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 Technical BBS > 1- Porsche Technical Forums > 911 / 930 Turbo & Super Charging Forum


Reply
 
LinkBack Thread Tools Rate Thread
Author
Thread Post New Thread    Reply
Crotchety Old Bastard
 
RarlyL8's Avatar
 
Join Date: Jan 2000
Location: Huntsville, AL
Posts: 13,408
Garage
I believe that is the same unit I have. It looks like this installed:

__________________
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 04-19-2008, 08:49 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #61 (permalink)
Certifiable
 
Quicksilver77's Avatar
 
Join Date: Jan 2008
Location: Folsom, CA
Posts: 194
Send a message via Yahoo to Quicksilver77
OK I'll pony up! Nothing like the right tool for the job! Plus buying tools makes a guy feel infinitely more manly!

Though in regards to the cold pressure vs. the warm pressure the settings: from BL these were 2.2 cold and 3.75 warm. Is this saying that the fuel pressure should be 2.2bar upon start up and 3.75bar after warm up?
Shouldn't these be reversed? more pressure/fuel at startup? and then leaning out at warm operation? I would tend to think that the higher pressure would push more fuel into the cylinder in a shorter amount of time leading to a rich air fuel mixture.

Or does a higher pressure result in a leaner air fuel mixture by creating a more aerosol-ed fuel spray from the injector, which would explain why BL set the WUR as he did? Not questioning BL in any way shape or form, just trying to understand!
__________________
Sean D. 1987 930
India Red/Beige/Black; Mahle 3.4L; Kokeln IC; K27 7200; GHL Headers; Borla Stainless Muffler; SC cams; Sachs Aluminum Clutch; Aluminum flywheel; Bilstein Sport Shocks; Adjustable Rear Sway Bar; Weltmeister Shock Tower Brace; Lowered and Corner Balanced; MOMO RSGT Seats...
Old 04-19-2008, 09:13 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #62 (permalink)
Registered User
 
lite75's Avatar
 
Join Date: Jan 2007
Location: Bellingham WA
Posts: 825
Garage
Fuel pressure and control pressure both need to be checked, the WUR only effects the control pressure. More control pressure less fuel, less control pressure more fuel.

Dan
__________________
75 930, 76 930, 83 SC EFI turbo
Old 04-19-2008, 10:42 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #63 (permalink)
Crotchety Old Bastard
 
RarlyL8's Avatar
 
Join Date: Jan 2000
Location: Huntsville, AL
Posts: 13,408
Garage
The spray pattern remains the same nomatter what the pressure. The volume of fuel changes.
The fuel head piston moves farther up the chamber as control pressure rises and allows more fuel to flow. An x-ray style diagram would help you see how that works.
BL likely set your WUR in the middle of spec for your application and region, I am simply suggesting you verify those numbers before moving on.
In order to take full advantage of the Leask modifications you need the pressure gage and an LM-1 or similar device reading A/F ratios that will allow you to fine tune the WUR to your specific application. You can rough tune using only the pressure gage but fine tuning must be done with an LM-1 or similar device.
If you need more info past what BL included with your WUR there are many threads on the subject.
__________________
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 04-20-2008, 05:33 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #64 (permalink)
Certifiable
 
Quicksilver77's Avatar
 
Join Date: Jan 2008
Location: Folsom, CA
Posts: 194
Send a message via Yahoo to Quicksilver77
Update

Alright it has been a while, but here is where I am at!

Installed wur and checked the cold pressure with wur unplugged:
Gauge Valve open: 8psi

I pulled the wur and sent 'er back down south for a quick look see from B. Leask
Seems some contamination made its way into the wur and was making it bench test at 4bar.

WUR re-calibrated and sent back.
Installed WUR and checked cold pressure:
Gauge Valve open: 8psi

WTF I say!! I'm not getting enought fuel!

Checked fuel pump relays: Good
Checked fuel pump operation: Both running

A month or so in... I decided to throw in the towel and take her to someone who knows what the eff they are doing. Been at the shop for two days, and the best they can say is that there is something down stream of the WUR that is bleeding the pressure (no sheite). But with the gauge valve closed they are seeing 90ish psi. So at least the pumps are working and the filter is not clogged. I guess?

The car ran before I:
-Pulled the WUR and installed the rebuilt adj. WUR
-Unplugged the Andial fuel enrichment system (shown above, I unplugged the two prong connector shown in the picture and removed the item it plugs into from the fuel line)
-Installed the RPM solenoid valve

What the heck did I do????? That would cause this shop with eons of experience to be in the dark? Any ideas???

