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school me on a 451 stroker

The way I understnd this from a somewhat limited engine building, but also a general physics and engineering standpoint is that the B block 451 package incorporates multiple small advantages that add up to form a better complete package.

Some of them are:

Lighter total weight
Thicker block casting
Lighter recoprocating mass
Better bore/stroke ratio
 
I think that's a good way to look at it.....I don't know about the thicker block deal. I've heard and read both sides to the fence. Until I see proof there, I don't know. But again.....that's kinda like the rod ratio arguement. It'll never really make a difference. It's fun to bench race with though.

;)
 
hey rustyratrod, why aren't u gonna stroke ur 383? Isn't that a 431 stroker, or is it an obsolete idea in this day and age?
 
hey rustyratrod, why aren't u gonna stroke ur 383? Isn't that a 431 stroker, or is it an obsolete idea in this day and age?

LOL

Cause I caint afford it. Maybe if I found a 400 block, I might do it. Stroker pistons for a 383 are pretty high.
 
LOL

Cause I caint afford it. Maybe if I found a 400 block, I might do it. Stroker pistons for a 383 are pretty high.

Yeah, I wouldn't waste a good 383. Just curious about the idea of it all. And it seems everything for the 383's are high.

Sorry guys, didn't mean to hyjack the thread. :)
 
The way I understnd this from a somewhat limited engine building, but also a general physics and engineering standpoint is that the B block 451 package incorporates multiple small advantages that add up to form a better complete package.

Some of them are:

Lighter total weight
Thicker block casting
Lighter recoprocating mass
Better bore/stroke ratio

The last one is what makes all the difference, otherwise if you build a 440 with a real good piston you save the same piston weight and end up with the same recip mass, doing it right and leaving the 400 rod you gain that and then some, going still further as i explained much earlier in the thread of further changes to the crank and using other rods will net a even further lighter recip and much more useable power EARLIER, or build the 440 in a short deck and gain a lighter piston.

Technical differences are, the 1.7 RR is better over the 1.8 changing the power band and making more power earlier

When you understand piston speed and it's effect on filling and evacuating you'll better understand, but no one is interested in learning anything about building a 451 which is ONLY the 440 crank in the 400 and utilizing the 400 rod.
Other differences

The bearing diameter, smaller is better
the bore is larger than the 440
the deck heights .740 difference

I will leave you to make your less powerful decision

Just out of curiosity, especially the guys with multiple objections to the better RR and building the 400 correctly, how many different motors have you done with different changes from what the factory told you is better ?


IQ52 said:
You're building it different from me, so that makes you, well, different, but, not wrong.

I don't see what you believe is so magical here other than a lighter piston, if you take the 440 crank and rods and install that WHICH does and are the characteristics that make up EVERYTHING about a 440 and put it in a block and use a piston that is FACT .150 less material you do in fact simply have a lighter piston swinging on a 440 recip assembly and moved the pin up around .35 thats it...

You have changed nothing to make it better than a 440 other than weight of the piston and if you order the right piston it's either 0.0 or .05 out depending on head and even adding a fire groove to the .05 out.
The same exact piston speed is there, the same higher rpm breathing characteristics are there, nothing has been done to help in the 2000 to 4000 area. Which is where you will p/u and where 90% on this board will be helpful too, and there is no loss upstairs

Meep-Meep said:
You also seem to be stuck on a difference of 1.8:1 and 1.7:1 R/S ratio. Is it really that much of a difference? Is the difference like adding a 100 HP nitrous kit? Or putting on a 2" single exhaust system with log manifolds? What exactly are you seeing by running a 400 rod on a 440 crank as opposed to a 440 rod on a 440 crank?

Im not stuck on this, but for everyone here worried about the costs of builds this build has a very cheap and non cost adding alternative, and this is the BEST way to p/u more power, and p/u earlier in the band and hold it longer without adding more expense.
A few piston companies offer the piston for the short rod, and others offer it for the even shorter rod.

I'm not against new technology, but have you noticed that all that new technology has been based on those several hundred year old laws of physics? Oh, and that whole outdated wheel idea..

Really, maybe then you should show me this hundred year old physics being used WHERE in the new automotive technology, bmw, benz even some ferraris and other exotics aren't in the 1.8's.
I also build motors, and the idea of having large RR and that dwell time theory hasn't been for some time now, it's now how quickly can we move the piston
Then why is it that EVERY company has gone away from the large RR, even mopar has finally, notice the fixed hemi is no where near that 9,000 rpm 1.83 RR, down to 1.73 like that of the 360 not the 340's need for rpm, no other company has been near 1.8.

I have been a mopar purist since the 60's and mopar has made tons of blunders over the years, the loss of certain W-2's, the cancellation of many perfect heads, parts and cars, the factory block machining that many are horrendous and the lifter bores are all over, the sticking with the same old same old FOR far to long.

What other company has been or is using these sustained high rpm rod ratios ?
Surely isn't the 455 buick, the supposed best of torque with its 1.6 ratio, the poncho with it's 1.5, or how about the new motors the ls7 with it's 1.5, in fact GM and ford haven't seen the mid 1.7s since the 60's.
The new viper is with it now with it's 1.5 ratio, look at that power and where it is, all the gm ls's are 1.6 or slightly less.

So because mopar made mistakes in the 60's with these not so optimal rod ratios the idea is to continue on doing the same.


Again the title says "SCHOOL me on the 451 stroker" no one is really teaching, just sticking a 440 rotating assembly in a 400 block.

.
 
The last one is what makes all the difference...........


Actually, the rod ratio makes the least difference. A higher rod ratio is better, but to argue 1.7 to 1.8?

So then, you seem to completely discount cutting METAL off the crank. Going from 440 to 400 main size. Carving off .250" from the counter weights and using lighter pistons. Man, I gotta say it. You're about as dense as frackin concrete.
 
You apparently didn't read the section where i stated SMALLER bearing is better, you also didn't read where i went further, you seem to only know weight, weight while important isn't better then the RR and piston speed which plays in cyl fill.

You do not understand RR.

Keep schooling this person on how to be the popular slower group.
 
All this is making my head hurt. I just want a big engine that I can pass off as a stock 383. :)
 
Nope, I think you want and recommend for him to run the shorter rod, but HE may want the longer rod.

Muscle Motors has some kits Photon440 can go with:

383/438 3.750 stroke & 6.760 rod 1.80 RR
383/456 3.910 stroke & 6.700 rod 1.71 RR
383/496 4.250 stroke & 6.535 rod 1.54 RR

I would go with the 496, run the 1.54 RR, just cause I like the thought of the big inch motor.

Unfortunately, unless we have a zillion bucks to play with and can design our own parts, we are generally stuck with what the suppliers can deliver to us.
 
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All this is making my head hurt. I just want a big engine that I can pass off as a stock 383. :)

I know and I apologize. I'm just gonna step back outta the pissin match. Sorry it turned into that. My apologies if I caused it.
 
Nope, I think you want and recommend for him to run the shorter rod, but HE may want the longer rod.

Muscle Motors has some kits Photon440 can go with:

383/438 3.750 stroke & 6.760 rod 1.80 RR
383/456 3.910 stroke & 6.700 rod 1.71 RR
383/496 4.250 stroke & 6.535 rod 1.54 RR

Unfortunately, unless we have a zillion bucks to play with and can design our own parts, we are generally stuck with what the suppliers can deliver to us.


As for the question concerning cost and unobtainable stuff using the 383 rod, yes in fact diamond pistons makes a flat top piston in the 383 x 3.75 configuration with the 383 6.3 rod.
So as for the issue of needing a zillion bucks and or unobtainable stuff here for photon well that just doesn't exist.

Though if he is needing a crank or complete recip assembly then it would be in his better interest to do the 3.9
 
WOW! I just read the posts added to this thread after the last time I checked 4 days ago - lots of info here and some very strong opinions!

This is the best mopar forum site out there and since I'm in the middle of a 451 build for my small block powered '68 Satellite and have never done it before, let alone ANY motor before, I welcome ALL comments and opinions, as I'm sure the original poster does. In doing so, please remember that if you have been doing this for awhile and have many motor builds behind you, there are just as many of us out there that have never built a motor at all and are learning as we go. We don't know if 1.7 vs 1.8 RR matters or not! We are trying to figure out if a shorter rod will work here or if a longer rod will work and what are the pros and cons of each. Can we keep it civil and present experience and data to support it so we can make our best judgements after we hear it from both sides? Much better than - this is the ONLY way to do it or you're wasting your time.

After some more research on other forum sites, I read in more than one place that a 451 built with the shorter 400 rod encountered fractures or cracks due to the connection angle to the 440 crank. Not that it would always happen, but I read about two forum members on another mopar site that this happened to. Maybe they didn't have the whole package built correctly to accommodate the shorter rod.

Anyone out there besides Supershafts that has built a 451 using a shorter rod with their experience to share? I'm already too far into my build and am sticking with the longer rod for now, but I was just curious...
 
Rod Ratios

WOW! I just read the posts added to this thread after the last time I checked 4 days ago - lots of info here and some very strong opinions!

This is the best mopar forum site out there and since I'm in the middle of a 451 build for my small block powered '68 Satellite and have never done it before, let alone ANY motor before, I welcome ALL comments and opinions, as I'm sure the original poster does. In doing so, please remember that if you have been doing this for awhile and have many motor builds behind you, there are just as many of us out there that have never built a motor at all and are learning as we go. We don't know if 1.7 vs 1.8 RR matters or not! We are trying to figure out if a shorter rod will work here or if a longer rod will work and what are the pros and cons of each. Can we keep it civil and present experience and data to support it so we can make our best judgements after we hear it from both sides? Much better than - this is the ONLY way to do it or you're wasting your time.

After some more research on other forum sites, I read in more than one place that a 451 built with the shorter 400 rod encountered fractures or cracks due to the connection angle to the 440 crank. Not that it would always happen, but I read about two forum members on another mopar site that this happened to. Maybe they didn't have the whole package built correctly to accommodate the shorter rod.

Anyone out there besides Supershafts that has built a 451 using a shorter rod with their experience to share? I'm already too far into my build and am sticking with the longer rod for now, but I was just curious...


Well Sport,

After following this thread with interest, I'm not sure anyone would want to stick their neck out and offer an opinion. Things kinda got nasty and for what reason I'm not sure.

Just remember that opinions are like a$$holes............Everyone has one.

That being said, I usually find it best to do your own research and come to your own conclusions.

Here is a good article for you about the subject from Stahl headers.
http://www.stahlheaders.com/Lit_Rod Length.htm
Hopefully reading this can shed some light on the suject for you.

Good Luck!
 
built a 451 around 2500...installed in 70 charger...ran 12.40's consistent...nice motor


I am seriously interested in details on how to build a 451 for ~$2,500....I have a '73 400 HP want to keep it stock looking, so will use stock intake and exhaust manifolds, likely do minimal port work to heads (clean up bowls, etc.) but want some more "oomph".....
Thanks!
 
After some more research on other forum sites, I read in more than one place that a 451 built with the shorter 400 rod encountered fractures or cracks due to the connection angle to the 440 crank. Not that it would always happen, but I read about two forum members on another mopar site that this happened to. Maybe they didn't have the whole package built correctly to accommodate the shorter rod.

Anyone out there besides Supershafts that has built a 451 using a shorter rod with their experience to share? I'm already too far into my build and am sticking with the longer rod for now, but I was just curious...



I have running right now, 4 different motors using RR from 1.4 to 1.65

I have had several B motors running with 1.7 to 1.5 ratios and none ever fractured or cracked a crank.
In fact the only crank i have ever had fail/break was a eagle crank using a 1.5 RR and that was because of eagles use of china garbage and nothing at all from RR, it broke thru the thrust main and it ran fine like that except for the limited to 65 lbs of oil pressure whether at idle or 7000 rpm and it didn't blow up even after repeated n20 use. It was after months of use listening to a very slight noise that was unlike any other normal noise that found the break in the crank and the thrust and perfectly straight thru allowing the motor to run without spreading any debri thruout the motor on technically 2 4 cyl halves.

Keep in mind, every motor that was/is stroked are also using 2 stgs, none make less than 450hp on muscle and all see up to 7000 and one sees beyond that, only the trucks motor built for increased low/mid power is not using n2o, and that can change though.
The key to the lower RR is increasing power earlier and then holding it longer, for the 400 build you want the 400 rod, going lower than 1.7 RR anything less and you better change the head to something that can breath with that or you'll be hurting your performance, which is the problem with building the small blocks with more than there original stroke, the heads, especially mag heads can not move what the bottom end can pull in.

If you do build a stroker and only cut the crank and do not have it heat treated or nitrided that may, could be the reason why a crack could occur.
If you have a crank welded and not retreated and then using it for performance you're playing with fire.

Besides my own personal stuff, no motor including the marine stuff which is by far more abusive than anything you'll ever do in car has ever cracked or fractured a crank due to a lower RR.
 
I have running right now, 4 different motors using RR from 1.4 to 1.65

I have had several B motors running with 1.7 to 1.5 ratios and none ever fractured or cracked a crank.
In fact the only crank i have ever had fail/break was a eagle crank using a 1.5 RR and that was because of eagles use of china garbage and nothing at all from RR, it broke thru the thrust main and it ran fine like that except for the limited to 65 lbs of oil pressure whether at idle or 7000 rpm and it didn't blow up even after repeated n20 use. It was after months of use listening to a very slight noise that was unlike any other normal noise that found the break in the crank and the thrust and perfectly straight thru allowing the motor to run without spreading any debri thruout the motor on technically 2 4 cyl halves.

Keep in mind, every motor that was/is stroked are also using 2 stgs, none make less than 450hp on muscle and all see up to 7000 and one sees beyond that, only the trucks motor built for increased low/mid power is not using n2o, and that can change though.
The key to the lower RR is increasing power earlier and then holding it longer, for the 400 build you want the 400 rod, going lower than 1.7 RR anything less and you better change the head to something that can breath with that or you'll be hurting your performance, which is the problem with building the small blocks with more than there original stroke, the heads, especially mag heads can not move what the bottom end can pull in.

If you do build a stroker and only cut the crank and do not have it heat treated or nitrided that may, could be the reason why a crack could occur.
If you have a crank welded and not retreated and then using it for performance you're playing with fire.

Besides my own personal stuff, no motor including the marine stuff which is by far more abusive than anything you'll ever do in car has ever cracked or fractured a crank due to a lower RR.

If you have a crank welded and not retreated and then using it for performance you're playing with fire.

You got that right! I'm a metallurgist by trade and my father was a welder for PG&E for 30 some years. After welding heat treated parts you need to heat treat post-weld or you'll get embrittlement in the softer heat affected zone next to the weld joint and it could be catastrophic failure. Sometimes you can reduce post-weld brittleness by preheating to slow the cooling rate, although you may also have to post-heat the weld to slow cooling further, but heat treat post-weld is your best bet. (Heat treat means heating the part to a known temperature and then performing controlled cooling via air, water quench, oil quench, etc., whatever the alloy heat treatment specification is as referenced from a standard or best practice for that alloy temper.)
 
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The other issue can be when the main journal and rod journal are cut and that section of heat treating has been machined away, cranks are only surface hardened to a point, that could also cause some issues with fracturing.
 
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