on a turbo than you need on a blower when shooting for a specific hp number, just because of the difference in parasitic loss.
...which brings us back to the point that one really should be shooting for a hp level and not a boost level
Old 11-24-2012, 05:44 PM
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Thanks for the info guys it is most helpful, I'll check the FI page for the chart. The reason I'm asking is because I may go twin turbo over the winter and was wondering if I needed to add fuel lines and rails to the budget. I have a pair of Turbonetics 62-1 Q trim .96 a/r turbos from another project that are just sitting around so I thought I'd look at using them since they're paid for already. I should be able to make ~ 850 - 900 rwhp with them, I already have a built engine but I'll either be swapping pistons to lower my scr or buying a set of AFR 210's with the 65cc combustion chambers to lower the scr.
Old 11-25-2012, 02:03 PM
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Will running 100 octane make it easier to keep a stock motor alive on boost? Im in the same boat but not worried about carnage look foward to updating.
Old 11-25-2012, 02:27 PM
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i m not quite sure on octane i think a/f ratio is the important factor im sure it wld help.I was always told 7-8 lbs was a tolerable amnt of boost for a stock bottom end. WITH a small supercharger i.e. p600 or a p1. But a safe tune goes a long ways towards saving ur bottom end.
Old 11-25-2012, 02:56 PM
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Octane could help since detonation is the fastest way to crack a stock piston. I wouldn't consider it a magic bullet though.
Old 11-25-2012, 03:01 PM
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93 with a meth kit is all you should need. The motor I have in my car had a D1 on with a stock engine for eight months before a ring land cracked.
Old 11-25-2012, 03:24 PM
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Originally Posted by 96capricemgr
Octane could help since detonation is the fastest way to crack a stock piston. I wouldn't consider it a magic bullet though.
Thanks thats what I was thinking. I Have a forged piston shortblock waiting just wanted a starting point before I swapped. Talked to a tuner he was telling me 10lbs would be safe but i questioned that. Madtuner is local to me I think Ill be calling him after first of year.
Old 11-25-2012, 03:55 PM
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Originally Posted by 96capricemgr
One difference between boost from a turbo vs a blower is a turbo is backing up the exhaust building heat, where the nice headers and free exhaust of a supercharger let the heat escape more easily.
There both going to have heat. Superchager is going to heat the heck out of your intake


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