The Tachometer issue...

[Fightfan]

Alright, after a boatload of searching I think I may have found some answers concerning the use of a tachometer with the 6.2L that is being shoehorned into my YJ. Feel free to chime in with anything useful that you can add.
1. The alternator has a "P" terminal, which I have on good authority is or can be used for a tach. That being said, it will work with a DIESEL ONLY tach.
2. There is a company called Dakota Digital that sells a diesel tachometer interface. This allows the use of any automotive tach to be used in a diesel application (according to their website and email feedback). It connects to the "P" alternator lead and then translates the signal for use with a regular tach. The "P" terminal is called a "W" terminal on the website. The part number for this potential gem is DSL-1. It called a universal diesel alternator tach interface.

My question to the forum is: Has anyone used this or something like it to run a tach on their vehicle? If you didn't use this and are running an after market tach, how are you getting it to pick up? This tach interface would be nice to use if it works because I could then pick any tach I want (to match other gauges as needed).
Thanks,
fightfan

[HH]

I have not used it, but have considered it. I am thinking about using a tach from a diesel boat. Typically they have a setting on the back that you can adjust for the number of inputs/revolution.

[trbankii]

I take it that you want to be able to use the tach in the YJ for the swapped in diesel?

Here is a webpage that describes how someone did that for a VW project he had: http://www.4crawler.com/Diesel/CheapTricks/Tachometer/index.shtml

He also offers a kit of the parts required (almost to the bottom of the page, but not quite).

Another option would be the Tiny Tach Diesel and mount it separately: http://www.tinytach.com/tinytach/diesel.php

[Fightfan]

Thanks for the input and hyperlinks. Now that I know that I have more than 1 or 2 options, it is going to take some serious thought on which way I want to go on this. I think overall, reliability is my main concern. I like homemade ideas and getting creative, but if it has a short life span it won't do me any good. The path of least resistance is sometimes the path to longevity. Over complicating the wiring or number of components in a vehicle that will be exposed to harsh conditions on and off road is not a good idea. The idea of a marine tach sounds good because it would make sense for the durability aspect since it is designed to be used in boats. HH, is there a brand of marine grade tach that you have looked into? Also, another thing I planned on doing with as much of the wiring and connections was using marine grade heat shrink. It has the glue in it to make it water proof-ish. I don't think that anything is totally waterproof, but I am going to do everything I can to prevent the destruction of my Jeep, to include electrical shorts and electrical fires. Again, thanks for the help and direction.
Fightfan

[trbankii]

I do have to give Roger Brown a lot of credit - he's been involved in the Toyota scene for the past decade and really knows his stuff. I can vouch that his writeup isn't some half-baked idea. But I also agree that sometimes the "bought and installed" route can be the better course of action.

[opto]

I think most aftermarket diesel tachos uses the generator pulses, which means you have to calibrate it with a reference tacho, for example from a timing tool.

Autometer has a fairly new tacho (which is a bit big I think, 5" something) that includes a probe to be mounted on either the flywheel or the pulley

The Dakota Digital interface I'm sure it works great, but I don't like the idea of using a gas-tacho as all aftermarket tachos have the range up to 8000+ rpms and then you wouldn't be using even half the scale

I found a marine diesel tach in a store nearby which is quite cheap($65) and clean looking, I will give it a try when I get the time

It's really annoying not nowing the rpm, isn't it

[Fightfan]

I think what irritates me the most is the fact that aftermarket companies don't make a diesel tach to match the other gauge sets in their product lines. After my first post in this string, I really searched the internet for gauges and came up with hardly anything at all. As much as I am going for form, function, and reliability, I also want asthetics. I don't plan on dumping $15k+ into my Jeep to have a mismatched interior. It might seem trivial to some, but the 4X4 of my dreams has a very specific look. It would drive me crazy if certain things aren't a certain way. The Air Force trained to be a mechanic and to do it a specific and very neurotic way. I blame them for my neurosis. Even if I don't use the upper range on a regular tach, I can at least get one that matches the other gauges. If it works the same, then I still have a tach and can get it checked for accuracy. I am really disappointed with the whole diesel tach issue in general, especially since I wasted about 8 hours of my life reaching the end of the internet searching for Unobtainium. I knew it wouldn't be easy, but it seems like the aftermarket has ignored the diesel enthusiast in some regards. This is something that I consider very important to monitor. As of right now, with the selection being what it is, the Dakota Digital option looks the sunniest. Excuse me while I go finish having my rage induced aneurysm...
Thanks for listening to me rant.
fightfan

[HH]

I have not picked a specific brand of tach. I looked at Kendor Marine, which is a local marine supply house that has bought out other marinas. Check out their selection http://www.greatlakesskipper.com/products.cfm?CatID=SS224.

You may want to check out ISSPRO gauges (http://www.isspro.com/index.php), they seem to be more geared to diesels, and you should be able to put together a set from them.

[4xjunkie]

Well here is a idea. You might need to do some research on this but here it goes.

You mentioned using the signal from the Alt right, then it must have a Pulsed signal, well a standard tach needs a pulsed signal to.

You could make a simple little black box, with a few componets and a IC chip and convert the incoming diesel signal with a output to match the standard tach.

You just need to know what the Pulse per Minute is for both. Then formulate a circut from there.


But then again, when doing custom stuff nothing ever going as planned.

[4xjunkie]

That way you can still use the matching tach.:D

[Fightfan]

HH,
Once again, thanks for great info. I went to the ISSPRO website and they had a good selection. Have you used these gauges before? I also looked at the boating supply website, it had some good stuff, too. More options than JEG'S or Summit Racing has to offer. The fact that I can buy the tach with an hour meter is nice. It's kind of unnecessary, but I like it. Options are always nice.
fightfan

[Fightfan]

Junkie,
That sounds great in theory, but I am semi-retarded when comes to "inventing and formulating" wiring applications. Figuring out a custom circuit, maybe a little out of my league. I like to stick to what I know. I can wire anything with a diagram and an established set of directions, but much beyond that I would be in over my head. Again, as you say custom stuff never goes as planned.
fightfan

[HH]

You could make a simple little black box, with a few componets and a IC chip and convert the incoming diesel signal with a output to match the standard tach.


Dakota Digital (http://www.dakotadigital.com/index.cfm/page/ptype=product/product_id=128/category_id=287/home_id=59/mode=prod/prd128.htm)makes a "little black box" that does this, but I have no experience using their products.


HH,
Once again, thanks for great info. I went to the ISSPRO website and they had a good selection. Have you used these gauges before? I also looked at the boating supply website, it had some good stuff, too. More options than JEG'S or Summit Racing has to offer. The fact that I can buy the tach with an hour meter is nice. It's kind of unnecessary, but I like it. Options are always nice.
fightfan

I, along with many other diesel enthusiasts here, have the ISSPRO gauges. I have water temp, oil temp, boost, and EGT in my 1993 K3500.

I agree the hour meter is nice.

[4xjunkie]

[quote=HH;240821]Dakota Digital (http://www.dakotadigital.com/index.cfm/page/ptype=product/product_id=128/category_id=287/home_id=59/mode=prod/prd128.htm)makes a "little black box" that does this, but I have no experience using their products.[quote/]


Sweet. I didn't realize there was one already out there. And for that price, I am not even going to mess with my own.