ls7 head sealing issue

[GARY C]

Not a LS guy, but I keep thinking 30* is too much for a 13:1 engine on E85.

I've used E85 for years with different engines, crappy cylinder heads to fantastic, 30+ psi and never approached 30 degrees advance.

Not sure where the 30 degree number came from. To clarify It was set at 27-28 degrees of ignition timing.

I don't think you could ever put a single blanket timing number on any engine or engine combo, especially comparing boosted to NA.

[n2xlr8n]

Not a LS guy, but I keep thinking 30* is too much for a 13:1 engine on E85.

I've used E85 for years with different engines, crappy cylinder heads to fantastic, 30+ psi and never approached 30 degrees advance.

Not sure where the 30 degree number came from. To clarify It was set at 27-28 degrees of ignition timing.

I likely misread your post- my apologies.

I don't think you could ever put a single blanket timing number on any engine or engine combo, especially comparing boosted to NA.

I agree- especially with modern combustion chambers being far more capable than 70s versions.

My 30+ psi reference was simply to point out that I have tuned a few different E85 engines.

[Newold1]

Be careful to verify all costs to equip your damaged LS7 block with Darton sleeves and make it a 454. Sometimes this can cost more than the cost of using a new LSX iron block from GMPP and the added 75 lbs in a Corvette seems like sacrilegious but remember the factory LS7 blocks were only rated for 640-650 HP max and that was before the weakening of cutting them bigger for Darton 454 size sleeves! If you plan on going over 650HP I would say go with the iron LSX block and the extra 75lbs and use a block that can take 2000HP. why do you think they build the COPO drag Camaros with LSX iron blocks. It's because that is what it takes to get to higher horsepower levels on bigger LS engines and MAKE THEM LIVE!

Lots of engine peddlers and shops will tell you they can build you a 700HP plus aluminum stock block LS 454. But then ask them to give you a full no questions asked warranty on their build. Their butt cheeks will tighten and their lips will quiver and out they will blurt "HELL NO!" its a performance engine HA! If you are going up there in power now or in the near future make sure what you do and spend now will keep it together and keep you from building it twice!

I am confident with my machinist. If he says the block is good to use then I will use it. The integrity of that block with darton sleeves doesn't bother me and should be plenty for what I'm doing. I recently tuned a z06 with diamond pistons, stock crank, rods, and block with an f1a procharger. It makes 16lbs of boost and probably close to 1000fwhp. This article is worth a read if you haven't seen it also http://samtech.edu/stock-eliminator-ls7/ . I would have trouble hanging another 80lbs on the front of a z06. The chassis works very well with its current weight bias. I doubt if it would stay that way with an iron block. Thank you for the input.

This is always a difficult hurdle in the performance engine building industry. How to build an engine with enough variability to provide good fun street manners, all out aggressive DRAG racing power and rpms and then use a chassis like a late model Corvette to accomplish all three! Not a great trio to accomplish. If you are building one to do all three well with exceptional results in all three uses, you are going to be faced with some compromises and generally the results will not be exceptional in any of the three! Just try and keep that in mind when trying to build that "so called perfect engine!" JMHO