Engine build

[sportsroof69 13]

But not disregarding the block, it's a full package, and no matter which one breaks, it results in catostrophic failure.

 

Aftermarket block = forged crank

 

Stock block = cast crank

[barnett468 418]

On one side-of-the-coin that seems reasonable. The more flexible the crankshaft, the more the forces applied to it are dampened by bending of the crank, and fewer are transmitted to the structure, in this case, this engine block. Actually, technically, maybe this is referring to an impulse. Not %100 certain without reopening an old text book but the idea is there.

 

On the other side, anything cast is more brittle than its forged counterpart. So disregarding the block, in theory, a cast crank will break before its forged counterpart.

you do not want a crank that flexes, or at least not one that flexes as much as many do . . in general, a crank that flexes less than another, will actually transfer LESS load to the block, it's simple physics, and you can get the same info from professional engine builders like scott main, owner of cam research whose engines have won world championships in NHRA and from joe sherman and even ATI crank dampers.

 

http://www.camresearchcorp.com/street-cred/

 

http://www.atiracing.com/products/dampers/101/

 

 

the whole purpose if a crank damper is to reduce crank twist which IS flex . . if as crank twists/winds up, it is flexing.

 

also, crank flexing reduces engine power.

.

Edited December 19, 2014 by barnett468

[sportsroof69 13]

Or you can get the same info I'm saying from professional builders such as Chris Uratchko, or Shafiroff. In a stock block, flexing is inevitable.

[sportsroof69 13]

And we can argue the theory behind it all day, and which builder says what, but......

 

i purposely put a Scat 9000 crank in my engine, and it's been 6.12@112 in the 1/8 @ 3380lbs, which most popular ET calculators put in the 800 hp range. It's been together for 4 years and has hundreds of hard nitrous passes on it. I don't consider it a risk, I consider the best way to build a stock block. The proof is in the pudding.....

[1969_Mach1 333]

you do not want a crank that flexes, or at least not one that flexes as much as many do . . in general, a crank that flexes less than another, will actually transfer LESS load to the block, it's simple physics, and you can get the same info from professional engine builders like scott main, owner of cam research whose engines have won world championships in NHRA and from joe sherman and even ATI crank dampers.

 

http://www.camresearchcorp.com/street-cred/

 

the whole purpose if a crank damper is to reduce crank twist which is flex . . if as crank twists/winds up, it is flexing.

 

also, crank flrexing reduces engibnbe powrr.

 

I certainly understand you don't want a crank that flexes, at least I don't. Just trying to make sense out of why a stock block will break with a forged crank and not with a cast crank under the same conditions. I tend to believe it happens. But there's some physical condition happening, impulse dampening through flexure, increased vibration transfer of the more dense forged crank.

 

I actually completely forgot and didn't have twist in mind when the idea of flexing was mentioned. But bending that can be from the forces applied to the rod journals by the connecting rods that not in the direction to rotate the crank.

 

It could be many things, I'm not certain.

Edited December 19, 2014 by 1969_Mach1

[sportsroof69 13]

A good cast crank won't twist.

[barnett468 418]

On one side-of-the-coin that seems reasonable. The more flexible the crankshaft, the more the forces applied to it are dampened by bending of the crank, and fewer are transmitted to the structure, in this case, this engine block. Actually, technically, maybe this is referring to an impulse. Not %100 certain without reopening an old text book but the idea is there.

 

On the other side, anything cast is more brittle than its forged counterpart. So disregarding the block, in theory, a cast crank will break before its forged counterpart.

you do not want a crank that flexes, or at least not one that flexes as much as many do . . in general, a crank that flexes less than another will actually transfer LESS load to the block, it's simple physics, and you can get the same info from professional engine builders like joe sherman and cam research whose engines have won world championships in nhra.

 

the whole purpose if a crank damper is to reduce crank twist which is flex . . if as crank twists/winds up, it is flexing.

