compression numbers, what exactly does it mean?

i’m goign to go ls/vtec with a setup of …

b16a head – stock cams, valvetrain

bottom end – CTR pistons standard, no overbore

that’s the extent of my block, i checked my compression, i’ll be running an OEM head gasket btw, and my compression is going to be 11.97 or so…

so what i’m wondering is what exactly does this mean for everyday use, ie what should i be upgrading due to this high compression?

obviously highest octane possible, i think its 92…
i’m getting a vtec oil pump/water pump

what else?


i’m not sure if 92 octane is enough for that high of compression. Thats a really high compression. I plan on running 11:1 and hopefully it’ll work with 91… i’ve been told it will. So, 12:1 like you’re running might be a little bit close for 92 octane. you may need to retard timing or add octane booster.

it seems like my compression is abnormally high or something, will 12.0 compression give me large numbers?

if i have to retard my timing to make it work, i think i will most likely do this, but am i traveling down the wrong path here? IE will retarded timing eventually lead to the downfall of my engine?

this is going to be my daily driver, and reliability is a must. i don’t expect to rev this higher than the stock redline, so i don’t think i’ll have problems of revving the engine apart, just problems with detonation.

tell me what u think

If reliability is a must, stick with a stock engine.

by reliability i mean i won’t blow myself up by running too high of compression due to lack of planning…

i don’t expect this thing to run forever untouched, but as long as it’s well maintained, i wouldn’t expect something to go wrong

well, if you’re going ls/vtec then you’ve already passed the reliability factor. And its sort of stupid to do ls/vtec if you aren’t planning on reving past 6.5k (stock redline). With vtec there is so much more power available higher up.

If it was me, and i only had access to 92 octane i’d drop the compression a bit. I’d probably stick below 11.5:1

if you’re going ls/vtec you really should do it right and do all the upgrades the block needs. You won’t be satisfied only reving to the stock redline… you’ll feel all that power still up there but it won’t be available cause you can’t rev any higher.

Do your research before you are going to build your motor…this is a good way to learn things…

I had the choice of JE 12:1 or JE 11:1, I live in CA and chose the 11:1 path because 11s still give me a opportunity to do a SuperCharger…or if needed some Nitrous…once you break into the 12:1 + CR you are limited to only ALL MOTOR applications…Gas will be a problem, and everyday use is definately going to be a pain in the ass…

Stock bottom block will hold up for a short while, but best thing to do is have new bearings / vtec oil / vtec water pumps / rehoned bottom block , basically redo the whole bottom end, the head should be fine stock…

There is a lot more to what I said up above…Do your research first…it has taken me 2 months to do everything correctly…

BTW: I have VTEC oil squirters…CAN WE SAY LS/VTEC freeway racing ??? hahahaha…Trust your mechanic is another important thing…later

email me if you have ??? about swap…

isnt the stock xsi redline like 7.2? or in the 8s?

Originally posted by x4evawizex
isnt the stock xsi redline like 7.2? or in the 8s?

yes, but you can’t rev an ls/vtec like an xsi. The head may be good to 8k, but the LS block isn’t unless you beef it up a bit. Get the rods shot peened and add arp rod bolts. That along with a full rebuild and balance should make you safe up to 8k for a redline. But still, once you start building you’ll realize that with vtec there is still power above 8k.

do some research dude. do a search for ls/vtec this topic has practically been done to death on this board.