"Originally used as a racing part by Volkswagen Motorsport, this is a high strength gasket suitable for any race engine. Autotech has found this gasket to be the perfect street upgrade for low-compression (8.6:1) engines. The thinner compressed thickness raises the compression ratio on an 81 mm bore JH motor (used in the Rabbit GTi) from 8.6:1 to approximately 9.4:1! The increased compression boosts torque and responsiveness. Fits all 1.8 liter engines, including 16V. 83mm max. bore. 1.4mm thickness compressed."
Does anyone know what the compressed thichness of a stock head gasket is? Based on the CR difference numbers claimed on the Platinum Europarts site, I calculated that this gasket must be 1.0mm thinner than the stock gasket. They say this gasket has a compressed thickness of 1.4mm that would make the stock gasket 2.4mm or almost 1/10" and that seems WAY too thick too me, those numbers can't possibly be right. Anybody out there have numbers that make sense?
I agree completely, it does not add up. When calculating the compression ratio of an 83 GTI head on it's original block after a port and polish job which included unshrouding the valveseats and polishing the combustion chamber i calculated that a 2mm head shave would raise the compression ratio from 8.5:1 to around 9.85:1. I used a compressed gasket thickness of 1.5mm and a head gasket volume of 7.73cc. Piston volume was 22.5cc and head volume was 29cc. Based on all these measurements, in order to get a compression change from 8.5 to 9.4 you would have to shave about 1.5mm of the gasket. Kinda hard when the stock one is about 1.5mm compressed to begin with. Even if the gasket was thicker you would still have to shave 1.5mm or so to get 9.4.
I don't think so, please enlighten me. BTW, I just measured an old head gasket off of my JH, its a felpro aftermarket gasket, it's 1.65mm thick so, the 1.4mm group A gasket would bump the CR from 8.5:1 up to a whopping 8.67:1. IMHO, that's a rip off.
I'd love to believe that you could get a 0.8 cr increase just by changing the head gasket but, I've tried everything I could to make those numbers work but, I don't come anywhere close to the increases claimed in the ad. Either there's a piece of information missing or someone's lying. If I'm wrong PLEASE prove it to me with details.
hmmm Im not quite sure what you were trying to say, but I dont need to do the calculations, I drove his car before the head gasket swap and then I drove it after and it was noticibly faster. So really I couldnt give a rats ass weather the calculations add up or not, it made the car faster.....
What catalogs? WTF are you talking about???? Dude IT DOES MAKE THE CAR FASTER!!!! Reputable companies such as autotech would not sell somthing that does not work. Why the hell would they claim somthing they cant back up, I mean damn*! Ask anybody who has it in their car and they will tell you that it makes it faster, what about that cant you understand!
Autotech has a catalog with a picture of head gaskets and listings for several different ones including the Group A but it says nothing more about it then what was mentioned above. It is supposed to have a compressed thickness of 1.4mm. If that is correct then the stock gasket would have to have a compressed thickness of somewhere around 2.9 to 3mm thick. Hmm.
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