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 > Porsche 911 Technical Forum


Reply
 
LinkBack Thread Tools Rate Thread
Author
Thread Post New Thread    Reply
Registered User
 
Chuck Moreland's Avatar
 
Join Date: Apr 2002
Location: Santa Clara, CA
Posts: 5,666
EFI / Independent Throttle Bodies - What size?

Phase 2 of my 73 project is in process. The car is getting a 2.7 with EFI, independent throttle bodies, and Twin plug. The car has 36mm intake ports and S cams.

I'm about to buy the EFI/TBs. Probably going with a TEC3 setup.

I'm trying to decide what size throttle bodies to get. And injector flow rates.

Seeking feedback from people who've done it.
__________________
Chuck Moreland - elephantracing.com - vonnen.com
Old 02-10-2005, 07:15 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #1 (permalink)
Registered User
 
Join Date: May 2004
Location: stuart fl
Posts: 389
any reason you are going with a electromotive setup? vs other efi systems, the tec is a little crude
__________________
KraftWorks
Jay@Kraftworks1.com
Old 02-10-2005, 08:02 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #2 (permalink)
Registered User
 
Chuck Moreland's Avatar
 
Join Date: Apr 2002
Location: Santa Clara, CA
Posts: 5,666
Enlighten me. What is crude about it? What is a better alternative and why?

What I like about TEC3 is it makes it real easy to drive my twin plugs.
__________________
Chuck Moreland - elephantracing.com - vonnen.com
Old 02-10-2005, 08:12 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #3 (permalink)
Registered User
 
Join Date: Dec 2001
Location: MA USA
Posts: 2,938
The thing that I didn't like about the Tech 3 is that it is fan cooled. In a dirty enviro. that is bad.
Most ECU's have pros and cons. I studied the different choices for a while.
Most EFI's make it easy to twin plug.
__________________
Dean
911 SC turbo, 3.0L 930 motor, G50, 930 brakes, DTA EFI, 352 RWHP DynoDynamic dyno,
Old 02-11-2005, 03:33 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #4 (permalink)
what? me worry?
 
TimT's Avatar
 
Join Date: Mar 2002
Location: Wantagh, NY
Posts: 6,979
40mm throttle bodies should be fine.

As for the EFI, Id choose Haltech, Autronic,DTA, even Accel before Electromotive.

Ive tuned cars with Electromotives from the Tec-1, to the Tec-3, and yes you can get get a good running, powerful tune from the Electromotive, I have found it easier to tune some of the other brand EFIs, ie Haltech.

Its not so much the the Brain itself cant handle the job, its the software interface that makes thing difficult sometimes. The WinTec software seem ponderous to me.

In any event almost any EFI makes twin plugging a cinch. You just need three ignition outputs, waste fired, you split the outputs and use two three channel ignitors.
__________________
who are those guys? <<< ( Butch Cassidy and the Sundance Kid)
Rent a GT3RS from us!! Call or e-mail.
Transportation and Track support
Rudtners Racing

'69 911 GT-5
'75 914 GT-3
Authorised Haltech seller and installer
Authorised Unichip installer
BBS wheels
Fikse wheels
Redline motors oils
Swepco
1500 hp chassis dyno
Old 02-11-2005, 04:29 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #5 (permalink)
Insane Dutchman
 
Join Date: Oct 1999
Location: Calgary, Alberta, Canada
Posts: 960
Garage
I've had the same question a few times, and while the response was somewhat limited, upon reflection I figure that for an EFI system, the available cross section area through the throttle body should be close to the port area. Idea is that there is no point having more cross section as the limiting factor is that port diameter. Have no real basis for that idea other than thinking about it.....

In the case of my 3.4 litre that is still in planning, it will have 39 mm ports, which has a cross sectional area of about 1194 square millimeters. Assuming a 7 mm cross shaft, that adds up to a blanked area in the manifold of about 273 square millimetres. Add the two up, convert from the total cross sectional area of 1468 square millimeters back to diameter, you come up with the need for a 43 mm intake manifold diameter to leave enough free air cross section to be equal to the 39 mm port.

