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school me on a 451 stroker

Here's an interesting 451 build: 440Jim

He used Hemi length rods which gives a RS ratio of 1.83 Looks like it was built back in 2001, I wonder how it turned out? He has a nice spreadsheet that can be downloaded from his Tech page. It calculates all that you care know about piston position and speed……he clearly put a bunch of time and effort into it.
 
I'm working on a 451 now and I picked the stock 440 R/S ratio because I thought Chrysler knew something when they decided the rod length and stroke way back in 1958. The 451 combo has a light piston on a 440 crank and that will relieve some stress off the crank, which is nothing to sneeze at. Lighter reciprocating assy should save on some HP too.

So let’s break this down by the numbers. A 440 rod is 6.76” C-C. A 400 rod is 6.36” C-C. That’s a difference of .400”. The stroke length difference is 3.38” vs. 3.75” for the 440. That’s .375” difference in stroke. To keep all things equal at the 1.80 R/S ratio you would shorten the 400 rod ~.300” - as it is the 400 has a 1.88 R/S ratio so shortening the rod will make it like a 440. Or you can lengthen the 440 rod on the 3.75” stroke and get 1.88:1 R/S ratio like the 400. Some have argued that changing the ratio is meaningless but others try to split hairs and will do anything to get their desired number. I understand NASCAR guys go upwards 2.0. You can uncover a whole can of worms when dealing with R/S ratios, which is why I’m just sticking with the MoPar plan, but in reality is a R/S ratio difference of .1 even worth the time it took me to type this? The 451 / 440 rod combo parts were off the shelf so it’s not like hundreds of dollars were spent on custom orders.

Something else to think about. The ratio is irrelevant when manufacturers are creating bigger engines under the direction of marketing. Let’s take the 400 SBC. It probably has the worst R/S ratio ever created but they built it anyway. Bottom line: It was a 400 CI engine when people were into “bigger is better”. It had to pass the warranty period. And GM was not going to make a special tall block SBC just to satisfy the marketers.

Another observation: If you look at all the American V8 engines around the big design change in the 50’s you will note that they all were originally designed for around 1.80:1. Ford, Chevy, MoPar, AMC, Buick, Olds, Pontiac, Cadillac, etc... So, following this logic, when the cubic inch wars started to heat up, the most economical way to increase displacement was to stroke it. And again, rather than casting a special block to keep up with marketing every time someone wanted to add some inches, piston, rod and crank changes are the more economical solution (Chevy 427 to 454). Yes new blocks were cast to accommodate larger bores (i.e. 413 to 440 MoPar; 427 and 428 Ford) or very long strokes (i.e. 425 to 455 Olds) but many just went the crank rods and piston route (i.e. Ford 289 to 302; 352 to 390 - even the 428 has the same deck height as the 352).



This isn't 1950, and ford, gm, pont, buick haven't had a ratio that big since 1950, no bb gm has ever seen the high side of 1.6 EVER.

The nascar motors are 1.85 to 1.9, and again if YOU are building a motor to hang out at 8000 to 10,000 rpm then use the 440 rod, this isn't a super speedway motor he's building, he is building a motor to work within idle speed and up 7500 of which the lower RR is key to making better power.

Using the 400 rod makes the RR 1.7 which is better on the street or strip since the ability to move more air by piston speed is helpful here.

Using the 440 rod you are keeping EVERYTHING about the 440 in a block that is simply losing 30 lbs. So again no one is building the 451 correctly when they use the 440 rod..

It seems that when this 1st started back in the late 70's early 80's it somehow got AFU when it became popular in the late 80's which everyone started doing it wrong and building a lighter 440, and all the gains were lost.

1 way of increasing power with a motor not able to see 10,000 rpms, you increase piston speed, how do you do that, stroke it and keep the same rod length or use a shorter rod and get into the 1.6 or 1.5 ratio, you increase piston speed and move more air and take advantage of better more aggressive cams on the street.

