Limiting factor for RPMs?

[TC]

Last one, and this guy is talking about what I'm talking about....

This also means a 4.25 stroke crankshaft, with the same piston speed as the 3.75 stroke crank, rotates at a slower speed. The slower crankshaft rotation results in a slower rate of engine acceleration, which results in a slower rate of vehicle acceleration.

http://www.rollingthunderz.com/rfs_f...s_piston.shtml

[TC]

I certainly agree with Mr. Morgan for classes limited in cubic inches. You should always use the largest bore available in the block you are using. Why have a 396 when you can have a 427? The whole reason I questioned you TC and got this started is your use of that short stroke NASCAR crank in your benchrace turbo engine. Why limit yourself to smaller c.i. than the block will support? More c.i. will make more h.p. and accelerate the car faster which is the goal. If you want 8000 rpm you will spend the same on hard parts regardless of final c.i. In the example above why have a 427 when you can have a 482 with the standard bore or 489 at .030 or 496 at .060? I will say I prefer to bore a block as little as possible to clean up so it can be used for a longer time.
You will admit that more cubic inches will accelerate a car faster all other things being equal won't you?

I think this article addresses how I feel......

The simple explanation is that raising rpm effectively increases an engine's displacement. This might seem nonsensical because the volume displaced by the pistons doesn't change, but consider the effects of filling and emptying the cylinders faster in real time. An internal combustion engine is an air pump, and if we turn that pump faster, we can theoretically burn more fuel in a given amount of time and consequently produce more power. For example, an eight-cylinder engine running at 6,000 rpm fires its cylinders 24,000 times in one minute (assuming perfect combustion). Increase the engine's speed to 8,000 rpm and it will fire 32,000 times per minute, a 33 percent increase. The volume of air and fuel that moves through the engine is now equivalent to an engine with a much larger displacement. There are also 8,000 additional power pulses per minute transmitted to the crankshaft that can be harnessed to turn the wheels and accelerate the car.

http://www.rehermorrison.com/blog/?p=201

You should check out the blog very good info to be had......

[TheSilverBuick]

Last one, and this guy is talking about what I'm talking about....



http://www.rollingthunderz.com/rfs_f...s_piston.shtml

How about that, you found an article with the same meaningless logic that you have. If you want to cripple the longer stroke engine with less fuel to slow down the piston speed to match the short stroke, then it matters, but given the same energy input (on the same displacement), the longer stroke is going to move faster.

[OldMachinist]

[QUOTE=TC;658143]I think this article addresses how I feel......

You really need to read your quotes. As Randal pointed out you want to handicap the long stroke by keeping piston speed the same. Totally irrelevant.
The Rehr-Morrison blog is also irrevelant as it talks about maximum RPM which you earlier stated and I agree is valvetrain related not stroke related.
Again I will state what you refuse to address. Use the maximum c.i. that the package will support so your short stroke benchrest engine will make less power than a longer stroke maximized c.i. engine will. You stated you want short stroke for faster RPM in your benchrest Monte Carlo. I am trying to point out the obvious. Go big or go home!

[TC]

[QUOTE=OldMachinist;658151]

I think this article addresses how I feel......

You really need to read your quotes. As Randal pointed out you want to handicap the long stroke by keeping piston speed the same. Totally irrelevant.
The Rehr-Morrison blog is also irrevelant as it talks about maximum RPM which you earlier stated and I agree is valvetrain related not stroke related.
Again I will state what you refuse to address. Use the maximum c.i. that the package will support so your short stroke benchrest engine will make less power than a longer stroke maximized c.i. engine will. You stated you want short stroke for faster RPM in your benchrest Monte Carlo. I am trying to point out the obvious. Go big or go home!

Did you even read the quote?? You asked why I like RPM, that quote gave you the answer.......

[OldMachinist]

I just re-read all my posts and I never asked why you liked RPM. The only thing keeping me from high RPM is like several posts from others said COST! I love it but can't afford it.
My constant theme has been MAXIMUM CUBIC INCHES the block will allow.
If you want people to have a discussion I suggest you quit lying about what they say and trying to change the subject when you know you are wrong. This is the constant theme with you when you finally realize you are wrong but won't admit it. Change the subject and never directly answer questions that are posed to you.

[dieselgeek]

Notice how TC keeps posting links and articles that don't agree with his original premise whatsoever? He always does this crap because he's still looking for an actual logical reason for the first fifteen pages of bullshit he's caused.


Face it, Alex. You don't really know what you are arguing about as usual, and this thread won't result in you having a running HotRod, as usual. Giant waste of everyone's time... As usual.

[TheSilverBuick]

That rollingthunderz quote he was using was taking the quote completely out context too. The author was using the same piston speed for the short and long stroke engines to make it so some people can understand why there is more vertical friction of the piston rings to cylinder wall on a longer stroke, by basically showing it has more vertical travel to "drag" against. Of course it completely leaves out the increased drag of extra surface area a wider piston has on the cylinder wall has. I don't claim to know A) what the difference is in contact area (don't care enough to calculate) or B) that it even makes a difference. But my guesses are that on A there will be a break over point where the frictional area of one will start to out pace the other as bore is decrease and stroke increased (I don't know which) and B it's not really going to matter as OEM's or others would be making engines in only that way for peak power and efficiency, which they don't. Bore's and strokes of engines are all over the place, under and over squared.

[squirrel]

And we seem to be neglecting the fact that ring drag is mostly a product of how much pressure is in the cylinder at that specific time, and it changes constantly. It's highest at the beginning of the power stroke.

[TC]

I just re-read all my posts and I never asked why you liked RPM. The only thing keeping me from high RPM is like several posts from others said COST! I love it but can't afford it.
My constant theme has been MAXIMUM CUBIC INCHES the block will allow.
If you want people to have a discussion I suggest you quit lying about what they say and trying to change the subject when you know you are wrong. This is the constant theme with you when you finally realize you are wrong but won't admit it. Change the subject and never directly answer questions that are posed to you.

You ask this....

The whole reason I questioned you TC and got this started is your use of that short stroke NASCAR crank in your benchrace turbo engine. Why limit yourself to smaller c.i. than the block will support?

I think I'm getting the RPM stuff from other posts, probably getting you confused with someone else...... But what I posted still represents why I'm going with a smaller stroke and why I plan on spinning this motor 8000rpm......

As for Benchrace, this motor is a camshaft, bearings, pushrods, shaft rockers and pistons away from being a reality..... Those are the only things I still need to buy before taking this motor to my buddy Rick for machining and final assembly, hell I even got the turbo headers and turbos already...........Oh and I guess we should add a carb on that list to.......