428fe, or 427fe, which one do you prefer? Please no other engines, thanks.

[blykins]

I would then ask him what he means by that. Usually when Barry puts something in "quotes", he's talking tongue in cheek.

Have any of you guys ever been to a drag race? Pro stock? Mountain Pro Stock? Top Fuel Alcohol? Do you know the Pro Stock and Mountain classes run strokes over 5"?

That's why you can't say, "Long stroke engines don't rev quick." Do you see the fallacy in that statement? These guys go from idle to 9000 rpm in probably a half second.

[patrickt]

Originally Posted by blykins

I would then ask him what he means by that. Usually when Barry puts something in "quotes", he's talking tongue in cheek.

Yet he specifically chose a shorter stroke for that build, so there must have been a reason that, in his view, a shorter stroke was superior. He certainly didn't choose it just because he had it sitting around the shop. He then said that he wanted to retain the "revvier" feel. That's pretty hard to explain away....

[blykins]

Good luck with your assumptions.

As Barry just texted, if you don't think a long stroke crank will rev, call Jon Kaase, Sonny Bryant, Pat Musi, or Warren Johnson, and ask them why they use such long strokes in their engines. Apparently, they're misinformed.

[cycleguy55]

On the matter of consensus I will say this - just because more people (even an overwhelming majority) get it wrong doesn't make it right. My preference is to look for verifiable facts and objective data.

FWIW, I'd trust the opinion of a reputable engine builder over the 'facts' spouted by thousands who've never even adjusted valve lash or lifter preload.

[olddog]

The old timers rules of thumb that short strokes can rev higher, and that long strokes make better low rpm torque motors came from the limitations of their time. When all you had was factory blocks, factory rods, and often factory cast iron cranks, sure it was a lot easier to rev a short stroke to higher rpm before ugly things happened.

When all you had access to was crappy factory heads that didn't flow well, small bores limited valves size, and small bore/long strokes just plain could not breath at high rpm.

Now even in the old days Chrysler had hemi head engines that flowed better than most. And canted valve heads came around. I remember when the multi-angle valve job made a big difference. Even though cast iron head could be ported back then, it was out of the reach of the hot rod guys. So even in the old days these rules of thumb were not absolute truths, but they did point you down the easier road to travel, that you could afford.

Sure all the technology has changed, and we can easily do what could not be done years ago. Brent is absolutely correct and I understand his frustration with people propagating old myths. However, to understand our history, you have to keep things in perspective.

Even today in a given block family, it is much cheaper to build a high rpm engine if you stay on the short stroke side of what's available for it. Likewise if you go to a long stroke and want it to breath at higher RPMs, you are going to have to shell out more cash for better heads. Even though we can afford to do what only a race team with factory support could have done back then, it still does cost more, but it is affordable today.

[AL427SBF]

It's all relative Brent. Take the same quality of build and materials on those motors and apply it to a shorter stroke engine and it will out rev them every time. Take that to "Barry" and see what he says

"An over-square engine configuration is ideal for high-rpm horsepower--it's how Formula 1 engines rev to seemingly impossible plateaus of 13,000-plus rpm--because the shorter stroke minimizes the maximum piston speed. That reduces power-robbing friction and heat, while also reducing stress on the crankshaft."

Pretty standard comment when you start looking at what's out there on the subject.
.

[blykins]

Again, sir, let me explain your own statements to you, since you are incapable of understanding them.

Most racing sanctions have rules. They are limited by displacement, either by the bore or by the stroke. Think Formula 1. Think NASCAR (358 ci rules).

When you are limited by displacement, then you *have* to turn the rpms WAY up to make horsepower. That's why Cup engines have to turn 9800 rpm. That's why F1 cars have to turn 12000-13000. When you only have bore and stroke to work with, then of course you make the bores large to help with head flow. When you don't have displacement rules, then you make both big.

Another reason for the short stroke on the Cup engines and F1 engines is because it's easier on parts. A smaller crank is going to be easier on bearings, and a short stroke will be easier on the pistons/rings/etc. because the piston travels a shorter distance. When you're racing for hours at a time, for 100's of miles, sometimes you do things for longevity. When you're drag racing, then you see what MAJOR race shops do.....add lots and lots of stroke.

You are incorrect in pretty much every statement you make. Of course you don't intend to be, you just don't understand things. That's why you cut and paste from Wikipedia and I go out and look at dyno sheets.



Have a nice night. I'm gonna shake the dust from my feet on this one.

[blykins]

I'll come back once more for this....

Jon Kaase won the 2013 Engine Masters Challenge with a DOHC modular Ford engine.

Bore size was 3.720".

Stroke was 4.700"

They pull them over 7000 rpm, averaging the hp from 3000-7000, if I recall correctly.

Those long strokes are just turds, aren't they?

Accufab was 2nd runner up with another long stroke Modular Ford.

[olddog]

As far as how quickly an engine can rev, it is physics.

FORCE = MASS * ACCELERATION

Rearranged

ACCELERATION = FORCE / MASS

For rotating systems, FORCE is TORQUE and MASS is INERTIA.

ACCELERATION = TORQUE / INERTIA

So if you can increase the torque by the same percentage you increase the inertia, acceleration is the same.

Reduce inertia or increase torque and acceleration increases.

No where in the physics does it say that longer strokes reduce acceleration. However be careful here. In the inertia calculation, the distance from the center of rotation is a factor. So as you move the center of the mass further from the center of rotation (increase the stroke) the inertia increases, even if the mass remains unchanged. In reality, you need more strength as you increase stroke, and you end up increasing inertia rather sharply, as you increase stroke. However if you can switch to light weight high strength materials, for a price, you can actually reduce inertia.

I expect these mountain motors either make huge power or utilize exotic materials that are a bit pricey. I would salivate if someone has the specs on one.

[AL427SBF]

Originally Posted by blykins

...Have a nice night. I'm gonna shake the dust from my feet on this one.

On your way out, tell Barry he was misinformed if he thought this was about "big stroke engines rev slow", think of it as rev them until failure, which one will fail first given equal $$ invested in two motors with same CID but different strokes.
.

[blykins]

Little of both....

High dollar parts, but anywhere from 5-5.5" of stroke. They make tremendous amounts of horsepower and torque, which goes along with your physics statements. Most guys want to focus in on the fact that a longer stroke crank is larger, but they should be focusing on the fact that a large amount of horsepower will still accelerate that thing like a chainsaw.

[blykins]

Originally Posted by AL427SBF

On your way out, tell Barry he was misinformed if he thought this was about "big stroke engines rev slow", think of it as rev them until failure, which one will fail first given equal $$ invested in two motors with same CID but different strokes.
.

Really stinks when you have to grasp for straws doesn't it?

[AL427SBF]

Originally Posted by blykins

Really stinks when you have to grasp for straws doesn't it?

Peace, understanding the forces involved in a rotating mass is not for everyone.
.

[olddog]

Originally Posted by blykins

Jon Kaase won the 2013 Engine Masters Challenge with a DOHC modular Ford engine.

Bore size was 3.720".

Stroke was 4.700"

They pull them over 7000 rpm, averaging the hp from 3000-7000, if I recall correctly.

Brent I'm with you on this, but just to keep things honest. The 4 valve per cylinder heads on the modular flow very well and Kasse certainly made them flow better. If you stuck 2 valve non-canted 60's factory style heads on this bore stroke combination, it would likely be all in by 3000 rpm. If you worked up a good set of modern Windsor heads, you could take it a long way, but I doubt you could match the 4 valve heads.

Good flowing heads have enabled the long strokes to do what was never thought possible. I believe emissions drove the technology that direction.

[blykins]

I know. Come back when you get it.

[patrickt]

The question is not whether big stroke engines will rev, it's whether or not a shorter stroke engine might feel like it's revving quicker, and may feel more responsive, than a longer stroke engine, even if that longer stroke engine is indeed more powerful and will indeed rev just as high.

[427forme]

Unless your going strictly race stay with the 428. I have one in a 67 falcon with factory 6V about all I do is change oil/filters and rear tires when needed. the 6V was adjusted by a friend with a smog machine over 10 yrs. ago - good mileage and performance even the way I drive it, almost twice as good as my 05 f-150 5.4.

[blykins]

Originally Posted by patrickt

The question is not whether big stroke engines will rev, it's whether or not a shorter stroke engine might feel like it's revving quicker, and may feel more responsive, than a longer stroke engine, even if that longer stroke engine is indeed more powerful and will indeed rev just as high.

Too many variables Patrick. Flywheel weight? Rod and piston weight? Piston ring pack drag? Crankshaft weight? Did you know that a cast 428 FE crank is lighter than a forged 427 crank? Otherwise, do you really think that the .200" of stroke is going to make that much of a difference? I don't.

[patrickt]

Well, under what circumstances would you choose a 4.125" crank over a 4.250" crank for a Cobra FE build?

[blykins]

I wouldn't. I have only used one 4.125" stroke crankshaft and it's because the customer requested it specifically.