Will this CR be safe on boost?
02-20-2014, 10:49 AM
#1
Will this CR be safe on boost? I'd like to use an L33 (5.3) with my current TSP 5.3 stage 2.5 heads. With that combo, I am at about a 10.5:1 CR. If I ran a .060 gasket, it would drop me down to about a 10.37:1 CR.
I am planning on running either a S475 or a PT7675 and running about 15#'s of boost regularly, and turning it up to 20-25#'s every once in a while.
This would be done on pump gas (93 octane where I am at) and an FMIC, with the help of meth injection.
Originally I was thinking I'd need around a 10.1:1 CR, or maybe even lower to keep me safe with that setup. But it seems lately more and more have gotten away with running higher CR and boost safely.
If I have to, I could sell my TSP heads, and just run the stock 5.3 heads from the L33 (which should be around a 9.9:1 CR). But if I could, I'd rather run the heads I have since they have already been worked over and flow very good.
What are your thoughts?
I am planning on running either a S475 or a PT7675 and running about 15#'s of boost regularly, and turning it up to 20-25#'s every once in a while.
This would be done on pump gas (93 octane where I am at) and an FMIC, with the help of meth injection.
Originally I was thinking I'd need around a 10.1:1 CR, or maybe even lower to keep me safe with that setup. But it seems lately more and more have gotten away with running higher CR and boost safely.
If I have to, I could sell my TSP heads, and just run the stock 5.3 heads from the L33 (which should be around a 9.9:1 CR). But if I could, I'd rather run the heads I have since they have already been worked over and flow very good.
What are your thoughts?
02-20-2014, 11:37 AM
#2
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well if it means anything to you im doing a very similar build. stock 5.3 heads and l33 bottom end. not running a 7675 but a 6673 borg turbo.
i did have a normal lm7 bottom end with 243 heads around 700+ rwhp with a pt7675. that was around 9:1 compression and meth injection. though the computer picked up knock at times on that setup the pistons were absolutely perfect when i took em out and i always suspected it was false knock. anyways with a good tune i believe you will be ok but big power on this compression will be far less forgiving in the tune
i did have a normal lm7 bottom end with 243 heads around 700+ rwhp with a pt7675. that was around 9:1 compression and meth injection. though the computer picked up knock at times on that setup the pistons were absolutely perfect when i took em out and i always suspected it was false knock. anyways with a good tune i believe you will be ok but big power on this compression will be far less forgiving in the tune