converting tq to hp

[MetalHeadZaid]

my dad has a 1976 corvette (yes, very different from what i drive) with a 350 and bolt ons. recently i was told that the stock power rating for that year is something like 190hp, but 270 pounds of tq. i know that horsepower is a property of torque, so would it be beneficial and possible to convert some of that torque to horsepower? currently hes runing an edelbrock carb (not sure about the cfm rating) and intake manifold, high flow side pipes (was told the stock exhaust manifolds get the best flow so we stuck with them) and a close ratio 5 speed trans, so if the rpm at which peak power is created is raised, it wouldnt be an issue. thanks

[Moppie]

Horsepower is work done over time.
Torque is work done.
Both are depedant on the engines ablity to pump air. The more air it can pump, the more hp and torque it will have.


As a general rule, increasing one, increases the other, but you can't take some of one, and put it onto the other.

[MetalHeadZaid]

thanks for clearing that up

[curtis73]

Torque and HP are mathematically linked. Its not a matter of conversion, its a matter of making more torque where you want it which therefore makes more HP. The formula for HP is tq x rpm/5250. If you maintain the same amount of torque, but make it happen at a higher RPM, you'll increase HP. OR, by simply adding more torque at the same RPM you'll also increase HP.

Moppie is wise; improve how much air it gets and it will improve HP. The four main ways to do that are improve carburetion, intake flow, head flow, and cam timing events. The heads and cam on that engine are probably one step better than pathetic so that's where I'd start.

[UncleBob]

and just because I have to say it....

Turbo it.

[534BC]

Originally Posted by Moppie

As a general rule, increasing one, increases the other, but you can't take some of one, and put it onto the other.

That's the job of a transmission, lol

[UncleBob]

Originally Posted by 534BC

That's the job of a transmission, lol

not quite.

The job of the drive train (tranny, differental/tranaxle/final drive) is to apply the power of the engine as effectively as possible.

The reality is, most vehicles don't apply it very effectively at all. A three speed tranny is going to have huge holes in keeping the engine at its best peak efficiency at all speeds.

Even a 6 speed will have huge holes, notably, at lower speeds, but depending on the rig in question, this might be an acceptable compromise due to traction issues when the drive train is TOO effective (rear wheel torque is way higher than availible traction)

A CV tranny is about the best in this arena, and some cars are starting to come out with it. Mopeds and snowmobiles have been using it for decades. Longevity has always been the biggest issue, but it appears that some car makers are finding some success with new approaches to the belt. BUT.....they have yet to attempt it with any high output engine, which I think is for obvious reasons. They can't hold the power....yet.

[534BC]

Yea, your right. I was thinking tork vs. rpm. Take away from one to give to the other. HP remains constant. The cv transmision is a favorite of mine. I'd like to see it in 'Radio control nitro vehicles. I thought the biggest issue was the power waste. I sure do like them though, can allow a very pipey engine to use the max power all the way up the speed range. They are great.

[UncleBob]

I don't have any numbers in front of me, but lets just say, all the hybrid cars are using the CVT setup, so I highly doubt they are REAL bad on the power efficiency.....

[534BC]

They must not be using the set-up like the snowmobiles then. I just hapen to have access to a hybrid soon, would like to ride in it. What is the design of the particular cvt in a car? I am only familair with the belt drive.

[KiwiBacon]

Here's how to convert torque to power (and vice-versa).
Torque is twisting force, power is torque times rotational speed.

Tip #1. Work in metric. It'll save you pages.
Torque = Newton Metres (Nm)
Rotating speed = radians/second
Power = kilowatts (kW)

Our theoretical engine has 300Nm of torque at 2000rpm and 100kW at 4000rpm.

Convert rotational speed to radians.
Radians = rpm*pi/30
= 2000*3.141/30
=209 radians per second

Power (2000rpm) = 209 radians * 300 Nm
= 62820 watts
= 62.8 kilowatts

Likewise to find torque at 4000 rpm.
Radians = rpm*pi/30
=419 radians per second

Torque = power/rotating speed
= 100,000/419
= 239 Nm

If you have the power curve you can find the torque curve, likewise if you know the torque curve, from it you can find the power curve.