I can think of about 350 things wrong with this simple calculation, but my conclusion is that I need about 42 or 43 mm throttle bodies for my engine....which matches some of what I have heard from people who actually know what they are doing....

Dennis Kalma
__________________
1975 911S with Kremer 3.2
1989 911 Carrera Project Car
Old 02-11-2005, 06:01 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #6 (permalink)
 
Registered User
 
beepbeep's Avatar
 
Join Date: Jun 2001
Location: Sweden
Posts: 5,569
You would want to find EFI that supports Alpha-N as well as MAP.

ITB's and hot cams means bad/pulsating vacuum, so you might have problems tuning the engine at low revs based on speed/density alone.

Ideal would be Alpha-N / MAP blend. That would give you as crisp throttle response and probably more power than MFI.

Twin plugs is not an issue...every EFI that supports direct-fire can do twin-plugs. Just a matter of using wastefire coils.
__________________
Thank you for your time,
Old 02-11-2005, 06:18 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #7 (permalink)
Registered User
 
KobaltBlau's Avatar
 
Join Date: Mar 2004
Location: City of Seattle, WA
Posts: 3,374
anybody here use SDS? I know several people outside this community that do, but I don't think i've heard it brought up much here.
__________________
Andy
Old 02-11-2005, 07:26 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #8 (permalink)
Registered User
 
Join Date: May 2004
Location: stuart fl
Posts: 389
the tec 3 systems are a good system just not a fan of them for there software.

as far as twin plugging goes i use autronic ecu and can direct fire the car using dual tower coils on a twin plug.

autronic is a verry powerful ecu and can do a good job at calculating map cells for you even without auto tune, ive seen a autronic ecu make a stedy pull on a engine dyno with solid afr with only a single cell in the fuel table entered. tec 3 cant even come close to that.
that is one reasons dont like the tec 3 systems.


autronic can use tps based mapping as well as map based for the pulsing vac readings from big cams
__________________
KraftWorks
Jay@Kraftworks1.com
Old 02-11-2005, 08:37 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #9 (permalink)
Registered User
 
Grady Clay's Avatar
 
Join Date: Dec 2003
Location: Arapahoe County, Colorado, USA
Posts: 9,032
Chuck,

If you havenít done so already, go up the street and spend some time with Jerry Woods. As I recall, an early breakfast and Huevos Rancheros or Eggs Benedict work well. (Of course that was 25 years ago and we all should now eat oat bran.)

I would amend your question to be:
What system?
What size?
What peripheral issues?

I assume you are talking about an integrated fuel management, ignition, and data recording. The key is properly closing the loop. It wonít be long until most of our hotrods have a laptop as the indispensable tuning tool.

I will be really interested in all the things you find.

Guys, something we should do on this thread is to post links and not use too much jargon and alphabet soup. There are lots of Pelicans who lurk and need to understand this technology.

Best,
Grady
__________________
ANSWER PRICE LIST (as seen in someone's shop)
Answers - - - - - - - - - - - - - - - - $0.75
Answers (requiring thought) - - - - $1.25
Answers (correct) - - - - - - - - - - $12.50
Old 02-11-2005, 08:46 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #10 (permalink)
Registered User
 
David's Avatar
 
Join Date: Apr 2002
Location: Houston (Clearlake), TX
Posts: 8,840
Garage
Here's a table out of 4 stroke performance by A. Graham Bell:

ITB bore(mm), hp per cylinder
36, 27-37
40 , 35-46
45 , 43-56
48 , 50-65
52 , 60-77
56 , 70-87
62 , 80-98

