I have emailed MoTeC Australia regarding their M800 and M880 engine management systems. This is their very interesting reply. Could some of you more technically-minded people decipher and summarise this for me so it's easier to understand.

Thanks

Michael

Message from MoTeC
Michael,
Both Motec Japan and Motec USA have installed an M800 on an RX-8, the factory ECU is removed. The engine is no trouble after a few issues are addressed:

1) Trigger wheel must be changed from 36-2-2-2 to 36-2

2) The DC Generator must be replaced with a conventional 3rd generation RX-7 (FD3S) alternator unit. It drops in, using all the stock RX-8 mounting points, belt, and terminals.

3) The secondary injectors need to be wired in pairs

The ecu will require the SERVO code for the OMP function to work, and an M800 will be necessary in order to get the OMP to work as we need the extra injector drivers.

The car however, is a whole lot more complicated. Removing the factory ECU will terminate the dash cluster (speedo, odo, temps, fuel level, warning lights, status lights, etc.), electronic stability control, power steering, cruise control, A/C control, engine cooling fan control, emissions control, secondary air injection, and so on. ABS still functions.

The information I've had from the US indicates that gains are very hard to come by on stock parts. Also, the intake system seems to be very sensitive to how it is manipulated. It presents less than 100 kPa under the throttle at WOT - around 95 kPa. The (70mm) DBW throttle may be the choke point, not sure. There appears to be a trade-off in the design of the intake system that was very carefully examined and massaged to give the best end result. It goes to show that some manufacturers are putting a lot of effort into development - certainly in this case, where the engineers were given a target hp figure... Aftermarket tuning with the Motec ECU will come into its own with a modified race engine.

Cost would be retail for the M800, a wiring harness, new trigger wheel, fitting and tuning by a Motec dealer.

Regards,
Andrew Naumann
MoTeC P/L

 

Sounds like a nice way of saying "You would have to be nuts to replace the stock ECU!"

Unless your aim is an all-out racemobile, you simply cannot remove the computer. Your best option is intercept the signal to the injectors and modify it - and I know a guy........

S

 

stealth

when you change from stealth mode are you going to finish your reply ???

 

haha... i'll pick that up for Doc.

canzoomer's piggy back will do just what Mr. Dual-Personality is implying.

 

Humm, sounds like it's easier to perform a heart surgery than to change this M800.

 

Thanks for the replys , however i still dont know what a trigger wheel is and need explanations .

 

I thought the trigger wheel was the doodad that gave you timing signals from the crank.

 

KEV

TA for the reply , but whats a dooda , hey your beating my posts .

 

A google search on 'trigger wheel' turned up this hilarious web page that explains installing a trigger wheel. The search turns up a bunch of other hits that also have pics etc. Basically, a trigger wheel is a small circular metal plate with 'teeth' around the periphery that mounts to a cam or crankshaft. A sensor will mount nearby, and sense the teeth passing by as the cam or crank rotates. From the passage of the teeth, the trigger wheel sensor can tell the exact position of the crankshaft, and the ECU uses that position information to control fuel injector and ignition timing.

Regards,
Gordon

 

Paul Yaw (username: yawpower) already designed a timing wheel for the 13B-MSP, as he's running a MoTeC ECU in the race car. ask him about it if you're actually serious.

 

Yeah, we've got the trigger wheels here. In fact we supplied Motec USA, and Motec Japan. I don't think we'll get rich selling trigger wheels though. We've only sold 7 of them so far.

Motec has done a tremendous job writing software specifically for the RX-8. The M800 controls the secondaries, high speed ports, oil metering pump, VDI valve, etc. It can even be programmed to give you a hummer during caution laps.

If you are going to race an RX-8, Motec is the only way to go.

 

The only problem with Motec is that they do not offer knock control. Not that that is important on a race car where quality fuel is a given.
I can't imagine the complexity of the M800.. the M4Pro on my Subaru is rather daunting.