boostin' ?s - 7A cam comparison
benswann at verizon.net
Fri Apr 4 18:35:23 PDT 2008
I was just talking with someone about this and had speculated similarly as Bernie. I
was looking to do this on my RS2ised AAN/3B going into COUPE Q ala. ES2, and will
probably do it regardless..
So does anyone actually have anything more quantitative on actual results with using
either 7A Exhaust and/or in conjunction with intake cam?
How does it effect emissions, fuel economy, low-end torque, etc.? How much difference
in top-end is really attained with just the cam and nothing else being changed?
Has anyone done any dyno testing using variations on the theme, but mainly comparison
between cams with other factors remaining the same?
[Date: Fri, 4 Apr 2008 08:35:05 -0700
From: Bernie Benz <b.benz at charter.net>
Subject: Re: boostin' ?s
To: "Brandon Rogers" <brogers at terrix.com>
Cc: 200q20V mailing list <200q20v at audifans.com>
Message-ID: <EB0FFBB7-F2BB-435B-9D55-049E3BB2FAB5 at charter.net>
Content-Type: text/plain; charset=WINDOWS-1252; delsp=yes;
An ill-considered mod IMO, unless one is only interested in top end
power and no cares about fuel economy and smog approval. Using, just
slapping in the 7A exhaust cam will advance the valve timing,
favoring top end power at the expense of low end torque. Further, it
will increase the 3B?s zero valve timing overlap and allow turbo blow
thru degrading fuel economy and smog.
On Apr 4, 2008, at 7:32 AM, Brandon Rogers wrote:
> Plenty of people use the 7A cam(s) (exhaust I know - not sure about
> intake) and make good power - IIRC dyno result show top end increases but
> low to mid decreases. To convert the 7A you will want (need) a compression
> dropping head gasket. Tons of info on Motorgeek.
> On Apr 3, 2008, at 4:04 PM, Tom Egbert wrote:
>> How is your son planning to mod the 7A's valve timing to reduce or
>> eliminate the NA's valve overlap, such that the turbo can't just blow
>> I am not sure, but a spare 3-b head modded for coolant flow should
>> take care of that. I am more interested in my 200 20v getting 24
>> pounds of boost reliably.
> The 3B and AAN heads have the 4 outlet external coolant manifold. The
> 7A does not, just a single outlet.
> Ask him to respond with his valve timing mod plans.
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