 

also, crank flrexing reduces engibnbe powrr.

[sportsroof69 13]

....

 

 

i purposely put a Scat 9000 crank in my engine, and it's been 6.12@112 in the 1/8 @ 3380lbs, which most popular ET calculators put in the 800 hp range. It's been together for 4 years and has hundreds of hard nitrous passes on it. I don't consider it a risk, I consider the best way to build a stock block. The proof is in the pudding.....

 

 

And not from Internet engine builders.....for me anyways

[cobra3073 24]

I think we may be getting quite a bit away from the OP's original query. He indicated he is wanting to put together a driver or occasional show car.

 

For this type build, I would still strongly encourage him to go with a crate motor (with a warranty) unless he has ready access to a machine shop and engine building skills. I do not believe there are many places now a days where a local machine shop or garage can put together a "regular" motor cheaper than the "bulk" builders. For that type build, a cast crank will be fine in my opinion.

 

Don't get me wrong, I am essentially a racer and my last two motors have been put together by professional engine builders to my specifications. It comes down to the intended use.

 

...my $02:001_smile:.

 

BT

[barnett468 418]

I certainly understand you don't want a crank that flexes, at least I don't. Just trying to make sense out of why a stock block will break with a forged crank and not with a cast crank under the same conditions. I tend to believe it happens. But there's some physical condition happening, impulse dampening through flexure, increased vibration transfer of the more dense forged crank.

 

I actually completely forgot and didn't have twist in mind when the idea of flexing was mentioned. But bending that can be from the forces applied to the rod journals by the connecting rods that not in the direction to rotate the crank.

 

It could be many things, I'm not certain.

 

yes its a bit complicated, you don't want harmonics either and some materials and/or levels of rigidity can induce this, which again, is one of the things a harmonic balancer/damper is supposed to address to some degree.

 

i have a few long time friends that are professional racers and engine builders for drag racing and one of them ran the 44th all time quickest et in his class and he uses stock blocks with forged cranks all the time . . now, one could say that being the 44th fastest person in a class in the history of drag racing is no great feat...well, for those that think that, they should try it some time, lol.

 

#44. et 6.809, mph 197.00 Mike Hayden Mike Hayden Chev 57 Chevrolet PST CA 2002

 

http://www.draglist.com/lists/pstq32.txt

 

 

Now, a 351 cleveland has a 2.749 main and 2.311 rod journal with a 3.5” stroke

 

A 400m engine has a 3” main and 2.311 rod journal with a 4.0” stroke.

 

This means that Ford engineers increased the pin overlap on the crank for the bigger displacement engine . . the more pin overlap a crank has, the less flex it will have with the same given material which simply means it will be stronger.

 

The 400 also put out around 225 gross hp and the boss 351 for example was claimed to be 330 by ford . . irregardless of their actually power ratings, neither of them are anywhere near 500.

 

Now, along comes the stroker cranks [mostly made from Chinese steel which is inferior to us steel even though they claim the same tensile strength etc.]for the 351 Windsor for example, and many of those stroker cranks are using the 2.749 main but with the smaller 2.100 Chevy size rod journal and a 4.0 stroke for example . . This means that they are using a pin overlap that is .230” [almost 1/4”] LESS than ford used on their low hp 400 ci eng and the overlap is .270” [over 1/4”] less on the 4.100 stroke cranks that use these same journal sizes, therefore, it's obvious that the load on these stroker cranks is horrendously greater than it ever was on a stock Ford crank, and even though the Chinese cast cranks may be a better grade of metal than the original Ford cranks, if I was going to run a non forged crank on a big stroker engine with big horsepower, I am going to do it with a crank that i know has better material and quality control than a Chinese one, but again, since imo, the cost difference is so incredibly small for incredibly greater amount of benefit and security one gets for it, I prefer to run the forged ones instead.

