i was wanting to know how much boost a composit gasket can handle with arp head studs with out blowing again?
how much boost on composit gasket on 7m-ge
- Thread starter chris1039
- Start date
If the phrasing of your question is accurate (albeit vague) I am getting that you have an n/a block w/ 7mgte turbo, manifolds, ecu, inter-cooler etc.
If that's the case there a few other considerations, such as the 7mge's higher compression, non-forged pistons and lack of oil-squirters to consider as well when calculating a (relatively) safe boost level. Also, condition of the rest of your motor plays a huge part.
If everything else is in good shape given the above conditions, I would say that 10lbs of boost w/ premium gas and a good tune would be pushing it pretty hard. Beyond that expect things to go boom.
If that's the case there a few other considerations, such as the 7mge's higher compression, non-forged pistons and lack of oil-squirters to consider as well when calculating a (relatively) safe boost level. Also, condition of the rest of your motor plays a huge part.
If everything else is in good shape given the above conditions, I would say that 10lbs of boost w/ premium gas and a good tune would be pushing it pretty hard. Beyond that expect things to go boom.
hey suprabad thanks for responding so quickly I have a titan motorsports 1.4 mm head gasket for my supra but I blew it and got a new one and haven't put it on because I haven't had the block resurfaced the head is in the shop gettin all done up but I am thinking of going with a composite gasket right now thats why I had inquired about the boost levels I have arp studs, gte injectors, gte turbo manifold and turbo and thats all, I blew my first head gasket cause I upped my boost a pound or 2 and lifted the head, then I blew the metal HG, and then I got the new one but thanks for the response i'm gonna go with composite for a little while until I get the time and money for the block.
So where was the boost when you blew the MHG? This should give you an absolute MAX.
Was the MHG properly installed?
Maybe someone will chime in with how much more dependable a properly installed MHG is than a composite. Then you can subtract the difference for a good safe boost.
Was the MHG properly installed?
Maybe someone will chime in with how much more dependable a properly installed MHG is than a composite. Then you can subtract the difference for a good safe boost.
It sounds like your a little worried about getting a tight seal at the deck of the block. That's a well founded fear because with a metal head-gasket sealing is dependent on the ra (roughness average) on the gasket mating surfaces, i.e. block deck and the bottom of the cylinder head. Any scratches or excessive roughness on these surfaces will cause compression leak and/or water and oil loss into the atmosphere or internally.
I'm guessing based on your posts that the failure you experienced was not because of your mhg, more likely it failed because of the mating surfaces not being machined to a high enough ra. The thing is... it might seal to the point where the car will run as long as you don't put any real pressure on it, but when you get into even medium boost levels that mediocre seal doesn't hold up, and wham cylinder leakage.
I'm guessing you're in a rush to get it done so you have wheels, but it would certainly be worth it to pull the block or even have the car towed in to avoid removal of the engine (if the deck of the block isn't to bad a good machinist might be able to get it to a high enough ra while the block is still in the car). I've done it by hand, although it's so fucking tedious that I don't recommend it and the chance for goofing it up is high. A composite head gasket is certainly an option and it will seal better than trying to put the mhg on an improperly prepared surface, but it's not going to allow you to boost much past stock for very long.
Let us know how it works out.
I'm guessing based on your posts that the failure you experienced was not because of your mhg, more likely it failed because of the mating surfaces not being machined to a high enough ra. The thing is... it might seal to the point where the car will run as long as you don't put any real pressure on it, but when you get into even medium boost levels that mediocre seal doesn't hold up, and wham cylinder leakage.
I'm guessing you're in a rush to get it done so you have wheels, but it would certainly be worth it to pull the block or even have the car towed in to avoid removal of the engine (if the deck of the block isn't to bad a good machinist might be able to get it to a high enough ra while the block is still in the car). I've done it by hand, although it's so fucking tedious that I don't recommend it and the chance for goofing it up is high. A composite head gasket is certainly an option and it will seal better than trying to put the mhg on an improperly prepared surface, but it's not going to allow you to boost much past stock for very long.
Let us know how it works out.
If you go composite, you may want to opt for a coating of copper spray as well, just to be safe 
.
.
i run, or ran (takin it easy these days) 14psi with a oem hg with copper spray and arp studs. seems safe
I ran a 57 trim on stock GE block with MHG.
Lasted about 2 months at 10 pounds. Went boooooooooom.
Lasted about 2 months at 10 pounds. Went boooooooooom.