I'm planning to use the Autronic ECU for my EFI conversion. I'll probably use the Autronic CDI to drive 6 waste spark coils for the twin plug ignition. Supposedly there's enough power coming from the CDI that I can split three of the outputs to drive the six coils. The CDI is about $1000 and dual ignitors are about $200 ea so for the extra $400 I'll go with the CDI. I'm still a month or so away from buying these components so any additional input is welcome.
__________________
2014 Cayman S
2011 Cayenne Turbo
1979 930 (475 rwhp at 0.95 bar)

Last edited by David; 02-11-2005 at 09:49 AM..
Old 02-11-2005, 09:43 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #11 (permalink)
Registered User
 
Join Date: Apr 2001
Location: Williamsville, NY, USA
Posts: 133
Chuck,

Give Clewett Engineering a call. He is a Porsche w/ Electromotive guru.

-Peter
__________________
www.competitiondata.com
Old 02-11-2005, 09:56 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #12 (permalink)
Registered User
 
KobaltBlau's Avatar
 
Join Date: Mar 2004
Location: City of Seattle, WA
Posts: 3,374
I Think TWM 3003 with weber manifolds and linkage are the most cost effective, I posted some costs here:

http://forums.pelicanparts.com/porsche-911-technical-forum/177474-efi-injector-mounting-outside-box-post1461444.html?highlight=twm+3003#post1461444

the 3006 and jenveys etc are noticeably more expensive iirc, and more often seen on the 3.6-3.8 motors.

what about a little bigger ports with Mod-S cams? maybe the motor is already built.
__________________
Andy
Old 02-11-2005, 10:02 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #13 (permalink)
Registered User
 
Chuck Moreland's Avatar
 
Join Date: Apr 2002
Location: Santa Clara, CA
Posts: 5,666
Thanks for the feedback so far. This is my first EFI setup, so I am on the learning curve. Feedback from others that have done this is really welcomed.

Looks like I need to take a step back and evaluate the software for the various controllers. Seems like that is a major differentiator.

My understanding is that alpha-n mode (Throttle position based) works better with lumpy cams at lower RPM. So what is the benefit of MAP (manifold pressure based) based control?
__________________
Chuck Moreland - elephantracing.com - vonnen.com
Old 02-14-2005, 08:10 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #14 (permalink)
Registered User
 
dweymer's Avatar
 
Join Date: Nov 2004
Location: Tucson, AZ
Posts: 2,356
Garage
I am also doing research for a 2.7(kindof) efi. MAP sensors are valuable on turbo's or superchaged motors so that you can change the fuel/ign map based on boost pressure. I am sure that is not the only reason map sensors are used, but that is my take on the benefit vs. no Map. I am leaning toward haltech ecu at this point. I have heard good things about it. One of the big differences in ECU is whether or not it is sequential, or batch fire. Also look at the "resolution", some systems can program for every 250rpm, some only 500; I am not sure that makes a real difference to me though. Have you looked into www.efi101.com? They have some links to mfgs. and other info.
__________________
Donnie

Currently Porsche-less.....
Old 02-14-2005, 08:26 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #15 (permalink)
Registered User
 
KobaltBlau's Avatar
 
Join Date: Mar 2004
Location: City of Seattle, WA
Posts: 3,374
Chuck, here's a brief description of alpha-n vs "speed density"

http://www.megasquirt.info/manual/mtune.htm#alpha

basically alpha-n works off of a map of throttle position and RPM, which you have to populate. speed density is more flexible because it can deduce from a MAP reading what the airflow through the engine is. This helps reduce tuning and improves fuel economy. For lack of a better explanation, the map that alpha-N works off of is sort of like the space cam in an MFI pump. The throttle bodies (at least TWM 3003s) have MAP ports, so it is possible to run speed-density, at least in part of the RPM range. depends on the cams.

One nice thing is that the manifold setup is essentially independent of the controller setup, unless you buy a full kit from someone like clewett.

Manifold setup: As I mentioned above I think the TWM 3003 with weber manifolds and linkage is the best bang for the buck in 911 EFI induction setups that can handle a hot cam. Not cheap, but others are more expensive and IMO offer small advantages at the most for a 2.7. The 3003 is available in several sizes, one to suit your engine for sure.

