400 to 451 stroker questions

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Brooks James

Brooks James

VET, CPT, Huey Medevac Pilot
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72 , 400 block, and rods
also have 413 rods, and forged crank
I have a 70 440 forged crank
What pistons and rods would be recommended for the pistons to be down the hole as little as possible ? ( Assuming just a clean up on the deck)
Hoping to dial it in 10 to one cr
With 452 heads
 
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if you want closest to zero deck run the numbers on that Mahle piston with the 4.375 bore and 1.35" CH...6.76 rod
 
Call Mike at B3 Racing. Then buy the rods and pistons from him for his time and advice.
 
A zero deck flattop piston should get you somewhere between 10 and 10.5 to 1, depending on specific parts.
I'll bet Icon has a nice forged flattop for that application.
I would use the RB rods, makes for a lighter piston. (Check the pin weight, if you order pistons, light pins are worth what they cost).
 
I'm putting myself in the same boat, wanting to build a low deck 426-ish I have a good untouched 64 383 I plan to stroke with rods and crank from a 72 440, and a pair of 452 heads.... initial plan was to just buy pistons to fit whatever over bore I need and to fit the 440 rods. As well as turn the crank down to fit the 383 mains.

By the time I pay to have all that done and balanced, should I just get a kit from 440 source and sell off the 440 rods and crank before doing anything to them.
Of course I'm still 5 years out on my timeliness
 
dodgedifferent2 said:
Machine that 440 mains down to 400 mains....

May as well call 440 source and get the 451 kit
Click to expand...
Yeah, I'm not crazy about cutting a factory forged crank. I just read that the main caps on the block can be bored and used with aftermarket caps to keep the 440 crank, yeah I know $$$
If I'm getting a kit it will be the 512 !!

BTW, what's the advantage of the larger mains on the 440, increased load bearing surface area and allow to block to hold more horsepower? I'm thinking that if I do it, I will have the advantage of the 440 crank, and the extreme beefiness of the 230 block


Estimates for the 72 , 400 , 230 block I have seen are 650, 750, 800, 900 hp
I'm planning 550 NA, up to 250 shot of n2o

I don't think anyone really knows
 
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PROSTOCKTOM said:
What parts you use and how much money you want to spend are all relevant to you intended use and your budget.
There is absolutely nothing wrong with turning down a stock crank, that was what everyone used to do before cheap offshore cranks became the rage. I have Mahle pistons in my 400" RB, but be aware they only have 1 mm, 1mm, 3mm ring width. Not what you want for a long street life or if you intend to shoot NOS on them. For street or nitrous use I would want a traditional 1/16", 1/16", 3/16" ring package.
Click to expand...
 
Great info on the rings !
Mahle cast/forged/hyper ?
Rpm you have spun the engine to ?
Any power adders ?
 
Brooks James said:
Great info on the rings !
Mahle cast/forged/hyper ?
Rpm you have spun the engine to ?
Any power adders ?
Click to expand...

Mahle pistons are very high quality Forged pistons.

I usually shift it around 6500 rpms, but it's still pulling over 7000 rpms.

No Power adders

Also I had to make a correction above. It's a 499" RB, not a 400 RB. LOL

Tom
 
PROSTOCKTOM said:
What parts you use and how much money you want to spend are all relevant to you intended use and your budget.
There is absolutely nothing wrong with turning down a stock crank, that was what everyone used to do before cheap offshore cranks became the rage. I have Mahle pistons in my 499" RB, but be aware they only have 1 mm, 1mm, 3mm ring width. Not what you want for a long street life or if you intend to shoot NOS on them. For street or nitrous use I would want a traditional 1/16", 1/16", 3/16" ring package.

Tom
Click to expand...


That ring info is dead wrong. There is ZERO reason to use a 1/16 ring pick anymore.

The rings are heavy. The thin rings will out power and out live a 1/16 ring and it’s not even close.

And skip moly rings. They are obsolete too. A steel ring with a proper coating is what you want.
 
Have any of the posters in this thread ever built and beat on a stock 440 crank equipped 400 based 451 stroker? It does not appear to be the case lol. There is no harm in turning down the 440 crank. That isnt where you are going to break anything. The cylinder wall is likely to be the weak link.

The Mahle pistons have 1.5/1.5/3.0mm rings. Use a GNS or hellfire top ring and life will be good.

1/16" = .0625"
1.5mm = .0591"

Are we really think .0035 is a game changer in the ring pack durability? No, it's not.

And lastly, Andy mentuoned he removed the 451 manifedto from his site because it was obsolete with the parts available in 2022.

My juice cam 451 dyno'd at 500/500 hp/tq with big valve 906's at 9:1cr. It made 572whp through the manifolds on a 175hp n20 shot. The standard plasma moly rigs look perfect after 50 bottles. It had to come apart due to a split cylinder wall that showed up when it was idling in the driveway.

