Pelican Parts
Parts Catalog Accessories Catalog How To Articles Tech Forums
Call Pelican Parts at 888-280-7799
Shopping Cart Cart | Project List | Order Status | Help



Go Back   Pelican Parts Forums > Porsche Forums > 911 / 930 Turbo & Super Charging Forum


Reply
 
LinkBack Thread Tools Rate Thread
Author
Thread Post New Thread    Reply
Turbonut
 
Raceboy's Avatar
 
Join Date: Jun 2009
Location: Estonia, Europe
Posts: 1,198
Garage
Quote:
Originally Posted by RarlyL8 View Post
Street turbos spend little time on boost which is where a properly sized tuned system helps out. There is also a bump in HP at the top end as the organized pulses hit the turbine in order.
This only applies to single-entry turbine. Twin scroll turbines with properly split (1+4 and 2+3 on 4cyl, 1+2+3 and 4+5+6 on 6cyl) exhaust manifold will neglect the necessity for making long tube headers. Thus, with twin-scroll turbine you get the best of worlds: short headers for fast spoolup+compactness without having to sacrifice top end.
Tube sizing is important as I said it already in my last post because the slower exhaust gases flow the more heat they lose -> less energy for turbine.

__________________
'83 924 (2.6 16v Turbo, 530hp),'67 911 hot-rod /2.4S, '78 924 Carrera GT project (2.0 turbo 340 hp), '84 928 S 4.7 Euro (VEMS PnP, 332 HP), '90 944 S2 Cabriolet
http://www.facebook.com/vemsporsche
Old 06-10-2012, 12:42 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #21 (permalink)
Registered
 
clutch-monkey's Avatar
 
Join Date: Nov 2010
Location: Brisbane
Posts: 917
is a twin scroll single turbo setup a bolt on proposition for 3.3 965?
Old 06-10-2012, 01:25 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #22 (permalink)
Registered User
 
Join Date: Nov 2008
Location: Austin, TX
Posts: 205
No black magic - just found some ways to reduce backpressure in the very limited rpm/boost band he was racing in.

At the time he was very quick - high 7's in the quarter in a 1.3L tube chassis car.

Both size and length of the exhaust manifold tubes have an impact on response and power. For a car with a narrow operating range, (ie. a drag car operating only from 7k to 9k rpms and with 36psi of boost) those things can be optimized.

Quote:
Originally Posted by Raceboy View Post
It is no black magic, it is common knowledge of 4stroke engine and turbochargers.

Since spinning the turbine is all about energy, the less energy you waste before it reaches turbine, the best spool and power you get as it is not the speed of the gases that turns the turbine, it is the heat energy of the exhaust. The faster you get the gas onto turbine blades, the less energy is wasted by cooling (=heating the exhaust manifold). This is the reason for opting for smaller headers.
The reason behind the most power with long headers was because the turbine was single inlet type and the primaries were just separated longer thus not letting the pulses to work against each other. Twin turbo (one bank of cylinders feeding each turbo) or twin-scroll turbine housing do the same with very short headers.
And when searching for the point where most energy is expanded (though I cannot see any reason why one needs to find it) can be found easier: using EGT sensor and moving it in the exhaust.
Old 06-10-2012, 07:12 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #23 (permalink)
Crotchety Old Bastard
 
RarlyL8's Avatar
 
Join Date: Jan 2000
Location: Huntsville, AL
Posts: 14,357
Garage
Short un-equal twin scroll design will narrow the gap of effectiveness when compared to a tuned system but the tuned system still has each pulse arriving in order. The twin scroll turbo has only one common shaft so cannot act independent. Off-boost torque is also improved with a tuned system. You don't want to be on boost in a street car tooling around town as fuel mileage will be horrific. Race cars are a different story with different design constraints.
This system we put together combines all of the above, tuned primaries and secondaries, split plenum for use with twin scroll turbo and dual wast gates that isolate each bank of cylinders. Many applications and options, this is just one.