The piston speed in a F-1 motor is almost exactly the same as that of a nascar motor, a 355" nascar motor turns at 9000 rpm to make 850hp and a 140" F-1 motor turns at 19,000 rpm to make 800 hp.

Making the speed brings the power in, however when you make the RR lower you make it breath heavier, and you need a good intake and heads, and you need a high flowing dual plane if you're going to use that and you need to address the heads and use a good head or do some serious porting.

Most drag motors are in the 1.3 to 1.5 range now, that 1.8 and bigger RR is for nascar and F-1, F-1 is at 2.0 RR, if you are going to idle at 6000 and make power from 12 to 20k then use the large RR.
Nothing is harder or more severe use on a motor than that of the marine world and there is where endurance is measured, not in street cars being sold to public for 2000 rpm use, marine motors are also in the 1.4 and 1.5 RR.

You want performance you have to think performance not what ma mopar did in the factory to sell cars and they had 1.8 RR, even the fixed hemi doesn't have 1.83 RR anymore its at 1.74.


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I will again suggest that a R/S ratio of 1.8 is considered ideal from the standpoint of minimizing friction and forces on the piston and rod due to acceleration through TDC while providing good vacuum during the intake stroke. It's all a compromise, which I'm sure those old out dated engineers from the 50's knew all too well. I will even suggest that a 1.7 R/S ratio is good but 1.4 is asking for trouble and will have significant power losses due to friction, not to mention higher stresses at high RPM. Also, most cams are designed and tested for production based engines that have not had their R/S ratio altered, so if you really want to split hairs you will need to reinvent the wheel in terms of cam selection and port design. It was just easy to stick to a tried and proven 1.8 ratio but I don't think 1.7 would have been the death of it either. At least in the 400 package there will be less rotating mass and isn't that worth something by itself?
 
You do know you can have a cam made for whatever you want, it's like you're just looking for excuses not to.

I have been using RR in the 1.5 and no more than 1.6 for years, my tow vehicle is 1.5

The op or anyone else isn't going to be past the 8k area and therefore won't be having higher stresses.
 
Well here's how I see it. I'm gonna build what I wanna build. Whether it's a 440, 451 or my lowly 383 that I AM buildin. I don't think Mr. Driveshaft is an physics engineer as neither am I......or we wouldn't be runnin a drive shaft joint like he is or a transmission joint like I am. So, that means opinions from either side are just that. Opinions. My thirty plus years of turnin wrenches is all the experience I need to build an engine good enough for ME, and that's all that counts.....to ME. Even though I'm building a 383, I like the 451 idea, because it uses factory hard parts. No 700 buck plus crankshaft required. No 600 buck connecting rods needed. Affordable, off the shelf pistons. Is it "just" a small 440? Maybe so. If that's all it is, then it's one HELL of an A body motor, now ain't it? I think the evidence on paper supports more than that, although I have no data to back it up, since I've never built a 451. I think the 451 Manifesto is spot on and there are just some points that cannot be argued, such as the rod angle with a longer rod. No gettin around it, a longer rod gives less side loading. Period. Lower piston speed. Period. More dwell time at TDC. Period. Does all that add up to somethin special? Hell if I know......but I do know several local people with 451s and they all haul ***. That's good enough for me.
 
I don't know who's point this proves, but here is a 451 with 440 length rods (6.76 h-beam), forged pistons, a factory forged 440 crankshaft, ported Edelbrock RPM heads, single dominator on pump gas. The dyno had a hard time holding the engine below 3,500 rpm. It pulls 500 lb-ft of torque as low as 3,500 rpm and will carry that to over 7,500 rpm. And yes the dyno sheet says 786.9 HP at 7,200 rpm.

IMG_0001.jpg


So if'n we're all building these things wrong, what the heck will they do if built correctly?

