H22A. Mugen head gasket.

I caculated ~7-8hp increase if the c/r was raised to 11.5:1...not too shabby.

My questions...

Is it safe to use a headgasket to raise the c/r? I know a few F/I guys use it to lower c/r.

is 11.5:1 safe on pump gas? like 93 octane?

I know a few people say 12.5:1 is safe....but I know that's total crap unless you're completely and utterly tuned....no way that's safe on 93 octane!

But how about 11.5:1? I'm not going to waste money on octane boosters...so if 93 and 11.5:1 don't mix...I'll just forget about it.

Does anybody have any experience with it? Does it seal properly? Any issues at all with it?



TIA. I hope somebody can help me out.

 

A thinner head gasket is a good way to boost your C/R slightly. You have to remember though that you're moving the cams slightly closer to the crank, so you're retarding your timing. You can use cam gears to correct this. As long as you spend a bit of time tuning it, I don't think you'll have any problems with 11.5:1.

 

eh...

I just found out if only raises it .4 of a point...

For some reason i thought it went almost a full point.

it only being .4 makes the HP gain only around 3 hp

 

Yeah, the Mugen gasket for the B18C1 is .47mm, if I recall, not sure about other applications. That's not going to make a huge difference, but it's an easy .3-.4 boost. I wouldn't take off the head just to put on a thinner gasket(well maybe if I was bored), but if you have it off for something else, then go for it. Other options are flat faced valves, higher domed pistons, or head milling. I'm not a big fan of head milling as it cannot be undone.


[Modified by TimoneX, 11:55 PM 10/4/2002]

 

Well I have a Mugen head gasket and my head was milled. Then I installed some JUN III cams and ooopps... valve and piston became friend. If you have milled the head a bunch, don't get the gasket. If you have a "stock" head then the gasket should be safe if you go to bigger cams. The gasket itself was great, no leakage and I did see about +.4 in compression. Works good with just about everything you throw at it. Not bad for 125$. Yes it is ok to run 11.5:1 compression on 92+ octane, without tuning.


[Modified by advanracing62, 11:57 AM 10/5/2002]

 

Sorry to hear it. This is why I don't care for head milling.

 

update... it actually turns out that they millled the head .04 and then decked the block. Combined with the Mugen head gasket it was about .09 total. Oh well... new motor is in with JUN III and they are happy. Anyone wanna buy a B16 block?

 

if you look at the increase that you will actually get in dynamic compression... not worth it. advance your cam gears and drive away happy. you will feel more change increasing compression by the pistons rather than doing a head gasket. been there, done it. I am enjoying my ITR pistons much, much better with a stock head gasket. alot of guys throw the mugen gasket in there to feel better about thier CR, I may do so later on to get a little bump when I have the head worked on... I figure 11.5:1 is the far I want to go this time around on my dual purpose car...

by the way, in response to the earlier post:

(milling the head, adding a thinner gasket retards the cam timing...)
if you think about it... if there is less distance than there was before and
you are bringing the valves in with less material, they come in SOONER
rather than later. You have to retard the timing 1 degree per .4mm of
removed material from the combustion area, wether that be decking the
block, milling or installing a thinner HG. it is a natural advance, its not
all that bad if you consider it, alittle cam advance never hurt anyone too
bad you get that much (eh) DCR increase too... hehe


[Modified by MikeSarr_GSR, 6:47 PM 10/8/2002]