How will you go faster?

[skinny z]

"we cut a couple tenths off of the 60' and an equal amount at the top end"

Somebody was trying to tell me this does not happen.

Wasn't me.
That car, IIRC as it's been over ten years, gained almost a half second overall with just the converter.
Some may be attributable to the weather, but the datalogs don't lie. Definitely much better recovery on the shift.

[F-BIRD'88]

"we cut a couple tenths off of the 60' and an equal amount at the top end"

Somebody was trying to tell me this does not happen.

Wasn't me.
That car, IIRC as it's been over ten years, gained almost a half second overall with just the converter.
Some may be attributable to the weather, but the catalogs don't lie. Definitely much better recovery on the shift.

Similar experience 4.5 ths 1 mph going from stock 2200 stall th700r4 to 10" 3600 converter th350.
The th350 is 50 lbs lighter. Was like night and day.
mild 350 sbc

[289nate]

A guy I used to converse a fair amount with used to run a high rpm all motor 306 in a Fox body. Kept having issues with the C4. No matter who built it and what he paid it would always have issues with the rpm he was turning. Tried a glide. Slowed down. Finally went to a Rossler built TH400. Held up great to 9.5x in the 1/4 and 9,500’ish rpm shifts.

I’ll add he was set on staying with an automatic.

[treyrags]

You have to remember that hp is only about the rate that a engine produces tq. Tq rules, it what moves the car, not hp! Not necessarily max tq but, the rate that it falls off. When the tq falls off, faster than gear ratio can multiply it, you loose hp. Hp is a formula but, tq is what actually moves the car. Hp works, because of gear reduction.

The hp concept, was how FAST a horse could lift 660 lb. The time frame they used was one second. In other words, how FAST you can create tq and not the tq, itself. But, you can not have hp w/o tq.

A way to look at it is: Say a F1 engine makes only 200 lb/ft of tq, with a 213 ci engine @ 20,000 rpm, that's 762 hp BUT, you can not use it @ that rpm so, you have to gear it down, to were the engine rpm, will get the wheel rpm, to the speed you need (gear reduction).

So, that engine needs a final drive of 7/1, to get 212 mph, with 25" tires. 7 x 200 = 1400 lb/ft of tq. Again, tq is what got the car there.

If a street/strip car, has 400 lb/ft @ 6000, that's 457 hp. Geared at 4.11, with 28" tires, that's 1644 lb/ft tq and 122 mph. This, geared to wheel rpm, still equals 457 hp.

If this engine has 502 lb/ft of tq, at 4200, with the same 4.11 gear, it has 2063 lb/ft tq, at the wheels. Hp for that tq @ that, wheel rpm is 401.

The above is minus parasitic lose, of course.

When tuning a engine, you need to look for ways to decrease the tq drop off, or increase average tq, between max tq & max hp rpms or at least between your widest shift splits. That's why peaky engines won't do as well.

I'm not sure I've explained it well but, those are my thoughts on it.

Geesus. How can we be on this forum and not know that horsepower moves the car.

Right? I guess all the SS, Comp, and Pro Stock guys have it all wrong?

[frnkeore]

Show me where I'm wrong, please.

The only reason that HP works, is because you mechanically, multiply the torque. I think it's been shown here, that tq at the wheel, is what moves the car.

If HP moves the car, then you should be able to launch at max HP/rpm and rigid drive train, with the same gear than you cross the line with.

Can't do it, well, how come.

My whole point, in this discussion, is to watch how the tq falls off, after max tq and try to raise that curve. In turn, that will raise hp, be cause of the hp formula.

[rapidride2]

Isn't horsepower the rate (speed) at which full torque is achieved?

Car crusher....major torque...lower horsepower. Moves slow....

[digger]

Show me where I'm wrong, please.

The only reason that HP works, is because you mechanically, multiply the torque. I think it's been shown here, that tq at the wheel, is what moves the car.

If HP moves the car, then you should be able to launch at max HP/rpm and rigid drive train, with the same gear than you cross the line with.

Can't do it, well, how come.

My whole point, in this discussion, is to watch how the tq falls off, after max tq and try to raise that curve. In turn, that will raise hp, be cause of the hp formula.

Force moves the car which comes from torque at wheels but max hp is a better metric than max torque for performance potential.

I can can use gears to get whatever torque I want at the wheels but you lose speed as a result of more gear so hp is a far simpler method to assess potential as it comes out in the wash.

To me if I run a cvt I’m going to run it at max hp subject to traction limits. So it’s a more streamlined way at arriving at the same result.

