opinions welcome on build.

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Where that 427” mentioned previously ended up.
Not a 4” crank though....... 4.125”.

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Reminds me running Super Stock on the Vogue tires
Darn Z-11 Chevies
Dyno Don (who did our chassis dyno as well as his chevy had a 62 F/X others like Hayden Proffitt had 63s )
roll out and not hit the secondaries till half way through low gear
 
I’m not going to give out the power numbers.
But, I will say the hp/ci improved ever so slightly with the new combo.

Why the big motor? He wanted more power....... and my suggestion was more cubes would def make more power, and that another/different set of expensive reworked stock heads may or may not make more power.
He was looking for tens, and I felt this was the easiest path forward.

It’s the fastest SB FAST car........ by a bunch...... so i’d say it turned out pretty well.

You can hear there’s a slight hesitation/stumble on the line of this run:


Btw, the current all time fastest FAST car also had a big cube motor...... almost 600”.
Built by BES iirc.

The highest HP BB Mopar wedge motors for the class have also been bigger cube as opposed to smaller cube combos.
With equivalent heads, induction, exhaust, compression, cams, etc........ 526’s have made more power than 493’s and 500’s.
The highest HP BB Mopar so far was a 541” MW combo.
Obviously....... better heads, induction, exhaust.

Edit- it appears the new record is held by a BBC Corvette.......9.77.
I have no idea what size the motor in that car is.

The previous record, which stood for several years was by a BBF Mustang...... 9.84.
Rumors at the time were the Mustang motor was either a 572 or 598.
 
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this has gone way off the rails...the question is 3.79 or 4" stroke 340, in an A body /demon.
 
You’re 100% correct.
My apologies.

Just giving examples and pointing out that in my experience there’s no reason to fear the 4”(or 4.125”) stroke or the cubes.

Carry on.....
 
none req'd...i'm as guilty too with my FAST class posts.
agreed...carry on guys.
 
Agree with PRH
no need to fear the stroke or rod ratio
go for cost effective big cubes and build from there
THIS
"that another/different set of expensive reworked stock heads may or may not make more power."

Heads are where the top end power is and you get about the same top end power with 370 or 426 cu in
but you get a lot more midrange with the big motor
and do not have to rev as high and do not have to have a cam that has to have high revs to work best.
 
I don't know why guys are scared of long strokes, I've had a 4" and have a 4.125". Both revved quick and made good power. I ran a 6.125" rod with the 4" crank and have a 6.200" rod in the 4.125" engine. The 4.125" engine made peak hp at 6750.
 
justinp61 said:
I don't know why guys are scared of long strokes, I've had a 4" and have a 4.125". Both revved quick and made good power. I ran a 6.125" rod with the 4" crank and have a 6.200" rod in the 4.125" engine. The 4.125" engine made peak hp at 6750.
Click to expand...


Depends on the heads and what you think a good power curve looks like.

By today's standards, 6750 is barely off idle. I remember when the 632 became all the rage. Most were shifted at 6000-6200. Today, 8000 is nothing.

If we are talking drag race engines, RPM is king.

Edit: on the street and in limited traction situations I can make the argument all day long for the shorter stroke and more RPM.
 
PRH said:
You’re 100% correct.
My apologies.

Just giving examples and pointing out that in my experience there’s no reason to fear the 4”(or 4.125”) stroke or the cubes.

Carry on.....
Click to expand...
Not to drag this off topic but all the FAST guys run huge cubic inch engines (which takes huge cubic $$) because they are not limited in cubes, but they do have to be Stock Appearing WITH factory exhaust manifolds!
The reason all FAST engines are huge is because they are saddled with a restrictive induction and exhaust tract AND they don't care how big the engine is as long as it APPEARS stock.

So we all know an engine is an air pump right? So we rev it higher to pump more or we make it bigger to pump more--correct? Anyways , I give up. I was just trying to spur on interesting and though provoking discussion on efficiency and FAST engines are not really the pinnacle of that. Carry on. J.Rob
 
So I have a question. Let's take two roughly 408 inch engines. Both are identical except for bore and stroke.


Better yet, let's do it this way...a .030 360 with a 4 inch stroke (actually 409 inches but who counts that close except every sanctioning body on the planet) and a 387 inches 360 with a 3.79 stoke.

Both are exactly the same. Both make the exact same HP. They both make 550 HP. The 409 does it at 6200 and the 387 does it at 7000.

Which one will be quicker and faster in the same car?
 
yellow rose said:
So I have a question. Let's take two roughly 408 inch engines. Both are identical except for bore and stroke.


Better yet, let's do it this way...a .030 360 with a 4 inch stroke (actually 409 inches but who counts that close except every sanctioning body on the planet) and a 387 inches 360 with a 3.79 stoke.

Both are exactly the same. Both make the exact same HP. They both make 550 HP. The 409 does it at 6200 and the 387 does it at 7000.

Which one will be quicker and faster in the same car?
Click to expand...

My guess would be the 7000 rpm engine , just because the lesser rpm drop when changing gears on the dragstrip , and more control of tire spin on the line .
-------------------------------????????.
 
