Horsepower or torque

[Silvertip]

Re: Horsepower or torque

QuietCat -- You said (and its true) "Another misconception is that the vehicle with the higher engine out torque number will always be the better tow vehicle. In reality it is torque at the wheels, not the engine, that ultimately matters for startability i.e. gearing. If you have the same vehicle with two different engines, one with half the peak torque at the same RPM as the other, they can have equal startability if the lowest available gear (+ rear-end ratio and tire size) is double numerically on the lower torque engine. This would theoretically give equal torque to the wheels." The problem is you tied this to the term "Tow Vehicle." While startability in your comparison is true, you are right back to the point of my original post, the smaller engine screems its guts out at highway speeds due to the deep gearing. Your point is strictly applicable to startability -- Heck I pull my boat around with an 11 horse garden tractor. It has good startability but its a darned poor tow vehicle.

 

[QC]

Re: Horsepower or torque

UIS,<br /><br />Agree. That is why on that point I only mentioned startabilty. It was more of a non-stop ramble on the realtionship of torque and horsepower than an indictment or endorsement of any vehicle style. Sorry if I wasn't clear.<br /><br />I think the basic point of my post was that you cannot separate the two and you also have to have RPM. All other things being equal the higher torque rise percentage spec will be the most drivable. Which is definitely agreeing with your post. Sorry if it sounded like I was disagreeing with you . . .

 

[gutshot grouper]

Re: Horsepower or torque

My old Cummins 855ci would out tow any of your wimpy short stroke gassers even with 15000 hours on the meter, and it got AN EASY 8MPG LOADED OR EMPTY, 73000GVW.

 

[QC]

Re: Horsepower or torque

This is my latest project.<br /><br />

<br /><br />12 Axles, over 200,000 lbs. GCVW, 500 bhp 1650 lb/ft. . . . runs on 90% Liquid Natural Gas 10% diesel.<br /><br />Take that, GutShot Oh, and it gets less than 3 MPG. Yeah, baby, yeah!!

 

[gutshot grouper]

Re: Horsepower or torque

Cool Cat, is that LNG fuel something new that y'all use on the Shaky Side? I was talking about my old White 4000 tractor from back in the dark ages when truckers didn't need training wheels, we used to haul 25 tons in a gooseneck trailer, all with only 14 wheels. Guess that was before we knew any better, Ignoramus in Raleigh

 

[QC]

Re: Horsepower or torque

GG,<br /><br />We started it in Shaky town, but that truck is Down Under. They run these heavy-weights across country. Triples and quads like that too. LNG is basically everywhere, but we've been working the last 10 years to get it into trucks. The closest units to you are in Houston where we have almost 100 running in two different fleets, but pretty tough to get the economics to work here. The Aussies are my best new deal as they burn so much fuel even a little savings adds up quickly.<br /><br />Sorry for the thread hijack. Just can't stop a couple of truckers from yackin' on the CB . . . This is Line-Haul know-it-all . . . clear.

 

[WSUDERMAN]

Re: Horsepower or torque

Been down under just last year. Those triples and quads comin at ya on the wrong side of the road, dirt no less, doin 60 + is quite exciting. The first time i saw the warning about "Truck Trains" i had no idea, only took one to figure it out though...<br />That one in the pic must be from down under, based on the Roo guard up front?!

 

[QC]

Re: Horsepower or torque

Yeah, I like to call it a kanga-banga, but I can't get the Aussies to take it up . . .

 

[imstillatwork]

Re: Horsepower or torque

Torque = hp / rpm * 5252<br /><br />HP = trq * rpm / 5252<br />^^^<br /><br />Read it again everyone. thats all there is to it.<br /><br />The trick part is the torque curve. Manufactures only advertise PEAK HP and PEAK trq<br /><br />I would rather have 175ft/lbs trq from 1000rpms to 5000rpms than 200ft/lbs trq from 3500rpms to 5000rpms<br /><br />then factor in weight, gearing, and the usable power band. I drive a 175HP 17ft/lb trq 6cyl car that outpaces many cars with more peak trq and hp, because it has a nice flat torque curve that covers a large rpm range.

 

[gutshot grouper]

Re: Horsepower or torque

Based on the formula, your auto should have a puny HP curve at low rpm if indeed the torque curve is flat, low rpm hp is solely due to a torque curve which is higher at lower rpm, somewhat harder to achieve with a short stroke engine, but enough on this subject.

 

[gonefishie]

Re: Horsepower or torque

my 2002 tundra with a 4.7 V8, towing 3500lbs running at 3200 RPM @75 MPH with O/D off, O/D on at 2200 RPM. It get up to speed the same with or without the boat.

 

[QC]

Re: Horsepower or torque

I'm with GG. OK for a marine engine, but not a vehicle. I have preached the opposite for years and now agree with most vehicle engineers. Torque rise (i.e. steep torque "curve" not flat) is more driveable, luggable, commfortable and probably more efficient. If I had 10 gears I might rethink, but with the available transmissions on the market, you need torque rise to keep from downshifting your way to oblivion. Over and out . . .

