sb punishment

[RACER X #99]

Which engine receives the most punishment?

600 HP drag race engine shifting at 8,000 rpms. Assuming five 1/4 mile passes a day.
or

600 HP road race race engine shifting at 6,000 rpms? Assuming four 30 minuite road race sessions per day.

or

600 HP street cruiser running at 2,500 rpms for 8 hrs.


Any ideas, opinions?

[DAVID GAGNARD]

Cranky;

Do not really know the answer,but about 7 or 8 years ago back in my dirt track days,a local drag racer friend told me he thought we put as much if not more wear on our engine in one night of racing as he did in a 6 month season of drag racing every other saturday night......

On a saturday nite at the dirt track the motor probably ran for about 45 to 60 minutes at speed on the track.......

I would think the road race engine would see more punishment,at least I know mine does,on and off the gas from 3000 to 6000 rpms 10 to 14 times per lap,15 lap sessions,three to five sessoins a day,gotta be hard on an enigne............

David

[mr0077]

Are they all built for 8000 rpm? If so, I think the drag motor takes the most punishment, as it is pushed closer to the limit more often.

[427sharpe]

I think the drag motor...instant full load shocks, followed by full rpm runs and a cold shut down. Not very pleasant for the machinery.

[RACER X #99]

With my limited math skills I figured as best I could how much each engines worked in one day.

The drag engine totaled 8,000 revolutions for the day.

The road race engine 720,00 revolutions for the day.

The street engine 1,200,000 revolutions for the day.


I did not count start ups, burn outs or idling, just when they were running at speed.

[TerrysSPF]

SB punishment??? Isn't having a small block punishment enough?


-Just kidding!

How about a car at idle for 8 hrs? Now THAT'S punishment.

[G.R.]

Originally posted by TerrysSPF


SB punishment??? Isn't having a small block punishment enough?


-Just kidding!

How about a car at idle for 8 hrs? Now THAT'S punishment.

Oh you mean that BB you have

-Just kidding!

[TerrysSPF]

..........ok, ok, it's a "Medium Block"

[Jack21]

True, it would appear the street motor is getting the most wear, but it will do so every day for 10 - 20 years with plug and oil changes.

[klayfish]

Cranky,
I think it would have a lot more to do with the type of work the motor is doing than the sheer number of revolutions. With my limited mechanical knowledge, I'd say it'd probably be the road racer (assuming all three motors are identical). The dragster will have 5 "balls to the wall" runs under maximum load. But how many times during a typical road course do you have your foot to the floor climbing through the gears? Then how about downshifting? Then back up through the revs...then back down.....on and on. Gotta be hard on the motor.

The street engine would cruise like that for years. Well....until someone convinced them to put it on the track and blow it up.

Steve

[turnpike boy]

Majority of wear occurs when the engine is accelerated. Meaning whichever usage causes the most run-ups, that will be the one that will wear it out first.

Steady-state operation is a virtual freebie, wear-wise.

[CobraBoy]

Okay, you guys. How about a 930cc Hillman Imp engine on a sprint/hillclimb, shifting at 9,500rpm. Maybe, 60 seconds? Probably upwards of 6,000rpm for the entire run.

At least she's built for it. Lightened and balanced, tuftruded crankshaft, full race camshaft, Webers, block girdle, Cosworth bolts and tappets...

Can't wait to get my car back...


Catch y'all later!

CobraBoy (aka ImpManiac)

[Toby]

I disagree with turnpike boy. I think 90% of engine wear is caused by cold startups, before oil is circulating good. Also aggrevated by whichever engine has tightest tolerances. Of course, on a lighter note benchracing wears out more engines than anything! LOL

Toby

[cobrashoch]

Cranky - as per normal you ask a question that can't be answered even on identical builds, due to the parts selection longitivity. The answer to your question is measured at/in drag racing I suspect though. There's a reason top fuel engines are rebuilt after each run. Could they be built a bit stronger? You betcha! But that would mean less power too. So there in lies a possible solution to your question.
All engines regardless of make and demeaner are measured by intended use vs, the build factors.
Another thing. ANY engine that's rated at say 350 horses at any given spec. will continue to produce that same 350 horsepower regardless of how you drive it, be it hard or easy. This implys that a given build will have a life expectancy range factored in too. For example most Ferrari V12 builds have a street life expectancy of around 30,000k.
Remember, that 350 horsepower has the same amount of measured power regardles of brand name or size of engine. Period!
The upshot of this is, different racing versions will put different requirments on different parts of our identical engine. If parts failures are what you are looking at, then if we drag race maybe it's spun bearings we will see. Road course racing may see a rods wrist pin failure, on the street we may see valvetrain failure. It's all moot though. In the real world no racing engine is the same. Only stockers are built the same.
Your question, though logical, is agenda driven in my eyes. That's not a bad thing though. Just keep it in mind when you ask such things. That way you won't be coming back at me with other factors such as engine weights, mileage, revability, torque vs. horsepower and so on yati, yati, yata.
cobrashock

[RACER X #99]

Ron,
I Just asked for opinions and you gave yours.
Thanks.

[speedlab93]

I have never seen a dyno sheet that the hp curve is a strait line. The hp of a motor is not the same regardless of how you drive it , but has every thing to do with how its driven.Just becouse it's there doesn't meen it's being used.
Road racing is defenetly harder on a motor than any thing else, it's a miny drag race out of every corner.It's not the total revolutions but the revolutions under load.