Horsepower again

This has been discussed the last couple days but I still have a question. For instance, what if a car engine rated at 300 h.p. was put in a large 4 wheel drive tractor and geared for regular working speed. You use the car engine tractor the same as before when it had a conventional 300 h.p. diesel engine. How long could the car engine stand up to a full demand of its rated power?

Not very long.

Automobile engines are HP advertised at peak levels. Such engines can deliver such power for very limited periods as might be needed/desired in automotive applications.

I had a similar discussioin with my Father about 50 years ago. My Father was a field engineer for GM truck and bus for over 30 years. His responsibility was technical support for commercial fleet operators using GMC (Detroit) diesels and hydramatic transit bus transmissions.

At the time, I had a 64 Impala SS with 327/300, which had been modified about as far as I could do, and still drive it on the street. I was well into hot rodding at the time and was well aware of CR, fuel injection, blowers, etc.

Having often traveled with my Father, I was also well aware that the Detroit 671 and 6V71 engines displaced 426 CI, hit every revolution rather than every other, and were both fuel injected and blown. At 18, in the late 60s, I was as yet unaware of the benefits of 4 valves/cylinder (whether all exhaust or otherwise).

At the time, it was inconceivable to me that the HD Detroit 6/6V71 engines produced only 180+ HP depending upon configuration while my 327 Chevy V8 was advertised (conservatively, at the time) at 300 HP. I was 18 - 19. My Father was mid 60s, and had been a GMC field emgineer for GM since WWII, when he spent 3+ years in the South Pacific on loan to the War Department.

Upon questioning, he stated simply: Your 327 may generate 300 HP at 6000+ RPM for a few seconds or minutes. The 6/6V71 will generate 180+ HP at 1800 RPM 24 hours/day, 7 days/week, day after day, week after week, month after month, until it is time to shut it down for oil and filter changes.

Dean

Just as Dean stated - few cars or trucks have engines rated for steady use. The only ones I can think of are a few heavy 3/4 ton trucks. Engines for heavy use (on the road) get "B" ratings. These ratings predict how many miles they last, on average, when used hard most of the time. Chevy Duramax has a B10 rating of 220,000 miles. That means that when used hard - 10% by 220K miles and 90% make it. You won't find any such rating for a car engine that is not made to endure steady hard work. Tractor engines got weeded out by the Nebraska Test Institute. Some HD engines came with two ratings: One for max power and one for continuous max power. One example is a four cylinder VP4 Wisconsin engine. It is rated for only 24.2 horsepower continuous, and 31 horsepower max momentary.

We're at 50% for Duramaxes hitting 110,000 miles. Yes, they get their oil and filters changed on time. The one that blew is the one that doesn't see a bunch of time idling in winter or crazy hillclimbs with a bale on the balebed leading cattle around/between/through pastures.

The neighbor and I put a 396 out of a Chevy pickup in his straight truck. We were TOLD it would work must fine. Burned up three pistons. If he would have used high octane fuel it probably would have lasted longer but with the price of high octane fuel at four MPG or whatever it got, well, you get the idea. Jim

If you burned up pistons then I'd say either the
carb mixture was too lean or your timing was too
far advanced. In 1984 I took a 350 out of my
granddads 73 C50 Chev and put in a 454 out of a 74
Caprice. That engine lasted over 15 years and he
sold the truck to a neighbor. Last I talked to him
it was still running in 2004.

not to mention diesels are torque monsters that gas buggy in a big 4-wheel drive tractor would have no lugging ability and would be gutless and overall pretty much worthless

Someone on here once said, "Car engines are designed to run at 90% max power 10% percent of the time while truck/tractor engines are designed to run at 90% max power 100% of the time."

Something that has stuck with me because it made so much sense.

Nate

I worked in engineering years ago for a crane company. Detroit Diesel and Cummins engines all had ratings for continuous duty and intermittent duty. OTR trucks were mostly rated intermittent. A continuous rating application might be a water pump, or a marine duty application where they worked hard continuously. In marine applications there were no flat pulls, or downhill runs. Uphill all the time.

(quoted from post at 12:12:08 03/16/14) This has been discussed the last couple days but I still have a question. For instance, what if a car engine rated at 300 h.p. was put in a large 4 wheel drive tractor and geared for regular working speed. You use the car engine tractor the same as before when it had a conventional 300 h.p. diesel engine. How long could the car engine stand up to a full demand of its rated power?

Click to expand...

As stated not long. Most car engines are intended to run between 1600 and 2000 RPM's cruising. If you look up the stats they achieve peak HP at much higher RPM's. But stats can lie too. A few years (10 or 12) back a non computer using friend was in the market for a new truck and wanted a diesel. He ask me to look at where the GM, Ford and Dodge made their power at. Was easy to find the GM and Ford specs but could not find the specs for the Cummins anywhere. I got on the Dodge web site and they had this instant chat option for technical questions. The, at the time, advertised max HP rating was achieved over the Max recommended RPM's. Now that isn't saying that the engine was bad. That was because the big 3 was in a diesel HP war and you can only get so much out of a smaller displacement engine. Torque was spot on. And for reports it would pull right up there with Ford and GM. Just a little customer disinformation to sell trucks.

Rick

since we aren't talking about how....
like said, it would depend on where-rpm the auto engine made
it's hp.
if it gets it's big hp from high rpm like a smallblock, it won't hold up.
Lots of hp and torque at low rpm with a strong bottom end,
like a FE Ford, or a 300ci 6cyl Ford for example(or pick your fav)...It would pull hard and hold up fairly well, at the price of lots of fuel.

Light duty, medium duty, heavy duty,intermitant duty, peak duty, continuous duty, standby duty...........
All depends on how long the engine will last operating at 10-20% of max power as a light highway vehicle (car or pickup) vs an industrial application.
Of course to a point the more you increase a Diesel engine"s power, the more efficient it becomes. So by default a diesel needs to be built to run at near peak power continuous . Or the fuel efficiency will drop. Look at the Nebraska tractor tests for diesel fuel efficiency at 50% load vs 100% load.
A gasser still keeps decent fuel efficiency when operating at 10-20% of max power.

As others have posted the horsepower ratings are different for tractor engines than for car engines. Therefore, replacing a 300 HP tractor engine with a 300 HP car engine is not an apples to apples swap. You might want to consider a car engine closer to 400HP (or higher) which would allow operation at a lower RPM point. For example, a Ford 6.8L 3 Valve Triton V-10 makes 362HP at 4750 RPM however, operating at it's torque peak yields 283 HP at 3250 RPM. Maximum cylinder pressure occurs at the torque peak so you are making power with pressure instead of RPM. At least the engine has half a chance running 1500 RPM below maximum power.

In answer to your question how long can a car engine live at full power; as part of Ford's standard engine development durability signoff testing the, 3.5 L Ecoboost was run at full turbo boost and maximum RPM for 360 hours. All manufactures have a standard durability test which I am sure is similar. How long is 360 hours in the life of a tractor.....at least 15 days.

Sorry, this is not an advertisement for Ford - I just knew where to get numbers quickly. I will admit to being lazy.