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911st 911st is offline
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Join Date: Jan 2004
Location: Sacramento
Posts: 7,269
Quote:
Originally Posted by jimmcc View Post
...where do the SSI 930 headers fall in design and what is the general consensus on their performance level?
Some thoughts and facts:

The late 930 headers are basically the same as the Carrera 3.2.

Per SW on a Carrera 3.2 w pre muffler and chip at 3500rpm makes about 122hp.
SSI w stock muffler and chip makes about 130hp or about 8 more HP at 3500 rpm.
At all other rpm they were equals.

Per a Bruce Anderson article that had dyno info for different exhaust combo's on a 3.2 Carrera that included comparing a stock header system with a RUF sport muffler against an SSI with 2/2 sport muffler, there was no real difference in hp anywhere except about 3000rpm. At 3k the came in:

98.6 for the stock headers.

102.8 for the SSI's or 4.2 more HP .

Thus on a normally aspirated 3.2 motor there was about a 4- 8hp difference between SSI's at stock headers. However, they were equals at all other points except at about 3000-3500rpm where the SSI's had a about a temporary 5% bump in power (savaging?).

From here we are just guessing!

First, it is debatable if Turbo motors at 3000-3500 would benefit from any savaging. It can benefit from more efficient timing of exhaust pulses.

From these two data points I would deduce or guess:

Boost onset would not change.

The time from boost onset to full boost goal might be shortened with the SSI's.

The HP in the early part of the mid range might be increased some.

What might be more reliant to shortening time to full boost would be the differences in total volume between the two. I would not guess SSI's have an advantage in this area.

What might be more relevant as to which might make the most HP could be tube sizes.

I believe the SSI's are 1.5" and the stock headers about 1 5/8's. However, the secondary tubes might change this. The SSI's may be modest by a big 930 turbo standards and the 930 header has the funky cross over and J tube. Call it a tie for now.

IMO with what I believe so far, the best thing about SSI's is the quality, heat, and maybe some increase in efficiency early and just past reaching one's boost target where the SSI might be a little more efficient.

My guess the SSI with the 1.5" primary tube's might be less than ideal for making HP on a track car but great for a street car.

I could very well be wrong but I would not expect a big difference between the SSI and stock late/euro headers if both use a great low restriction muffler.

Last edited by 911st; 01-13-2010 at 11:37 AM..
Old 01-13-2010, 11:34 AM
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