Roush vs 427FE vs Keith Craft

[blykins]

Yes, someone did.

Madmaxx made the statement that "the small block will out-rev the big block". I asked why he thought that, and you replied that it's a much lighter rotating mass.

That sometimes is the case, but what he said (if that's what he meant) is a generalization, and it's false. I don't even accept it as a general rule of thumb. One of my 482 FE's would absolutely spank a factory 5.0L Mustang engine, not just in terms of horsepower and torque, but in "rev-ability" and acceleration.

There are two parts to how well an engine accelerates. Its rotating inertia is one of them (not all big block rotating masses are heavy, not all small block rotating masses are light), and the other is how much power you're using to accelerate it. You'll find that the camshaft, compression ratio, cylinder head, intake, etc. all affects that.

Have a good evening too sir.

[madmaxx]

Been getting plowed on jet ski all day. Kawasaki 4ever. Yamaha is better but I only paid 800 and it goes 60mph.

1). Roush didn't make heads afr did. Tell ur mechanic he is dumb****. Mechanics like whores tell u what they want to make u feel better about giving them money.

2). Brent the big blocks I drove revved linear compared to 427 small blocks, maybe cam intake. Who knows my experience.

3). If I was buying new I would go with blykins he is an engineer. He helped me in past, he has his but on line with each build.

4) buying used I have no reservations with roush, blykins or kc.

[xb-60]

Don't we need to define 'rev'?
If you're revving the engine with no load, then OK an engine with lower rotational mass will rev quicker (all other variables being equal), but when loaded (accelerating on the road), a higher rotating mass won't make a measureable difference.
Cheers,
Glen

[madmaxx]

It would also seam there are infinitely more combinations for a small block. Cam design, due to hydraulic rollers, intake manifolds, carbs heads. I don't know due Fe use hydraulic rollers. FE seams old technology.

[blykins]

Originally Posted by xb-60

Don't we need to define 'rev'?
If you're revving the engine with no load, then OK an engine with lower rotational mass will rev quicker (all other variables being equal), but when loaded (accelerating on the road), a higher rotating mass won't make a measureable difference.
Cheers,
Glen

Yeah, we should have defined "rev" a good bit ago. I'm pretty sure what we're talking about is an engine's ability to accelerate though. There's a lot that goes into that, and as Ed mentioned, the flywheel weights along with the trans, and the rest of the car can affect the engine's ability in the car.

On the dyno, it's a different story though, and it's easy to hear how well an engine accelerates as it's going through its powerband.

You have to also remember that angular acceleration is caused by something. It's caused by torque, or a force applied at a distance.

Rotating assemblies have their own rotational inertia that has to be overcome, but horsepower and torque will easily overcome that and will accelerate the assembly.

FE's are certainly dinosaurs in the fact that they stem back to the late 50's/early 60's, but that doesn't mean that they are all antiquated. You can hamstring them with 40 lb flywheels, numerically low rearend gears, short camshaft duration, low compression, poor intake flow, etc......just like you can a small block.

But....

Just because the rotating assembly is heavier doesn't mean that it won't accelerate quickly or won't seem zippy, and in a lot of cases, I wouldn't even count on the rotating assembly being heavier.

[AL427SBF]

Thanks CobraED, we get the science but Brent not so much.
Nor does Brent know what the word generalization means, but so be it.

Brent, it is clear you can't breakaway from your trick engine builds which are clearly not in family with the majority of engine builds. Your dyno charts are a good example of this, you start recording at 3500 or 4000 RPM and have stated loading the engine at lower RPMs "will suck the guts out of the motor" ... enough said.

Revving faster is not a difficult concept to grasp, time to a given RPM is all it is.

Here's a curve ball that I expect will have you scratching your head for some time. Take a figure skater who has started a spin with both arms outstretched and one leg. Did you catch the Sochi olympics? The energy put into that spin will dictate the skaters RPM based on the rotating mass of that skater. Now that skater pulls in the arms and leg and WHAM quadruple the RPM! I'm also willing to bet that skater didn't loose any weight during the spin. Your bob-weight argument has some relevance to the big picture but not much, and you don't understand mass versus weight. In this case rotating mass = how that weight is distributed from the center axis of rotation and is a huge multiplier of RPM as shown by that skater who decreases rotational mass by pulling in the limbs.