Control Unit: If I were in your situation I would use the megasquirt system, which was put together as a non profit "open source" project by a bunch of guys that just wanted to make their own EFI controller. No doubt the high price of units like MoTeC was a factor in the development of this project. While this system doesn't have bells and whistles like traction control, etc, in my opinion it has everything you need. It is made so you can buy a kit and build the electronics yourself, but you can buy a unit from someone who has built one, such as this one (for $325) from tbitz on this board:

http://www.bitzracing.com/products/Megasquirt/index.html

there are other sources as well.

Here is the FAQ for megasquirt to give you a little more information (clicking on "all the FAQs on the left side gives even more info):

http://www.megasquirt.info/

This is the same unit that tbitz has used successfuly in his kit for CIS motors. I don't think he has the development platform (read:car) for individual throttle bodies, but he might be more than willing to work with you to come up with something. It may depend on how busy he is with work etc.

The megasquirt system has a bunch of very neat tuning software that is made to run with it:

http://www.megasquirt.info/manual/mtune.htm

the best way to use this is on a laptop, but it can be a very slow/cheap old unit from ebay or wherever, I think a pentium 200 would probably be more than enough.
__________________
Andy
Old 02-14-2005, 09:14 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #16 (permalink)
Registered User
 
KobaltBlau's Avatar
 
Join Date: Mar 2004
Location: City of Seattle, WA
Posts: 3,374
MAP sensors are just one way to do speed density measurements. they are usually the easiest and cheapest to set up physically, especially on a individual throttle body setup.

Flapper door air flow meters and hot-film or hot-wire air mass meters are other ways to measure speed density.
__________________
Andy
Old 02-14-2005, 09:16 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #17 (permalink)
Registered User
 
dweymer's Avatar
 
Join Date: Nov 2004
Location: Tucson, AZ
Posts: 2,356
Garage
Andy, you obviously know more than I, any good resources(books etc.) you would recommend? I am looking to do dual plug ignition also, and I can't tell if MS can do that; but the price is certainly right!
__________________
Donnie

Currently Porsche-less.....
Old 02-14-2005, 09:34 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #18 (permalink)
 
Registered User
 
Mike Bonkalski's Avatar
 
Join Date: Feb 2004
Location: Geneva, IL
Posts: 666
Megasquirt can do dual plug. You need the appropriate software (free), a DIS controller, dual coil packs, VR sensor and a toothed wheel. I am working on this package right now.
__________________
1971 Targa RS - Sold
1964 BMW 1800Ti
1969 BMW 2002
Old 02-14-2005, 10:13 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #19 (permalink)
Registered User
 
KobaltBlau's Avatar
 
Join Date: Mar 2004
Location: City of Seattle, WA
Posts: 3,374
The other nice thing about the megasquirt dual plugs is that it uses widely available (cheap) coil packs. you don't use an RSR style distributor or anything, just mount the coil packs where you have room (lots of people do this on the firewall). This sort of setup reduces the cost of twin-plug to almost nothing other than the machine work, as long as you're already rebuilding the engine.

As far as books go, the megasquirt FAQ information is really good. there are lots of books on amazon about tuning efi systems etc, but I haven't seen them so I can't really comment. I do have "bosch fuel injection and engine management" which is a blue book that covers the basics of EFI, but also provides a lot of detail specific to bosch systems that you may not need. Still, it's a good book and if you understand the bosch systems you will be able to understand aftermarket systems too. This book covers K-jetronic as used in the 74-83 cars and Motronic as used in the 84-89 cars, plus most of the stuff that is used in the 3.6s. You should be able to find one used on amazon or ebay. Shoot, I could sell you mine.
__________________
Andy
Old 02-14-2005, 10:18 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #20 (permalink)
Reply

Thread Tools
Rate This Thread
Rate This Thread:

 


All times are GMT -8. The time now is 02:48 AM.


 
Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2019, 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.