[s-cars] 7A exhaust cam advantages

[Elijahallen92 at aol.com]

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In a message dated 12/7/2002 9:16:02 AM Eastern Standard Time, QSHIPQ at aol.com
writes:


> I'd be more interested in the duration and it's potential problems,
> especially on a 20vt application.  In the 10vt application, the Schrick 272
> gives 2mm more lift than the standard audi turbo cam, but that is majorly
> offset by duration (since it's a N/A cam).  So, the overlap causes really
> crappy VE below about 4000rpm where all hell breaks loose for the big HP
> number.  The VE is so crappy below that the turbo spoolup takes longer, is
> lower at the same rpm, and the gas mileage just sucks.  BTDT
>
> This would make me think that in a 20vt application, the 7A EC is probably
> going to affect the turbo motor application in much the same way.  This
> could
> be a really high problem in terms of O2 sensors, Catalysts and passing any
> type of rolling road emissions test.  I should perform better at the higher
> rpm's tho, where overlap on a turbo is less critical.  Another take some to
> get some application.
>
>

 I have a 7A cam and you are right on with the below 4000rpm it is pretty
slow. I also have a large turbo so I know that is part of the problem but I
had this turbo with the stock cam and it spooled up by 3200rpm and now it is
more like 3800rpm. The difference up top is that with the 7A cam boost does
not drop off until after 7000rpm and with the stock cam it started to drop
off at around 6500rpm. Also with the 7a once the turbo gets spooled you can
feel the power build all the way through the rpms. On the track were you are
in the 4000+rpm range it is great but around town you have to gear down if
want anything other than drone.

Elijah