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911st 911st is offline
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Join Date: Jan 2004
Location: Sacramento
Posts: 7,269
Dave I get what you are saying and may use that technique in the future. I to was wondering where it came from and thought the artical I referanced was the first place said quote was used.


I am still learning.

It is not the best writing but thought it better than mine if you labored through it.

I will look for some more reference but that article reflects the major points I am thinking are the keys to a split system.

The big one being, it keeps there from being two exhaust valves from being open at the same time which can reduce pressure at the only open exhaust valve on that bank. In turn this makes for better cylinder filling.

The other is it creates an advantage at the turbine by how the exhaust relates to the wheel.

They get a little deep saying we can increase over lap.

My take away from that I might put like this: A C2 cam has a small amount of over lap. A 930 has none. I am guessing he is saying that if there is less pressure in the cylinder when the exhaust valve closes, they can run a little bit more overlap to a benefit. Overlap if used right should increase HP for two reasons. Longer duration and cleaner cylinder fill.

I do not think comparison to scavenging on a normally aspirated race motor made it any clearer though I get his point.

I love that picture of the BMW 6 posted.

What I see is two banks to a split turbinee. Each side has log style manifolds inside an encasement not unlike our heat exchangers to be more thermally efficient, be easer to build, and weigh less than a cast iron system.

They seem to have sized the turbine such that they can control boost by only bleeding off one bank.

All cool stuff.

What am I missing or getting wrong please.

Thanks if you can help.

Last edited by 911st; 06-06-2010 at 08:22 AM..
Old 06-05-2010, 09:02 PM
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