CIS to EFI Conversion

[Don Middleton]

This month's issue of Excellence magazine has an article on Bitz Racing's CIS to EFI Conversion. From checking it out on the 'Net, it appears that most are happy with the conversion and experiencing better engine response and 10% improvement in HP and MPG. But, there are some that have experienced some problems with hot-starts, etc.

Do any of the club "guru's" have any feedback or knowledge of it?

[Dan Chambers]

This month's issue of Excellence magazine has an article on Bitz Racing's CIS to EFI Conversion. From checking it out on the 'Net, it appears that most are happy with the conversion and experiencing better engine response and 10% improvement in HP and MPG. But, there are some that have experienced some problems with hot-starts, etc.

Do any of the club "guru's" have any feedback or knowledge of it?

Don:

When I first bought the SC, John Rickard said he likes the variability of the CIS system over the Motronic Engine Management system in regard to adjusting air/fuel ratio's and ignition timing. (I think it was John ... )

From my own experience dealing with the 1987 Motronic system vs. the 1983 CIS, I like the variability of the adjustability as well, particularly when it comes to preparation for smog, and enhancing performance for the track events.

Having said that: the Motronic system appears to give a much better torque/power curve through the rev's, and I've heard Motronic also gives better lower- rev torque/power vs. CIS. There is also the advantage of knock sensors and instantaneous anti-knock timing/fuel adjustments in Motronic that CIS doesn't provide. So detonation may occur less frequently with Motronic's. (For our cars [SC's] detonation could really destroy the rings, rod-bearings, and pull/break the head studs that much sooner. )

As for conversions: I'm not a big fan of fixing what isn't broke. Aside from the hardware cost and labor, you have to wonder if all that work and headache is worth it to a 3.0-L vs. just buying a 3.2 with engine harness/computer and just doing the entire swap. (Of course, you'd want to save the 3.0L in a box, or sell it to recoup costs.) And if you're going to go 3.2 with Motronic ... what about a 3.6? (Oh, that slippery slope... )

Finally: when I bought the SC, Grosekemper and Rickard both said the SC was one of their favorite 911's. They both drive one (Steve's is his daily driver right now), and they run them on CIS systems (to the best of my knowledge). If these guys drive a CIS ... and they should know 911's ... why change?

Just my opinion. Others will likely disagree. I'm no guru.

Dan

[cam]

I think you will find it comes down to personal preference. Ive known people that swear by one type of (insert here)carbuerator,injection,suspension bushing,tire,etc....over another because it worked for them. I like the challenge of adjusting a mechanically operated engine to it's best ability, but I also enjoy being able to make changes electronically. Not much help huh

[Steve Grosekemper]

It is an interesting article and a pretty good idea for modified engines. I did some work with a system like this a few yours back on a highly modified engine and it was very fast and reasonably drivable.

However, a properly set up stock CIS injected motor really runs nice. The problem is that not very many people know all the tricks to make this happen and get fed up with a car that someone tells them is "Supposed to run like that".

BTW- 3.2L Motronic does not have knock sensing, that didn't appear until 3.6L's.
Motronic is great, CIS 98% as good when set up right. Motronic is just easier to deal with.

Also, changing the injection on a nice street car is going to kill the resale value. For a carburator car, like the article car in Excellence it sounds like the way to go, and really interesting reading.