Read this entire thread and feel dumber for it. C'mon guys...how long will fairy tails with unicorns and crap like that go on? I have posted several examples of why stroke is not all that and then some. There are WAY more important parts of the equation than stroke. For me (and there are many of us out here who know the truth) torque is a by product of stroke length, port area, overlap, @.050 timing and rod ratio. I know some long haired type will post on here and try to tell us that HP is calculated from torque blah blah blah. Again, the reality is that torque is the by product of the above. To be realistic, we need some definitions to start with so we are all talking the same lingo.
I like simple best so here it goes:
Torque = twisting force.
Horsepower = time to do the twisting.
Really simple, isn't it?
So, here is an example I read probably 25 years ago that fits. Torque is the amount of WORK required to twist a doorknob (whatever the exact number is, we don't care, we just know work happened when we twisted the knob).
Horsepower is the amount of TIME it took to twist that knob. Again, we don't care what the time is we just know it took time to twist the doorknob and that time is HORSEPOWER.
If we make the knob harder to turn, it requires more TIME to turn so we used less HORSEPOWER. If the knob is still hard to turn and we turn it faster, we made more HORSEPOWER.
Simple really.
So what we are talking about is that really, horsepower is how long it took to do work. In drag racing (and horse racing and golf cart racing and about any other kind of racing) if you did the work in less TIME you had to have more HORSEPOWER. Period. That is why every power speed calculator I know of uses HORSEPOWER to calculate ET and not torque. Torque is a by product.
Real world example: Had a customer come in the shop and tell us he wanted 850 lb/ft of torque. I said what the ruck for? He said, because I want to go 10's. I said well what does the car weigh? He says 3600 with me in it. I calculated about 600 HP and that would get him about 600 lb/ft of torque (because his combo was already screwed up I couldn't dump any more torque of I would have). After hours of discussion we gave in and built him what he wanted, all the time me telling him his disappointment would be great.
Put the pig together and it made 425 HP and 880 lb/ft of torque. I told him to plan on 11.40's or so. He was pissed because he should go 10.60's by his torque numbers (I should have bet him but I don't like taking money from an already pissed customer.
So, down to the track. It starts off in the 11.65 range and it was tuned to the 11.50's that night. He fought traction issues. So he spent ANOTHER grand on upgraded suspension and it went into the 11.30's and that was where it lived. He was pissed and sold the car.
If he would have LISTENED, for the SAME money I could have made way more HP with way less torque. The car would have been faster and easier to drive. Torque is a by product and has little overall impact on ET in the real world application (yes I can prove that too).
The problem is that the real hot rodder is dead. Those of us who don't mind a 3.90-4.56 gear on the street (I use 4.56's in my car) don't lose sleep over 50 lb/ft of torque or even 100. But I get berserk over 10 HP for damn sure. And I'll give up 50 lb/ft of torque at 2500 to gain 15 HP at 6800 ALL DAY LONG.
I'm also confused by this current idle speed issue. Seems like if you idle is faster than 1200 RPM some guys wet the bed. Idle is just a number. Unplug your tach and see if you can tell
the difference between a correctly set 1200rPM idle and a correctly set 1600 RPM idle. Bet you can't. So we give up midrange torque by using a wide LSA so we can lower the idle speed? That's what GM did with the old 30/30 Duntov and the first LT-1 cams. The 30/30 was on a 114 LSA and the mighty LT-1was on a ridiculous 116 LSA!!! Sure was fun using my 292 DC cam to take money from fools, suckers and chumps.
My point is this: Horsepower is KING. To dispute this is stupid.
A man much smarter than me said this words probably 30 years or more ago. It hasn't changed. I would take a 4.125 bore 3.58 stroke engine over a 4.03 4.00 engine every day of the week and ten times on Sunday when they are signing the checks. And I would use a 6.25 rod in the 3.58 stroke. Then set my cam numbers to my RPM range, and gear and tire size would follow.
Simple really.
HORSEPOWER is KING for sure.
Rant over.
