Torque vs Horsepower

[Greg Morgan]

I was reading a thread yesterday about building a 401 and as usual the subject of torque vs horsepower raised it's ugly head. I understand the differences and advantages of both. However not being an engine builder, what I don't understand is how one builds for torque. Other than increasing displacement (preferably through stroke, I assume) what is the basic process? Are there components (cams, heads,carbs, etc) that increase torque more than horsepower?

Obviously a 401 will generate more torque than a 360 (displacement again), but 360's are more common. Are there significant increases to be had out of a 360, short of boring and/or stroking?

[fulsizjeep]

Sure, cam, heads and carb can make a difference as well as bore and stroke, etc. I am by no means an expert, but how the engine breaths can affect HP and Torque. So intake, carb and exhaust should also be considered. I am running a Edelbrock SP2P on my 401 mainly for the torque aspect. These intakes have smaller runner diameter than the Performers or even stock as they were developed for the 304. I run out of power on the highway around 75 with 33s and 3.73 gears. Don't need to go any faster than that anyways. When crawling up slickrock and mountain trails in low-low, it provides plenty power to get the job done from 4000-13000 feet so far. I also run a Comp Cams 260H which is also designed for more torque in lower rpms and is generally referred to as an RV cam. Opening up the exhaust will raise HP but generally torque will drop off.

[Stuka]

Biggest thing is having a cam and intake that is suited for lower rpm. If they are suited for higher rpm, then the engine is going to have a lot less low end grunt, but a fair amount more top end forse power.

As for the exhaust be opened up, it depends how much its opened up. You just dont want to open it up so much that exhaust gas velocity drops off. Also, headers wont hurt your low end if they are coupled with a correctly sized exhaust. You just need to be sure the carb is richened up to offset the high flowing exhaust as it will lean the engine out.

[jeepsr4ever]

Torque gets you going and horsepower keeps you going

A SP2P with a 256XE comp cam work well together but run out of power after 3000rpm. A performer and a Summit K8600 work well and are good to 4500rpm. Alot depends on your gearing and tire size. Everything works together in a drivetrain and in todays market good advice is only a click away.

[rockjeep44]

One thing people forget is that you can generate torque with gearing to make up for a lack of torque by the motor at low RPMs

[Ralph Rogers]

Before you go spending money and making changes, make sure you tell folks at what RPM you want the torque and/or HP.
Most people on this board assume you want it in the low range, as that's what we typically look for playing off road, but if you are a sand jockey, it's different. Or maybe you're just a road guy looking to haul his horses or camper around the highways, but in style.
There are big differences on what to do for what you want.

Ralph

[billyrb]

..........Or maybe you're just a road guy looking to haul his horses or camper around the highways

Or maybe a road guy that wants to smoke the heck out of some large tires!

[MistWolf]

I suppose we talk about torque vs horse power to keep things simple, but in truth, horsepower is a measurement of how far the torque move how much weight within a certain amount of time. You can have torque without horsepower, but you cannot have horsepower without torque. To increase horsepower, you either must increase torque or increase how much work your existing torque will do for you. One way to increase how much work the existing torque will do is to increase the RPMs at which you achieve that torque

[mdill]

They are the samething at any given RPM, the torque * constant = HP.
So the goal is to build the most torque as you can though the expected operating RPM range.
For a Indy car this maybe 10K RPM
For a daily driver that maybe 2K RPM (Highway in overdrive)
By selection of cam, heads, exhaust, pistons, porting ... you can move and
shape the torque curve around and flatten or make it have sharper peaks but for the most part you can't have everything and end up trading torque in one area to build torque somewhere else in the RPM range.

Hence why a 1000hp Indy engine does not beat a 200hp truck engine in a tow truck.

Mike D.

[Ghinmi]

Horsepower is just a function of torque vs. rpm

Horsepower = (Torque * RPM)/5252

Torque up high = big horsepower
Torque down low = low horsepower

Where you're making torque is just as important as how much you are making.

[Hammer]

One thing to think about when you are talking about torque.
Peak torque is always at the same rpm as peak volumetric efficiency.
Basically, where the cam, heads, intake, exhaust, etc. all let the motor breath the best will give you the most torque.

[Hammer]

Which is also why you see really FLAT torque curves with turbocharged engines.

[Ralph Rogers]

Or maybe a road guy that wants to smoke the heck out of some large tires!

I was gonna say that, but thought maybe it wasn't PC or us.

Ralph

[billyrb]

sure, and the children in Africa, and such as Iran.

[fulsizjeep]

There may be some people here that would smoke some large tires but do they inhale? I prefer to call it "roasting fat tires" instead.