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Johnnyblaze370

L92 heads

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What do you guys think of putting a set of L92 heads on one of these trucks? I have a complete engine laying around, but dont want to swap to the 6.2 because of the knock sensors, crankshaft sensors and things like that. If I did the swap I would also replace the cam add headers and around a 2800 stall.

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It all depends on what your goals are for the truck, what future mods you plan for it and what kind of hp improvement you expect from the amount of money that mod will cost you, because you could possibly benefit better from doing a cam instead depending on what future plans you have. As far as if the heads will gain you hp, yes you would pick up some hp. The stock 317 heads have a combustion chamber of around 72cc and the l92/ls3 heads are about 70cc so you would come up on compression. Would definitely want to make sure your running premium, which you already should be, and suggest you have a good tuner since running even higher compression. And if you haven't thought about it more air = more fuel so you will need some re tunning done, not thinking of you as a dummy just trying to help you cover everything before you pull the trigger. Also the stock 317 heads flow around 245 cfm's and the l92/ls3 flow around 318 cfm's so you would be moving some more air as well. Would suggest to optimize the extra air coming in you had a set of long tubes and a good exhaust set up. Im not here to argue cfm numbers cuz different places that flow test will all come up with different numbers but those are the rough numbers of the stock heads. If you were to get the heads cnc ported which would obviously be more $ the cc would change depending on who does the work atleast it did in my case and could come out around 68cc bumping your compression even more and cfm's in the 368 range depending who does it. But it all comes down to how much moding you plan to do to it. Obviously doing heads, cam, long tubes, and exhaust would all benefit from each other, plus many other mods intake etc. But if your just looking at possibly one thing that is the price of what the heads would run you, I think I would personally be looking into a cam swap. Then later on you decide you want more the cam will benefit great from the extra air of the heads. Just my 2 cents.

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I plan on doing a cam swap, and hopefully a turbo next year. Haven't decided on what cam to run yet. The heads I already have. Just need gaskets, and bolts, I would also upgrade the springs and lifters and more than likely add the cam while I was in there.

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If you are planning a turbo in the future the l92's may not be a good route. You already have a 10.4:1 compression ratio, and it you put l92 heads on it since they have a slightly smaller cc you will bump your compression ratio up. not quite sure what it would raise it to but its that fact that it would raise it. Now I am not a turbo expert but most guys running any type of blown forced induction setup usually shoot for around a 9.5:1 compression ratio, or sometimes lower. That is the reason I was saying you need to be sure and look into your future build plans. I like to say im fairly knowledgeable with when it comes to building engines but I will not lead someone in the wrong direction about something im not experienced on and turbos is something im not good at. But I would think the compression ratio you would come out at would be too much to turbo later on which would mean another head swap later on. hopefully someone with some turbo knowledge will chime in

Edited by dieseltech320

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Double check my info, but wouldn't you have to change intake also? The stock 317 heads are cathredal port and the L92 heads are LS3/rectangular ports on the intake side. A new intake will add quite a bit to the price unless you have a stock truck intake to go with your heads. Like I said, double check my info. I am still learning my way around the various LS style engines with my engines being the LQ4 in my 75 Blazer and LQ9 in my SSS.

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I talked with my G8 buddy who also owned a GTO with the LS2 cathedral port heads. He said the GTO guys have put on LS3 heads and intakes on their LS2 engines for years with an increase in power at lower RPMs with a smaller cam due to the increased flow. The L92 heads and intake should respond that way too. You will that small increase in compression as stated above. I hope that helps!

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