 

 

Here’s some fun reading and you can also give them a call to get their opinion . . I already know what it is . . They actually measure the amount of twisting in a crank, and if a crank did not twist at all, there would be little need for a crank damper in which case one could theoretically remove it or at least remove the the inertia ring on a neutral balanced engine and run it like that which in general would increase the acceleration rate of the engine, however, i haven't seen anyone, including the auto mfgs, doing that . . I can just picture Dale Earnhardt Jr. now with a wrench in his hand trying to yank the ATI crank damper off his engine as he's saying to his crew chief, "I need more speed"...

 

http://www.atiracing.com/products/dampers/101/

 

As Chris Straub occasionally says, just because one has gotten away with doing something, it does not mean that they "should".

.

Edited December 20, 2014 by barnett468

[sportsroof69 13]

FUN FACT

 

 

 

 

Chris Straub (who did my camshaft) also agrees with the cast crank.

[sportsroof69 13]

And again, I don't have the dedication to type 5 paragraphs worth of stuff, but I can say.

 

 

i purposely put a Scat 9000 crank in my engine, and it's been 6.12@112 in the 1/8 @ 3380lbs, which most popular ET calculators put in the 800 hp range. It's been together for 4 years and has hundreds of hard nitrous passes on it. I don't consider it a risk, I consider the best way to build a stock block. The proof is in the pudding.....

 

 

 

And considering what the OP wants, based on my experience (and advice of many professional engine builders), a cast crank is best.

[barnett468 418]

.

For this type build, I would still strongly encourage him to go with a crate motor (with a warranty)

 

if i was going to buy a crate engine, i would buy it from ford racing even though they do not build most if any of them.

Edited December 20, 2014 by barnett468

[barnett468 418]

.

Below is just a partial list of factory production vehicles that came with forget cranks since 1955 . . The number of all the American vehicle mfg’s that came with forged cranks in their engines easily totals over 1 million . . I don’t think all the race engine builders in the world have built anything even remotely approaching that amount.

 

Since the engines were originally designed by actual card carrying engineers and were covered under warranty which the mfg’s didn’t want to use, and since they were expected to have an average service life of around 100,000 miles, it seems reasonable to think that they just might have known what they were doing…but I guess they could have been wrong.

 

Smokey Yunick has also built a few Pontiac, Chevy and Ford engines with stock blocks and forged cranks and his record speaks more clearly than most others I am aware of….but I guess he could be wrong too…

 

I even had an experimental GM intake with his name stamped on it that came with my 1966 427 ci, 450 hp, factory steel cranked L72 engined Dana Chevelle.

 

 

Here's just a few factory engines that came with a forged crank.

 

361 and 391 truck blocks

 

65 – 66 high perf 427

 

67 – 68 427 side oiler

 

68 boss 302 tunnel port

 

69 – 70 boss 302 trans ams

 

69 – 70 boss 302

 

69 – 70 boss 429

 

 

Pontiac 421 super duty

 

 

1986 Dodge Shelby GLHS Turbo

 

 

Several Mopars including 426 Hemis, 440 hp engines, all 440 and 340 6 pack engines, 426 Max Wedge engines etc..

 

 

Over 40 Chevy’s came with forged cranks including many small and big block Vettes, Chevelles, Novas, Impalas, Z28’s AND Trucks etc . . The very first engine I am aware GM using a forged crankshaft in was a 6 cylinder way back in 1929 . . It was also installed in at least some of the 265 V8 engines starting in 1955.

 

 

The preponderance of the evidence seems to lead to a logical conclusion...forged cranks will NOT cause blocks to break and were relied upon NOT to break under ALL conditions by the most knowledgeable people in the industry, which means that it IS the best choice for a build like this.

 

 

Oh, I almost forgot, the 1970 Trans Am series was won by a Boss 302 with a…forged steel crank in it. The Camaro that ran in it 1968 won 11 of the races with an engine that had a forged crank in it.

.

