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 > Porsche 924/944/968 Technical Forum

Reply
 
LinkBack Thread Tools Rate Thread
Author
Thread Post New Thread    Reply
Registered User
 
Join Date: Feb 2018
Posts: 8
DME capabilities?

I have a 87 N/A that I do track days and autocross with. I absolutely love the way the car handles. My question is this: what sort of mods is the stock dme capable of handling (without tuning)? Web cam, head porting, larger injectors, higher compression, limited amounts of boost?

Thanks.
Old 02-09-2018, 05:44 AM
  Pelican Parts Technical Article Directory    Reply With Quote #1 (permalink)
Registered User
 
Join Date: Mar 2008
Location: Ontario, CA
Posts: 3,190
with a totally stock DME...

yes:
porting, cam

no:
larger injectors

"maybe":
boost, compression

the DME using the AFM flapper is quite forgiving for airflow mods.
the stock injectors should be good into the ~180hp range however you would need to tweak the DME fuel quality switch and/or the AFM clock spring to make sure your air-fuel ratio was good at high rpm. however without a DME tuner theres no way to tell the DME what size your non-stock injectors are so fueling would be off, everywhere.

the reason is that past about 4500rpm at WOT the AFM door is stuck wide open and isn't measuring airflow anymore - so the DME is sort of guessing at the fuel based on its programming (2.5L engine with stock cam at 5000rpm takes in X air so needs Y fuel, etc)

compression the DME can deal with but there's only a very limited amount of spark timing adjustability built in to the fuel quality switch, i think it's something like -2.7 degrees which might be sufficient for a 1/2 point of compression (stock 9.5 up to 10:1 maybe?). same goes for boost, you would really want to run the highest octane fuel available if you intend to boost.

realistically you're about 50 steps ahead if you contact Lindsey Racing and get their MAF conversion with DME tuner kit.

Last edited by v2rocket_aka944; 02-09-2018 at 07:33 AM..
Old 02-09-2018, 07:29 AM
  Pelican Parts Technical Article Directory    Reply With Quote #2 (permalink)
Registered User
 
Join Date: Feb 2010
Location: Holden, MA
Posts: 420
Garage
V2Rocket (Spencer) - Knows these cars, and is providing some good advice.

If you aren't trying to stay in a certain class....and the Track days & Autocross is more for fun .... I would do the MAF Conversion and add 4 degrees advanced timing (with an offset camshaft key). These can be done in an afternoon and yield some good (safe) results.

Depending on your suspension and tires, that is really where your money needs to go to keep this car up to the pace of the other cars on track. Koni Shocks, Turbo or 968 Sways, upgraded or new rubber suspension bushings.

You can really go deep into the rabbit hole chasing hp on an 8V NA, and the money would be better spent on an S2, 968, or Turbo if Hp in a 944 Chassis is the goal.
Old 02-09-2018, 08:43 AM
  Pelican Parts Technical Article Directory    Reply With Quote #3 (permalink)
Registered User
 
Join Date: Feb 2018
Posts: 8
Thanks for the info guys. I totally agree with not doing too much. I am just trying to arm myself with a little information on what I can easily and safely do to get "what is worth getting" when I decide to refresh the motor.

I am rebuilding the control arms and replacing all bushings this weekend and a 4' cam key is on the way.
Old 02-09-2018, 11:08 AM
  Pelican Parts Technical Article Directory    Reply With Quote #4 (permalink)
Registered User
 
Join Date: Mar 2008
Location: Ontario, CA
Posts: 3,190
no other way to say it, sorry pelican, but...

driving the first time with the cam advanced 4 degrees will give you a strong erection.
Old 02-09-2018, 12:03 PM
  Pelican Parts Technical Article Directory    Reply With Quote #5 (permalink)
Registered User
 
Join Date: Feb 2010
Location: Holden, MA
Posts: 420
Garage
Quote:
Originally Posted by v2rocket_aka944 View Post
no other way to say it, sorry pelican, but...

driving the first time with the cam advanced 4 degrees will give you a strong erection.
HAHAHA.......

Thanks for making my Friday!
Old 02-09-2018, 01:15 PM
  Pelican Parts Technical Article Directory    Reply With Quote #6 (permalink)
 
Now Available for Ordering:   101 Projects For Your BMW 3 Series 1982-2000  [more info]
Reply

Thread Tools
Rate This Thread
Rate This Thread:

 


All times are GMT -8. The time now is 10:17 AM.


 
Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2018, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2017 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.