we have all heard it, " you need massive low rpm tq" "you need a screaming high rpm hp peak" well heres some info,
More in-depth description:
http://www.revsearch.com/dynamometer...orsepower.html
http://www.dynacam.com/Product/Torqu...orsepower.html
http://vettenet.org/torquehp.html
http://auto.howstuffworks.com/horsepower4.htm
http://homepage.mac.com/dgiessel/engine/hpvstq.html

first thing to keep in mind is that theres no such "thing" as horsepower, horsepower is a mathmatical formula for the RATE at which TORQUE can be applied the formula for hp is (tq x rpm/5252=hp
example
450 ft lbs of torque at 3000rpm=257hp
450 ft lbs of torque at 6000rpm=514hp
because the torque at the higher rpm useing gearing can be applied faster
here read this
http://www.69mustang.com/hp_torque.htm

http://www.ubermensch.org/Cars/Technical/hp-tq/

http://vette.ohioracing.com/hp.html

where most guys go wrong is in not correctly matching the cars stall speed and gearing to the cars tq curve, if you mod the engine for increased high rpm performance but fail to also match the stall speed and gearing to that higher rpm tq curve much of the potential improvement is wasted.IT DOES NO GOOD AT ALL TO BUILD AN ENGINE THAT MAKES 600HP AT 7500RPM BUT VERY LITTLE LOWER IN THE RPM RANGE IF YOUR TRANSMISSION AND REAR GEARING PLUS YOUR TRANS STALL SPEED KEEPS YOUR CORVETTE ENGINE IN THE STOCK 1600RPM-5500RPM BAND
example

in the close to stock engine above, the engine should be geared to stay in the 3500rpm-5000rpm range for max acceleration (lower in the rpm range if mileage is a big factor)

in the moded engine above the rpm range moved to 4000rpm-6500rpm requireing differant rear gears and slightly higher stall speeds to gain max acceleration in the same car,
you should readily see that a trans that shifts at 5000rpm will work in the first example but would waste most of the power curve in the second example,where shifting at 6500rpm under full power acelleration would make more sence.
a 3.08 rear gear and 700r4 trans matches the first example well but it would take a swap to a 3.73-4.11 gear to allow the engine in the second example to keep its most effective power band matching that second power curve well.

links youll need to figure out correct rear gear ratios

http://www.miata.net/garage/tirecalc.html

http://www.wallaceracing.com/reargear.htm

http://users.erols.com/srweiss/calcmph.htm

http://users.erols.com/srweiss/calcrpm.htm

http://users.erols.com/srweiss/calcrgr.htm

http://www.prestage.com/Car+Math/Ge...io/default.aspx

http://www.geocities.com/z28esser/speed.html

http://server3003.freeyellow.com/gparts/speedo.htm

http://www.pontiacracing.net/trannyratios.htm

http://www.tciauto.com/tech_info/gear_ratios.htm

 

Thanks for all the info and links grumpyvette!

 

GrumpyVette, I wish I had a dollar for every time I've had to debate that very point, HP being a calculated value based on torque and rpm.

Glad to see you, too, understand that very basic principle.

Now, if I had another dollar for everytime I've had to debate that boring and/or increasing the stroke of an engine, with no other changes, increases CR, I could buy a new 2004 Vette and pay cash.

Nice post, thanks.

Jake