Edited December 21, 2014 by barnett468

[beecj0 11]

wow.

 

Be honest with yourself. How are you goin to use this thing? Forged cranks are cool, but unnecessary for most. Strokers are cool, but also unnecessary. You can build to much hp with stock stuff! Don't get caught up in the hype! The after market doesn't push multi carb setups cuz most cant tune them. You WILL make more peek (not average) hp with multi carbs if tuned properly. It is your money, spend it how you want. Nothing is a wast of money if its what you want to do. It may be easier if you asked how to make xx hp under 2000 rpm, or i want to spin 8k and blow the tire off at 60 mph for under $10k.

 

Some people have a hard time thinking outside the magazine box. The guy with the time slips and odometer to bake it up is who I would take advice from.

[beecj0 11]

YOU CAN'T DO THAT! Wrong!

YOU NEED THIS AND THAT! Wrong!

THOSE WILL NEVER WORK! Wrong!

GOOD LUCK WITH THAT! Thanks

[1969_Mach1 333]

barnett468, thanks for taking the time to write up the information. After reading through it, it's obvious by design that as pin overlap increases the crankshaft stiffness (or rigidity as we M.E.'s would say) increases. Which apparently Ford engineers consider when designing them.

 

I don't doubt there are instances where a 351W block broke with a forged crank. But for my curious mind, I wonder why. Simply because the crank was forged doesn't make sense. Other factors must come into play. Maybe an issue with not quite the correct balance.

 

It seems across the board, imported metals are inferior. They may have the same designation and chemical make up but the imported metals always seem either more brittle and fracture or yield (take a permanent deformation) at lower loads then the US counterpart. I worked for a food equipment mfg. for 10 years and occasionally they would purchase imported Stainless Steel. The welders and fabricators always had issues with cracking while forming, poor weld ability, and gauge thicknesses always at the minimum of the range for a particular size.

[1969_Mach1 333]

barnett468, thanks for taking the time to write up the information. After reading through it, it's obvious by design that as pin overlap increases the crankshaft stiffness (or rigidity as we M.E.'s would say) increases. Which apparently Ford engineers consider when designing them.

 

I don't doubt there are instances where a 351W block broke with a forged crank. But for my curious mind, I wonder why. Simply because the crank was forged doesn't make sense. Other factors must come into play. Maybe an issue with not quite the correct balancer.

 

It seems across the board, imported metals are inferior. They may have the same designation and chemical make up but the imported metals always seem either more brittle and fracture or yield (take a permanent deformation) at lower loads then the US counterpart. I worked for a food equipment mfg. for 10 years and occasionally they would purchase imported Stainless Steel. The welders and fabricators always had issues with cracking while forming, poor weld ability, and gauge thicknesses always at the minimum of the range for a particular size.

[barnett468 418]

barnett468, thanks for taking the time to write up the information. After reading through it, it's obvious by design that as pin overlap increases the crankshaft stiffness (or rigidity as we M.E.'s would say) increases. Which apparently Ford engineers consider when designing them.

 

I don't doubt there are instances where a 351W block broke with a forged crank. But for my curious mind, I wonder why. Simply because the crank was forged doesn't make sense. Other factors must come into play. Maybe an issue with not quite the correct balancer.

 

It seems across the board, imported metals are inferior. They may have the same designation and chemical make up but the imported metals always seem either more brittle and fracture or yield (take a permanent deformation) at lower loads then the US counterpart. I worked for a food equipment mfg. for 10 years and occasionally they would purchase imported Stainless Steel. The welders and fabricators always had issues with cracking while forming, poor weld ability, and gauge thicknesses always at the minimum of the range for a particular size.

 

No problem, you're very welcome, glad you at least found it interesting.

 

Yes, as I posted, well over one million production vehicles and race vehicles using production based blocks can’t be all wrong, lol.