The weather is perfect and I want to be driving!!!!
__________________
Sean D. 1987 930
India Red/Beige/Black; Mahle 3.4L; Kokeln IC; K27 7200; GHL Headers; Borla Stainless Muffler; SC cams; Sachs Aluminum Clutch; Aluminum flywheel; Bilstein Sport Shocks; Adjustable Rear Sway Bar; Weltmeister Shock Tower Brace; Lowered and Corner Balanced; MOMO RSGT Seats...
Old 06-03-2008, 09:45 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #65 (permalink)
Infidel
 
JBL930's Avatar
 
Join Date: May 2006
Location: UK
Posts: 1,172
I'm simply asking this question so i can better understand how you plan to achieve what you are saying, i know you know your stuff so i'm all ears.
A stock WUR starts to enrich the fuel at about 3psi, which is 0.2bar, anyone can see that with a modern turbo fitted this amount of boost comes in really early, even below 2000rpm in some cases! Brian Leask states that the WUR boost threshold can be raised to as much as 8psi, this is 0.55bar. This boost pressure will be reached by around 2500rpm which is still way too early. In all of the applications that i am aware of I am told that boost enrichment needs to be delayed until above 4000rpm, sometimes as late as 4500rpm. By this point full boost has been reached for way over 1000rpm of the rev range, how can adjusting the mechanical boost enrichment threshold inside the WUR delay enrichment in this way? It can't, you can only delay it until a certain boost level and not a certain RPM point, full boost is reached long before it needs enrichment so the only way i can see of getting a flat AFR is with the RPM solenoid, Brian Leask clearly agrees with this.
If i am missing something here please enlighten me, cheers


Quote:
Originally Posted by RarlyL8 View Post
No, what I am saying is the RPM switch is a good bandaid but does not actually fix the problem, it masks the symptoms.

The problem is that as the WUR ages it goes off spec. In order to recalibrate you need to go inside the WUR and do some adjusting. Once back in spec you re-gain the full spectrum of the threshold adjustment.
The RPM switch simply delays the onset of boost by hiding the signal until a preset RPM, effectively overriding the threshold system by shifting the threshold to a point requiring less adjustment. The resulting A/F graph looks better but the WUR is still off spec.
Old 06-03-2008, 11:51 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #66 (permalink)
 
Registered User
 
Join Date: Jul 2006
Location: S. Florida
Posts: 7,210
Hey JBL, you're 100% correct lol

and, from a post above your's...

"The fuel head piston moves farther up the chamber as control pressure rises and allows more fuel to flow."

Isn't it the other way around....?

Control pressure from the WUR is pushing down on the top of the fuel head piston which when moving downwards covers up more and more of the metering slits in the cylinder wall letting less fuel through to go to the injectors.
The air flow metering plate through it's lever and linkage is pushing up on the fuel head piston from the bottom. So, more airflow then pushes the piston upwards exposing more of the metering slits and letting more fuel go to the injectors.
The position of the fuel head piston is a balance between the force on the bottom of the piston from the air flow meter and the force or fuel pressure on the top of the piston which is being governed by the control pressure regulator or WUR.

The WUR or control pressure regulator is regulating that pressure on the top of the piston by simply bleeding it off and letting return to the fuel tank. The amount it does that is defined by ambient temperature when cold, and then heater element and engine block temperature when warming up, and in a turbo's WUR the boost pressure routed to a diaphram in the bottom of the WUR when the turbo spools up. This one lowers control pressure when you are on boost letting the piston rise because the airflow meter is really pushing up on it now which finally sends more fuel to the injectors.

Last edited by JFairman; 06-04-2008 at 12:29 PM..
Old 06-04-2008, 04:34 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #67 (permalink)
"I wuz the liquor..."
 
sand_man's Avatar
 
Join Date: Oct 2005
Location: Cooterville, Cackalacky
Posts: 6,401
Quote:
Originally Posted by JBL930 View Post
I'm simply asking this question so i can better understand how you plan to achieve what you are saying, i know you know your stuff so i'm all ears.
A stock WUR starts to enrich the fuel at about 3psi, which is 0.2bar, anyone can see that with a modern turbo fitted this amount of boost comes in really early, even below 2000rpm in some cases! Brian Leask states that the WUR boost threshold can be raised to as much as 8psi, this is 0.55bar. This boost pressure will be reached by around 2500rpm which is still way too early. In all of the applications that i am aware of I am told that boost enrichment needs to be delayed until above 4000rpm, sometimes as late as 4500rpm. By this point full boost has been reached for way over 1000rpm of the rev range, how can adjusting the mechanical boost enrichment threshold inside the WUR delay enrichment in this way? It can't, you can only delay it until a certain boost level and not a certain RPM point, full boost is reached long before it needs enrichment so the only way i can see of getting a flat AFR is with the RPM solenoid, Brian Leask clearly agrees with this.
If i am missing something here please enlighten me, cheers
In my low-brow primitive mind, your description and the one in Brian Leask's manual for the solenoid, is how I understand it. Rather than a "band-aide" (I know this wasn't said with malice), the solenoid, from my perspective, is a timing mechanism; a way to achieve a some what flat fuel curve by delaying the enrichment fuel until it's really needed...obviously that's dependent on the engine in question and what mods are in place. I don't think it has anything to do with the WUR being out of spec.
__________________
-jeff
back in the saddle: '95 993 - just another black C2
*SOLD*: '87 930 GP White - heroin would have been a cheaper addiction...
"Ladies and Gentlemen, from Boston Massachusetts, we are Morphine, at your service..." - Mark Sandman (RIP)
Old 06-06-2008, 09:05 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #68 (permalink)
Reply

Thread Tools
Rate This Thread
Rate This Thread:

 


All times are GMT -8. The time now is 08:36 PM.


 
Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2018, 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.