Torque vs. Horsepower, AGAIN

[kevinthenerd]

I know it's been on here a million times, but I wrote a little something and I want to hear some comments. Thanks. (I might do some editing based on suggestions from another formum. I'll try to post here if that happens.)

(The original host required a password to log in, but the link should work now.)

First let me know if this works. (Google hosting.)

If that doesn't work try this. (Yahoo Geocities with ads.)

[UncleBob]

the link asked for username and password

[kevinthenerd]

Originally Posted by UncleBob

the link asked for username and password

Fixed (hopefully).

[wilson4]

very good read, the part towards the end refering to hammering nails really hits the nail on the head but seriosuly, thats a great way to look at it

[UncleBob]

a well written piece. I would have added speed vs torque multiplication, just to make it hit home that gear changes have severe disadvantages.....but I'm nit picking

[KiwiBacon]

I think you should add another section. Comparing an engine with a big fat torque curve to an engine with a a slimmer torque curve but providing similar power.
In particular showing how average power throughout the rev range is so much more useful than peak power and how a fatter torque curve provides this.

[Bootsgamer]

Worked for me!

[GreyGoose006]

well written article
now post it in every forum. lol

agreed with kiwi tho on why engines with more torque feel faster than engines with peaky torque curves

anyone who has ridden in a 60s muscle car knows that even if it isnt as fast as the car in the next lane, it feels faster because the power is there throughout the powerband, whereas the vtec screamer in the next lane has the same or more peak power, but cant use it all the time and the average power is lower.

[Moppie]

Originally Posted by GreyGoose006

whereas the vtec screamer in the next lane has the same or more peak power, but cant use it all the time and the average power is lower.

Actually the VTEC screamer probably has more usable area under the torque curve.
The first generation B16a made 90% of its torque from 2,200 to 8,200rpm.
Mine used to pull from 30kph and 1,000rpm in 5th gear, all the way to the speed limit cut in at 180kph. With out the speed limiter it would have gone all the way to the rev cut at 242kph.

From there the VTEC engines have only gotten better in thier power delivery.


The longer and flatter the torque curve, the easier an engine is to drive.
The longer and flatter the power curve, the longer it can accelerate in any given gear.
And of course the more area under the graphs for both power and torque, the faster the car will be.

[UncleBob]

what is usually pictured as the uber-ricer car is a over-sized turbo'd import.....some 2ish liter making 400+ hp.

There is no doubt if you compare that to a 400hp pushrod NA V8, the V8 will win hands down as far as drivability, width of torque curve, etc.

As a general rule (IMO) the best street cars have at least 50% of their rev range within 20% of their peak torque. This goes for torque monster diesels, high strung turbo gas engines, or well built muscle cars. Any time you infringe on that 50% rule, you are compromising the streetability of the vehicle to make a "exobition" rig. Cool dyno charts, but not fun to drive/ride

if you can make the *UPPER* 50% of the rev-range, preferably a high redline engine......the meat of your torque curve, then you have the best of both worlds. Good drivability mated with very effective HP for the engine design

As with all aspects of engine tuning/building.....compromises are the name of the game

[kevinthenerd]

Originally Posted by Moppie

Actually the VTEC screamer probably has more usable area under the torque curve.
The first generation B16a made 90% of its torque from 2,200 to 8,200rpm.

That's in a stock engine. Typically, though, a modified small-displacement engine ends up with a short power band in the pursuit of horsepower. It can't make a lot of torque, so to get power it needs speed. With VTEC, you can operate on two different power bands, but you're still limited by displacement and by the maximum speed of the valve train and bottom end.

[Moppie]

Originally Posted by kevinthenerd

That's in a stock engine. Typically, though, a modified small-displacement engine ends up with a short power band in the pursuit of horsepower. It can't make a lot of torque, so to get power it needs speed. With VTEC, you can operate on two different power bands, but you're still limited by displacement and by the maximum speed of the valve train and bottom end.

This is true for any sized engine tough, regardless of the displacement.
At the end of the day power and torque will always be relative to displacement, the difference is how each engine makes use of he displacement it has.

Imagine VTEC implemented on a 5L, quad cam V8.
An easy 500hp with the kind of flat power curve that shreds tyres in top gear from a standing start.

[GreyGoose006]

hence the popularity of the Lexus DOHC V8 and Cadillac Northstar V8
actually, i believe infinity makes a OHC (either single or dual, im not sure) VVT V8 in the FX-35 and FX-45

all of these are between 3.5 and 4.8 litres and are easily more streetable and reliable than your typical american pushrod engine, while making the same power.




imo, the worst mistake GM ever made was discontinuing the LT5 in corvettes.
i know it was expensive, but it would have been an amazing engine if it had 10 more years of development

[slideways...]

alot of manufacturers are making DOHC VVT v8s. nissan/infiniti has at least 2 in production right now, lexus has a couple, bmw, benz, ect, ect. i do like BMW's new v8/v10 that uses 100% variable valve actuation, using no cams (thats right kids).

that article is pretty basic, but is mostly true. but the examples given arent practical to everyday applications. when tuning on a dyno, you dont get to have that same kind of versatility with the drivetrain. but the same lessons apply.

[kevinthenerd]

I'd love to build a project car with a Toyota 1UZ-FE.