tachometer recommendations

[bugbitten]

Folks,

I'm big on engine instrumentation. My 9.2A came with zilch. I've added a temp gauge and now would like to add a big, round tach (I've got lots of dead, old instruments on either side of the companionway and need to start filling some holes) for my Yanmar 2GM20F.

I don't think my Hitachi alternator has a tach connection, but I understand one can usually be added fairly cheaply. Would you recommend I do that, or go the mag pick up route? Any suggestions, preferences, or experiences you can share would be appreciated. I'm thinking about one of Teleflex's heavy duty tachs, but could easily be swayed to another brand/model.

Thanks.

John

 

[woodster]

there was a post a couple of weeks back about the tach and as i remember there was a site that had a very good price on the tach as well ...it was alt driven but that is ok if you calabrate it correctly.......the factory tack if purchased from them is way to expensive...the pick up alone is about $150. so if you dont have any part of the tach system now i would say go for tha alt driven one ....i think it was around $100. and that is about as good as its going to get as far as cost....unless you watch ebay and bide your time you may come up wit a deal there ....

regards

woody

http://www.egauges.com/vdo_ind.asp?Type=Tachometer&Series=Vision&PN=333-163

this is the site

 

[bugbitten]

Thanks, Woody. I've been finding alternator-driven units for around $50 to $100, which is certainly reasonable. I'll look for that other thread.

 

[BobM]

A tach is an absolute must on a diesel.

 

[bugbitten]

Thanks, Bob. Did yours come with a tach, or did you add it?

Pulled the fuel tank sender today. Not finding any resistance, so it looks like that'll be added to the replacement list.

John

 

[BobM]

It came with one. You can't baby a diesel. It is a recipe for disaster. I had the hardest time convincing a sailing friend of mine about that. I cranked his boat up to 80 percent of its max r and made him listen to it and feel how much smoother it was running. Stopped smoking too. Be nice to see his boat without a stern mustache this season!

 

[bugbitten]

If I'm just warming it up at the dock, would you still run it up to 80 percent? While I'm working on it, I need to fire it up fairly often w/o going anywhere. I've been running it on medium throttle for about ten minutes, idling back for a bit, then shutting it down. No smoking issues yet.

John

 

[bugbitten]

Just ordered one of these. The entertainment value should be endless! Figured it would help me calibrate the alternator-driven tach once that's installed. I think the redline on the 2GM20F is surprisingly high. Something like 3800. (Redline might not be the right term. That's the speed at which it reaches it's rated HP.) Should I run it up to around 3000 when just fiddling at the dock?

http://www.amazon.com/Digital-Photo...T9ZS/ref=sr_1_2?ie=UTF8&qid=1332412627&sr=8-2

 

[BobM]

The continuous rating output at the crankshaft is 11.8 kW, and 3400 revolutions per minute (rpm). The maximum output at crankshaft is 13.4 kW, and 3600 rpm.[1]
The engine delivers roughly 16 horsepower, for a weight of about 114 kg.

Listen for a sweet spot in the power band under load at about 80% of 3600 or 2900 rpm. The engine will tell you when it is happy. Max rpm for my 2QM15 is 3000rpm, but my boat runs best at 2500-2800rpm...which might just reflect variability of the factory tach.

 

[bugbitten]

I ordered what I hope was a Teleflex 3" heavy duty, alt-driven tach from our good friends here at the sailboatowners.com chandlery. They list it as a Sierra, but it has the same part number (82430P) as the Teleflex unit. Now I need to get my alternator modified so it has the proper connection on it.

 

[ewoden1]

Run a one-lunger YSM8 and you will come to appreciate what BobM says about sweet spot.

I have no tach at the helm (next spring maybe). I've got a digital optical like the one you just purchased and trained myself to recognize the peak output and the sweet spot by ear with reference to that tach, both in neutral and under load.

The sweet spot on a YSM8 is when your fillings stop rattling out of your head

 

[bugbitten]

I need to update this! Hope I haven't forgotten anything essential.

I had my alternator modified to have a tach tap by a shop in Norfolk for $45. It was then a simple job to use the existing gauge wiring to hook things up. There was already a piece of reflective tape on the crank pulley, so it was a cinch using the optical tach to calibrate the Teleflex unit.

I've used the tach maybe half a dozen times and it's worked flawlessly. I was worried, after I'd read a thread about tachs in a different forum, that the tach might cut off when the batteries reached full charge. For whatever reason, this has not been a problem.

I'm very pleased with the overall set up. The 3" guage went into an existing hole near the companionway. It's easily read from the helm.

John