I was just trying to spur on interesting and though provoking discussion on efficiency and FAST engines are not really the pinnacle of that.
Click to expand...

In a series like FAST, there is no award for having your engine be “efficient”.

It’s a “run what ya brung, and hope you brung enough” class.
All you’re trying to do is make more power.
If you added 50 cubes, and that only netted 20 additional hp....... as long as it didn’t come with at the expense of a bunch of extra weight....... it’s still a win.

The point of my original example was........ I added cubes, and tweaked the cam to an existing combo......... one that’s pretty severely hindered on both the intake and exhaust.
And it made more tq and more hp....... and the car went faster.

I really don’t see any reason why the same approach wouldn’t apply for similar type street/strip builds.
Is there a chance the efficiency might go down?
Sure.

But I’ve never had a customer ask me to build to a hp/ci figure.

It’s just, I want *** hp...... how do I get there?

As with anything, there’s more than one way to get there.
The OP was asking for opinions....... mine is..... don’t fear the stroke.

Oh, and if both the 427 and 402 builds were starting from scratch, there wouldn’t be any additional cost for the extra cubes.
 
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Which one will be quicker and faster in the same car?
Click to expand...

Which car?
The 3500lb Dart with 1-5/8” headers, 2.5” full length exhaust, 11” converter, 3.55’s, P/S and A/C? That car?

I’m gonna say the 408”.:steering:
 
ir3333 said:
Same gears and suspension?
The 387 will rev quicker.
Click to expand...

Just out of curosity, have you had a 4" or bigger stroker small block?

for some reason it seems a lot of guys think these strokers are dump truck engines. My experience has been just the opposite. Both of mine have revved very quick.
 
no but i have number of friends that do, and they make big numbers. Quick is a relative term.
Compare a 4" stroke to a 3.5" stroke.In one crankshaft revolution the 3.5" stroke piston travels
14 " while the 4" stroke travels 16"..or 2 inches more. Now multiply that by 6000 rpm.
..each 4" stroke piston will have to travel 1000 ft. further (12000 inches) than the 3.5"
in same amount of time.
 
justinp61 said:
Just out of curosity, have you had a 4" or bigger stroker small block?

for some reason it seems a lot of guys think these strokers are dump truck engines. My experience has been just the opposite. Both of mine have revved very quick.
Click to expand...


Lots of them. Takes a lot of cylinder head and cam to get the power curve where I want it.

For me, making 550-560 HP at 5400 isn't where it's at. You could either reduce the stroke some and move the power curve up and make more power, or, you have to get the heads and cam timing up to where most guys would snivel about it.
 
Frankly, I’ve never seen an instance where making a small change to the stroke, and it’s accompanying change in displacement, with NO OTHER CHANGES, has much affect at all on where the peaks occur.

Build a 10:1 387 with bowl blended RPM heads and intake, and enough carb and cam to peak at say 6200.
Swap out the rotating assy only, retest...... it’s not like it’s going to peak 500rpm lower.

Tq/ci would likely be very nearly the same, hp/ci would go down....... but the hp number would still be higher.
 
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yellow rose said:
Lots of them. Takes a lot of cylinder head and cam to get the power curve where I want it.

For me, making 550-560 HP at 5400 isn't where it's at. You could either reduce the stroke some and move the power curve up and make more power, or, you have to get the heads and cam timing up to where most guys would snivel about it.
Click to expand...

i like having 550-560 hp at 5400 on its way having well over 600 at 6800. I also like having over 600 ft pounds of torque at 5000 rpms.
 
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As long as the cam is sufficiently sized for decent high rpm operation....... the only stuff I’ve seen in the last several years that didn’t carry the power band high enough to where I thought it was satisfactory....... have been motors with hyd lifters of some sort.
And in those situations...... a shorter stroke peaks no higher.

Even the solid lifter stuff that peaks fairly early hangs on reasonably well if there is sufficient duration.

Even a 511 with a modified stock 1969 383 intake manifold, ex manifolds, and moderately ported 906 heads can peak at 5800...... and hangs on pretty well for another 500rpm.

Driving the car....... there is no real perception that the motor is “laying down”. It would zing right up to 6500 no problem.
 
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YR my 2 cents
depend on how close you can keep the short stroke smaller motor to its peak HP curve the more gears the better
both motors can make the same top hp but the short stroke motor will typically have a narrower power band and the larger longer stroke motor a wider power band making it easier to keep it in the power band
short stroke motor can have a longer rod and less friction and less side thrust on the cylinder walls
longer stroke motor can have a longer lever arm (crank) and more leverage
we ran 304 with strokes from 2 5/8 -and just under 3", { 3.25 (forged 327 crank 3.28 3.44 (stock AMC 304) test mules prior to using 4.060 360 blocks and 4.165 401 blocks and the out the back door 4.25- 4.315 blocks)
AMC has same bore centers and 455 Buick
The bigger bores/ shorter strokes made more power and cylinder heads were modified along the way so no direct comparison
so Big Bore
More Cubes
what's not to like
now on the street I'd take more cubes if cost effective package that has off the shelf parts
 
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