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Crotchety Old Bastard
 
RarlyL8's Avatar
 
Join Date: Jan 2000
Location: Huntsville, AL
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Tony your setup should have little lag. Short tubes, twin turbos, EFI. All reduce lag.
A tuned system isn't about lag (or lack of) but rather it is about off boost torque and on boost horsepower. A CIS engine that is on boost all the time is very inefficient. It would suck gas like no tomorrow and be "twitchy" to drive. What I was after is a strong engine off boost that is more fun to drive in town. You retain the true turbo experience with a hit of boost when you want it. So many dynos you see show 100 HP at 3000RPM then a big jump when boost kicks. My goal is to maximize power on both sides of the bell. The turbo will do the rest.
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RarlyL8 Motorsports / M&K Exhaust - 911/930 Exhaust Systems, Turbos, TiAL, CIS Mods/Rebuilds
'78 911SC Widebody, 930 engine, 915 Tranny, K27, SC Cams, RL8 Headers & GT3 Muffler. 350whp @ 0.75bar
Brian B. (256)536-9977 Service@MKExhaust Brian@RarlyL8
Old 05-10-2014, 06:22 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #41 (permalink)
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Equal length does matter on a turbo setup. We want each puls to enter the turbine alone, not in clusters at the same time as this will increase back pressure. Equal length is desirable because we have unequal firing order. If all cylinders were to fire at same time, we would build un-equal length headers to reestablish separated puls entries. Same reason we pack each bank in a twin scroll setup with cylinders having each stroke most apart. Having said that, equal length is not the #1 critical consideration or priority when designing a correct sorted header, in fact compared to many of those branded 930 equal length headers on the market, you are still able to build by your self a much more efficient un-equal length headers if you know what you are doing!

In regards to primary tubing diameters. Unless running a false mixture of BIG +1000hp turbine area for 300hp applications, then on a turbo header + turbo setup it is the turbine housing area that primarily dictates the velocity to the turbine wheel, not the primary runners. You may tune for off-boost, but when we are building boost from 2500rpm upwards we go for most effective boost vs. back pressure setup. There is both much more power and spool-up in configuring a header and turbo correct and then set correct sized tubing for lowest possible back pressure.
Old 05-11-2014, 03:41 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #42 (permalink)
Rocket Scientist
 
Join Date: Jun 2008
Location: Detroit
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Well, this went better than last time. Three pages and it hasn't descended into name calling yet.

So, there are 240 degrees between engine firings on a bank, and the longest exhaust event is around 200 degrees. Hmmm....
Old 05-11-2014, 12:31 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #43 (permalink)
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Obviously my idea about tapering to Square has already been done thanks Vouitue
looks like no royalties for me
hmmm unless when hearing my idea you quickly went out and built that system when you heard me mention it???!!



Ok I get that velocity is a primary objective for reduced lag and peak output,
Is there anyway that we can we speed up that velocity?
Some like myself ceramic coat the inside of their turbos

So what about the other bits wold that improve velocity by reducing friction??
If i ceramic coated the inside of my headers and pipes would that show good gains?

friction = Heat
less friction = less heat = higher velocity without damage = ultimate 930
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Old 05-11-2014, 05:25 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #44 (permalink)
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[QUOTE=Robbbyg;8059505]Obviously my idea about tapering to Square has already been done thanks Vouitue
looks like no royalties for me
hmmm unless when hearing my idea you quickly went out and built that system when you heard me mention it???!!



Not me, I just have the car, builder was Bob Norwood, Dallas area, built 2002 to 2006. Started by someone and finished by AMAC and yours truly. Great car.



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Old 05-11-2014, 06:20 PM
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That engine bay shot never fails to produce wood!
Old 05-11-2014, 06:37 PM
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Crotchety Old Bastard
 
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Page 1 Post#16 you can see the transition from round to split plenum square with our headers.
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RarlyL8 Motorsports / M&K Exhaust - 911/930 Exhaust Systems, Turbos, TiAL, CIS Mods/Rebuilds
'78 911SC Widebody, 930 engine, 915 Tranny, K27, SC Cams, RL8 Headers & GT3 Muffler. 350whp @ 0.75bar
Brian B. (256)536-9977 Service@MKExhaust Brian@RarlyL8
Old 05-11-2014, 07:48 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #47 (permalink)
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