500 lb-ft of torque from 451 cubic inches for a 4,000 rpm range? I think it might work on the street and the race track. Guess we'll never really know until I learn how to build them correctly.
 
What a pile of crap, Jim. lol

Ain't that the truth Rob!

Ain't that the truth..........someday I'll learn how to build a 451.............
 
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Ain't that the truth Rob!

Ain't that the truth..........some I'll learn how to build a 451.............

Yeah and in the meantime, how bout keepin your junk outta the magazines, ok? lol
 
You do know you can have a cam made for whatever you want, it's like you're just looking for excuses not to.

I have been using RR in the 1.5 and no more than 1.6 for years, my tow vehicle is 1.5

The op or anyone else isn't going to be past the 8k area and therefore won't be having higher stresses.



Of course you can. But do you know what grind will be optimal? I believe there has been lots of dyno testing done over the years optimizing cam profiles using factory architecture so why not reap those benefits? Not saying that a lower R/S ratio will not work, and possibly work better for some applications, but can you really tell me you will feel a difference between two engines that have a R/S ratio difference of .1 or .2?


I never implied that the bottom end will suddenly fall out of you go below 1.8:1 and if it's working for you that's great. I just think one of the benefits of having a MoPar is the 1.8:1 R/S ratio - otherwise I would just get a Chevy 454.


The stress difference between 1.4 and 1.8 may be so small it's not worth talking about, but without doing anything special the 1.8 will have less stress. Longer rod motors also have less internal friction and that's fine with me too
 
Well here's how I see it. I'm gonna build what I wanna build. Whether it's a 440, 451 or my lowly 383 that I AM buildin. I don't think Mr. Driveshaft is an physics engineer as neither am I......or we wouldn't be runnin a drive shaft joint like he is or a transmission joint like I am. So, that means opinions from either side are just that. Opinions. My thirty plus years of turnin wrenches is all the experience I need to build an engine good enough for ME, and that's all that counts.....to ME. Even though I'm building a 383, I like the 451 idea, because it uses factory hard parts. No 700 buck plus crankshaft required. No 600 buck connecting rods needed. Affordable, off the shelf pistons. Is it "just" a small 440? Maybe so. If that's all it is, then it's one HELL of an A body motor, now ain't it? I think the evidence on paper supports more than that, although I have no data to back it up, since I've never built a 451. I think the 451 Manifesto is spot on and there are just some points that cannot be argued, such as the rod angle with a longer rod. No gettin around it, a longer rod gives less side loading. Period. Lower piston speed. Period. More dwell time at TDC. Period. Does all that add up to somethin special? Hell if I know......but I do know several local people with 451s and they all haul ***. That's good enough for me.

Pretty much how I see it.
 
You do know you can have a cam made for whatever you want, it's like you're just looking for excuses not to.

I have been using RR in the 1.5 and no more than 1.6 for years, my tow vehicle is 1.5

The op or anyone else isn't going to be past the 8k area and therefore won't be having higher stresses.

How in the world do you presume to "know" what anybody here "has"? One of our slingshot dragsters, Ancient Orange has the rev limiter set at 7500 and it bumps it REAL QUICK. It's due for an engine upgrade, so it will probably see close to 8K when done. Ancient Orange. C&R Transmission, Milledgeville, Georgia. Can you read? Look it up. We're a member of The Southern Slingshot Dragster Association. If you knew half as much as you thought you knew and twice what you really know, you might know half as much as the rest of us.
 
I don't know who's point this proves, but here is a 451 with 440 length rods (6.76 h-beam), forged pistons, a factory forged 440 crankshaft, ported Edelbrock RPM heads, single dominator on pump gas. The dyno had a hard time holding the engine below 3,500 rpm. It pulls 500 lb-ft of torque as low as 3,500 rpm and will carry that to over 7,500 rpm. And yes the dyno sheet says 786.9 HP at 7,200 rpm.

IMG_0001.jpg


So if'n we're all building these things wrong, what the heck will they do if built correctly?

