Spiyda rev counter upgrade

[AliK]

My rev counter has never fully behaved itself and the time has come to address it. I could just replace the capacitors and transistors inside, but I figure if I’m taking it apart properly, then I may as well do a guaranteed fix that will last a long time (and will effectively give me a 5v signal out - with a small mod - for future data logging).


I seem to recall a thread on this topic from the past but I can’t find it. Has anyone been down this road and has a write up or advice on it? If not, I will do a write up on it, when I take the plunge.

Also I know there is a club discount, but forget how to go about getting it.


https://spiyda.com/smiths-rvi-rvc-conversion-board.html

 

[jonbills]

The discount code is in the members/discount code forum

 

[Geoff-R]

Be great to see a write up on this, assume the job isn't that bad if the dash is already out of the car? I guess really the work is in getting the calibration spot on. Looking forward to seeing your write up

 

[AliK]

Spoke with Chris at Spiyda just now and he was very patient with my techie questions etc, a really top bloke.

Apparently, when 123 Ignition updated their design, they didn't send one to Chris to test. So on the website it says it's not guaranteed to work with the latest 123 ignition like mine - so I thought I'd volunteer myself as a Guinea pig! Will definitely do a write up on this one for others.

 

[Turn & Burn]

I’ve done it recently, the only aspect that I couldn’t get to work was using sound frequency to drive the tacho. I bought a signal Generator for about £5 of ebay and it made the job easy and I could test full scale. There’s a bit of info on my build blog.

 

[Rob Gaskin]

That rev counter doesn't go high enough for Jon.

 

[Turn & Burn]

That rev counter doesn't go high enough for Jon.

I’ve had a similar issue with mine, I was wondering why the motor was going flat at 6500rpm, I thought perhaps not enough advance so did a bit of testing with the laptop hooked up, turns out the ecu rev counter scaling was down by 25%. Once corrected 6500 rpm becomes 8200rpm so at least I know it revs through just fine now!

 

[jonbills]

That rev counter doesn't go high enough for Jon.

you're getting there Rob!

 

[AliK]

View attachment 46048 View attachment 46049 View attachment 46050 I’ve done it recently, the only aspect that I couldn’t get to work was using sound frequency to drive the tacho. I bought a signal Generator for about £5 of ebay and it made the job easy and I could test full scale. There’s a bit of info on my build blog.

Thank you sir! That’s good work there. I can’t remember your thread, got a link to it please?

That rev counter doesn't go high enough for Jon.

Totally cracked me up!!! He’ll have to halve the frequency and rewrite the numbers on the clock face to say x2000 rpm

 

[jonbills]

or...

 

[Bazzateer]

Needs to go up to 11.

 

[jonbills]

Needs to go up to 11.

When I get the engine to go past 10, I'll get the rev counter to 11

 

[AliK]

Wow that was quick!!! Ordered 15:45 yesterday, arrived 11:00 this morning!! I hadn’t planned on starting this job so soon, but now the temptation is too great!



it even comes with an adjustment screwdriver! Cool!

 

[AliK]

Couldn’t help myself! Started this one today on my spare rev counter - but ran out of time to try it on the car. I too can’t get the wav file to work but I can make the movement go up and down to 200rpm by creating my own “impulse” wave with a wire and battery, so I’m pretty confident of it working.



i’ll likely leave the existing rev counter in, wire this one up under the bonnet and use the 123 ignition app to calibrate it. After all, the 123 distributor “should” know what revs its doing

Detailed write up to follow.

 

[AliK]

Last night I managed to wire it up and give it a quick test. I did manage to get the test tone to work off an iPad and calibrated it. It’s definitely more responsive than the original circuit so the rev counter is reacting faster.

But here’s the rub - the rev counter in the dash says 1.1k rpm at idle. The 123 Ignition app says 1k idle. But the newly calibrated Spiyda rev counter is around 1.4k!!!

All I can think of is that it’s picking up a second falling edge on the tail of the impulse wave when the coil “rings” after the actual ignition pulse. The Frequency to voltage converter chip is designed to pick up a falling edge. A flamethrower coil will “ring” louder than a lower output coil, so I may try the old 3ohm Bosch one. The diagram below probably better explains what I’m trying to convey in words ...



Finally, I think it needs a diode somewhere as turning the ignition on or off causes the movement to bounce between the extremes before settling down to zero. It may be Le Mans race car cool but not what I want.

I’ll get in touch with Chris to see what he suggests. But in the meanwhile, has anyone actually put theirs on the car and found it to work accurately? If so, what coil and ignition are you using?

or...
View attachment 46053

Linking this a LOT Jon!! It really fits well with the car and the font is pretty close. Who makes it?

 

[jonbills]

Liking this a LOT Jon!! It really fits well with the car and the font is pretty close. Who makes it?

Thats Speedhut. Font, colour, everything is configurable.

If it was a result of ringing, surely it would be double?

1400 is awful close to what you'd get at 1000 if the counter is configured for 4 cylinders

 

[AliK]

Thats Speedhut. Font, colour, everything is configurable.

If it was a result of ringing, surely it would be double?

1400 is awful close to what you'd get at 1000 if the counter is configured for 4 cylinders

Well I had a similar thought, but I’m wondering if it’s picking up intermittently.

I would agree with 4cyl except that I configured it with the 100,200and 300hz files for the quoted RPMs under 6cyl