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 > 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 2007
Location: Houston, TX
Posts: 66
Quote:
Originally Posted by RarlyL8 View Post
I am not familiar with how that timing table is setup (X axis) so cannot comment on it.
Your AFRs need not drop much below 11.0:1 at boost onset or max torque. 11.8:1 is a good safe target for redline, which is close to what you now have.
Thanks Brian.

Is the enrichment RPM correct?
Old 04-25-2010, 06:54 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #41 (permalink)
Registered User
 
Join Date: May 2007
Location: Houston, TX
Posts: 66
BTW, i just want to comment on what a great community this is.

The continued help is invaluable!

Richard just sent me a new timing map based on the dyno graph - how great is that!!!
Old 04-25-2010, 07:05 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #42 (permalink)
Crotchety Old Bastard
 
RarlyL8's Avatar
 
Join Date: Jan 2000
Location: Huntsville, AL
Posts: 13,427
Garage
The lowest AFR should coincide with peak torque. Having a large fuel dump when the engine is not at full torque or at full boost bogs the engine and will wash the cylinders a bit with excess fuel. The excess fuel also cools the heads so there is some benifit in moderation.
__________________
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 04-25-2010, 10:51 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #43 (permalink)
Registered User
 
Join Date: May 2007
Location: Houston, TX
Posts: 66
Quote:
Originally Posted by RarlyL8 View Post
The lowest AFR should coincide with peak torque. Having a large fuel dump when the engine is not at full torque or at full boost bogs the engine and will wash the cylinders a bit with excess fuel. The excess fuel also cools the heads so there is some benifit in moderation.
Excellent information. Thanks!

I uploaded the new timing settings that Richard sent me and the car already feels more responsive than before.

I will probably schedule another dyno session for next Saturday to get the fueling adjusted.
Old 04-25-2010, 03:29 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #44 (permalink)
Registered User
 
Join Date: Apr 2010
Location: California
Posts: 15
Pardon me. You are correct. I was looking at the torque line not boost. So the boost is good.

I find most dual plug engines on 91 pump gas to need about 22 degrees at 1 bar boost. Sometimes a little more and have seen less. Start with conservative advance. If you put in too much timing the engine develop more heat than power.

When you change the timing from 16 degrees to 22 degrees the power will come up and the engine should lean out as you will have a more complete burn. What I'm saying is monitor your mixtures after changing the timing. It will likely need more fuel.

The increased CR to 8:1 will have a little influence timing. The biggest influence on timing has to do with chamber design, crush area on the piston, exhaust system and fuel. Using premium pump gas, not so much fuel.

Richard
Old 04-25-2010, 04:05 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #45 (permalink)
Registered User
 
Join Date: Jan 2004
Location: Sacramento
Posts: 7,269
Don,

Great info on stock CDI!



I am wondering why the stock components can not be tuned to get close to an ideal for max acceleration from idle through full boost to red line?

This is not a chalange, just a hope to learn. I know adding a programable function to the stock components or a full upgrade would be much better.


It seems we should be able to get pretty close by playing with the mechanical advance curve & total. We also have control over the total amound boost-retard the pot gives as that can be adjusted. Further, we can use or kill the Vac-Ratard function.


Thus, if a single plug 930 needed say -20 at WOT on full boost that is of coursde easy.

Are you saying we can benifit from running more than say about -32 between idle and full boost (apx 3000rpm) at WOT off the line?

I know cruse advance will be less than ideal but seems we should be able to get close on the at temp WOT range.


I love this stuff so any help you can give would be appricated.

Thx in advance.


Quote:
Originally Posted by DonE View Post
If you wanted to spend the money on quality crank fire CDI ignition, you could get some great torque numbers with CIS. Despite some of its limitations, CIS is a great platform even 30 years later.

You really can't do too much to the stock ignition system and that's a big problem when tuning for peak torque and HP. Leave it stock unless you get a quality system. And although Richard Clewett is tops in the Porsche world, the wasted spark system that Electromotive builds is nowhere as good as the stock CDI - even though you can set a timing curve. Given the choice, I would always opt for the stock CDI system over a wasted spark because of spark energy and the quality of Electromotive.

And yes, my 36 degrees is up to about 3000 rpm. At WOT, its closer to 18 degrees.
Old 04-26-2010, 07:32 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #46 (permalink)
 
Reply

Thread Tools
Rate This Thread
Rate This Thread:

 


All times are GMT -8. The time now is 11:19 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.