 

[imported_bjs]

Re: Horsepower or torque

if your worried about towing buy a powerstroke cant beat it have 30 ft.enclosed trailer with race car she run 85 m p h all day long.and still gets 14 mpg cant do that with gas motor.im not a ford fan but the ol truck will get on down the highway durmax aint that bad either buddy has one she run to.but fuel is high but so is for that big 21 ft bass boat!!!!!!!!!!!!!!!!

 

[Realgun]

Re: Horsepower or torque

That 5 in the Canyon is not up to power unless you like to run RPM

Well let me tell you I have to eat those words my new Truck is a Colorado I-5. Can't tow yet as its under 500 miles!<br />

<br /><br />Its not hooked up just placed on bumper.

 

[Realgun]

Re: Horsepower or torque

Undouble!

 

[Silvertip]

Re: Horsepower or torque

The I-5 is 3.5L, it should feel peppier than the 3L Ranger. My issue with HP vs Torque is with the need for high reving on these small displacement engines. As I pointed out in my original post, they are generally not fuel efficient at those high RPMs. Out of curiosity, what differential gear ratio did you choose. 3.42:1, 3.73:1, or 4.10:1? I considered trading my S10 crew cab for a Colorado but I would give up 25 ft/lbs of torque, four wheel disc brakes, and a host of other less important features that are extra cost on the Colorado. Bedliner, Sliding rear window, heated mirrors, to name just a few. I have a problem with the "cheap suit" appearance of the fabric interior. Leather is nice but my dog's toe nails would ventilate that in a hurry. Keep us posted on how the Colorado tows. Give us some economy numbers, speed, and RPM at those speeds. I haven't totally dismissed the idea. Sure wish they would put the TrailBlazer motor in the Colorado. I'd have one in a heartbeat.

 

[Realgun]

Re: Horsepower or torque

Its basically fully loaded no leather (I hate leather) 3.73 as I know I am pulling plus I am at 4000-6000 ft altitude too. Limited slip.<br /><br />I like it and 4 Wheel Disc is not needed as much as people say it does 80% of stopping power is from the front brakes.<br /><br />Actually it feels pepier than the 5.4 in my F-150 supercrew!<br />I have not really stepped on it as I break them in gently.<br /><br />I still need another 200 miles before I tow the boat.<br /><br />Seems to have enough torque though. Ride is much better than the old S-10 and seems to have more power than that 4.3 V-6 to boot.<br /><br />Interior seems fine to me. I think people are spoiled with the plastic wood grain or chrome stuff and anything else is said to be cheap.<br />I actually like all the controls on the stalk as I am left handed. its easier to set cruise and adjust it than on the steering wheel.

 

[DJ]

Re: Horsepower or torque

Quietcat,<br /><br />I agree with you that torque rise is important for driveability. For best towing capapbility, the torque rise should be at low rpm and the torque and HP curves running together and flat after that.<br /><br />The truck engine makers proved that when they were able to accomplish it with electroncs, in the early 90's. Electronics revolutionaized the truck engine industry.<br /><br />With elec's. they were able to keep RPM's down and still provide monstrous torque at very low RPM ending with peak HP, also at low rpm's-usually around 1600 for a "premium" diesel (over 11 liter). Elec's. also allowed them to bump up combustion pressures also. All of this was done to improve emissions. The benefits also included improved fuel economy and power.<br /><br />However, those engines drove differently and there was some backlash among drivers, until they got used to it. Drivers were used to 2300 RPM engines with very narrow torque bands, hence the need for 13, 15 and 17 speed transmissions. Those engines did have allot of HP, but it was at a price, that being RPM. High RPM wasted fuel and prompted higher engine wear. Allot of trucks, in that timeframe were mis-spec'd.<br /><br />Todays, high torque, low rpm diesels are quite happy with a 10 speed.<br /><br />All in all, the commercial side proves that keeping RPM down is a good thing.

 

[QC]

Re: Horsepower or torque

DJ,<br /><br />Agree with all. We're in sync now. I spent a good part of my career retraining those very same drivers. High torque rise, you can live with fewer gears. Lower torque rise, more gears can get back some if not all of the performance. Me? I want both . . . Give me a two-stick and a 2050 lb/ft C16.<br /><br />BTW, my 10 gear comment was about light-duty like most of this group uses. We were forcing a lot of 9 speeds out in the HD market; still are. I personally like the fully synchro European truck trannys; usually 16 speeds. Why those haven't caught on here I'll never know . . . Those of us who like to shift without a clutch shouldn't care, but downshifting when you are in a hurry definitely favors the synchro deal.

 

[Realgun]

Re: Horsepower or torque

Well I towed the boat up the hill and that a 5% grade with a 7% kicker at the top. I had no issues pulling the boat and accelerating up the hill. They are correct the torque curve is pretty flat on that 5 cylinder. Pulls and handles the boat better than the 3.0L Ranger I had.