[Tom68]

Isn't horsepower the rate (speed) at which full torque is achieved?

Car crusher....major torque...lower horsepower. Moves slow....

The car crusher action is slow, but it takes the same amount of horsepower to chew up all that metal at that speed whether it's a ridiculously gear reduced 1000HP Turbo 2 litre, a not so gear reduced massive lump of a 1000HP Diesel or a 1000HP Electric Motor.

[Tom68]

then you should be able to launch at max HP/rpm and rigid drive train, with the same gear than you cross the line with.

You can't go from zero to 200mph without a time factor. Well you can but you won't be you after you drop the clutch, you will be dead.

[David Redszus]

By now we should all be able to agree that the acceleration curve, in each gear, tracks to the torque curve not the horsepower curve. And that peak torque or peak horsepower have little or no contribution.

The vehicle movement is a function of torque applied at the drive wheels. It starts with engine torque, is reduced along the driveline due to friction losses and is then multiplied by gearing. In addition, we have weight, aero, and rolling forces that must be overcome.

Torque to the wheels can be increased by gearing, but horsepower cannot be increased.

The shape of the torque curve plays a significant role in the selection of gearing and tires.
The acceleration curves, for each gear should overlap in order to optimize shift points.

Perhaps the most critical race aspect is the launch where the highest acceleration forces
are developed, but only for a very short time. We have clutch slippage, wheel slippage,
torque converter effects and stability issues. And the least amount of knowledge.

Ideally, the shape of the torque curve would determine whether an automatic transmission
or stick shift should be used, and how many gears are needed. Most often that choice is
made for us and difficult to change.

Automatic transmissions make use of a torque converter in order to lock onto the torque
curve in first gear. Its performance is difficult to assess independently of other variables
without proper data collection. But even stick shift systems make use of clutch slippage
that is not easily quantified.

We have not yet visited vehicle weight, aero drag, rolling losses, and weather conditions.

[weedburner]

The data you need to create a drag strip simulation is nearly impossible to nail down, especially considering a dyno session is not conducted under real world conditions.

Put a data recorder in an actual car, then the car itself becomes the dyno. You won't get torque/hp numbers to play with, but you will get actual data that tells you what variation was quicker, as well as where it was quicker, in real world conditions.

Grant

[Tom68]

By now we should all be able to agree that the acceleration curve, in each gear, tracks to the torque curve not the horsepower curve. And that peak torque or peak horsepower have little or no contribution.

OH WOW.

[frnkeore]

I think many guys are hung up on the word Horse Power. It has been in there life as the "standard" for how fast a car can go but, HP actually has no real relevance to cars, that use torque to move them.

Original HP is a linear measurement. If a Horse can lift 550 lb, 1 ft high, in 1 sec, it's done 1 HP of work. That is a simplification of the actual measurement, done by Watt.

[frnkeore]

By now we should all be able to agree that the acceleration curve, in each gear, tracks to the torque curve not the horsepower curve. And that peak torque or peak horsepower have little or no contribution.

OH WOW.

I think your mis-reading that Tom. Please correct me if I'm wrong, David but, I read it as saying that the short time it's at peak, as opposed to the whole curve, can/will add little to a speed or et.

Such as if a engine has flat curve of 300 hp, from 5k to 5.95k and has 400 hp from 5.95k to 6k rpm, it can't add enough to matter.

[David Redszus]

The data you need to create a drag strip simulation is nearly impossible to nail down, especially considering a dyno session is not conducted under real world conditions.

True. A dyno session never represents track performance. Even the dyno power curves are bogus. But some engine builders (F1) have built dyno cells with rolling roads and actual climatic conditions that closely mimic track conditions anywhere in the world.

Put a data recorder in an actual car, then the car itself becomes the dyno. You won't
get torque/hp numbers to play with,

Yes you will using the proper sensors. In addition to engine data, driveline data, wheel slippage, and vehicle dynamics data will be available for every foot of track.

As an example. If we multiply the aceleration G force curve by the vehicle weight, we obtain the force (in lbs) that is moving the vehicle down the track. That can be done for every foot of track from launch to finish line and the force curves overlayed for examination. Now we can visualize the effect of the torque converter on the acceleration curve.

but you will get actual data that tells you what variation was quicker, as well as where it was quicker, in real world conditions.

Obviously very true and quite apparent. So then why do so few racers make use of data as a tool? Why do they piss away thousands on engines and yet fail to understand what is actually happening on the track?

Brain power always beats horsepower.