Stock OEM 87mm K24 head gasket will be fine for 87.5mm. Anything larger will require a custom gasket.

 

Hi, I don't quite understand. Would'nt the 87mm be to small for a block with a 87.50 bore. I though you had to always go bigger or the same size gasket to match the bore of the block. So, what your'e saying is if I go with an 88mm or 89mm they would be too big? Also, how does the thickness effect the compression ratio? Does a thicker head gasket raise or lower the compression of the block? I hope I am making sense. Thanks

 

Using a size over then would not be a good idea? e.g 88mm gasket. Thanks for the help.

 

im with alex on this one, ive always heard that if in the middle like that your always go to the larger one

 

Maybe some other builders will chime in. I've used this method on numerous builds with good results. Also oem gaskets seal the best by far.

 

You say OEM gaskets seal the best. So using a Cometic or other brand will not be any better then?

 

The logic "Better over than under" doesnt necessarily apply to this case here. As Scott said, the 87mm gasket will function just fine with the 87.5mm block. I ran an 86mm headgasket on an 86.5mm setup with no issues..

 

I'm running a 87mm head gasket on my 87.5mm bore. No problem. Was told to use that size by Cometic, machine shop and a few others.

 

thats funny because i called cometic about this exact question and they told me to use 88 mm so thats what i bought and i havent had any issues at all. im sure it doesnt really matter since other people have done it both ways.

 

Hey guys. I have an 87.5pm bore, and the gasket I have is 87mm but measured out to 87.5. So it clears the cylinder bore in almost every part but in some areas the gasket goes slightly into the cylinder.

Should I get a different head gasket or will the piston not hit the gasket. Please any help will be appreciated.

ATM I only have 1 dowel pin on the block but I aligned the other side to check clearance and on the right side of Cyl #4 the gasket bore slightly over laps the Cyl bore. Please LMK.

 

I'm running 86.5mm bores and originally fitted a cometic 86.5mm gasket which went pop after only one track day. Since been running a Honda oem 86mm gasket and it's been perfect for a good year now.... :up: with much higher boost & power levels.

 

Would be better to use 88mm gasket than 87. You can get cometic to make you a 87.5

 

My tuner told me a 87mm would be ok for a moderate tuned motor, he said that extra .010" around would jsut be burned off. Though he said when a motor is tuned to the max like mine and several others on here are, he would imagine that it could pose a slight issue with maybe detonation but he hasnt 'been there done that' he always goes next size up which is what Im going to do.

 

You need to stop listening to your tuner before he ruins your engine for you, LOL, burn off excess head gasket, LOL good one I havnt had such a good laugh in days.

doing a build as we speak on a k20z3 head on k24a4 block gonna need to bore it out to 87.5mm (spun crank bearing) on a n/a set up running 8 psi whats size gasket should i get thickness and bore,please help??

Why does it need to be bored out for spun crank bearings? I am not questioning the need for being bored out, just the cause behind it.



The head gasket should MATCH the bore dia, a difference in size that overhangs the cylinder walls creates a veritable hotspot that will cause tuning issues with detonation, the same goes for oversized head gaskets where the edge of the cylinder walls then cause the hotspot. We hone the gaskets bores to match the bore dia perfectly.

 

doing a build as we speak on a k20z3 head on k24a4 block gonna need to bore it out to 87.5mm (spun crank bearing) on a n/a set up running 8 psi whats size gasket should i get thickness and bore,please help??

 

Are K24 and K20 head gaskets the same other than the bore size.

I have a K20 87mm block so can I use a K24 standard 87mm gasket on it?