500 lb-ft of torque from 451 cubic inches for a 4,000 rpm range? I think it might work on the street and the race track. Guess we'll never really know until I learn how to build them correctly.
Very nice Jim! I'm sure rod ratio was at the top of your consideration list when building this one wasn't it? (extreme sarcasm in case you didn't notice!)
 
I don't know who's point this proves, but here is a 451 with 440 length rods (6.76 h-beam), forged pistons, a factory forged 440 crankshaft, ported Edelbrock RPM heads, single dominator on pump gas. The dyno had a hard time holding the engine below 3,500 rpm. It pulls 500 lb-ft of torque as low as 3,500 rpm and will carry that to over 7,500 rpm. And yes the dyno sheet says 786.9 HP at 7,200 rpm.

IMG_0001.jpg




So if'n we're all building these things wrong, what the heck will they do if built correctly?

500 lb-ft of torque from 451 cubic inches for a 4,000 rpm range? I think it might work on the street and the race track. Guess we'll never really know until I learn how to build them correctly.

You posted A dyno run of a 440 is all you posted.
I can see that as the same happened with the build of the 451 you are not understanding what you aren't doing and apparently no matter how i say it you can't seem to understand all you have is a 440.
You built a 440 in lighter block, it's a 440 the entire reasoning of doing JUST the 440 crank in the 400 block with the rest of the 400 internals are lost.

You all seem to be wanting to argue that a 440 isn't good unless it's in a 400 block or you can't build a 440 in a 440 block to do the same apparently, which is not what i am saying but you're implying, do the same motor and lose the long rod.

Of course you can. But do you know what grind will be optimal? I believe there has been lots of dyno testing done over the years optimizing cam profiles using factory architecture so why not reap those benefits? Not saying that a lower R/S ratio will not work, and possibly work better for some applications, but can you really tell me you will feel a difference between two engines that have a R/S ratio difference of .1 or .2?


I never implied that the bottom end will suddenly fall out of you go below 1.8:1 and if it's working for you that's great. I just think one of the benefits of having a MoPar is the 1.8:1 R/S ratio - otherwise I would just get a Chevy 454.


The stress difference between 1.4 and 1.8 may be so small it's not worth talking about, but without doing anything special the 1.8 will have less stress. Longer rod motors also have less internal friction and that's fine with me too

Finding the optimal cam is like anything else, attention to detail, which is what everyone is missing here, the attention to the detail of why you put a 440 crank in the 400 and use the 400 length rod is the detail you're missing.

You aren't going to have greater internal friction, been working for us and many more for more than 20 years


RustyRatRod said:
Well here's how I see it. I'm gonna build what I wanna build. Whether it's a 440, 451 or my lowly 383 that I AM buildin. I don't think Mr. Driveshaft is an physics engineer as neither am I......or we wouldn't be runnin a drive shaft joint like he is or a transmission joint like I am. So, that means opinions from either side are just that. Opinions. My thirty plus years of turnin wrenches is all the experience I need to build an engine good enough for ME, and that's all that counts.....to ME. Even though I'm building a 383, I like the 451 idea, because it uses factory hard parts. No 700 buck plus crankshaft required. No 600 buck connecting rods needed. Affordable, off the shelf pistons. Is it "just" a small 440? Maybe so. If that's all it is, then it's one HELL of an A body motor, now ain't it? I think the evidence on paper supports more than that, although I have no data to back it up, since I've never built a 451. I think the 451 Manifesto is spot on and there are just some points that cannot be argued, such as the rod angle with a longer rod. No gettin around it, a longer rod gives less side loading. Period. Lower piston speed. Period. More dwell time at TDC. Period. Does all that add up to somethin special? Hell if I know......but I do know several local people with 451s and they all haul ***. That's good enough for me.
Pretty much how I see it.