I know you won't get it, I don't expect you to get it, but thank God there are engineers out there putting that simple law of physics to work for us everyday.

[blykins]

Degreed mechanical engineer here, probably have had more statics, dynamics, and physics classes than 90% of the people here.

Also, I will have to ask you sir, how much engine building experience or dyno experience do you have? If you recall, Mr. Rabotnick also agreed that it's not prudent to pull engines down to 1500 rpm to see their manners at low rpms. You will also notice Mr. Crafts online dyno sheets that do not start at 1500-2000 rpm.

As far as I'm concerned, experience trumps ideas, thoughts, or computer simulations.

Sorry you disagree, but I'll be the first to tell you that it doesn't always work the way the physics books say.

Also sorry to be crass, but you simply don't understand what you're referring to and I'll let you get back to your figure skating and I'll get back to building engines.

BTW, feel free to call Mr. Kaase and tell him that your small block will out rev one of his pro stock big blocks.

[Dimis]

Originally Posted by AL427SBF

Thanks CobraED, we get the science but Brent not so much.
Nor does Brent know what the word generalization means, but so be it.

Brent, it is clear you can't breakaway from your trick engine builds which are clearly not in family with the majority of engine builds. Your dyno charts are a good example of this, you start recording at 3500 or 4000 RPM and have stated loading the engine at lower RPMs "will suck the guts out of the motor" ... enough said.

Revving faster is not a difficult concept to grasp, time to a given RPM is all it is.

Here's a curve ball that I expect will have you scratching your head for some time. Take a figure skater who has started a spin with both arms outstretched and one leg. Did you catch the Sochi olympics? The energy put into that spin will dictate the skaters RPM based on the rotating mass of that skater. Now that skater pulls in the arms and leg and WHAM quadruple the RPM! I'm also willing to bet that skater didn't loose any weight during the spin. Your bob-weight argument has some relevance to the big picture but not much, and you don't understand mass versus weight. In this case rotating mass = how that weight is distributed from the center axis of rotation and is a huge multiplier of RPM as shown by that skater who decreases rotational mass by pulling in the limbs.

I know you won't get it, I don't expect you to get it, but thank God there are engineers out there putting that simple law of physics to work for us everyday.

Oh brother... Why so antagonistic?

From my reading Brent is not challenging the laws of physics, just the simple fact that this one law stand alone is not the sole and only reason that results in an engine reving faster.

Therefore to conclude "that" as a general statement of fact would be erroneous, as you'd be omitting other influencing factors.

At least that's how I've read it.
Clearly Ive read it differently to you.

[blykins]

Originally Posted by Dimis

Oh brother... Why so antagonistic?

From my reading Brent is not challenging the laws of physics, just the simple fact that this one law stand alone is not the sole and only reason that results in an engine reving faster.

Therefore to conclude "that" as a general statement of fact would be erroneous, as you'd be omitting other influencing factors.

At least that's how I've read it.
Clearly Ive read it differently to you.

That is true. There is more to it than an example of a figure skater. He is right that the less weight you have slinging out there (skater's arms and legs) makes for a quicker revolution, but what everyone is ignoring because of either pride or ego is that you can't say that all small blocks will out rev all big blocks.

I can't understand why that point is so obtuse.

Do you all realize that some big block rods weigh less than some small block rods? Or some big block pistons weigh less than some small block pistons? Or that the ring tension on a big block can be less than the tension on a small block ring pack? What happens when one engine has more parasitic drag than the other through piston to cylinder contact?

You do not need to look at an exotic build to see these things either.

There's a whole lot more to it than an example of a figure skater.

I still don't understand what all the hub-bub is about. I actually agree that most big blocks seem lazier than the small blocks.

However, you can not make the generalized statement that "a small block will out rev a big block." That is simply not true due to a myriad of variables especially when you consider the larger Windsor combinations.

[AL427SBF]

Originally Posted by blykins

... but what everyone is ignoring because of either pride or ego is that you can't say that small blocks will out rev big blocks ...

Another one who doesn't understand revving faster or what general rule of thumb means.

[blykins]

I edited my post before you caught it, typing on phone is much harder...

Go take your geritol and come back when you're in a better mood, or when you understand what point I'm making.

