12:1 compression with Type-S pistions - Honda Prelude Forum

LVSBB6 · 09-20-2005, 10:00 PM

I have been trying to get a definitive answer, and have searched everywhere. I have found not much useful info yet, so I hope someone can help me out on this.

I want to get 12:1 compression with the Type-S pistons, 20 thou milled head, Spoon thin gasket & high compression valves.

My only concern is whether there is enough clearance for my Jun valvetrain revving up to 8500.

I did a search and somebody from H-T.com have Crower rods, Type-S postons, .030" milled head and stage 3 crower cams, which gave him ~12:1 CR and not have any problem.

Here are the specs of the cams:

Crower stage 3 lift:IN .468'' EX .468''
Jun cam valve lift: IN .480'' EX .468''

Another guy from H-T milled the head 40 thou, with Type S cams and pistons and not have any problems as well.

So is my setup considered safe and reliable?

Thanks guys!

AllMotorBB6 · 09-20-2005, 10:08 PM

well your only going up one point. I would think a head milling, flat valves and a thin headgasket would put you over 12:1.

Whenever you get everything assemble, be sure to clay the pistons to make sure you have good clearance.

sharkcohen · 09-21-2005, 12:19 AM

head milling + thin head gasket and I think you are getting into dangerous territory. Everyone says 'clay the motor', but if it turns out not to work, you are looking at additional expenses for new parts and labor. Do it right once, sleeve the block and get pistons for the compression you want.

LVSBB6 · 09-21-2005, 08:26 AM

Clay the motor cannot replicate the same situation at high revs.

Here's the reply from Corey regarding his setup:

Quote:

Originally Posted by Honda318dx

I have Jun cams, type S pistons, 1 layer headgasket, block decked (slightly, can still make out the cylinder code letters) and head milled (twice, just enough to make it flat) No clearance issues.. I'll do a compression test to see what I'm running..

If this setup works for him, then mine shouldn't be a problem.

sharkcohen · 09-21-2005, 10:08 AM

Corey's response to you doesn't quantify anything. How much material did he have removed from the head and the block?

71dsp · 09-21-2005, 09:06 PM

You would have to be stupid to run a setup so close to the ragged edge and not do a clay test.

A clay test is NOT meant to simulate what happens at high revs. It's to give you an accurate idea of what kind of clearances you have in a STATIC state. From this you can estimate whether or not there is enough clearance to allow for metal expansion, rod stretch, etc.

71dsp · 09-21-2005, 09:07 PM

Quote:

Originally Posted by sharkcohen

Everyone says 'clay the motor', but if it turns out not to work, you are looking at additional expenses for new parts and labor. Do it right once, sleeve the block and get pistons for the compression you want.

Shark, you're smarter than that. You clay the damn motor before anything is modified. If you want to do it right, you mock it up with pistons, rods, and all before you do any milling.

AllMotorBB6 · 09-21-2005, 09:39 PM

i > shark

sharkcohen · 09-21-2005, 10:12 PM

Quote:

Originally Posted by 71dsp

Shark, you're smarter than that. You clay the damn motor before anything is modified. If you want to do it right, you mock it up with pistons, rods, and all before you do any milling.

Sorry guys, I wasn't implying not to clay the motor, just saying it might be better to get the compression you want with appropriate pistons. I'm not sure I would want to run 12:1 on OEM pistons, anyway.

precisionelite · 09-27-2005, 03:53 PM

Can the H22 take 8500 revs?

71dsp · 09-27-2005, 05:06 PM

Don't clay your engine, and maybe you'll end up like this guy.

http://www.honda-tech.com/zerothread?id=1384173

AllMotorBB6 · 09-27-2005, 06:10 PM

Quote:

Originally Posted by 71dsp

Don't clay your engine, and maybe you'll end up like this guy.

http://www.honda-tech.com/zerothread?id=1384173

OOOOOOOOOUUUUUUUUUUUUUCCCCCCCCCCCCHHHHHHHHHHHHHH!! !!!!

petern101 · 09-27-2005, 06:22 PM

that's some engine failure

forbidden710 · 10-08-2005, 08:00 PM

what time you running on the quarter mile lvsbb6? any problems as of yet?

camarokiller · 10-09-2005, 07:36 PM

Quote:

Originally Posted by 71dsp

Don't clay your engine, and maybe you'll end up like this guy.

http://www.honda-tech.com/zerothread?id=1384173

That makes me sick just thinking about it... weeks of labor and thousands of dollars right down the sh*ter!

SoCalude98 · 01-14-2006, 06:59 PM

(I have no idea how old this post is, so if this is old news... whatever)

Im not a fan of the spoon gasket, by going that route your going to drop your piston to head clearance below .030 which isnt a very good idea. I would recomend welding the chambers to minumize combustion chamber volume to get you close to if not over 12.0:1.

Heres an example, 49cc chambers: