Who has the best 451 crate motor with cast heads that makes 500 HP

[RemCharger]

Any issues using a 383 based stroker build? Especially since there are more donors available?

One issue can be valve to cyl wall clearance , if using big valve heads.
Buddy of mine ran a 496 383 with RPMs for years,, 9.90/10 ohs.

 

[ckessel]

Kind of what I figured. I know the 400 is more desirable but 383's are more plentiful and less dough.

 

[BSB67]

Here is my silly answer...............Before I had my own dyno I ran my 451 stroker on another dyno. It made 787 HP @ 7,200 rpm and the dyno operator/owner said, "It rev's like a small block Chevy." Later we ran our 500"/440 on that same dyno where it made 848 HP @ 7,200 rpm and the Dyno operator/owner said, "It rev's like a small block Chevy!"

We can all draw our own conclusions I guess.

Exactly. Thanks.

My RB based 508 has 530 gram pistons, 140 gram pins, and 7.1 rods. It revs like, well, a motorhome going up a hill in third gear. Maybe my cam has something to do with it?

 

[451Mopar]

As mentioned, at 500 HP, a stroked 383 would work fine. Actually you could do 500 HP with an unstroked engine, just won't have as much low end torque.
Don't know about "crate" engine 400's? Maybe more of a norm in the 2000's when Muscle Motors was really big on building 451" strokers with 440 cranks and rods and ROSS pistons before the affordable aftermarket stroker cranks and rods (and ICON pistons) started popping up from 440 source and Eagle.
In the 1990's the 451 was popular because 400 blocks were really cheap, like $50 and it used a 440 crank and rods with the mains and counterweight turned down to fit in a 400 block. Back then I bought a Muscle Motors 451 assembled short block for about $3,500 including a Bullet solid roller cam, lifters, and timing set.
I then bought a set of B1-B/S heads from Koffels. Around that time in 1991, very limited choice of aftermarket heads. The Koffels stage 1 ported heads, 1.6:1 rocker arms, pushrods, head studs, and spark plugs was right around $3,000. So I had $6,500 into the basic 451 engine without the oiling, intake, exhaust and ignition systems.
I think Edelbrock finally came out with the RPM head around 2000? Then it seemed there were several knock-off of the RPM head.

Now, with all the avaliable and fairly affordable stroker kits, and heads, and cams you can have an engine built more to your specific needs than what might have been a "crate" engine which may have been built for bracket racing only?

 

[Challenger340]

I've wondered about the "it revs faster" comment before.
I would think, all other things being equal, if 2 engines were tried in the same car, if one revs faster it must make more power.

The lighter Bobweight may Rev faster in Neutral ?
But
when pulling against a 'load' then 500hp/500ft lbs is 500hp/500 ft lbs.....

all I'm saying is I think we're confusing the effect of less parasitic power losses of the lighter bobweight ? but whatever 'power' is whatever 'power'.
Once you make 500/500 with a 400 based build at the flywheel.... then it is still the same 500/500 with a 440 based build at the flywheel..... no matter the 'load' applied to either.

 

[Challenger340]

Like I said earlier looking for header clearance, spark plug maintenance ease, and I don't need 650 to 800 H.P. I've had it. Just looking to build a 500 H.P motor for a stock factory appearing 70 Roadrunner, and I think a 451 is a good candidate to make that easily on pump gas, and the stealth heads sound like a good option for the stock look.

Yeah I think there are certainly some benefits to maintaining 'factory' under hood appearances by using a 400 based /451 if it's a 383 Car ? and that was the intent around the STEALTH Heads by 440 Source.
Just be forewarned.... that the most common way to do the 451 is by using the relatively short-skirt Pistons @ 1.34" CD, and the 6.76" Rod Length..... which the downside can be some Piston "slap" or audible "noise" in mufflered street cars ?

The only way around it... to avoiding any potential Piston noise in a std 451 build you are averse ?
is to go with a more expensive format for building the 451's that utilizes the shorter 400 Based Connecting Rod(6.358") and a set of Diamond Forged Pistons with a much longer skirt that can be fit to run dead nuts quiet in that application.

