View Full Version : Individual runner intake ECUs

01-05-2005, 05:36 AM
Has anyone had any experience using individual runner FI intakes (TWN, Kinsler etc.) ? Specifically, Iím interested in the EFI units used to run these IR systems.

(Notes: Motor is an early SBC. Looking at IR systems for the visual ďpopĒ over TB systems.)

Iíve been reading and talking with as many people as I can and this is what Iím hearing:

Electromotive: good, but hard to set up and work with, poor support

Accel DFI: good overall, but hard to get to work w/ IR systems b/c needs a MAP sensor and it is difficult to get a vacuum accumulator to work correctly with 8 throttle bodies. (Apparently Roush had a lot of trouble getting it to work w/ their new IR crate set up.)

MoTec: the best, outrageous price, overkill for most street applications

I appreciate your thoughts.

01-05-2005, 07:09 AM
I ran one with a FAST that worked awesome. Any of the aftermarket units that are speed density like the FAST, Gen VII, and Holley Commander 950 will all work great, but they all need a map sensor. Not a big deal on a single plane manifold, but with IR you need to have a single line from each runner, tie them into a junction box, and then to the map sensor. If you want to run idle air control you'll need an additional line per runner, and the same for power brakes or pcv. PB and pcv can share a line, but the map and IAC need to be on their own circuit.

On my Hilborn setup I had three separate lines into each runner. Think nitrous system for how the lines were run and junctioned. What mine had though was the lines were hidden under the manifold with the junction block just like a hidden nitrous system. I then used a bulkhead AN fitting through the rear of the manifold to give a connection up top for the IAC, map sensor, and pcv/pb


Fuelie Fan
01-05-2005, 09:38 AM
We've only had one customer so far do an IR setup, and we ended up doing it alpha-N. Worked as well as one can expect alpha N to work, he was quite happy

01-05-2005, 10:44 AM
I'm going to try an Electromotive unit on my converted Hilborn. It has a feature that is interesting for IR setups. They call it Alpha blending. Essentially, you can smooth out your MAP signal at low throttle openings using the throttle position sensor output. On paper it looks like an interesting solution to the pulsing MAP signal issues encountered on IR manifolds. Unfortunately, I won't be able to try it until I get back to the states in November, so I don't yet have practical experience with it to tell you about. The other thing I really liked was their 60 tooth crank trigger setup.

From a software standpoint, I downloaded the FAST, Accel, and Motec software. I preferred the Electromotive interface. I also downloaded all the different manuals for comparison and was impressed with the Electromotive documentation. That might be because I already used an Electromotive system in college for an SAE Formula car, but it seemed clearly explained to me.

For right now, my Tec3 is running only the ignition on my car (I installed it on vacation in the states last year). It worked fine at first, but I did blow two of the coils for some reason. Electromotive was a great help in diagnosing the problem and replaced them immediately with appologies. With the two new coils it runs great again. I was very happy with their support. I just hope I don't have any more trouble. I never had trouble with their old system that I used before.

Hope this helps...

01-05-2005, 10:51 PM
Ditto what Jody did (hidden underneath); DFI works no problem.

01-06-2005, 04:48 PM
Why is it necessary to separate the MAP and IAC? Do they interfere with each other - how? Has anyone actually tried using a common block for these sensors/controls or is it just the "accepted" understanding that it won't work? -Bob

01-06-2005, 08:05 PM
Why is it necessary to separate the MAP and IAC? Do they interfere with each other - how? Has anyone actually tried using a common block for these sensors/controls or is it just the "accepted" understanding that it won't work? -Bob

The IAC is a controlled vacuum leak. The MAP needs to read engine vacuum. All the fuel adjustments are affected by that vacuum. It would cause instability every time that IAC moved positions to try to stabilize the idle. You just don't share the map signal with anything else. I also wouldn't share the IAC with anything else.


01-06-2005, 08:55 PM
Hmmm, so then, just to play devil's advocate for a moment, you believe that the "localized" pressure perturbation caused by the IAC on the MAP in a common block (because of their close proximity) would be much stronger than if they were separated?

Would you expect the MAP to see a lower than actual pressure when the IAC is operating? Wouldn't the IAC only impact MAP readings during idle - and during that time wouldn't the IAC effect be fairly constant? If that is the case, it seems that the percieved lower pressure by the MAP theoretically could be tuned out by adjusting the fuel requirements?

And if that is possible then a common block technique would greatly simplify the plumbing issues. Since the conversion of stack units to EFI is not that common there may not be any actual testing to draw conclusions from to verify or refute which way is better or necessary.

Just trying to reason this through - I have no EFI experience to base it on. -Bob

01-06-2005, 09:08 PM
Thing is that IAC is moving around at idle which I would THINK would create an unstable idle due to the map fluctuations, but maybe not. It also changes related to temp and even off idle will "park" at some opening value, so it's virtually always open to some point all the time other than if you have the idle stop adjusted too high for the commanded idle speed and the IAC is trying to slow the idle down.

I'm sure the car would still run with the two connected, just doesn't make a lot of sense to me to do that when you can eliminate any issues by keeping them separate. If it sat still at certain points or rpms you could tune around it, but it's "alive" constantly doing something at idle, and moving to a park setting off idle and will also move on throttle shutting, acting as a buffer to prevent stalling on decel.


01-07-2005, 05:34 AM
Thanks for all the input.

If a distribution block is all you need to make the MAP sensor work with IR intake, I wonder why Roush had trouble getting the Accel unit to work? Of course, I heard this from someone else (reputable, I'm sure) and I donít know how they got that information.

TWM's IR system comes with this vacuum accumulator which should solve the issue. (see attached picture)

Jody, the system you referred to is the Cobra set up? Did you tune it on an engine or chassis dyno (or both)?

To circle back to the question of which EFI to use, I still havenít found consensus on which are ďbest.Ē But, if Accel, FAST will work w/ IR systems they may be the most cost effective and user friendly.

01-07-2005, 07:32 AM
I tuned it on a chassis dyno and then did the final blending on back roads. It requires a bit of fabbing as you don't want to pull your vacuum signal from just one runner, and since there is no common plenum you have to pull from all eight, run to a junction box, and then to the map sensor. Same for the IAC, eight more separate lines as you don't want the IAC pulling off only one cylinder either as it would always be leaner than the rest, quite possibly to the point of detonation and damage.

On the Accel difficulty, it is one of the more difficult systems to tune. Unless you have someone experienced with it many tuners get frustrated with it, they have lost a few dealers because of it. Not a bad system at all when tuned, but often more trouble to get there than it needs to be. The Holley and FAST will definitely do what you want and are relatively simple to tune. The new Big Stuff 3 is also a nice way to go, but I have not tuned it yet (sitting ready to go in my garage). It's the latest system from John Meaney who developed FAST and assisted in other EFI systems.