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 > Porsche 924/944/968 Technical Forum


Reply
 
LinkBack Thread Tools Rate Thread
Author
Thread Post New Thread    Reply
Registered User
 
chapstic2001's Avatar
 
Join Date: Aug 2002
Location: Northern VA
Posts: 530
Send a message via AIM to chapstic2001
laaaaag BOOOOOOOOOOOST!!!

I need a Turbo 101 lesson. I have no clue how to measure boost. The only thing I know is BAR = barometric pressure.

How much boost does the stock '86 951 have?
What does 1 BAR equate to (.8 and 1.2 etc)?
Is it a HP gain?
What is the max boost one can have before the engine blows?

Anything else my simple mind needs to know, feel free to chime in.

__________________
'08 BMW e90 335i 6MT stock [aka 'take two']
'12 Dodge Durango [family hauler]
'86 951 (K&N Cone, Welt Chips, Tial, Zeitronix, P&P O-ring PH Head, WFHG, AFPR) [in storage]
Old 03-05-2003, 02:28 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #1 (permalink)
Registered User
 
Join Date: Oct 2002
Location: Loveland, CO
Posts: 610
Cool

Not sure what the stock 951 runs for boost, i think i heard 12 psi.
1.0 bar is equal to about 14.7 PSI.

Ive heard of stock 951's hitting 1.6 bar just fine, there is no way, thats like 24 lbs.

Wait till scott, or Jared responds, they are the turbo guys
Old 03-05-2003, 03:04 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #2 (permalink)
Registered User
 
Join Date: Oct 2002
Location: Loveland, CO
Posts: 610
PS - Get an aftermarket boost gauge to really know
Only $20 from here:
www.gaugepods.com
Old 03-05-2003, 03:05 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #3 (permalink)
Registered User
 
Join Date: Jun 2002
Location: Seattle, WA
Posts: 53
Send a message via AIM to DangerIsland
on the 951's boost gauge 1bar is equal to 0psi. less than the 1bar mark indicates a vacuum (no boost) which is the case for idling, etc. Anything over the 1bar mark is boost, therefor 1.6bar on the gauge is .6 bar of boost, which is about 9psi. 2 bar on the gauge would be 15psi, at which point the stock chips would cut fuel. Anything over 12 or 13psi on the stock chips will cut off fuel as a precaution. (1 bar is just about 15psi, just a little under, actually)

The aftermarket gauge is a much better way to know what kind of boost you are running.
__________________
p-car profile: http://p-caronline.com/directory/dangerisland/
Old 03-05-2003, 03:15 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #4 (permalink)
Registered User
 
Sam Grant's Avatar
 
Join Date: Mar 2002
Location: Indianapolis, IN
Posts: 639
.75 bar stock. Boost really doesnt blow engines, its not having the correct fuel to go along with the added air that causes lean mixtures causing things to go south. Also to much fuel isnt good either. To run more boost you need to tune with something, ie fuel controller/dyno. For any given boost level there is one correct fuel map. Up or Lower the boost and then you have botched the curve. I would say 25psi is about the limit I hear of people running on 951s.
__________________
1986 951
1995 M3 LTW
Old 03-05-2003, 03:24 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #5 (permalink)
Registered User
 
Scott R's Avatar
 
Join Date: Feb 2001
Location: Aspen CO US
Posts: 15,280
Garage
Yea my aftermarket boost meter was showing 12PSI during cutoff with the original chips.

Also as the above post stated with the correct fuel and management you can boost higher.

On stage 2 with my afterburner I have it set to 18PSI, stage 1 I keep around 16.


http://www.lindseyracing.com/boost5.htm


(BTW for those of you looking for some serious power, I might be selling soon. I have an itch for a Ferrari thats for sale locally, unless I just keep both and build another garage.)
__________________
2018 Q5 Hybrid
2005 Cayenne Turbo
2012 Panamera 4S
1980 911 SC
1999 996 Cab

Last edited by Scott R; 03-05-2003 at 05:13 PM..
Old 03-05-2003, 05:05 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #6 (permalink)
 
Registered User
 
Join Date: Jul 2002
Location: Washington DC
Posts: 619
Stock 951's should be around 12PSI - most aftermarket chip setups will put you around 14-15PSI.

As far as max boost - I wouldnt try to go any higher than 18PSI on an 86 - the K26 runs out of steam quick after that. (K26 = your turbo).

The block handles high boost well - but youll need a bigger blower to push it.
__________________
96 993
88 911 (Sold)
87 951 (Sold)
Old 03-05-2003, 06:47 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #7 (permalink)
Registered User
 
924turbo's Avatar
 
Join Date: May 2001
Location: Simi Valley, CA, USA
Posts: 70
Not to nitpick too much, but 1 bar = 14.50326 psi.

Bars are not equal to atmospheres.

1 atm = 14.6959 psi.

Yeah, I know they're really close.
__________________
Jon Furst
Old 03-06-2003, 02:57 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #8 (permalink)
Registered User
 
chapstic2001's Avatar
 
Join Date: Aug 2002
Location: Northern VA
Posts: 530
Send a message via AIM to chapstic2001
Bear with me on this. I think I am getting it. So basically .1 bar above 1 = 1.5lbs of boost. Then the max bar on my 951, 2bar is equal to 15lbs, but Porsche stock tells the fuel brain (KLR or DME, I can never remember which) to cut off at 12lbs, or 1.8BAR? So is it the wastegate that holds the pressure until it is set to release and thus the surge of booooost?

