bgiere

anyone using an hour meter for their race car? if so, what type is recommended.

amondc

We got a cheap one from O'Reilly's and it works fine. We wired ours in so that when the key is on it runs but it would have been better to find a circut that is only hot when the key is in the run position that way you have true hours.

Geo

I am installing a standard clock wired so it only runs when the ignition is on.

Geoffrey

I have a digital one and wired it to the fuel pump relay so it is running only when the engine is running.

Adam@Autometrics

We go one step further and hook it up to an rpm activated module (typically used for shift lights) so that we get only on-track time (time over a specified rpm, typically 3-4000.)
Warm-up/idle time can really bump up the clock without actually putting any wear on the engine.

bgiere

i like that idea Adam...how is the wiring done? what brand of meter do you recommend? thanks all!

jrotsaert

Adam,
Can you explain how you do it and what meter you use?
THX
JM

Adam@Autometrics

We typically use an Autometer rpm activated module with a 3000 rpm pill.
It installs just like a shift light, but you hook up the hourmeter instead of the light. I believe we are also using Autometer hourmeters.

mroberts

The cool one to get would be an aircraft "tach timer" - it gives you equivalent hours at a certain RPM. You set a "base" speed, say 3000 RPM, and it records 1:1 at that speed, and proportionally faster at higher RPM.

bgiere

some tractors use the aircraft style hour meter as well...i have a John Deere with a VDO hour meter...records "hours at 1850 RPM".... that might be the ticket!!

fatbillybob

I'm a little ignorant. What do you do with this data? For certain motors is there data that says: 1000 hrs. 10% horsepower drops off
2000hrs 20% drops off or something like that? I never did know when it was worth it to refresh a motor unless it blew up then it was pretty obvious. I would think you would get compression leak down numbers after break in then look for a certain percentage of increased leakdown before you rebuild.

jrotsaert

Thanks Adam, any idea of where they can be bought (I've moved to England so need to order over the net...)
JM

SundayDriver

Most high strung race motors have a life spec. If you go beyond that, you risk catastrophic failure, but you may not see any leakdown change prior to that point.

If you have a 30 hour motor, then you best freshen it at that point or the bill can get really big.

BTW - The more sophisiticated 'hour meters' are done in data aq. MoTeC, for example, generates a hisogram so you can see how much time in various rpm ranges. You could see how many hours over 5,000 rpm instead of just hours. And how many hours over 11,000 rpm too.

fatbillybob

Interesting, How do engine builders determine hour life? Do they just build a bunch of V8's and test until destruction to get data? It seems that with the new F1 V-8 they need more testing....

SundayDriver

At the high end, like F1, clearly they have the resources to test and test and they are always dealing with new designs. I suspect for amateur motors, it is some testing, some trial and error in the field (we are the test drivers) and shared knowledge.

I think you are right on target about the new F1 motors needing a little more testing.