[mert]

Many engine builders o-ring their cylinder head and engine block. This method saves the combustion pressure inside the combustion room. Why don't we also o-ring the heand and / or block? Or did someone?

 

[MADMKIV]

Maybe it isn't neccesary?

 

[65vette396]

Leave the O-ringed heads on race cars. True they seal the combustion chambers completely, but they cause some pretty serious issues with coolant leaks. Drew

 

[mert]

Drew

what do you mean by coolant laeks?

mert

 

[65vette396]

We have O-ringed several small block chevys, big block chevys, and Buick GN motors with the same results. The cylinders are sealed amasingly well. However, the coolant passages/ oil return passages between the head and the block are a bitch to seal up. They always tend to seap just a little bit on the outside of the block. Drew

 

[FattyCBR]

Drew-

I'm looking at down the line going na-t on an originally NA engine (5vz-fe). A certain engine builder has told me that with this engine and head the only reliable way to boost over ~1 bar is to use a metal wire around the combustion chamber without o-ringing it. Have you ever heard of this? If this is OT please feel free to PM me.

Thanks,
Milan

 

[65vette396]

I am sticking to my word on this one. I have done it in the past and won't do it again unless neccesary. Just buy fel-pro fire ring style gasket. These gaskets are as close as you can get to an O-ring w/o having to do any extra machine work and w/o the water leaks. I would have my machine shop true up the head and block by shaving the least amt. possible to get a level surface. Get a good low compression set of pistons or shim style head gasket (pistons preferred) and go to town. I would not o-ring it unless I had blown a couple sets of head gaskets first. I currently have a big block chevrolet (obviously originally N/A) with a T-100 that has made probably 40-50 passes on 25psi or so with no head gasket issues. Tuning is the key. Always stay a little fat, always stay a little ahead with the timing curve, always use good gas for the amt. of boost i.e. 14 psi or so on pump 93 and 116 for 25 psi in my case. I also have the msd 6btm ignition box pulling about a 1/2 degree of timing per psi of boost. In short stay away from running lean or detonation and you should have no head gasket problems. Look at it this way, the head gasket is a safety margin, if you are blowing head gaskets something is causing it. If you O-ring it it will likely kill pistons instead. Drew

 

[Grant]

Drew, are you using a copper HG with the o-rings? I've heard of coolant and oil problems with such a setup, and it doesn't sound like a good thing for a street car.

The stock Toyota gastek holds a lot, although the most boost I've seen is 2.5 bar, so I guess if your going to be running > 40 psi you might need something else. I think Titan might be doing something like that on their car, or so I've heard.

 

[65vette396]

I am using the stock toyota gasket with no problems (knock on wood). Although in the past I have used both copper and composit gaskets with the o-rings. The copper gaskets are a nightmare and the composit gaskets arent much better with the o-rings. I have actually seen 3 bar with the stock toyota HG. Drew