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View Poll Results: short vs long stroke
Short stroke engines 21 52.50%
longer stroke engines 19 47.50%
Voters: 40. You may not vote on this poll

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  #1 (permalink)  
Old 02-09-2005, 06:40 PM
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short stroke VS long stroke pool

Cast your vote and give your opinion and thoughts on short stroke motors and strokers

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Old 02-09-2005, 08:28 PM
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Optimum For Block

It depends on the size and weight of the engine.

I am into road racing more than drag racing, so a small engine which fits inside a sprts car would be the engine I prefer, and those would tend to be short stroke engines.

For a small block Chevy, a 3.48 inch stroke is quite efficient in taking advantage of that block design. A 302 Chevy would be best for a small sports car with a low hood, but only in a non-existant shorter deck-height block which weighs less (one-half an inch shorter). The 350 works great on the track and on the street because it is efficiently designed. The Chevy 302 in the 1969 Z-28 wastes too much space per hp and still weighs a bit too much per cubic inch.

I'd say a bit longer for street use, and a bit shorter for on the track, but not too much.
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Old 02-10-2005, 04:26 AM
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ummmmm all the sb's are the same size? yes.

anyways. Stroke has nothing to do with engine size per say. The engine its self stay the same size outside wise the CI (cubic inches) increase.

So a 383 is no bigger out side in terms of size. The displacement of the engine is bigger.

So anyways for most people a small block provides them with everything they need and therefore even though this post does not show it being either bb or sb. I will just stick with the sb.

In the case of the sb. normally this leads to the question what is the car used for.
a 350 is the std. for engines in the sb world.
a 383 (3.75 stroke crank in 350 block) is a tq. monster giving great low end and good for getting off the line.
377 (destroked 400) is the high rev. engine normally good for upper rpm's.
400 the upper class of the sb which can be made to give great power and to many is the anwser.

Help clear things up?

Chris
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Old 02-13-2005, 01:43 PM
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engine size

There is no correlation between the external dimensions of an engine and the displacement of said ingine.

IE: a 396 Chevy is the same block as the 427/454, and the 400 is the same basic block as the 265/350.

In engines, size does matter only in displacement, as far as output goes.

Other factors to consider, especially if going to a limited displacement class to race.
For instance, racing in a 5 liter class, while this may get a lot of arguement, a 302 Ford (460 lbs) has an advantage, weight wise over the 302 Chevy (500 lbs), being 40 lbs lighter, and power outputs are almost identical.
If you are limited to a 6.75 liter class, a 400 Chevy would have definate advantages over a 396, mainly due to about 270 lbs difference in weight, with the 396 only capable of putting out only nominal more power, with both engines built to the max, and in a lot of occasions, these kinds of classes are also carb restricted, making power output numbers almost identical.
If engine weight is not a concern, then go with whatever pulls your trigger.

All that being said, there is no replacement for displacement.

Another consideration for opting for the lighter weight blocks is that they are externally dimensionwise, more compact as well.
(Exceptions being with running an aluminum big block vs an iron small block, weights being much more similar).
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Old 02-13-2005, 01:47 PM
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Again

Didn't we just do 350 verses 383?
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Old 02-13-2005, 01:49 PM
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size does mattter

An item of note here on engine size and weight.
Ford made 4 different engines with the same displacement, all having a 4 inch bore and 3.5 inch stroke; 352 FE (635 lbs), 351W (525 lbs), 351C (550 LBs, and 351M (575 lbs). Power output wise, the 351M has the most potential but it is not the lightest engine, nor does it have as much equipment avialable for it. So on that basis, its down to the W and the C blocks. While the C block in basic stock trim has more potential, aftermarket goodies, makes the W a more viable option of the two in this day and age.
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Old 02-20-2005, 04:11 PM
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Longer rods are like using a longer breaker bar. They have a mechanical advantage. They will increase torque.

Shorter rods have less reciprocating weight. They can be spun faster.

It all depends on what you want your engine to do.
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Old 02-22-2005, 12:12 AM
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Quote:
Originally Posted by brian12c
Cast your vote and give your opinion and thoughts on short stroke motors and strokers
If you want to make a lot of power at high RPM you want to tend toward a short stroke, large bore combination. Piston speed in feet per second is the limitation when you get into long strokes at high RPM. The issue is totally based on engineering and part strength.

Here is some nice information relating to rod length which explains the advantages and disadvantages of each.
http://victorylibrary.com/mopar/rod-tech-c.htm
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Old 02-25-2005, 10:43 PM
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Quote:
Originally Posted by lluciano77
Longer rods are like using a longer breaker bar. They have a mechanical advantage. They will increase torque.

Shorter rods have less reciprocating weight. They can be spun faster.

It all depends on what you want your engine to do.
I've read that they decrease low end torque and increase high RPM power.

K

Last edited by killerformula; 02-25-2005 at 11:05 PM.
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Old 02-26-2005, 04:24 AM
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Encyclopedic volumes could be written on the subject but for a given dispalcement the oversquare engine is still the best IMHO. That would be an engine that has a larger bore than stroke. These are engines that rev faster and live better at high rpms. And as mentioned one of the advantages is piston travel which is usually figured in feet/mile.

Last edited by willowbilly3; 02-27-2005 at 07:08 AM.
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Old 02-26-2005, 08:24 PM
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Quote:
Originally Posted by willowbilly3
And as mentioned one of the advantages is piston travel which is usually figured in feet/mile.
Feet/minute. Feet/mile doesn't change with stroke, or rod length or bore size.
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Old 02-27-2005, 07:11 AM
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Quote:
Originally Posted by Rick WI
Feet/minute. Feet/mile doesn't change with stroke, or rod length or bore size.
You are 2/3 right, it doesn't change with bore size or rod length, but it most certainly does change with stroke. The stroke and the gearing are the only factors that can change the Ft/Mi. ratio. If you have a longer stroke the piston goes up further and down further hence more piston travel. think about it.
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Old 02-27-2005, 10:46 AM
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I see where your coming from, but when making these engineering calculations the ratios are always distance/time not distance/distance. The piston speed is calculated at feet/min @ the specified RPM peak the engine is designed for. Gearing is also not a factor.
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Old 02-28-2005, 05:43 AM
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Hmm.. I guess times have changed. Piston travel in feet per mile used to be something that was a factor and was often quoted in magazines. Care to explain how that ratio wouldn't change if the gearing was different? How would a car with 4.11s have the same piston travel in feet per mile as a car with 3.00 gears?
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Old 02-28-2005, 08:41 AM
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The calculation of piston speed is based off of the crankshaft. The only measurement you care about is piston speed at max RPM's the engine is designed to run at for peak power, at the crankshaft. So introducing any variables after the cranshaft such as gearbox and rear end ratios is.......unnecessary. I have no doubt you have read it in a magazine. Engine builders, and all computer modeling calculations use ft/min at peak RPM at the crank.

As it relates to piston speed/minute @ designed RPM, at the crankshaft, there are guidelines setup to determine the quality of parts needed to withstand the associated g forces that will be encountered.

Last edited by Rick WI; 02-28-2005 at 08:47 AM.
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