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Cobalt Cobalt is offline
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Originally Posted by 911st View Post
Sorry but my spell check did not work.

Porsche sized the K27-7200 almost perfictly to match the fueling of 930 CIS fuel head. What is happening with the C2T 3.3 is it dose start to run up against the limits of the turbo. Thus, it can not maintain full boost to red line.

The C2T 3.6 is alread at the limit for the 7200. Adding boost will mostly help in the mid range but there will be little gain up top.

The limit of the K27-7200 is in the 370-380hp range. Again this is about the limit of the fuel head. To deal with this Porsche changed the on boost control pressure that gets a little more fuel for the 3.6.

I would use that simple caluclation as the most just changing boost would get. In most cases losses in effecency will make the gain a percentage of this.

Changing the exaust increasses effecency with not change in boost. This can add HP. Changing the turbo to one with a larger more effecent compressor wheel will see increasses in effecency from not heating the air as much and allow the car to maintain boost higher into the upper RPM range.

The 3.6 if taken to 1 bar is potentally a 400hp motor. However severl things have to be addressed to do this. It needs a turbo cappable of supporting it, it needs a fueling strategy, it needs the restrictive cat to be removed, it may need the intake ports to be opened up a bit.

As to triggering the overboost switch. All WG's tend to overshoot there target at first and then stabilize at there target pressure. They also start to leak boost some before they hit there target level. Some of the electroic boost controlers go through a set up and learn how the WG responds. With this the can keep the WG clamped untill the desired boost level is reached. They also work on the other end to keep it from over shooting.

Not an expert, just my thoughts.
Makes more sense. I ended up changing out the exhaust and using a HF K27 to reach the 380 rwhp I am at right now. Boost comes up to 14psi and does creep ever so slightly to 14.8 psi but no where near the fuel pump cut outs

Originally Posted by 911st View Post
Great idea! This increases the pressure differential on each side of the hot wheel for earlier boost onset, quicker boost build, and extended boost level up top.

Then if it is a 930, a better inter-cooler for another 20-30hp on the same boost.
I agree more is gained by changing out the exhaust than adding the additional boost.
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Old 02-27-2009, 06:40 AM
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