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WERK I WERK I is offline
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Join Date: Jan 2003
Location: Wisconsin
Posts: 3,291
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Quote:
Originally Posted by 911st View Post
I am sure the vote of support is appreciated by Brian.


As to equal length increasing efficiency and power on boost I totally agree.

In my opinion, saying that Brian's or any equal length system will contribute to off boost response is a stretch without testing or some other technical cause in support of such a position like reduced volume via greatly reducing the WG circuit lengths and or smaller tube id's.

I might hope, and it may very well be, that we see an improvement over a stock late 930 header in all such areas as it dose have its weaknesses (cross over & long J pipe).

However, it would not think it should be expected to make improvement pre-boost over a well designed lower volume non equal length system.

If better pre-boost operation were an expectation of equal length 930 headers, the others that came before would have been screaming so from the highest roof tops. After all B&B proved 930 owners will spend a fortune in search of less lag.

It just seems to me concluding such would be more a leap of faith than logical conclusion.

Please do not get me wrong. I think Brian's system is potentially the best new product to some along for a 930 in some time and may buy one some day as it is targeted right inline with my goals.

I just don't understand how you can think this can be a leap of faith instead of a logical (actually it's been proven) conclusion. We're not colliding neutron's here, this stuff has been around and proven for over half a century.

Equal length primary's have been proven since.......the 60's, maybe even before that.

Furthermore, B&B headers are not considered a fortune, actually they're considered more of a modest-priced solution. If you want to scream about headers, check out a set of Bob Holcomb's equal length turbo headers.

Please don't use volume when talking about intake or exhaust tracts. It implies that the closer one gets to a zero diameter pipe, the more power can be extracted by the turbocharger. Exhaust primary size is calculated by number of cylinders, displacement, port size and target operating rpm range.

It's really quite simple so let's not over think this.

1.) An ideal header for a turbocharger will have the shortest primaries possible.
A turbocharger is driven by the velocity and energy of the exhaust gas.
2.) It will incorporate equal length primaries to aid scavenging (correct spelling) and insure exhaust pressure pulses do not overlap, which build up back pressure on overlapped cylinders and create uneven exhaust pulses fed to the turbine.
The length of the primaries before the joint is determined by calculating the desired rpm operating range and pipe diameter. The traveling pressure wave out one primary pipe will create negative pressure in the adjacent cylinder which will aid the scavenging of exhaust when that cylinder's exhaust port opens.
3.) And there's the quandary; Doing both without compromise, is impossible.

Study the turbo'd CART and F1 engines. The engineers of these engines squeezed every possible HP out of the engine and........they had equal length primaries.
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Dave
'85 930 Factory Special Wishes Flachbau
Werk I Zuffenhausen 3.3l/330BHP Engine with Sonderwunsch Cams, FabSpeed Headers, Kokeln IC, Twin Plugged Electromotive Crankfire, Tial Wastegate(0.8 Bar), K27 Hybrid Turbo, Ruf Twin-tip Muffler, Fikse FM-5's 8&10x17, 8:41 R&P
Old 01-13-2010, 04:58 PM
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