Full Race Application

[gtpilot]

About a year ago, SCCA decided to allow FI back into GT Racing... I am looking for information on the best ECU to run for my purposes...the particulars about the motors:

In my class, I can only run the 84-87 series 1.3L to 1.5L motors.
I currently run a crank fired Electromotive Ignition, no distributor.
Rev range of the motor ~6K to 9K (translated...no torque!)
Compression ~12.5:1

Are their alternative ways of triggering the ECU (besides a distributor)?

Since this is a race application I assume that a custom harness will need to be built...do you know of any fabrication shops?

I am sure that I will have more questions as I gain further knowledge of the Honda ECU's...thanks to all who can help out!

Kirk

[gtpilot]

Does anyone know why this scenario won't work?

Use a P30-A ECU in conjuction with a S200 and a hybrid distributor using the 16 tooth trigger wheel housed in an 86 CRX Si distributor housing (unless the B16A distributor will bolt up directly - I don't know if it will). The VTEC option would have to be disabled as it is not needed on these motors. It would require a semi-custom harness to mate to the injectors in my custom intake manifold, etc.

What do you think?

An additional question...does the P30-A look for two O2 sensors?

Thanks for your help!

Kirk

[AndyE]

I can answer your additional question...the P30 ECU (and all OBD-I ECUs for that matter) only look for one pre-cat O2 sensor.

In contrast, OBD-II ECUs need two sensors (one pre-cat, one post-cat), and some (all?) of the OBD-0 ECUs have a pair of pre-cat O2 sensors.

-Andy

[gtpilot]

Thanks Andy - that makes life a little simpler. It is going to be a problem nonetheless, I have to run leaded race fuel so the O2 sensors are not going to last long. In fact, I will probably use it just for the initial tuning and then create the sensor signal electronically to keep the ECU from throwing codes.

Can anyone explain the signals that are generated by the distributor and exactly how they are used by the ECU?

Thanks for the help!

Kirk

[Peter]

well whati know about the distributor the honda ecu on obd1 consist of 3 pick up sensors they rotate a bladed object on a set of magnets which general generates an A/C voltage back to the Ecu. But if your ignition is set off the crankshaft then whats the point of using a honda ecu with hondata cause u won't be able to control the timing at specific rpm ranges anyways. just wondering where u are coming from.

[gtpilot]

Peter,

First, thanks for your insights into the OBD1 distributor - everything helps with trying to choose what helps and what can't work.

I had included in my original post the way the ignitionis triggered for informational purposes. I am not oopsed to using the ECU to do all the work, clearly to me it is a better solution. I do run the motor in such a limited application - 99% of the time at WOT and full advance that it may not gain me much, except to have better throttle response when coming on throttle. The Electromotive ignition is a much hotter spark (up to 70,000 volts and energy of 120mJ ) compared to the Honda ignition and the crank fire timing is much more accurate at finding TDC. As you stated, the Honda distributor utilizes 3 magnets and interpolation is used to find TDC, that is 20 times less accurate than the Electromotive - it uses 60 teeth. Coupled to this is the fact that Honda uses the camshaft as the drive mechanism - the belt stretches and contracts as I rotate the camshaft (we run 100 lb. seat preasure on our vavles to keep up with the camshaft lobes...) so we have seen plus or minus 2.5 degrees of timing variation at a constant 7K RPM...that is not good!

Now maybe you understand why I asked if anyone knows of alternate ways of triggering the ECU...this is why I also asked if anyone knows specifically how the ECU interprets the signals from the distributor.

This is wide open territory - I know a lot of GT racers that need this kind of setup and would like to come up with a plausible solution.

Again, thanks for all the input!

Kirk