[Jerry Clayton]

Brent----I want to say that I'm on your side of the table here and that I am sorry the discussion slid over to you--------But being more foemally educated than I, you have the best choice of words.
I have hundreds of balance cards of bob weights of about every kind of engine used in any arena of performance from basic bracket to stock block Indy car, pro stock, top fuel, funny car, and piston, rod weights ARE all over the place----------these guys don't understand that rotating and recip weights are taken differently and that rod angles, ratios, wrist pin off set, etc are factors in the game--------

My last build pro stock engine was 1400 hp at 10.200 rpm and it ran the 1/4 quicker than these guys quick revving small blocks came off idle and got the centrifugal advance starting-----------

I will go to the shop where we have done lots of tuning and see if I can get some printouts of sb vs bb runs based on time for the graph curve-----------

Hope you didn't have damage from the weather--------

Jerry

[patrickt]

FWIW, I had my FE specifically built to be, in my uneducated words, "a quick revver." The builder went with a slightly shorter stroke, and all light weight stuff that cost a bit more, like Wiseco, and what not. Light aluminum flywheel, 3.54 rear, and she's just what the doctor ordered....

[Jerry Clayton]

There is no such thing as VARIBLE MASS----a fiqure skater does not change mass as they pull in there arms/leg----------

An engine on acceleration cannot reduce the radius of the mass as a fiqure skater does during a spin----------

A figure skater is considerably LESS than ONE horse power, however, can and maybe does benefit from variable rotational radius during a spin and variable stroke with the judges before/after contest-------------

[patrickt]

Originally Posted by Jerry Clayton

There is no such thing as VARIABLE MASS-----------------

... except when the Priest's homily just won't end....

[Dimis]

Originally Posted by hercf16

No problem, good discussion on the differences and issues. I am a little color limited in my search; black, black with stripe, silver with stripe, darker blue
With stripe in that order. A few are starting to pop up with different engines
So the more info the better.

Should have bought Sharpatas? Black with champaign stripes and 638 hp
Keith Craft stroker a few years back, brand new in the low 60s

Herc

Herc,

A couple of things.

1. A New paint job isn't that expensive. Body work is mostly done so labour costs aren't as high as they otherwise could be. Perhaps broaden your search with his in mind.

2. SPFs are great, and while you can put anything in them, making for a great cobra. They do recommend going SBF.

3. ERA arguably the gold standard in fibre glass cobras. So if you were set on an FE, then perhaps investigate this option also.

4. If you are having an custom engine built and wanted a boutique, non-cookie-cutter engine, you'd be hard pressed to go past Brent (George Anderson, Barry R, others can add to this list).

5. If buying an FE built by KC, You'd be wise to double check the build isn't using an eagle crank, they are offered as standard equipment in KC builds (see their website). There's documented history of them failing.


I hope that helps. Enjoy your hunt.
It's all part of the fun.

[Dimis]

Originally Posted by Jerry Clayton

There is no such thing as VARIBLE MASS----a fiqure skater does not change mass as they pull in there arms/leg----------

An engine on acceleration cannot reduce the radius of the mass as a fiqure skater does during a spin----------

A figure skater is considerably LESS than ONE horse power, however, can and maybe does benefit from variable rotational radius during a spin and variable stroke with the judges before/after contest-------------

Air resistance (drag) of flailing limbs reduces speed.
Removing this resistance force, by tucking in, aids the acceleration.

As per above eg: It's about factoring in all things, and not closing your mind to prove/justify a hypothesis, just because it's the perceived norm

[AL427SBF]

Originally Posted by Jerry Clayton

There is no such thing as VARIBLE MASS----a fiqure skater does not change mass as they pull in there arms/leg----------

yeah, that's my point - skater's mass remains unchanged but the rotational mass changes dramatically, read it again.

patrickt's comment illustrates exactly what we're talking about ...

I had my FE specifically built to be, in my uneducated words, "a quick revver." The builder went with a slightly shorter stroke, and all light weight stuff ...

patrickt's engine builder reduced the rotating mass of his engine by incorporating those mods.

[patrickt]

Originally Posted by AL427SBF

...The builder went with a slightly shorter stroke,

We had the "does a shorter stroke make a revvier engine" debate a few years ago. We had four very smart, very experienced FE builders chime in. Two said it absolutely did, two said it absolutely didn't.

[CobraEd]

A fatter figure skater will rev faster than a thinner figure skater unless they are wearing a blue outfit with ruffles or if there is a full moon out.


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