I didn't say you couldn't use the FACTORY 400 rod, in fact i have used many a factory 400 rod in builds

You can get a piston and use the factory rod if you want.
Lower piston speed and increased dwell are things from the past that used to be a area that everyone swore by had to remain, they said the same thing about playing in the plenum another big no no well guess what else has been proven wrong, you're stuck in the old ideas and past what works, move to the new times of increased performance try something new find out it's better.

Just because my shop is a driveline shop doesn't mean im not building motors and other things, some things start as one and the reputation you build with that name is more important than changing it for something else.



How in the world do you presume to "know" what anybody here "has"? One of our slingshot dragsters, Ancient Orange has the rev limiter set at 7500 and it bumps it REAL QUICK. It's due for an engine upgrade, so it will probably see close to 8K when done. Ancient Orange. C&R Transmission, Milledgeville, Georgia. Can you read? Look it up. We're a member of The Southern Slingshot Dragster Association. If you knew half as much as you thought you knew and twice what you really know, you might know half as much as the rest of us.

Here we go now we're gonna run with a sentence and carry on and make it all about something it's not.

Re-read the tread title again, it doesn't read looking to make 3500hp it says "school him on 451's" and that is what I am doing, something the rest of you are not, the rest are schooling him on building a 60 over 440 basically.

So as stated "The op or anyone else isn't going to be past the 8k area and therefore won't be having higher stresses."
For the record i exceed 8k and have a shorter RR than your rail, i haven't had any issues.

.
 
It's not a 440 and it will never be a 440, because of the piston you can use in the shorter block. Sure its the same rod, stroke, heads and yada, yada, yada, but it's not a 440 even if you bore the 440 out to 4.380" or 451 ci, you can't use the same 451 piston in the 440 without changing the rod length. Oops, and then you screw up the rod ratio even more! You can make them the same cubic inch size, but they'll never be the same engine.

AND yes, I agree, it is okay to use the shorter rod in the 451, which you can't use in the 440, because you would have a piston as long as a rifle barrel. But would the shorter rod make it a better 451? Would the average guy building a 451 EVER be able to tell the difference? Would he CARE?

I don't think you're anywhere near average Supershafts and that is why it makes a difference to you if someone, what was it, "hurts the need on the big end"? I'm personally glad you don't have any issues with the shorter rod ratio! That's hot rodding baby! Good for you, you're building it your way. But that doesn't mean I'm building it WRONG.

You're building it different from me, so that makes you, well, different, but, not wrong.
 
Supershaft seems to be stuck on the idea that a 440 crank and a 440 rod in a 400 block is the same. To reiterate what I said earlier and what IQ just said, it's not!! I will say it again. NOT THE SAME. Same means identical. Same rod. Yes. Same crank. Yes. Lighter piston. Uh-oh, not the same! Cut .125" off the radius of the crank counterweights. Uh-oh, not the same! The special short piston and 440 rod combo is lighter than the factory 440 piston on a 440 rod. NOT THE SAME!!!

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?

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......
 
I don't who ever came up with the rod ratio but it's ridiculous to even think it's a consideration in engine design. It's someone's byproduct calculation to somehow compare what can't be compared. It's an absolute waste of time even thinking about it. You've wasted precious moments in your life even calculating it.
 
I don't who ever came up with the rod ratio but it's ridiculous to even think it's a consideration in engine design. It's someone's byproduct calculation to somehow compare what can't be compared. It's an absolute waste of time even thinking about it. You've wasted precious moments in your life even calculating it.

I wouldn't say it's a waste of time, and there is something to it, but arguing over the difference between 1.7 and 1.8 sure is. My point was to just leave well enough alone by using the 440 rod on the 440 crank.
 
Exactly. The weight difference alone is reason enough to do the 451. I would also say that the idea of light reciprocating assemblies is certainly not "stuck in the past". New lighter pistons, rods and cranks are being developed all the time. In fact, I'd say that was a pretty cutting edge idea. But what the hell do I know?
 
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