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.
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