[flash]

it would be interesting to see just how 9m got that much out of it. i read that they blew one up trying, and then had to drop the compression ratio and run headers. i wonder what else they did, because the OEM manifold is reported to be a limiting factor. perhaps they used the S2 manifold?



craig - i would not be trying to get that much power out of an air cooled unit though. the heat is going to be potentially very ugly. i've heard stories of people blowing up that particular unit when they get it hot, and nowhere near the output you are talking about.



as for the head gasket, as i remember, a 1.4 (versus the OEM 1.1) on a standard thickness head only drops it to somewhere around 10.5

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[craigawoodman]

Flash,



THe only issue raised in the article on the car is that the OEM Cat could not cope wit hthe flow (the headers were glowing red) and the Cat melted, so they replaced it with a high flow cat which reduced the back pressure from the exhaust. This was part of the reason for going with the RSBarn high flow Cat and cat back exhaust - to de-restrict the exhaust.



As for the SC unit - the manufacturer is recommending an upgrade, which is higher capacity bearings and newer, reduced internal drive which lowers friction. I think the biggest issue with the Raptor unit is not over-speeding it, but if they have strengthened it, perhaps there is some merit in the stories.



I am a bit like a test pilot here, exploring the possibilities. Once this round of mods is complete and right - that is it for mods to the engine - it will be whatever it works out to be.

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[flash]

there is more than that article out there about their kits. i don't want to go bashing or anything. frankly i have no experience with their kit. i am actually just interested to see what they found about the manifold and any terminal pressure problems. i'd also like to know how the reliability has been.



i chose not to run the raptor specifically because it was air cooled. knowing what temps things get to there, that's just not a great idea. even porsche gave up on that. if they had an oil cooled unit, i might have thought differently.



good luck though. i certainly have to give you credit for plowing through. i'd have tossed in the towel a long time ago.

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[Eric_Oz_S2]

Craig



OK checked the effect of the thicker gasket. According to my crude calcs the 1.4mm gasket would drop the CR from 10.9 to 10.5 (S2) only, or in the 968 case to about 10.6. I'm not sure of the benefits of a wide fire gasket, especially at only 10 psi which is what a stock 944 turbo runs (albeit at a lower CR). You need a 1.9mm gasket to get down to 10.0:1.



You may have read the article on the UK car in 911 & PW (perhaps a year ago) where they dropped the CR for a 968 turbo engine build by machining the tops of the pistons (ie increasing the "bowl"). I think they dropped the CR to about 8.5:1 using this method. Apparently there is enough strength on the 968 forged pistons to remove some of this material without overly reducing their strength.

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[flash]

that's about what i remember too. i think pete told me that cometic makes a 2mm thick gasket that made it 10:1.



eric. i'd love to chat with you about your tuning. drop me a note.

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[Eric_Oz_S2]

Flash - send me a PM with your email

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