Tom M'Guinn's SpeedoBooster
05-26-2015, 05:50 PM
#1
Tom M'Guinn's SpeedoBooster
As I upgraded from the stock Bosch Mo(t)ronic to a standalone ECU several years ago, and since I have always used an external aftermarket boost gauge for increased accuracy, having the original dash boost gauge to work again was never really high on the to-do list that kept getting longer with all the newly-acquired tuning freedom provided by the new ECU.
As my intention to have a functional dash boost gauge grew again in the last months, browsing the RL archives brought up some older posts explaining how the factory KLR fed the gauge.
However, my lack of any solid understanding with electronic signals kept getting over my interest, and there was always something more important to do on the car, until it came to my attention that electronic guru Tom M'Guinn had analyzed the signal and even made a calibrating tool. Tom had casually mentioned in other posts that he had also made a calibrating tool for the notoriously-inaccurate factory speedometer, and he kindly agreed to help me out - enter the SpeedoBooster.
The SpeedoBooster consists in a small box hosting a chipboard, throttle pots for calibrating the boost gauge output and the speedometer output, and wires for inputs/outputs that must be soldered in the correct wires of the factory wiring harness. The boost gauge can work with different input signals, which can be adjusted with several switches on the chipboard.
Being able to calibrate the speedometer in addition to the boost gauge adds driving comfort, in particular when using wheel and tire combination larger than in the stock 16" size, with which the stock speedometer is already going to read wrong anyway.
As for accuracy I was able to get the speedometer pretty much spot on, the fastest drive showing an indicated 260 kph on the speedometer against 257 kph on the sat nav (on a derestricted German Autobahn). It goes without saying that such an error is unlikely to be visible at any legal speed anywhere else in the world.
If anyone needs to have a fully accurate speedometer and/or a working dash boost gauge with their aftermarket ECU, I would highly suggest getting in touch with Tom who has made here a neat and useful device - thanks Tom!
As my intention to have a functional dash boost gauge grew again in the last months, browsing the RL archives brought up some older posts explaining how the factory KLR fed the gauge.
However, my lack of any solid understanding with electronic signals kept getting over my interest, and there was always something more important to do on the car, until it came to my attention that electronic guru Tom M'Guinn had analyzed the signal and even made a calibrating tool. Tom had casually mentioned in other posts that he had also made a calibrating tool for the notoriously-inaccurate factory speedometer, and he kindly agreed to help me out - enter the SpeedoBooster.
The SpeedoBooster consists in a small box hosting a chipboard, throttle pots for calibrating the boost gauge output and the speedometer output, and wires for inputs/outputs that must be soldered in the correct wires of the factory wiring harness. The boost gauge can work with different input signals, which can be adjusted with several switches on the chipboard.
Being able to calibrate the speedometer in addition to the boost gauge adds driving comfort, in particular when using wheel and tire combination larger than in the stock 16" size, with which the stock speedometer is already going to read wrong anyway.
As for accuracy I was able to get the speedometer pretty much spot on, the fastest drive showing an indicated 260 kph on the speedometer against 257 kph on the sat nav (on a derestricted German Autobahn). It goes without saying that such an error is unlikely to be visible at any legal speed anywhere else in the world.
If anyone needs to have a fully accurate speedometer and/or a working dash boost gauge with their aftermarket ECU, I would highly suggest getting in touch with Tom who has made here a neat and useful device - thanks Tom!
Last edited by Thom; 05-27-2015 at 03:51 AM.
05-26-2015, 11:49 PM
#4
Rennlist Member
05-28-2015, 02:18 PM
#5
Rennlist Member
The name and sticker were a bit tongue in cheek, but glad it's working well. With the trim pot, you should be able to adjust out that 3kph, but as you say if it's that accurate at 160mph (!!!) then it's probably already more accurate than most new cars, and virtually spot on at any sane speed. I bench tested it until I pegged a 180mph speedometer, so glad to see it working on the road as well. The boost gauge driver runs off any linear 0-5 map sensor, and can be configured like the stock gauge or to show only boost -- so for example the 1 on the gauge means either 1 bar of boost or 10psi of boost (your choice)... I only made the two (one for Thom and one for me) but could rustle up another for worthy rennlisters on a pay-it-forward basis...