Limiting factor for RPMs?

[jcharliem]

That makes no sense at all.

It does to TC... and that's all that matters in his mind. LOL.

[TC]

Really? Seems like your changing your viewpoint now. The article references larger bore allows for monster valves and unshrouding (which is what I stated on page 6 to your question as to why Pro Stockers use large bore / short stroke combos). I thought your original premise was shorter strokes can "rpm faster" (whatever that means). Now you're singing the tune of Dave Reher. The entertainment meter is on tilt again.

He also said if he could run a stroke that is more than twice as small as the bore he'd do it in a heart beat........

[OldMachinist]

I'm not, that is what I'm trying to get across to OldMachist, who cares about stroke when you got turbos and are making 1200hp.........

Tried to stay away before before my head explodes but this thread draws me back like a moth to a flame.
TC I can't seem to get across to you I don't care about stroke except that it limits your total cubic inches when your stroke is shorter than the block will allow. When I am building an engine for horsepower I want the maximum c.i. I can get if not limited by rules. I assume your turbo motor is not limited this way since I don't recall that it is being built to fit any racing class.
For your application I would build the biggest engine I could and if it is too much for your chassis I would dial back the boost to make the engine live longer.
Can't you admit that a 421 or 427 sb will make more h.p. than a 358 and will accelerate your car faster all else being equal?
My wife is uncompromisingly pigheaded but even she can understand this.
You come on here bragging about your short stroke Nascar crank and can't seem to comprehend that it is limiting the h.p. of your benchrace engine. And I call it benchrace because it will never be finished like all your other projects that you have most of the parts for but are just sitting.
If you spent 1/10 the time wrenching as arguing your stuff would be done and worn out by now.

[TC]

That makes no sense at all.



That makes no sense at all.

Think about it........ 5.88 means the pinion turns 5.88 times to one rotation of the ring gear or tire if you prefer....... A 2.73 gear will only turn 2.73 times for one rotation of the ring gear/tire, so in essence the 5.88 is applying twice the amount of power to the tires per revolution of the tire than the 2.73 would do.......

As for tire diameter, you should know this..... A 28" tall tire has a circumference of 87.96", a 31" tall tire has a circumference of 97.40", so for one revolution of the tire the taller tire contacts the ground 10" longer.......

[TC]

Tried to stay away before before my head explodes but this thread draws me back like a moth to a flame.
TC I can't seem to get across to you I don't care about stroke except that it limits your total cubic inches when your stroke is shorter than the block will allow. When I am building an engine for horsepower I want the maximum c.i. I can get if not limited by rules. I assume your turbo motor is not limited this way since I don't recall that it is being built to fit any racing class.
For your application I would build the biggest engine I could and if it is too much for your chassis I would dial back the boost to make the engine live longer.
Can't you admit that a 421 or 427 sb will make more h.p. than a 358 and will accelerate your car faster all else being equal?
My wife is uncompromisingly pigheaded but even she can understand this.
You come on here bragging about your short stroke Nascar crank and can't seem to comprehend that it is limiting the h.p. of your benchrace engine. And I call it benchrace because it will never be finished like all your other projects that you have most of the parts for but are just sitting.
If you spent 1/10 the time wrenching as arguing your stuff would be done and worn out by now.

Let me get one thing straight, I respect you and your opinions, I totally understand where your coming from and if I didn't have these old parts and didn't want to give them life again I might have done what your saying, though I would probably use a LS motor...... Thing is I already have a 400 cubic inch small block in another car, this is just going to be something different, and it's not like that Monte weighs a lot, 3200lbs from the factory.......

[Bob Holmes]

Tried to stay away before before my head explodes but this thread draws me back like a moth to a flame.

Welcome to the party!!

I'm the same way. I try and stay away, but the "TC bait" keeps me rising to the surface.

[TheSilverBuick]

Think about it........ 5.88 means the pinion turns 5.88 times to one rotation of the ring gear or tire if you prefer....... A 2.73 gear will only turn 2.73 times for one rotation of the ring gear/tire, so in essence the 5.88 is applying twice the amount of power to the tires per revolution of the tire than the 2.73 would do.......

As for tire diameter, you should know this..... A 28" tall tire has a circumference of 87.96", a 31" tall tire has a circumference of 97.40", so for one revolution of the tire the taller tire contacts the ground 10" longer.......

I know you are aware that Squirrel is a degree'd mechanical engineer, and this is basic basic basic stuff for them. Do you really think your pot logic is going to trump that

[squirrel]

Think about it........ 5.88 means the pinion turns 5.88 times to one rotation of the ring gear or tire if you prefer....... A 2.73 gear will only turn 2.73 times for one rotation of the ring gear/tire, so in essence the 5.88 is applying twice the amount of power to the tires per revolution of the tire than the 2.73 would do.......

Either gear set will transmit the same amount of power to the tires, assuming you are providing the same amount of power at the driveshaft. The steep gears will go half as far, with twice as much torque applied to the tires.

As for tire diameter, you should know this..... A 28" tall tire has a circumference of 87.96", a 31" tall tire has a circumference of 97.40", so for one revolution of the tire the taller tire contacts the ground 10" longer.......

So....what does this have to do with how much power the different size tires deliver to the ground?

Words like "power" mean something specific when you're talking about machines. You need to understand what the words mean.

[skullbucket]

Geeze, Its a small block Chevy, there are no secrets, grab a magazine at Walmart and go from there.

[TC]

Words like "power" mean something specific when you're talking about machines. You need to understand what the words mean.

So I should replace the word power with torque??, as in the 5.88's will deliver twice the torque to the tires than a 2.73 will per revolution of the tire??......

As for the tire height, I'll have to dig up the article again, it has to do with the taller tire covering more distance per tire rotation, which effectively transfer more torque to the ground per tire rotation........

[Bob Holmes]

Off topic:

TC, your google-fu is much better than mine. Can you find coefficent of drag and frontal area for a second gen Probe?

Back to your regularly scheduled program.

[TheSilverBuick]

So I should replace the word power with torque??, as in the 5.88's will deliver twice the torque to the tires than a 2.73 will per revolution of the tire??......
.

Yes, but go half as far as the 2.73's.

[TC]

Off topic:

TC, your google-fu is much better than mine. Can you find coefficent of drag and frontal area for a second gen Probe?

Back to your regularly scheduled program.

You talking the '93-'97 model?? From the numbers I found, the frontal area is 1.98 m(^2)...... The CdxA is .63. So according to those two numbers the CD(coefficent of drag) would be around .318.........

[squirrel]

So I should replace the word power with torque??, as in the 5.88's will deliver twice the torque to the tires than a 2.73 will per revolution of the tire??......

yes, and they tires will turn half as far.

As for the tire height, I'll have to dig up the article again, it has to do with the taller tire covering more distance per tire rotation, which effectively transfer more torque to the ground per tire rotation........

Taller tires are the same as going to a numerically lower gear. So....you say it's good to run lots of gear, and also tall tires. That's true, if you're traction limited and need more sidewall height to get a good contact patch. But it really doesn't have much to do with what limits RPM capability of an engine.

[Bob Holmes]

You talking the '93-'97 model?? From the numbers I found, the frontal area is 1.98 m(^2)...... The CdxA is .63. So according to those two numbers the CD(coefficent of drag) would be around .318.........

Thanks, where did you find it? I've been looking for weeks.

Oh crap, I got the break year wrong, its '93. Mayfield has the '93. Thanks.