Which fuel injection

[Rawb]

I have a 1975 CJ5 with a 500hp Donovan. I'm looking at fuel injection I already have a edelbrock pro flo 1 but need to buy some missing parts now I'm looking at the FiTech system for ease of install and simpler system. Any thoughts on which would be better performance. I run the keep in the sand and pavement.

[andrewb70]

Is the Pro-Flow a multipoint system? dedicated intake manifold and 8 injectors?

Andrew

[Rawb]

Is the Pro-Flow a multipoint system? dedicated intake manifold and 8 injectors?

Andrew

Yes it is but its 1st gen and to upgrade wiring and programmer is $1500

[Jk918]

If you could sell what you got you could get some $ for a new system, I am running the FItech and like it

[l2azorback]

I am using the Holley HP MPI system on my Shafiroff 540 Ultra Street with great success. I am also using Injector Dynamics injectors. This system has lots of flexibility and performs very well for me.

[Fuelie Nova]

Ok I used to know the pro flo stuff pretty good but that is a long time ago... A couple of things about the intake manifold ( at least on the one I had), the throttle body flange on the manifold is not a standard 4150 flange, it is a odd ball that can only use the Edelbrock PF throttle body on it. Second, the manifold is very restrictive, the runners are small and so in the plenum.
You will probably have to buy a new intake to mount the FItech on.
Make sure you check the throttle body mounting flange, maybe they all were not like that.
Tom

[dirty rick]

I would never consider a Throttle body injection setup for any EFI setup (high or low power).
For the same reasons, fuel distribution. There is a reason none of the OEMs uses it anymore.
They are always in a state of "not quite right".
The object of an EFI system is to make every cylinder firing the same.
You can't just hold a sprinkler over a big open hole and get all the holes fed the same.
Port injection is your friend. A long runner large plenum manifold is really your friend.

[battenheaded67cutlass]

I know this thread is a little "aged", but thought I would throw my pennies in the well..........




If you had a very mild small block with no intent of truly ever pushing over 400hp, the Pro flow system would be "ok", but support is weaksauce.

You are at 500hp now on a Donovan small block, which means you may turn it up or just be happy where it is at. In all honesty, almost ZERO people are truly pleased with the bolt-on, throttle body style injection systems with "self-tuning" when you pass the 400hp mark.

Buy once, cry once on fuel injection.... There is no quick-fix, easy-install, turn the key and it's done solution on higher power combinations.

Multi-port fuel injection definitely has it's advantages for airflow and equal fuel distribution (and more power overall!)


I know many have good success with Holley systems, and they are ok, but, if you are on a budget and willing to buy something used, look for a system by MOTEC.

With the right throttle body, a good single plane intake plumbed for 8 injectors (Victor #29135), and a good tune on the MOTEC, you will be very pleased.

Almost every tuner worth their salt has tuned on a Motec at some point, and the fastest cars in the world usually run MOTEC for a reason. The older systems run DOS-based software, but are very user friendly with lots of help tips for setup parameters and typical tuning "ranges" to get you started so you aren't constantly calling someone for help. If you do call, they answer, both phones and emails, on either coast of the USA; there is a Motec East and Motec West and Motec Australia if you stump the techs here in the USA.


Also, MOTEC rules the roost when it comes to super high-end cars and leading technology. MOTEC probably has the best customer service support of all the systems I have ever seen. They continue to support very old ECM's, which is another thing that 99% of all other brands don't do at all; Heck, some will drop their systems they were selling last year and act like they don't know anything about them; that is bad news for hot rodders who may take a long time to get a project up and going. At Motec, they don't care if you bought it used or new, and you don't have to go to the most expensive unit to do what you need, as even their older entry-level M4 unit will run a V8 better than some other brand's top-shelf units. The entry-level Motec units won't do sequential fuel injection. Read all about it... big whoop, unless you are trying to knock a few tiny, almost indiscernible points off of your idle emissions numbers and get it to idle at 600RPM, sequential injection is not very important overall.....

Make sure your 500hp hot small block engine doesn't have too large of an overlap with a bunch of duration (for example, if you have 108 degree lobe separation and 250 degrees duration at .050) there will be no fuel injection that will work well. If you want a lot of duration, you will have to bring the lobe separation up to the 112+ range to work better with fuel injection. That is something small that really kills a lot of would-be successful fuel injection swapped car projects. People will spend $4,000 on wheels, $3,000 on suspension, etc., but not be willing to spend $400 and the work to install a cam that will work within the parameters of what every fuel injection wants.

The motec systems are probably the most flexible for really wild cams and crazy tunes, but running alpha-N for part of your curve isn't desirable, but possible if necessary.



Their reliability is trusted by aircraft manufacturers and even the Gub'mint on specialty vehicles if that tells you something.

[berdunord]

they are expensive

[OLDFLM]

http://www.chevelles.com/forums/89-e...ed-fitech.html

[MonzaRacer]

FI TECH for the win, plenty of power ,tunes well and doesnt act crazy.

[minendrews68]

I'll have to agree with Lee, I've got a few friends running the FITech and they really like it. Everything I've read about it on different forums seem to agree..