Sam, good point, I didn't take into consideration fuel management and the proper injectors balancing more air/fuel mixture.
__________________
'08 BMW e90 335i 6MT stock [aka 'take two']
'12 Dodge Durango [family hauler]
'86 951 (K&N Cone, Welt Chips, Tial, Zeitronix, P&P O-ring PH Head, WFHG, AFPR) [in storage]
Old 03-06-2003, 02:25 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #9 (permalink)
Registered User
 
Join Date: Dec 2002
Location: Monett, MO
Posts: 1,085
Hmmmm, I think you got it. When the KLR box senses around 11psi it will trigger the timing valve to open pressure from the intake system to the wastegate letting it open to bleed off exhaust before reaching the turbo to reduce it's speed therefore reducing the pressure it's putting on the intake. does that make sense? The surge of boost that you're getting is the "lag", not the wastegate opening. It's the time it takes for the turbo to spool up and compress the intake air, that's what you feel(when it's starting to compress). It really doesn't take long for the klr to start bleeding off the boost, as mentioned earlier the k26/6 can boost alot even up over 27psi, but it really runs out of steam in the upper rpm band and falls to 18 or so, but that is also the limit of the stock wastegate not necessarly the turbo. The most I run right now is 25#'s but that's w/ a garrett T4, it feels good! Did I make any sense or was that just a bunch of bla??? I'm not feeling too well and I think I'm on too many meds to think right, right now.
Old 03-06-2003, 07:43 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #10 (permalink)
Registered User
 
gearhead290's Avatar
 
Join Date: Dec 2002
Location: South Dakota
Posts: 1,131
Send a message via AIM to gearhead290
Made sense to me highboost. How much boost can be run on stock internals? Which turbos came on which models? How much boost will eash turbo hold to redline? What do you all need to get the fuel system to handle 25 psi?
__________________
95 240sx-track slut w/ too much done to list
87 944 n/a-old "toy" that broke too much
Old 03-06-2003, 08:23 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #11 (permalink)
Registered User
 
Join Date: Dec 2002
Location: Monett, MO
Posts: 1,085
The stock internals(engine that is) can hold a lot of boost, just as long as there's enough fuel to go with it. I and many others have run 24-25psi on stock internals, but when doing that you need to expect something to go wrong if the car hasn't had proper maintenance. The cars where built to last, but helping them out doesn't hurt, that's way it's nice to lighten the crank/rods, do coatings on the piston tops, piston skirts, cyl. head, put in a widefire gasket, raceware studs, etc.

To run that kind of boost you'll need a bigger fuel pump such as the S2 or 928gts fuel pump, bigger injectors, fuel pressure regulator, and of course new fuel mapping/controller/or new engine mgmt.

But also, to not have to run that much boost you can improve the stock internals to accept more air easier; therefore lowering the amount of boost you have to run to get it in there, ex. cams, porting, valve jobs, etc.

the k26/6 was offered on the stock turbos, and the k26/7 was offered on the turbo S, the S holds more till redline due to it's large hotside, but it suffers from more turbo lag due to it's size in comparison w/ the k26 hotside.
Old 03-07-2003, 09:04 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #12 (permalink)
 
Registered User
 
Join Date: Jun 2002
Location: Seattle, WA
Posts: 53
Send a message via AIM to DangerIsland
The TurboS has a #8 hotside actually, making it a 26/8. It's a great unit by all accounts, I'm considering upgrading to one if my turbo is dead.
__________________
p-car profile: http://p-caronline.com/directory/dangerisland/
Old 03-07-2003, 11:13 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #13 (permalink)
Registered User
 
Join Date: Dec 2002
Location: Monett, MO
Posts: 1,085
you're absolutely right, it's a k26/8, not sure if that was some brain fade or a mis-type, hmmm too many cold and sinus pills today. Anyways, I'm not too happy with them, too much lag unless you have a map/maf/standalone to help it out. You can rebuild your k26/6 and trick it out get some more out of it, faster spool up and better flow when you stick a larger compressor in it, they can reprofile the hot side to take a larger one, crop the blades, etc.
Old 03-07-2003, 12:06 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #14 (permalink)
Registered User
 
chapstic2001's Avatar
 
Join Date: Aug 2002
Location: Northern VA
Posts: 530
Send a message via AIM to chapstic2001
Thank you. I spoke to a buddy at work about boost pressure. Stock vs. chipped....and I sounded intellegent!
__________________
'08 BMW e90 335i 6MT stock [aka 'take two']
'12 Dodge Durango [family hauler]
'86 951 (K&N Cone, Welt Chips, Tial, Zeitronix, P&P O-ring PH Head, WFHG, AFPR) [in storage]
Old 03-10-2003, 02:37 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #15 (permalink)
Registered User
 
Join Date: Dec 2002
Location: Monett, MO
Posts: 1,085
Ah yes grasshopper!

Old 03-10-2003, 09:22 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #16 (permalink)
Reply

Thread Tools
Rate This Thread
Rate This Thread:

 


All times are GMT -8. The time now is 08:23 AM.


 
Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2020, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2018 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.