Revisiting Torque

[Bill Miller]

Now you know why I was confused.

And thanks to both you and Greg for the 'welcome back', but I probably won't be staying long. If nothing else, reading that entire thread on ITB wheel widths reminded me why I took a hiatus from this place to begin with. Honestly, I just don't have the energy for those kinds of discussions any more. Especially when it's just the same crap from the past 8 or so years just getting re-hashed over and over again. I now totally understand how it burned Darin out. You know the old saying, the more things change, the more they stay the same.

I'll pop in from time to time, just to say Hi, but Jake's got no worries about losing his position atop the post-count mountain. Let's chat off-line.

[lateapex911]

............. but Jake's got no worries about losing his position atop the post-count mountain. Let's chat off-line.

Damn........that's one thing I really don't WANT to win. Hi Bill! c'mon...skip the board, get a car, and get out and race!

[Marcus Miller]

or at least skip the rules & regs forum.

[TomL]

Jake - Thank you for finding the Paul Yaw dissertation. He has basically written the rant on this topic that I had threatened to write and post here. He even included the F1 engine versus diesel truck engine comparison I was going to use. For those of you who haven't read the link on Jake's post, answer this question. If you put into the same 2500 lb car, an F1 engine with 800 HP and 281 lb ft of torque, or a diesel with 305 HP and 550 lbft of torque, which one would accelerate faster? Then check out the answer - it's near the bottom of that article. If you guessed wrong, you need to read the whole article, and even if you were right, you might learn something.

One point for the folks who say that torque is what accelerates the vehicle. Yes, that's right. But at any given car speed, it's torque at the drive wheels, not torque at the crank. And the high HP, low torque engine (i.e., the one with higher revs) can multiply crank torque a lot more (through shorter final drive, gears and/or tires) than the lower HP, high torque engine.

Phil - do you have some dyno charts to demonstrate your argument that high torque/low rpm engines respond less to IT tuning? Because if you do, that would say that we need to give high torque engines a weight decrease! Definitely not conventional wisdom.

[Bill Miller]

Damn........that's one thing I really don't WANT to win. Hi Bill! c'mon...skip the board, get a car, and get out and race!

Got a race car, that's the easy (and cheap) part. Need someone to pony up the $$$$$$ so I can go racing.

As far as your post count goes, you've got no one to blame for that but yourself.

[ekim952522000]

Found it.
Read this:
http://www.yawpower.com/tqvshp.html

Best article I have ever read on TQ and HP.

[chuck baader]

I would guess that the consensus it that those of us with the 50# torque adder should have that removed post haste. Chuck

[Bob Roth]

My apology if these points have been made, I've been busy for a while.

There is no difference between any of the engines at the conditions you list, but there is a big difference in the racing potential of them.

Look at the Honda VTEC 1.6 which is the 160 hp 110 ft pound torque at 8000 RPM. It is limited by valvetrain to 8500, which is kind of academic because everything in its VTEC "racecam", to intakedesign, to 10.5 to 1 compression to 4-2-1 stock exhaust system means there is little to be done unless you wanta cheat big time. Its already 1 hp per liter which is very good for internal combustion engines. If I can't make it rev more, and displacement is fixed, 150 wheel hp at 8000 rpme is all its going to give. And since its torque curve is flat from VTEC cut in, it also means when it shifts loses 25% rpm to 6000, it loses 25% HP to 112 hp.

Meanwhile look at a non VTEC ITS '93 prelude S with a 2.3 liter 160 hp engine that produces 70 hp /liter at 6700 RPM. Given that its heads and valves are the same as the prelude VTEC and given that this was the base prelude, it has no VTEC "race cam" trick intake filters and exhaust and Honda wants to have a significant derate compared to the 190 hp prelude VTEC, its reasonable that there is some increased RPM range and breathing to be found and that the prelude can be revved for good power to 7500 RPM before really bad power falls off. I would assume a 10% increase at the rating point with constant hp at speed above with a drop at redline.

Lets compare the HP across the 75 to 100% for the respective ranges
75% 80% 85% 90% 95% 100%
1.6 6000 6400 6800 7200 7600 8000
hp 120 128 136 144 152 160

2.3 5625 6000 6375 6750 7125 7500
hp 150 158.4 167.2 176 170 150

Delta 30 30.4 31 32 18 -10

The point is that its extremely difficult to increase high Hp per liter engines because there is nothing left to get for torque, or RPM range. On the other hand a non optimized engine "probably" will respond to the headers, air filters and releasing of artificial rev limits allowed in IT. Soo, a long the point is, its easy, get a large displacement, low HP/liter (0.6 to 0.7) engine which is the high torque one. Assuming that its a 2000sx, BMW or Honda Non VTEC with decent chassis, reliability and brakes, things look good. Note this rule falls apart with cars like gremlins, Monza's, and straight 6 ford mustangs, and other crap cars. As long as you avoid the high torque junk, I think you have a good chance wherever you race.

So, if HP is equal, get the lowest stock torque as it has the highest hp potential and area under the resulting curve.