__________________
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 06-10-2012, 10:45 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #24 (permalink)
Registered
 
totle's Avatar
 
Join Date: Oct 2008
Location: Norway / Miami
Posts: 1,324
Garage
Nice setup Brian
__________________
Trond R.
1979 930: Garret GT35r turbo, EFI, carerra intake, Link EMS, custom GT2 cams, 98mm JE P/C, 964 crank (stroker), custom valves & ported (XtremeCylinderHeads) etc..etc..
1972 914-6 GT replica project
1986 944 Turbo
Old 06-10-2012, 12:10 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #25 (permalink)
Registered
 
clutch-monkey's Avatar
 
Join Date: Nov 2010
Location: Brisbane
Posts: 917
Quote:
Originally Posted by RarlyL8 View Post
Short un-equal twin scroll design will narrow the gap of effectiveness when compared to a tuned system but the tuned system still has each pulse arriving in order. The twin scroll turbo has only one common shaft so cannot act independent. Off-boost torque is also improved with a tuned system. You don't want to be on boost in a street car tooling around town as fuel mileage will be horrific. Race cars are a different story with different design constraints.
This system we put together combines all of the above, tuned primaries and secondaries, split plenum for use with twin scroll turbo and dual wast gates that isolate each bank of cylinders. Many applications and options, this is just one.


for a street car 965 that is otherwise stock, do you just bolt the headers with wastegates and turbo's on, and away you go? no efi or anything, stock 3.3
Old 06-10-2012, 06:18 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #26 (permalink)
 
Crotchety Old Bastard
 
RarlyL8's Avatar
 
Join Date: Jan 2000
Location: Huntsville, AL
Posts: 14,357
Garage
Yes this system can be used on a CIS 965, however there is no provision for the driver's side tailpipe which is occupied by the wastegate catalytic converter. Turbo choice needs to match projected output which would be ~400WHP for typical CIS mods. Heater hard pipe may need to be exchanged for SCAT tubing. Turbo lines up in the stock location and can use my 965 muffler or any other that fits OEM.
__________________
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 06-10-2012, 07:40 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #27 (permalink)
Turbonut
 
Raceboy's Avatar
 
Join Date: Jun 2009
Location: Estonia, Europe
Posts: 1,198
Garage
Very nice setup!
Though my point was that tuning primaries is not that important when using twin-scroll (equal length) compared to traditional turbine where pulses collide.

And twin turbos eliminate many problems by default (pulses are split, no restraints of header length etc).

Having tested both single and dual wastegates, I prefer single because there was no noticeable difference in spoolup and response. Since the pulse splitting is done to improve transient response, the wastegate is closed anyway during spoolup (at least when both chambers are controlled, the proper way). Plus single wastegate eliminates differences in wastegates.

But I think we do realise that we are talking about the last few percents of performance here, right? When you see some setups that look like they would never work, yet they do, it is clear that to have fun with the car (and that's why we do it, right?) one should not overcomplicate things.

Here's my favourite example: Old Soviet Moskvich, built by Finn Ville Oksanen, has original engine with 1500cc, factory Volvo pistons+rods, original head, crank, block and 800hp with two turbos (one feeding other, compund setup). Has driven for more than 10 years and not a single failure at the drag-races, best time so far is 8,8s @ 257 kph (1/4 mile of course). Everything is selfmade, only ECU (Hestec) and gearbox are bought items. Basically built from scrap, even turbine housing is self made of sheet metal. Though the guy is aeronautic engineer, that would explain things. He has videos in youtube also, do a search if interested.

Cheers!





Quote:
Originally Posted by RarlyL8 View Post
Short un-equal twin scroll design will narrow the gap of effectiveness when compared to a tuned system but the tuned system still has each pulse arriving in order. The twin scroll turbo has only one common shaft so cannot act independent. Off-boost torque is also improved with a tuned system. You don't want to be on boost in a street car tooling around town as fuel mileage will be horrific. Race cars are a different story with different design constraints.
This system we put together combines all of the above, tuned primaries and secondaries, split plenum for use with twin scroll turbo and dual wast gates that isolate each bank of cylinders. Many applications and options, this is just one.

__________________
'83 924 (2.6 16v Turbo, 530hp),'67 911 hot-rod /2.4S, '78 924 Carrera GT project (2.0 turbo 340 hp), '84 928 S 4.7 Euro (VEMS PnP, 332 HP), '90 944 S2 Cabriolet
http://www.facebook.com/vemsporsche
Old 06-10-2012, 11:33 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #28 (permalink)
Reply

Thread Tools
Rate This Thread
Rate This Thread:

 


All times are GMT -8. The time now is 03:30 PM.


 
Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2021, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2020 Pelican Parts, LLC - Posts may be archived for display on the Pelican Parts Website -    DMCA Registered Agent Contact Page
 

DTO Garage Plus vBulletin Plugins by Drive Thru Online, Inc.