Ignition system help?! Somewhat of a novice.

mdw48009 · 07-02-2003, 06:33 AM

I have a 2.7L modified to RS specs with a Bosch distributor with mechanical advance.

The mechanic says that I need to recurve the distributor since it is not giving the correct advance.

He suggested that it might make sense to go to direct ignition. By this, I believe that he means using a sensor and a CPU with programmable spark.

Which system would I use?
Are there any good resources so that I can learn about this?

Is there a significant benefit to this modification?

911pcars · 07-02-2003, 11:50 AM

Direct ignition (e.g. Motec) is indeed an option, but not sure this is needed for single plug applications and your budget. Why not just use an RS or early 911S Bosch distributor with an aftermarket ignition box (MSD, Crane, etc.) for better spark. You could even have your distributor recurved.

Sherwood Lee
http://members.rennlist.org/911pcars

beepbeep · 07-02-2003, 04:38 PM

Is your engine dual-plugged? If answer is yes, then i suggest to use stand alone computer-controlled ignition with wastefire coilpacks.

One of possible choices is Haltech E11:

http://www.haltech.com/Products/ECUs/E11/e11.html

Also, if you opt to use one of those you'll have to manufacture a trigger (usually just a couple of magnets glued to the crank-pulley) it might be a good idea to purchase combined fuel- and spark ECU. It will use same trigger-wheel and allow you to convert engine to EFI later on if you wish.

One of the cheapest fully programmable fuel and ignition computers is SDS:

www.sdsefi.com

It's somewhat tedious to program though. If you want well-known and easy to map ECU then Haltech and Motec are well-known ones.

Benefits of fully computer-controlled ingition (and fuel) is that you can map them so they fit your engine perfectly.

While "rough" ignition map can be done on the street, "mapping" fuel delivery is usually done on the dyno.

Cheers!

mdw48009 · 07-02-2003, 04:43 PM

I do not have dual plug ignition.

What does it cost to go this route?

I am looking for reasonable performance for reasonable $$. Therefore, it may be best to recurve and go the MDS route.

Where/how do you recurve?

911pcars · 07-02-2003, 06:26 PM

Cost of direct fire ignition? Others will have more accurate costs, but it's on the other side of $1k. Unless you need to control both engine fuel and ignition, I think this is not necessary. If it's just ignition control, an aftermarket ignition box controlled by your distributor should be sufficient. It doesn't sound like you have any special needs requiring computer-controlled fuel and/or ignition. RS-spec engine indicates either MFI or Webers, right?

"Where/how do you recurve?"
Check with your local dynomometer shops. Some may have a distributor machine which is required to plot the advance/rev. Basically, recurving a distributor is a combination of changing/adjusting spring tension, advance weights and the advance weight limit to arrive at the correct distributor advance at a certain engine rpm. Someone know of a place mdw48009 can get this done? You can also check with the shop owners on this forum (John Walker, Steve Weiner, etc.)

Sherwood

dad911 · 07-02-2003, 06:50 PM

I have been happy with Electromotive Crankfire. You can buy a kit that allows you to remove the distributor, and replaces stock crank pulley with a machined pulley that has 'teeth' to trigger unit. Curve is easily adjustable, and you can add a second unit if you ever need twin plugs. Reliable, no more cap/rotor/points, and complete unit should cost less than $1000.

power · 07-06-2003, 07:14 PM

I like the MSD 6al ignition with distributor and electronic points. I installed this on my 72 911S and like the combination with MFI (around $320 Canadian for MSD if I recall correctly). I think I will go to the same on my T next time I have trouble with CD unit....