That's the way we've done more than a few 451's for clients with very high dollar restorations($100K)...... that wanted an absolutely "Factory Appearing" under hood including factory Air Cleaners/Hoses/AC and HP Manifolds/Pipes/quiet Mufflers..... which we've still managed 515 HP/545 Ft/Lbs on the Dyno with all that crap installed using Ported STEALTH Heads and an HR Cam.

 

[IQ52]

Thanks, that made me laugh!
I figured you would have some real world experience with that I appreciate it!
What would you anticipate from
a stroked 451 B ( 4.375) vs a .050 (4.370) over 440 (450ci), both have 3.75 stroke and 6.76 rod ,CH being the difference everything else being equal.
Anything to gain ?
Thanks IQ!

The lighter Bobweight may Rev faster in Neutral ?
But
when pulling against a 'load' then 500hp/500ft lbs is 500hp/500 ft lbs.....

all I'm saying is I think we're confusing the effect of less parasitic power losses of the lighter bobweight ? but whatever 'power' is whatever 'power'.
Once you make 500/500 with a 400 based build at the flywheel.... then it is still the same 500/500 with a 440 based build at the flywheel..... no matter the 'load' applied to either.

Here is your answer. I could not have stated it any better.

 

[451Mopar]

The "when pulling against a 'load' then 500hp/500ft lbs is 500hp/500 ft lbs..... " is only true if the load and rate of change are the same.

An engine dyno takes measurements as the engine RPM increases at a set rate of x amount of RPM per second. Change the acceleration rate and the measured output power changes.
As the acceleration rate increases, the engine with the lighter rotating assembly shows an increase in output power compared to a simular engine with a heavy rotating assembly because it takes power to accelerate the engine components. On the other hand, if a dyno test started with the engines at a high rpm and pulled the RPM down, decelerating the engine, then the engine with more inertia weight will show more power.

Engine Masters did a dyno test with two like engines, but one with alot of mass removed from the rotating assembly.

Anyhow, other factors are that lighter components (like pistons) put less stress on the block and rods take less pounding when the piston changes direction. This can improve durability as long as the parts are not built so light that it makes them to weak for the job.

 

[beanhead]

This may be a silly question, but it's based on rumor, not experience, but has anyone ever compared a B build to and RB- CI being similar ,stroked/bored, similar/same valve train/induction and looked at how fast the rpm builds?
Simply put, many say that the stroked B build rpm faster than does an RB and therefore prefered.
Just curious if there is any truth to it.
Thanks

I don't know....my 440/505" would rev up through the range like a motorcycle, even with my 3.73 gears.. I had to shift earlier because I wasn't making it happen in time to stay off the rev limiter.

That is, until I ditched the Coopers for M/T drag radials and dialed in the suspension a bit better...

It's amazing how much slower it revs with the tires actually touching the ground

 

[Carcinogen]

This may be a silly question, but it's based on rumor, not experience, but has anyone ever compared a B build to and RB- CI being similar ,stroked/bored, similar/same valve train/induction and looked at how fast the rpm builds?
Simply put, many say that the stroked B build rpm faster than does an RB and therefore prefered.
Just curious if there is any truth to it.
Thanks

Remember reading a test between RB and B of same size with same parts. RB had a bit more power due to intake manifold having more internal volume.

 

[Challenger340]

The "when pulling against a 'load' then 500hp/500ft lbs is 500hp/500 ft lbs..... " is only true if the load and rate of change are the same.

.

Exactly ! and to illustrate for all practical purposes.....

So as 'installed' with both in the same-same 4,000 lb Car.... which one will Rev quicker in gear in that car ?
A.) a 500 hp 500 ft/lb 400 Block based 451
or
B.) a 500 hp and 500 ft/lb 440 Block based 451

This one is like asking what's heavier fella's .... a TON of feathers ?... or a TON of Bricks ?

 

[Mike67]

Here is your answer. I could not have stated it any better.

That's why this place is awesome, so many knowledgable people willing to share! Thanks again