Anyone test new engines by measuring turn-over torque? Standard Practice in NASCAR
 

My engine builder suggested I ask any of the engine builders on Pelican if anyone is measuring turn-over torque (I'd call it a measurement of static fraction) to turn over a new or rebuilt engine via the crankshaft pulley. That is without plugs, so no compresssion.

He measure 23 ft. lbs for my rebuilt 3.6 engine.

He said with NASCAR engines (he's a Porsche guy, not V-8 guy BTW) the builder will assemble the engine and turn it over and if the torque threshold is too high, they'll take it apart and try it again.

Is this a valuable metric to anyone outside of NASCAR?

Just curious, anyone else do this?

Doug

Not to my knowledge but frictional HP loss is real. Certainly this is one way to measure. I once knew of an engine builder (20 yrs ago) that stated a 454 chevy big block in street tune consumed close to 100 hp frictional loss.

That is a h3ll of a lot considering the average street engine made @ 425 HP at the flywheel.

I don't measure the torque but I do turn the crank at several points during the build process. I've developed a general feel for what turns out to be about right.

I also start by spinng the rods after installing them on the crank.

John Edwards ( Costa Mesa R&D) has a SIM tester that we have used to turn new engines (usually race engines) that are going to be run /raced with limited break in.
The principle is to hook the engine (spark plugs removed) to a large motor that will turn the engine with total loss oiling ( no pan or in the case of Porsche, no sump plate or drain plug.) This will flush the engine of assembly lube and any possible contamination.
As the motor turns the engine generally for 3 or 4 hours you can watch the amp draw of the motor drop when the amps stop dropping the engine is in effect broken in and ready for full power runs.
It's a cool way to check oil pressure as well as oil leaks before the engine is installed.
This process will also seat the rings.
I guess if you save load readings then compare output readings you could correlate that number to some sort of performance figure. How knows?

What Henry describes (with variations) is a NASCAR technique that I guess is being adopted in other venues. Especially for "restrictor plate" or air-restricted engines. I believe that Smokey Yunick developed a special sort of dyno called a "Spinitron" which spins a motor at race speeds and measures the HP required to do it. This allows the engine builder to develop and test a motor based on the frictional losses. This is key if the motor is air- or rev-restricted.

I'm curious why in the example that Henry describes they run the oil-system open rather then in the normal configuration with a filter just like a normal break-in? I would think that you'd wind up pumping an awful lot of oil on the one-way trip through the engine.

The oil in the SIM tester is circulated via an external pump and filtration system in the engine stand itself and then reused.

Smokey Yunick ..................now there is a real genious. That guy was so far above anyone in his day that even now his research is still used as a base. Really the Enstein of the auto technology

It's sad that Smoky will be remembered for cheating more than innovation.

"Genius when use for evil negates the accomplishment of the genius."

3.8 RSR 24# Supercup, Gt3r 36# after the breadaway torque measured with a beam troque wrench.

regards

Why should he be any different then Colin Chapman or for that matter Gordon Murry (designer of the F1 "Fan-car"). All were geniuses in my book, but will most likely be remembered for things like the "Fan-Car" and the "Dual Chassis" which were both quickly regulated out of existance.

Regulated out of existence is different than creative ways of hiding what you are doing.

One is exploiting a loophole, or unthought of (by the rules makers) development, the other is breaking the rules, but not getting caught.

A HIDDEN NITROUS SYSTEM IS CHEATING NOT EXPLOITING A LOOPHOLE.

Don't get me wrong, I am not naive enough to believe that cheating is rare.
When Jeff Gordon won his second championship his team also set a record for more fines for regulation violations.

Some of you might remember BAR Honda F1 team sitting out 2 races last year for cheating.

That's just freekin cool!

Henry, I didn't realize they had such machines, though they make sense.

Racing97 - thanks for the details on your motor.
all- thanks for the comments, you've provided some interesting information.

Anyone else have breakaway torque #s?
Thanks,

Doug

Doug, breakaway is naturally higher once get it going you have three cyl's valve springs opening and three closing so the effort becomes less.
Rotational average is what we are looking at, low tension rings are what we are actually measuring.

regards

Yes, makes sense. I did understand that position within the cycle effects measured value because of valve tension, etc.

Do you measure breakaway at TDC and then average torque throughout two rotations?

Do you have a desirable spec?

I would think mine is similar to yours, but not exact.
It is a 3.6 w/ back dated solid lifters and Super Sport cams along with AASE springs.

The breakaway torque was measure at 23 ft lbs.

Doug

Doug, I literally turn the motor over with a beam dial and watch it as it circulates. It is just for future reference . The Nascar builders set ring tension when installing the pistons and check the fastner to block defelection (cam and bore) in this manner. When in development you
try to establish parameters and this is one way of course it is ecouraging to reduce parasitic loss and this is a inexpensive way of doing so. Align bore used to be an issue with the Mag blocks and that is where we started paying attention to detail as I see you are also.
You have the same results I used to see when I built those type motors
with the exception of our bore being 102.
Nice to see you using good valve springs. We spent alot of time with those things.

regards

Dumb question for a guy facing an engine build....sort of scary as I have new Mahle pistons/cylinders, brand new crank, brand new case....going to be a 3.4 litre with EFI etc etc.

How about if I find a large electric motor at some salvage yard, say 10 hp. Ought to be about 7500 watts, on 220 volts should be able to run it on a 50 amp breaker. May not be able to find a single phase motor, but let's just pretend I find one.

Hook it to my newly rebuilt engine, which I would hook up to the oiling system (oil tank/filter, cooler etc) all on a test stand. Fire up the electric motor and let it run for a couple of hours, measuring the input current with my trusty Fluke until the curren draw goes down. Normally they run at 1760 rpm, so ought to be just about right...

Would it work? Advantages over just firing the sucker up and doing a conventional break in?

Dennis

The SIM tester runs at 350 rpm and has a preheater so the oil can heat the engine to operating temp.

You could just send it to a shop with a SIM and pay the $200 and you win.

What does "SIM" stand for ??