M60 Swap tachometer reading

[Garageaholic]

I was reading through the M60 swap thread that was written here and elsewhere. I have a question regarding "half the signal" for the tachometer. I understand that you must use a 4cyl E30 tach plug, but how exactly do you half that signal coming from the M60 engine?

[g3n0cid3]

Here is the cheapest way using a single flip flop circuit.
http://www.electronics-tutorials.ws/...r/count_1.html

I have never tested this circuit as I don’t have a scope. But my guess is that the DME will not modulate the wave from the ckp/cmp which would mean that the wave would be a sign wave. This circuit will produce a square wave and might not work.

[JGood]

There's a guy selling a device in this thread for $100 shipped:

http://www.r3vlimited.com/board/showthread.php?t=213858

Although if you're handy with electronics you could make something up. I'd think it would only take a 555 timer chip and a simple circuit. It doesn't need to be adjustable, just needs to half the signal (if using a 4 cyl coding plug).

[M3 euro ltw]

RE: Dakota Digital

They have some items useful for this too, but I think more than $100 or DIY if you can do the timer

[JGood]

They have some items useful for this too, but I think more than $100 or DIY if you can do the timer

Yeah, looks like this guy would do the trick, and it's packaged nicely.

http://www.dakotadigital.com/index.cfm/page/ptype=product/product_id=127/category_id=287/home_id=59/mode=prod/prd127.htm

[dirty30]

Still have one signal converter for sale... $100 shipped.

[LJ851]

This guy is offering a universal 4-6-8 cyl/tach converter for a good price. It looks well made to me.

http://forums.pelicanparts.com/porsche-911-technical-forum/627935-tachometer-adapter.html

[JGood]

This guy is offering a universal 4-6-8 cyl/tach converter for a good price. It looks well made to me.

http://forums.pelicanparts.com/porsc...r-adapter.html

Nice find! Doesn't list a price in the thread but he does mention a $50-$60 price range goal. I'll be contacting him.

[Garageaholic]

I want to make my own I've decided and I think it can be done as per Justin's suggestion by using a 555 timer.

Does anybody know what the frequency (or period) of the m60 ignition for all 8 cylinders?

Edit: it changes with RPM. Got it. So whatever the frequency is, it needs to be halved. Why can't you modify a m60 coding plug?

[Garageaholic]

Bringing this back from the dead, but I think it's important.

A buddy of mine, who is an EE (I'm ME, so I don't understand this stuff to the lower level) took a stab at a schematic for a tachometer reading adjustment from 4 cyl plug to the 8 cal M60. 6 cylinders is possible, but the math is more difficult.

12V Power Input
Ground
Input Tach from ECU
Output Tach to cluster



Haven't tested. I'm going to do a first crank on my M60 in about a week or two, so I'll have something to report back then.

[Jonsku]

It's a very simple thing to do if you know anything about electronics. I don't, so I bought the ready-made thing from Stifter (e30.de) :)


If you search "stifter impulsteiler" there'll be quite a bit of discussion (in electronic-language as well :) ) on the subject.

[iamsam]

Frank your circuit schematics are scaring me. Circuits 1 is as far as I will go into the electrical engineering field in academia, and that scared me enough.

My loud exhaust and rev limiter will be my tach.

[noid]

Bringing this back from the dead, but I think it's important.

A buddy of mine, who is an EE (I'm ME, so I don't understand this stuff to the lower level) took a stab at a schematic for a tachometer reading adjustment from 4 cyl plug to the 8 cal M60. 6 cylinders is possible, but the math is more difficult.

12V Power Input
Ground
Input Tach from ECU
Output Tach to cluster



Haven't tested. I'm going to do a first crank on my M60 in about a week or two, so I'll have something to report back then.

I asked this in an electrical engineering sub-forum:

http://www.physicsforums.com/showthread.php?t=550469

I am not sure why your friend wants you to use a NOT gate before the D-flip flop and an AND gate after the D-flip flop.

[JGood]

Frank, how do you plan on packaging this circuit?

That was my main concern, and the reason I'll likely go with the Dakota Digital unit. To get something small, reliable, and durable packaged up may be a bit of a PITA as opposed to just forking over the $85 for a nice little plastic box with mounting tabs. But if you do find a way to do it nicely, I'd rather send my money your way, so keep us updated!

[OoPEZoO]

Does anyone know what the signal actually looks like on an O-scope? I mean details or an actual screen shot, not a vague description.

Justin, I have an O-scope here at the house. If you want, we could take a look some time. Depending on what the signal looks like, I could easily whip you up something reliable with just cheap parts from Radio shack or crap I have laying around at work. it would be a complete no brainer if I knew what the original signal looked like.