The Diesel Garage banner

1 - 17 of 17 Posts

·
FORD For Off Road Driving
Joined
·
209 Posts
Discussion Starter #1
Hey guys, I'm considering adding an aftermarket Tachometer to my early 99 PSD. I want to have a more accurate reading than the vague OEM in-dash tach. Anyway, is this even possible? I know on gasoline engines you just connect to the coil and voila you have a tach reading. Where do you connect to add an aftermarket tach in a 7.3L 99 PSD??? BTW, I think the Tach wire is under the dash somewhere, I just don't kno where.....

Thanks!!
 

·
Senior Member
Joined
·
214 Posts

·
Senior Member
Joined
·
6,337 Posts
Isspro has several... But there not going to be anymore accurate then the stocker... You just want to add another gauge I get that, but to say the stocker is vague is a strech...LOL
 

·
Registered
Joined
·
1,339 Posts
ISSPRO (and other gauge manufacturers) make tachometers which use an output from the alternator for engine speed. These outputs are common on larger diesels, but I don't recall seeing it on my 7.3L's alternator (I didn't drive it today, so I'll have to look at it tonight when I get home). We also make units which can work with Hall-effect sensors (which may be installed to sense flywheel teeth) or inductive sensors (which require a magnet to be installed somewhere on the crank). In some future systems, we will tap directly into the OBDII data from the engine, but then you're reading the same data which is driving the factory tach!

What kind of problems are you having with the factory tach?

Regards,
Michael Pliska
 
4

·
Guest
Joined
·
0 Posts
Why don't you just get an AIC? It has a digital readout of the tach...and is much more accurate than what's in the dash. Plus you can idle the truck up if you need to.
 

·
Senior Member
Joined
·
1,854 Posts
I second daves answer. I have the AIC box under the dash in my truck and it reads a little less than the tach in the dash
 

·
FORD For Off Road Driving
Joined
·
209 Posts
Discussion Starter #7
^^ Yeah, I thought about the AIC and that might be the route I take. Im not having any problems with my stock tach. I just dont like how it only reads every 500 RPM's For example, if you're between 1500 and 2000 you have to estimate what you're running. I know this is not that big of a deal for most but I'm running 6.72 gears and 46's. At ~65mph the OEM tach is showing about 2300 to 2400 RPM. I want to know exactly what I'm running so I can slow down a little if needed. I dont feel confortable running the truck for long distances at that high of an RPM. However, I don't really know what I'm running since its between the hash marks...

And yes, I do like gauges and thought a nice 5" tach would look pretty friggin sweet!! haha:woot:

Thanks for the info guys!!! I will look into it!
 

·
Senior Member
Joined
·
6,337 Posts
You could run that motor all day at 2800-2900 and not hurt a thing. Your fuel milage will suffer but the motor will love you.
 

·
Senior Member
Joined
·
1,854 Posts
Explain Joe...

Doesnt the high rpms wear out the motor quiker
 

·
FORD For Off Road Driving
Joined
·
209 Posts
Discussion Starter #10
^^^ Yeah, I thought the optimum range is around 2200 to 2300 RPM. :shrug: I thought for a long distance drive, that the motor would not like the 2400 to 2500 RPM range... I know on heavy equipment, you run your machine wide open though, so maybe it wont hurt it. Im also thinking about MPG's At 60mph and 2200 RPM I was at 600* EGT's and 4lbs of boost. At 65mph and 2400 RPM, I ran 650* and 7lbs of boost. The motor is not working at all.

So you're saying its fine to run a PSD for long periods of time at a high RPM like that?? I just never heard that before but it makes sense to a point.

thanks!
 

·
Senior Member
Joined
·
1,854 Posts
wow thats some low gearing!!
do the big tires cause that?

im runnin 2400 at 75
 

·
FORD For Off Road Driving
Joined
·
209 Posts
Discussion Starter #12
Well, actually the big tires are why I need that much gear!! lol

I mounted a pair of Rockwell 2 1/2 ton military axles under my truck due the massive bearings, shafts and brakes they come with. This fixed many of the issues I had from running 49" Iroks on the SD axles. The rockewells only offer one gear ratio, 6.72's so you have to run a large tire or not go ver fast!! Right now, in OD im running the high RPM's I mentioned with the 46" military tires. I just want to continue to take care of my PSD for many more years to come. This is why I was concerned about the high RPMs. it seems that its not that big of a deal though...

thanks!

BTW I found a couple TACHs on TDS.


This one requires a mod to the flywheel though!

http://autometer.com/cat_gaugedetail.aspx?ref=search&gid=2749



this is what Im leaning toward!!

http://autometer.com/cat_gaugedetail.aspx?gid=3331&sid=11




thanks!
 

·
Senior Member
Joined
·
1,921 Posts
Muddin said:
And yes, I do like gauges and thought a nice 5" tach would look pretty friggin sweet!! haha:woot:
Ahh the REAL reason comes out! You and joe will get along well with your buddies in the civics! :pointlaugh :pointlaugh

Honestly do you really need to know the exact rpm you are running? Can you not figure out the rpm you are running? If you want to run a lower rpm then just slow down a bit. As stated the engine will run all day long at 2800rpm and not care a bit. And if you REALLY cared about MPG you wouldn't have put the rockwells with 49's on it. Not trying to bust your chops (Ok well maybe a little :) ) just being realistic. If you want a monster tach so you can make your buddies with their civics jelous then just say it and get one for that reason.

circle5 said:
Explain Joe...

Doesnt the high rpms wear out the motor quiker
Well being you are moving faster you get there sooner and the number of revolutions that engine made are exactly the same. When you have solid gears between the engine and the ground higher rpms doesn't mean the pistons move up and down a greater number of times per mile.
 

·
FORD For Off Road Driving
Joined
·
209 Posts
Discussion Starter #14
^^^ LOL yeah yeah, let the trash talk begin LOL

No worries, MPG's are not my main concern but if running a couple hundred fewer RPM's made a difference, then I would do it. Right now the truck is getting between 12 and 15 mpg depending on if its in town vs hwy driving so the Rockwells and 49's dont really hurt it as much as most people think. The rockwells actually help b/c of the lower 6.72 ratio which put my EGT's back around stock ( 600* cruising on the hwy at 4 PSI ) Before, with 5.13's the egt's were around 1,000* at 70 mph!!!! I still got 10 to 12 mpg with that but the motor was working all the time which added to my choice to do the rockwell swap.

Anyway, that said, I can "guess" what RPM I'm running but with the stock tach thats all it is, a guess. I dont know about you but I prefer to know as much detailed info as possible about the engine while running down the road etc. I know its overkill but what the heck. BTW, thanks for confirming the 2800 RPM statement. Its good to know the motor can handle that high an RPM for long periods of time.

Muddin
 

·
Senior Member
Joined
·
1,921 Posts
Well then just slow down 5 or 10 mph and see if it makes a difference in your fuel mileage. A tach isn't going to help your mileage get better. It's like having an extra volt gauge that has the exact numbers on it. Is there anything you can actually do to change it? NO. Is the gauge you have now going to let you know if you are dangerously low? Yes. So what's the point of the redundancy? Unless you just want to be like the ricer guys with the gauges all over that don't do anything. But are you really going to drive slower for more than a day or two to try to get better mileage?
 

·
FORD For Off Road Driving
Joined
·
209 Posts
Discussion Starter #17
^^ thats pretty cool, thanks!
 
1 - 17 of 17 Posts
Top