stock headgasket owned by 35psi. about to buy a cosworth head gasket but while reading about it i noticed it a has an 86mm bore and when rebuilding my motor i went .020 over so (85.5mm) is this 1/2 a mm going to matter????


and also they have diffrent thickness gaskets , any input on that is great...

 

thats the one you want; i over bored to 85.5mm as well and am running the cosworth 86mm head gasket.

https://www.evolutionm.net/forums/ev...ld-so-far.html

As far as thickness goes the thinner head gasket will raise your compression ratio, thicker will lower it. at one point i knew what the oem evo head gasket thickness was but i dont anymore, youll have to search on that one.

The guys at slowboy racing had the best prices and were great at answering all my questions, give them a shout.

 

Why not looking into other gaskets also? Hks makes a very stout gasket and so does tomei. Both have vaious thicknesses and bore sizes. Probably comparable in price too.

Or since your running such high boost, have you looked into oringing?

 

A rubber valve stem holds more than 35psi, i doubt boost was your issue. i would look more into the root cause of the problem. Plenty of people are making more power ( ie more cylinder pressure) than what you are running on a stock headgasket.

 

we have had OEM headgaskets at well over 40PSI many many times without issues. You must have had some other issue.

 

Stock Headgaskets have been known to warp over the 500+hp mark. Mine was about to go out at 30psi w/ arp studs... Just food for thought.

Mikey

 

Wow....stock headgasket is perfectly fine for upwards of 500whp. The OEM headgasket is multiple layer stainless steel, which makes it a great headgasket. IMO, upgraded headgaskets are a waste of money. If you are stretching the limits of the OEM headgasket, you should be looking into o-ringing the block.

For those of you blowing OEM headgaskets and using ARP headstuds, what did you torque the headstuds to? Also, did you re-torque them after several heat cycles? Did you use the ARP Moly lube when you installed them and did you use the 1x1 method?

 

how does an oem headgasket work with an 85.5mm bore?

 

Power Enterprise is the best HG in my opinion!

Mikey

 

sorry for taking so long to reply , its been real crazy at the shop.....


the guy tuning my car said hes seen it a 100 times stock head gaskets going around the 500hp mark 35psi (not sayin no one has ever made 600hp stock head gasket) but it is common he said (sean from iveytune)

i did not re tighten the hg after heat cycles (noob)...

also did a cylinder leak down test to confirm the prob to all the skeptics

all i needed to know is if the 86mm bore of the hg is ok with a 85.5mm bore on the block..


thanks guys

 

PM me I am not sure who this is.

500hp is fine on the stock headgasket.

There is a bit more to it than just the gasket please contact me.


Sean