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 Engine Rebuilding Forum


Reply
 
LinkBack Thread Tools Rate Thread
Author
Thread Post New Thread    Reply
Registered
 
Daviboy's Avatar
 
Join Date: Jul 2008
Location: Cape Town, South Africa
Posts: 702
Garage
CIS Ignition Tuning

Ok heres the deal got my cams back re-ground to 964 specs, have my 9.8:1 pistons coming. Should start the rebuild soon. My question is whats the ultimate ignition timing specs for my 3.0L SC? I have decided to stay with the CIS as it is/was working fine and I want to keep the motor as close to original as possible. Do I need to have my distributor re-curved or will it be ok as stock. I will be fitting an MSD 6AL box as well.

__________________
Davy

82 911 SC Targa Sold
12 Audi A5 Sportback 3.0 TDI Quattro
03 996 C4S
Old 07-26-2010, 09:57 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #1 (permalink)
Registered
 
Sigurd's Avatar
 
Join Date: Dec 2000
Location: Norway / Merritt Island FL
Posts: 220
Suggestion: Get the programmable MSD 6 box. Then you can fine tune the curve by the help of a computer with a seriel port.
__________________
Sigurd
73.5T 3.2SS EFI
X87 944S 3.0
Old 07-26-2010, 10:37 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #2 (permalink)
Registered
 
Join Date: Jul 2001
Location: Portland Oregon
Posts: 7,007
Davy,

Your flexibility with ignition timing is really based on your compression ratio (its high for CIS) and what octane fuel you will use. I would recommend that you check your AFR's to make sure you are not too lean.
__________________
Steve Weiner
Rennsport Systems
Portland Oregon
(503) 244-0990
porsche@rennsportsystems.com
www.rennsportsystems.com
Old 07-26-2010, 10:41 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #3 (permalink)
Registered
 
Daviboy's Avatar
 
Join Date: Jul 2008
Location: Cape Town, South Africa
Posts: 702
Garage
Steve I have 95 octane at the pump hence using the 9.8:1 which is what the stock motor (euro) had. Another question how should the cam timing be set retarded or advanced?
__________________
Davy

82 911 SC Targa Sold
12 Audi A5 Sportback 3.0 TDI Quattro
03 996 C4S
Old 07-26-2010, 11:08 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #4 (permalink)
Registered
 
Join Date: Jul 2001
Location: Portland Oregon
Posts: 7,007
I'm assuming you are using factory Mahle pistons.

Given the use of 95RON fuel, I would not use more than 32-33 degrees total timing. With 98RON, you have more leeway.

Cam timing affects where the power is in the RPM range so this depends how you use the car. Normal 964 timing is 1.26 and thats where I would set it.
__________________
Steve Weiner
Rennsport Systems
Portland Oregon
(503) 244-0990
porsche@rennsportsystems.com
www.rennsportsystems.com
Old 07-26-2010, 04:11 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #5 (permalink)
Registered
 
Daviboy's Avatar
 
Join Date: Jul 2008
Location: Cape Town, South Africa
Posts: 702
Garage
Steve no I am going to be using JE pistons.. Car is a daily driver which sees very little track use
__________________
Davy

82 911 SC Targa Sold
12 Audi A5 Sportback 3.0 TDI Quattro
03 996 C4S
Old 07-26-2010, 09:45 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #6 (permalink)
Registered
 
Join Date: Jul 2001
Location: Portland Oregon
Posts: 7,007
Quote:
Originally Posted by Daviboy View Post
Steve no I am going to be using JE pistons.. Car is a daily driver which sees very little track use
I would not use more than 30 degrees total timing unless you use 98RON fuel.

Porsche's CR spec using Mahle or Kolbenschmidt pistons was always higher than measured values and thats what afforded the flexibility with fuel & timing. With custom JE's made right to factory published specs, that detonation margin is all gone, especially with lean-running CIS engines.

__________________
Steve Weiner
Rennsport Systems
Portland Oregon
(503) 244-0990
porsche@rennsportsystems.com
www.rennsportsystems.com
Old 07-27-2010, 08:00 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #7 (permalink)
Reply


 


All times are GMT -8. The time now is 11:37 AM.


 
Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2025, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2025 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.