So this is what I think I might want out of a supercharged A8
01-17-2005, 10:05 AM
#11
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Something we haven't talked about yet -- emission legal
Our motors have very aggressive cams with quite a bit of overlap, intake and exhaust valves simultaneously open. When I modeled the S8 motor with even a low boost twin-screw supercharger, there was short circuiting -- at almost every engine speed, some air/fuel mixture just blows straight thru the cylinder into the exhaust.
At 4.9 psi boost at 5000 rpm and before the exhaust valves close, 1.1% of the unburnt air/fuel mixture blows into the exhaust pipes at the beginning of the intake cycle. The oxygen in the exhaust will probably result in the CEL being on continuously, and when the air/fuel mixture hits the cats, they'll overheat badly. Even if they don't melt, I'd expect them to be damaged. You could always remove the cats, but you'd never pass an emission test. PA won't even test the car with a CEL.
This may be the big advantage of either centrifugal superchargers or turbos. Since they're providing negligible boost at lower rpm's, they might still pass emission tests. You will still have sort circuiting at high rpm, though, so perhaps the cats will need quick disconnect fittings.
At 4.9 psi boost at 5000 rpm and before the exhaust valves close, 1.1% of the unburnt air/fuel mixture blows into the exhaust pipes at the beginning of the intake cycle. The oxygen in the exhaust will probably result in the CEL being on continuously, and when the air/fuel mixture hits the cats, they'll overheat badly. Even if they don't melt, I'd expect them to be damaged. You could always remove the cats, but you'd never pass an emission test. PA won't even test the car with a CEL.
This may be the big advantage of either centrifugal superchargers or turbos. Since they're providing negligible boost at lower rpm's, they might still pass emission tests. You will still have sort circuiting at high rpm, though, so perhaps the cats will need quick disconnect fittings.
01-17-2005, 01:54 PM
#20
Me and my bad grammar is here again.
I didn't know, that people have a tough time reading my posts. To move to another country at age of 33 is not easy. Make a living support the family and learn another language at the same time is tough, but thanks to you guys, I think I am on the right track. I never purchased anything from Motodyne and obviously I never will. The person who started the whole thing with the ebay auction didn't even posted after that. Maybe it was a retaliation from a ripped off customer or reading 2-3 or I don't know how many chairs posts, maybe one of his own employee started the whole dirt digging. I guess I started digging, when he called Paul a liar. The whole thing went the wrong direction because of the missing belt. Being a metal fabricator, I can see that the SC is a nice work whoever made it, but we never saw any timeslip or written proof. Even if it works, you can put it only an older car because it would void the warranty, but the price tag is ridiculous. For example Toyota sells their SC for around $4500 and it is emission legal with full factory warranty and that is real. You can see it, you can test drive it and they kissing your b*tt to buy it. I don't see any butt kiss here. Actually I see one. Anyway, this is my last post about this mysterious SC and I just want to apologize to all AW members who came here to relax and couldn't find peace a last couple of days.