as far as "where the torque is being made"...peak torque in that supercharged 3.8 in the GTP is 280 ft/lbs @ 3600 RPM, and looks like it starts at about 230 @ 1700.  looking at this dyno sheet for the stringray, the torque at 2800 RPM is 320 ft/lbs (at the wheels), and it peaks at 411 ft/lbs @ 4400 RPM.  nod sure what the stall in the corvette is, but the curve on the sheet starts at 2800 RPM.

another theory that was tossed out there by a friend was that the perception of "pinned to the seat" is different between the FWD GTP and the RWD corvette.

I'm gonna have to get a look at this magazine.

It would help if I had a working tach

"Perception" is everything!!
I'm not sure, but I would think the 'Vette carries a few more pounds, no? May take it a wee bit longer to get rollin...

There have been many good points made dispite the fact the original statement can be misleading.

First, there is a difference between fast and quick.  Fast is how fast is it?  What is the top speed?   Next there is quick.  How quickly does it increase speed?  How rapidly does it reach it speed potential?

There is a huge difference in these two concepts.  Some vehicles can be very fast in a 1/4  mile, but not have as much top speed as others and vise versa.  Some come out of the hole like lightning, but at 1/8 mile are topped out and can only maintain speed the rest of the way down the track.     Fast or quick?

Now to horsepower vs torque.  Horsepower is a measurement of how much work something can do.  It is not necessarly how quick something is, or even it's top speed.  Earthmovers have a LOT of horsepower but are lousy in a 1/4 mile or the big oval track.  Torque is what is really important to us in our cars performance.  Torque is the amount of twisting power applied to the wheels, and what make the car move.

On to gear ratios.  The tire does not care what the gear ratio is at a specfic point, other than the ground.  It does not matter what the transmission or rear ratio are indivudually.  It DOES matter what the two of them are together.  The total ratio from the engine to the tires counts.  It could be a 3to1 trans and a 4 to one diff, or a 4to1 trans and a 3 to 1 diff.  They both produce 12 to 1 total ratio.  That's what counts.  Due to the fact the rear was in question, we will assume at this moment that the trans will always be the same ratios, and we will only change the rear.

If you increase the ratio you will increase the torque.  Period.  Discounting drive line drag, if you have 100 foot lbs of torque at the flywheel and have total ratio of 10 to one you will produce 1000 ft lbs of torque.  With a total of 12 to one ratio you will produce 1200 ft lbs of torque.  This will twist the axles and tires harder and produce more accelleration starting the car off of the line.  This always applies.

When you shift the trans to a higher gear the final ratio drops a lot.  With the trans in a 1 to 1 ratio, a 4 to 1 rear will now multiply the same torque to 400 ft lbs, and a 3 to 1 rear will produce 300 ft lbs of torque.

The higher numerical ratio the more torque.  The flip side is the engine can only turn so fast.  If the engine can turn at 4000 (keep the math simple) with a 12 to 1 total ratio the tires will turn at 333 rpm.  Depending on the tire size, that will produce a given road speed.  At a 10 to one it will turn the tires at 400 rpm.  More road speed.  At a 3 to 1 it will turn tires at 1333 rpm, much more road speed.

The bottom line, almost, is the greater total ratio the more launch (seat of the pants) and the less top speed.  The lower ratio will provide less accelleration, but more top speed.

Why almost?  There are other limiting factors. One is (ready) horsepower verses drag.  There are several forms of drag.  One is friction drag.  This is how much power is lost due to parasitic drag of the car itself.  It requires power to turn gears, joints, tires flex, etc.  This comes off the top of the torque to the wheels numbers.  So if you figure the engine torque with ratios it will be much higher than the actual torque transmitted to the wheels.  

Next is aerodynamic drag.  You need to push air out of the way.  That takes power.  The faster you go the more power it takes.  Add both of the drag factors in and you have a increasing force as the car speeds up.  WHen you get to the maximum the engine can produce, you have reached top speed and cannot go any faster.

If you supply enough gear ratio, there is enough power to overcome all of the drag all the way to top speed.  Top speed is now limited by the ratio and engine speed.  Once the engine cannot turn faster, the car can't go faster.  With the greater ratio, this happens a lower speed.

The key is to balance the power and drag so the top speed and drag vs the engine power matches.  Now the question is where do you want that match to take place.  End of the 1/4 mile track?  150 on the highway?  The next stoplight? There are choices to be made.

Now consider one more thing.  WHERE???does the engine produce it's power?  If it makes a lot of power at low end a lower total ratio can help.  The car can take advantage of that low end power by using a ratio to keep it in the correct power range. this is quick.  But if the engine loses it's torque at high rpm drag takes over and it's not fast.

If a low ratio is used and the engine does not produce power until high rpm, when the engine is turning slower and NOT producing much power, the car will launch like a dog, then pick up as engine speed increases.  Fast but not quick.

So the high rpm engine can use a high ratio.  This brings up the speed of the engine at launch and produces a lot of power to be used at launch.  Very quick.   But it winds up rapidly.  Not fast.

Yes there is a balance of all of these.  It does not start with the engine, or the ratios of the trans or rear.  It starts with what you want the car to do.  Decide that first.  Do you want a launch that will make the skin slide off you face?  Do you want 175 mph?  The only way to have both is to make remarkable torque at the engine.  Good by economy.  Everything is a trade off.

The final factor is the tires.  The tire is the last gear in the drive train.  A smaller tire produces more torque and less top speed.  A taller tire give less torque but more top speed up until the drag overcomes torque.  It then evens out and tops off.

One more thing.  If the tires cant grip the ground, you cant accellerate.  You can then increase grip with tires and suspension tricks, or back off the torque until you launch, then reapply torque.  Just don't spin the tires if you want to get somewhere quick.

Every set up is different.  But the laws of science always apply.  Choosing the right combination for you is the trick.

The only difference between front and rear wheel drive is how good the tires can connect to the ground.  If they do that the other factors apply equally.  Weight transfer tends to supply more grip to rear wheel drive.  If the tires spin, steering is lost on FWD.  Other than that there is no difference in lauch or top speed.

And don't forget total power vs weight.

What soup you make depends on the stuff you put in the pot.

 

kstyer38962.4386921296

The doctor is definitely IN!

Thank you Ken for providing such a succinct run-through of the dynamics
of torque vs. horsepower...trans/diff ratios...fwd vs. rwd...and much
more.

Math ain't my favorite subject, and my head usually hurts when I try to
pound this kind of info into it from other (non-forum!) sources. So it was
a real education--and an enjoybale one to boot--to read your doctorly
dissertation...

  Ken never ceases to amaze me.

yup , Ken is the master, he has taught many students, hopefully we are the wisest of them, 

Ken has forgotten more stuff than most of us will ever know. He has a unique way of 'splainin things so everyone can unnerstand....I can only dream of that gift!

Joel, I beg to differ--

the Dean of Duncanville takes a back seat to no one (well, except maybe
the Mrs.--??).

Just do what I can.

I gotta admit.  It would be great if Joel and I lived next door and had a BIG garage.  I know things Joel may not, but he knows things that I don't.   Together we could be dangerous!