A Little Long, Sorry - NA w/ Blown Head Gasket(?) - Advice?, "While-I'm-In-There"?
09-03-2004, 09:48 PM
#16
Race Director
Dan, don't worry about increasing combustion pressure in the engine, that's where extra power comes from! Considering that this block and head can support 500hp in boosted applications, no worries about that. I'm even using an '86 944NA with 9.5:1 compression in my 951 at 18psi boost and no problems! My head was old, so I may need to redo it soon since the valve-stem seals are leaking.
Also on the headgasket, the compression ring is a solid 5mm wide ring, unlike the hollow 0.1mm thick compression ring in the stock & widefire headgaskets (photos of cross-section in my PDF dissertation). The solid compression ring is also slightly thicker than the surrounding headgasket, so you end up with extra clamping force on the compression-ring for tighter sealing.
No worries about anodic corrosion with different materials because the stock gasket's compression-ring is steel also. The anti-corrosion additives in the coolant is what prevents this type of corrosion. As for expansion-rates, aluminium does expand more than steel, so when the engine warms up, the clamping on the headgasket gets tighter and tighter. That's because the head-studs are steel and doesn't expand as much as the aluminium head and block.
This gasket has been used for numerous years in high-boost (45psi+) drag-racing applications with hot-rod Mustangs, Corvettes, even Hondas. It's the standard in cart-racing engines and motorcycles and jetskis. It's just taken some time for the Porsche folks to accept it that's all; it's quite a bit above & beyond the stock & widefire gaskets in technology and performance.
If you want a standard 3-angle valve-job, Frank can get you one for cheap, just a couple hundred bucks. Might as well mill it for higher compression as well. The one I'm using on top of my 9.5:1 NA engine has been milled a full 0.060", which should raise compression to about 9.8:1 or so.
Also on the headgasket, the compression ring is a solid 5mm wide ring, unlike the hollow 0.1mm thick compression ring in the stock & widefire headgaskets (photos of cross-section in my PDF dissertation). The solid compression ring is also slightly thicker than the surrounding headgasket, so you end up with extra clamping force on the compression-ring for tighter sealing.
No worries about anodic corrosion with different materials because the stock gasket's compression-ring is steel also. The anti-corrosion additives in the coolant is what prevents this type of corrosion. As for expansion-rates, aluminium does expand more than steel, so when the engine warms up, the clamping on the headgasket gets tighter and tighter. That's because the head-studs are steel and doesn't expand as much as the aluminium head and block.
This gasket has been used for numerous years in high-boost (45psi+) drag-racing applications with hot-rod Mustangs, Corvettes, even Hondas. It's the standard in cart-racing engines and motorcycles and jetskis. It's just taken some time for the Porsche folks to accept it that's all; it's quite a bit above & beyond the stock & widefire gaskets in technology and performance.
If you want a standard 3-angle valve-job, Frank can get you one for cheap, just a couple hundred bucks. Might as well mill it for higher compression as well. The one I'm using on top of my 9.5:1 NA engine has been milled a full 0.060", which should raise compression to about 9.8:1 or so.
