Someone explain to me this...

[crawlin92]

...ok.... this doesnt really have anythign to do with Jeeps but I figured someone here might be able to answer this. My buddy has a 89? Chevy Custom, he swapped in a 350 small block that he had a guy build for him.... problem is he isnt getting the power he should be. It sounds nice... but its a pooch. And the build he did he should be running high hp... like 500+, and hes maybe pushing 400 if he is lucky and I'm giving some credit by saying that. He has tried different carbs, hes tried getting it tuned over and over, and other stuff but nothing really helps. So I asked him what compression he was running... he said 8.5:1 I beleive... it was 8 something. Now to me being a 4cyl guy thats low.... reeeaaalll low. And I know if you want a higher hp N/A 4cyl you raise the compression... is it the same with his motor? I told him to raise it to around 10:1 and it should help a lot and help with his gas milage to but he tells me its different with a V-8.... so is it?... or does he need to raise his compression a lil bit? I also told him to advance his timing a touch but he insists that that wont help either cuz its a V-8 and they are different.... can someone straighten this out for me?

[Old Fart]

Unless things have changed a lot since I was into the "gofast" cars, you're not going to make 500hp with 8.5:1

FWIW I dyno'd a bit over 475hp with a 12.5:1 open chamber Rat (427) back in the early 80's, and that took two carbs, open chamber heads, a tunnel ram and about 20% aviation gas.

[crawlin92]

Well thats what I thought to. As far as I see it every motor runs off the same principles with a few exceptions (ex: rotary) and just cuz its a V-8 doesnt mean it has its own principles on how it runs.

He also tells me that at 10:1 compression he will have to run race fuel or 93+ octane... this also sounds dumb to me. Yes a higher octane should/could be run, but he shouldnt need race fuel. I know with my car I wont need race fuel until 12:1 but I will need to run atleast 93 once I'm around 11:1 or slightly under.

[Old Fart]

A few other things should come into play (like ignition advance), but I think you see the picture. I can run low test in the Jeep and Bronco, the Boxster cringes at anything under high grade. I probably _should_ know all the compression ratios, but don't.

[Dukes69]

...ok.... this doesnt really have anythign to do with Jeeps but I figured someone here might be able to answer this. My buddy has a 89? Chevy Custom, he swapped in a 350 small block that he had a guy build for him.... problem is he isnt getting the power he should be. It sounds nice... but its a pooch. And the build he did he should be running high hp... like 500+, and hes maybe pushing 400 if he is lucky and I'm giving some credit by saying that. He has tried different carbs, hes tried getting it tuned over and over, and other stuff but nothing really helps. So I asked him what compression he was running... he said 8.5:1 I beleive... it was 8 something. Now to me being a 4cyl guy thats low.... reeeaaalll low. And I know if you want a higher hp N/A 4cyl you raise the compression... is it the same with his motor? I told him to raise it to around 10:1 and it should help a lot and help with his gas milage to but he tells me its different with a V-8.... so is it?... or does he need to raise his compression a lil bit? I also told him to advance his timing a touch but he insists that that wont help either cuz its a V-8 and they are different.... can someone straighten this out for me?

Where do I start.

1) Its a chevrolet, everyone knows they dont make HP . . . or torque for that matter.

2) It sounds like the dude built him a nice smog motor. There is no way in hell you can make 500 or even 400 w/ 8.5 compression, unless you have a huffer of some kind. Forget gas milage.

3) I run 10.5:1 in my charger with iron heads and about 28 degrees of timing lead. I run 100 low lead (Av. Gas) cause it smells better. Everyone knows gas is for washing parts.

4) You friend doesnt sound like he knows what he is talking about.

If he doesnt have a bunch of CR, try taking the heads off and replacing with some aluminum ones. Or maybe taking off the iron ones and milling them down to get some more compression. Also you could get a thinner head gasket.

and remember: if you want something right, do it yourself!

[Bachman]

Come on, the bow tie can make some power when they want to. The 2006 ZO6 is pretty cool and on pump gas.

Inside every Z06 is an LS7 aluminum–block V8. It puts out a SAE-certified (Society of Automotive Engineers) 505 hp and 470 lb.–ft. of torque.

I love my I-6 but that is some good numbers!