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DandyDon · 04-17-2019, 08:47 PM

This sound like a very simplistic question but I'm a simplistic guy! I own a 99 Gulfstream Scenic Cruiser with a 325 HP Cummins. I've found a low mileage 03 with a 400 HP Cummins. As I look at the Gulf Stream brocures which are still available on line it shows my lower HP engine having more torque than the 400 HP one. Sounds illogical to me?? Could it be a mistake on one of the brocures or is it entirely possible??

Mr_D · 04-17-2019, 08:56 PM

Need more info as to engines but it's doubtful the 400 has less torque.

DandyDon · 04-17-2019, 09:02 PM

Quote:

Originally Posted by Mr_D

Need more info as to engines but it's doubtful the 400 has less torque.

That was my thought too.

dix39 · 04-17-2019, 09:55 PM

I'm thinking that a lower torque higher rpm engine could have more hp. HP = (Torque in lb.ft x Rotations per minute)/5252). I've always placed more value on torque than horsepower for diesel engines.

I know nothing about the engines in question though.

Steve

CaptainGizmo · 04-17-2019, 10:10 PM

Entirely plausible. HP has no relevance to Torque.

Torque is all about displacement and stroke.

Case in point, my Raptor’s baby 3.5L V6 puts out over 450hp. However, it’s torque is a measly 510lbs.

Compare that to the new Cummins ISL 8.9L that puts out the SAME horsepower yet cranks it out a massive 1250lbs!

So, you need the SPECS to the engines, not just the HP rating...not reliable for much at all.

You might also get all the specs on the Cummins website.

2002guy · 04-17-2019, 10:14 PM

Give somewhat similar motorhomes the one with the most hp will pass you at the bottom of the hill and the one with the most torque will pass you at the top. Horse power numbers are easier to manipulate for years gas 454 chevy's claimed more hp than the same ford 460 but it was a rpm that the governor would not let the rv engine hit, torque peak is at a much lower rpm and harder to manipulate.

Skip426 · 04-17-2019, 10:26 PM

In order to provide any good input we'll need to know , both engines displacement and exactly the difference in the torque ratings .

Is it 25 ftlbs , 200 ftlbs

Theunz · 04-18-2019, 08:34 AM

While this doesn't answer your question, I'd place more value on torque than HP for heavy loads. Another figure to look at is what is the RPM that torque is achieved at and what is the final drive gearing. You want the gearing to allow maximum torque at your comfortable crushing range. I read this somewhere, and think it's a very good comparison of torque and HP---Horsepower is how hard you hit the wall, Torque is how far you move the wall!

jharrell · 04-18-2019, 08:58 AM

Torque is one component of horsepower, the other is rpm. A engine that creates the same power at a lower rpm will have higher torque. A engine that creates the same power at a higher rpm will have lower torque. So you see a 400 hp engine can have less torque than a 325 hp engine as it creates that power at a much higher rpm.

Power determines how fast you will be able to accelerate or go up a mountain, gears will trade torque for rpm to get the correct amount to the wheels, gears cannot increase horsepower, they can increase torque.

A 400 hp engine will accelerate faster and be able to go a up grade faster than a 325 hp engine regardless of torque, assuming they both have transmissions that can keep them in the power band to produce the peak power.

A higher torque engine will be more pleasant as it denotes running at a lower rpm for the same power, among other things.

DandyDon · 04-18-2019, 08:56 PM

Just got the info from Cummins. My 325 has 960 lbs whereas the 400 has 1200. There was a mistake on the Gulfstream Brocure.

**TonyDi** · 04-18-2019, 10:09 PM

Thanks for letting us know you got it resolved.

Piker · 04-19-2019, 04:59 AM

Quote:

Originally Posted by jharrell

Torque is one component of horsepower, the other is rpm. A engine that creates the same power at a lower rpm will have higher torque. A engine that creates the same power at a higher rpm will have lower torque. So you see a 400 hp engine can have less torque than a 325 hp engine as it creates that power at a much higher rpm.

Power determines how fast you will be able to accelerate or go up a mountain, gears will trade torque for rpm to get the correct amount to the wheels, gears cannot increase horsepower, they can increase torque.

A 400 hp engine will accelerate faster and be able to go a up grade faster than a 325 hp engine regardless of torque, assuming they both have transmissions that can keep them in the power band to produce the peak power.

A higher torque engine will be more pleasant as it denotes running at a lower rpm for the same power, among other things.

Nice explanation. Few people take the time to actually understand the relationship between torque and hp.

-cheers

NevadaNick · 04-19-2019, 08:48 AM

I was once told horsepower is what you feel, torque is what moves you. Dont know if its right or wrong.

jharrell · 04-19-2019, 10:28 AM

Quote:

Originally Posted by NevadaNick

I was once told horsepower is what you feel, torque is what moves you. Dont know if its right or wrong.

You feel acceleration, you need power to accelerate, you need torque and rpm for power. Torque without rpm does nothing, the two together are power.

Voltage and current have similar relationship to watts.