 

As you say suggest, if a block broke with a quality forged crank in it, it was NIT because of the crank . . If forged cranks could break old production blocks then the engineers at GM, Ford and Chrysler all got it wrong and they were just all extremely lucky that their engines didn’t blow up left and right, otherwise they might have been looking for new jobs as food service workers or something else they might have been a bit more qualified for.

 

I would also not want tom be the person to suggest to them, or the likes of Smokey Yunick, that they should be running non forged cranks in their cars, especially Chinese made ones.

 

Also, I can't imagine why these engineers [and Smokey Yunick] would intentionally make an engine weaker and spend all that extra money to do it by installing forged cranks in them when they could have simply improved the metal in the existing crank if they wanted . . its certainly not like they had no idea how to do that...but again...i could be wrong.

 

.

Edited December 20, 2014 by barnett468

[sportsroof69 13]

YOU CAN'T DO THAT! Wrong!

YOU NEED THIS AND THAT! Wrong!

THOSE WILL NEVER WORK! Wrong!

GOOD LUCK WITH THAT! Thanks

 

Exactly right. A crank is forged, so it must be better for every application, right? Right guys??????

 

 

 

Nope, but the Internet builder will tell you otherwise.

Edited December 20, 2014 by sportsroof69

[sportsroof69 13]

Edit: double post.

[BuckeyeDemon 211]

The cast/forged crank discussion goes a lot farther than cost. Contrary to popular belief, a forged crank will not always live longer in all applications. These 351 blocks are pretty strong, but they do flex, and there's no way around it. As the block tries to flex around a forged crank, it tends to break around the main caps. A cast crank will flex with the block. Some people are going to call this crazy, and that's fine, everyone is entitled to an opinion, but there are many many examples of this, if you know where to look.

 

do you have any links to these other professional builders where this was discussed or examples that you are referring to?

[sportsroof69 13]

No, I sure don't. I didn't talk to them on the Internet.

[BuckeyeDemon 211]

No, I sure don't. I didn't talk to them on the Internet.

 

so where are these places to look then?

 

I'm not really one to just call up a popular internet builder (or any business) and just shoot the shit and waste their time about general topics.

 

i am a little confused though. you mentioned you want the crank to flex with the block and you also mentioned that cast cranks don't twist.

 

wouldn't flex/twist be correlated? meaning it's the twisting of the crank resulting in it flexing? i would think on the power stroke the force would be applied to the cylinder head and piston with the ultimate resistance being the flywheel (...driveline). therefore the head would pull on the block, the force on the piston applied to the rod, crank arm and then the main of the block. with more flex in the crank, the force applied to that local main of the block would be greater. with less flex in the crank, the force could then possibly be distributed to more of the mains and shared for less peak stress at any one point at one time.

[sportsroof69 13]

Well, as I said from the beginning.

 

 

 

The cast/forged crank discussion goes a lot farther than cost. Contrary to popular belief, a forged crank will not always live longer in all applications. These 351 blocks are pretty strong, but they do flex, and there's no way around it. As the block tries to flex around a forged crank, it tends to break around the main caps. A cast crank will flex with the block. Some people are going to call this crazy, and that's fine, everyone is entitled to an opinion, but there are many many examples of this, if you know where to look.

 

I purposely put a Scat 9000 cast crank in my engine, and it's been 6.12@112 in the 1/8 @ 3380lbs, which most popular ET calculators put in the 800 hp range. It's been together for 4 years and has hundreds of hard nitrous passes on it. I don't consider it a risk, I consider the best way to build a stock block. The proof is in the pudding.....

 

 

 

 

I don't care if it's forged, or cast, these parts flex and move. So maybe I should have been more specific for the literal types we have. Everything will flex and the amount of flexing (twisting) that you'll see in this application is acceptable. If anyone doesn't believe it, put a forged crank in and it'll be fine. I'll keep using my crank that apparently breaks at 500 horsepower, and it'll be fine as well. The best option is to use what your builder suggests.