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911st 911st is offline
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Join Date: Jan 2004
Location: Sacramento
Posts: 7,269
Cheep, cheep, cheep!

I missed the concept of "grassroots" as in Grassroots Motorsports 2010 challenge.

Could build it as a 'blow through' using the existing CIS system.

Blow through would cut the plumbing in half and increase turbo response and efficiency.

Would have to fab the plumbing to the CIS and probably make a sheet metal plenum.

The old turbo off a stock 930 is a good fit for the HP, works with oil cooling and is cheap used.

Using a 930 J pipe would make it easy. Alternately, just stick the turbo in place of the cat to the side of the motor and up a bit and drain it into the valve cover. If so just keep the stock muffler ( I would add a second tail pipe on the other side). This would make it stealth.

Could just put an air filter on the turbo or if put in the stock location could use a 930 snorkel with an air filter on the end of it.

Get a cheep adjustable WG off of ebay. Or maybe use a Porsche take off and make a spacer to fit under the spring can for lower boost pressure.

Use a 1" plastic Bosch BOV or aftermarket. As a blow through system the WG can vent to atmosphere.

More fuel could be had from just setting CO fat, shimming the control pressure some, and or by tweaking the WUR for more fuel with loss of manifold vac. The Lambda might be left in place to keep freeway MPG.

As to the ignition, I believe SC's have a Vac-Retard can and the late models a very short mechanical advance. Might be able to re-plumb it from the ported vacuum directly to the manifold and change the pot to a 930 pot or other boost retard pot and use the boost retard side only. This should get rid of the idle retard which is only for smog, and give us on boost retard. Could always use the MSD retard. Or, just disconect the vac reg and set the timing at -20 or so full advance.

If one wanted to get crazy might be able to hide a 944T intercooler in the fender wheel and cut a hole in the fire wall between the wheel wheel and motor compartment. This might work by reindexing the turbo, adding an elbo, and running the IC sideways.

Originally Posted by DPHANS View Post

Last edited by 911st; 01-29-2010 at 05:34 PM..
Old 01-29-2010, 04:12 PM
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