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
Registered User
 
Join Date: May 2002
Location: Up North
Posts: 1,434
BOV opens up too early...

As the title says, I find mine opens up wwaaayyyy too early - as soon as I do a gentle lift or maybe even a slight pause on throttle then I'd hear the BOV wide open.

I am using a Tial 50mm one, and it vents to atmosphere. Would a stiffer spring help here? And, how would one choose which spring to get? I followed Tial's recommendation, but its really opening too often/soon IMHO.

thanks!
__________________
87 930 K27HFS/B&B/Twin-Plug... Megasquirted
Old 08-10-2008, 11:43 PM
  Pelican Parts Technical Article Directory    Reply With Quote #1 (permalink)
Crotchety Old Bastard
 
RarlyL8's Avatar
 
Join Date: Jan 2000
Location: Huntsville, AL
Posts: 13,258
Garage
The BOV/recirculation valve should be open whenever the engine is not under load.
__________________
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 08-11-2008, 01:37 PM
  Pelican Parts Technical Article Directory    Reply With Quote #2 (permalink)
Registered User
 
Join Date: May 2002
Location: Up North
Posts: 1,434
Quote:
Originally Posted by RarlyL8 View Post
The BOV/recirculation valve should be open whenever the engine is not under load.
Understand that... but what I'd like to see is whether there is a way so that the BOV would remain closed longer when the engine load decreases slightly.

Right now, as soon as the load is not increasing, the BOV seems to open right away. Hence, throttle response really suffers due to boost loss in transient throttle situations.
__________________
87 930 K27HFS/B&B/Twin-Plug... Megasquirted
Old 08-11-2008, 04:00 PM
  Pelican Parts Technical Article Directory    Reply With Quote #3 (permalink)
Cynical Misanthrope
 
AFM744's Avatar
 
Join Date: Dec 2001
Location: Campbell, CA
Posts: 382
Send a message via Yahoo to AFM744
With aftermarket BOVs you can install different springs.
BOV opens when:
TB press < (I.C. press + spring press)

So, reduce spring, and valve will open sooner, and vice-versa. With more spring you'll have more run-on tendency methinks, and I'd guess a more abrupt lurch when it finally does open. I've never driven a turbo car w/o BOV, but I did ride a GSX-R 1000 with a turbo kit under development. It did not have a BOV and accordingly had an UNNERVING run-on after the throttle was shut.

With my EFI I'm definitely going to experiment with a mechanical (spring valve) Boost Control, and this tickles my thinker into experimenting with different BOV springs too.
__________________
X-1, AFM744, Jon, '92 C2 Turbo
JE 8:1 pistons, 964 cams, 38mm intakes ported/polished/twinplugged, ARP hardware, B&B headers/exhaust, 355whp. Full-blown GT35R 3.2 intake EFI pending...
Where my misspent time and money is currently going.
Old 08-11-2008, 04:48 PM
  Pelican Parts Technical Article Directory    Reply With Quote #4 (permalink)
A fellow Pelacanite
 
NathanUK's Avatar
 
Join Date: Nov 2006
Location: UK
Posts: 2,002
Garage
Just to add, they also do shims to fine tune between the different springs.
__________________
1981 UK 930. G50/01 shortened, 964 3.8RS Fibreglass Body Kit, 18" Alloys 8.5" F & 10" R, 225's F & 285's R, Special Colour Metallic Blue Paint, FIA Sparco Evo's, A/C and Air Pump removed, Electronic Boost Controller, GHL Headers, Tial46 WG.
Fitting - New service kit.
Needs Fitting - Innovate XD-16 Kit, Kokeln IC. Stephen's K27 HFS, EVO Intake Assy & his Modded USA Fuel Head.

1983 UK 911 3.2 Carrera Sport Coupe. Black, Black Leather with Red Piping, Black Alloy Gear Knob, K&N Air Filter Element, Turbo Tie rods.
Needs Fitting - K&N CO Sensor, Round A/F Dial Gauge, Factory Short Shift Kit.

http://www.danasoft.com/sig/Iamnotanumber.jpg
Old 08-12-2008, 12:10 PM
  Pelican Parts Technical Article Directory    Reply With Quote #5 (permalink)
Reply

Thread Tools
Rate This Thread
Rate This Thread:

 


All times are GMT -8. The time now is 11:58 PM.


 
Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2017, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2016 Pelican Parts - 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.