All of the above are facts that I know first hand. Aka not internet expert speculation lol
 
Jeremiah said:
Have any of the posters in this thread ever built and beat on a stock 440 crank equipped 400 based 451 stroker? It does not appear to be the case lol. There is no harm in turning down the 440 crank. That isnt where you are going to break anything. The cylinder wall is likely to be the weak link.

The Mahle pistons have 1.5/1.5/3.0mm rings. Use a GNS or hellfire top ring and life will be good.

1/16" = .0625"
1.5mm = .0591"

Are we really think .0035 is a game changer in the ring pack durability? No, it's not.

And lastly, Andy mentuoned he removed the 451 manifedto from his site because it was obsolete with the parts available in 2022.

My juice cam 451 dyno'd at 500/500 hp/tq with big valve 906's at 9:1cr. It made 572whp through the manifolds on a 175hp n20 shot. The standard plasma moly rigs look perfect after 50 bottles. It had to come apart due to a split cylinder wall that showed up when it was idling in the driveway.

All of the above are facts that I know first hand. Aka not internet expert speculation lol
Click to expand...


Actually, yes going from a .0625 ring to an .0394 ring is a HUGE move. Friction drop by a big percentage. That’s just the fact of it.

And that Hellfire ring is nothing more than a ductile iron moly ring, both of which are horribly obsolete. It’s damn near 2023 so it’s by far past time to force the idiotic piston manufacturers to stop producing ANY piston with a 5/64 ring pack and to make one, maybe two part numbers with 1/16 ring packs for guys what want to stay in the Stone Age.


The thinner ring will make more power, less heat, last longer and seal better after 50k miles than a thick ring. This is 2022 common knowledge and FACT.

What’s funny is 20 years ago the same guys were crying about 1/16 rings being too thin to seal in a street car, that they had no benefit blah blah blah. Same **** we hear today.

The OP can spend his money any way he wants. To make a ring decision based on 1980’s technology is bad policy.
 
Rat Bastid said:
That ring info is dead wrong. There is ZERO reason to use a 1/16 ring pick anymore.

The rings are heavy. The thin rings will out power and out live a 1/16 ring and it’s not even close.

And skip moly rings. They are obsolete too. A steel ring with a proper coating is what you want.
Click to expand...
What ring coating do you run?
 
Jeremiah said:
Have any of the posters in this thread ever built and beat on a stock 440 crank equipped 400 based 451 stroker? It does not appear to be the case lol. There is no harm in turning down the 440 crank. That isnt where you are going to break anything. The cylinder wall is likely to be the weak link.

The Mahle pistons have 1.5/1.5/3.0mm rings. Use a GNS or hellfire top ring and life will be good.

1/16" = .0625"
1.5mm = .0591"

Are we really think .0035 is a game changer in the ring pack durability? No, it's not.

And lastly, Andy mentuoned he removed the 451 manifedto from his site because it was obsolete with the parts available in 2022.

My juice cam 451 dyno'd at 500/500 hp/tq with big valve 906's at 9:1cr. It made 572whp through the manifolds on a 175hp n20 shot. The standard plasma moly rigs look perfect after 50 bottles. It had to come apart due to a split cylinder wall that showed up when it was idling in the driveway.

All of the above are facts that I know first hand. Aka not internet expert speculation lol
Click to expand...
I completely agree the PARTS selection with the manifesto may be obsolete. What idiot couldn't figure that out as time goes by? Technology is always evolving. But the theory itself and the article are both still good information.
 
The thinner ring simply requires less radial tension to do it's job, so less friction.

Obviously, better , more durable,ring material makes this possible.
 
Bakerlite said:
The thinner ring simply requires less radial tension to do it's job, so less friction.

Obviously, better , more durable,ring material makes this possible.
Click to expand...


Radial tension isn’t much of a friction saver. As the piston is coming up the bore, gas pressure forces the ring into the bore. The thicker face has the same pressure behind it and it causes more drag.

A thinner ring will out seal a thicker ring every time.
 
Rat Bastid said:
Radial tension isn’t much of a friction saver. As the piston is coming up the bore, gas pressure forces the ring into the bore. The thicker face has the same pressure behind it and it causes more drag.
Click to expand...
The gas pressure is only a factor on the firing stroke.
Talk to any of the ring piston/ ring manufactures, and they'll tell you that the radial tension is of significant value.
 
Bakerlite said:
The gas pressure is only a factor on the firing stroke.
Talk to any of the ring piston/ ring manufactures, and they'll tell you that the radial tension is of significant value.
Click to expand...


Who’s arguing? Only YOU. I don’t call it “significant” unless you are comparing a 5/64 ring to a .8 mm ring.

Most ring drag is when the piston is coming up the bore on compression and until cylinder pressure decays below some point I can’t think of right now.

Run a thin ring. And a 1/16 ring isn’t thin.
 
Jeremiah said:
Have any of the posters in this thread ever built and beat on a stock 440 crank equipped 400 based 451 stroker? It does not appear to be the case lol. There is no harm in turning down the 440 crank. That isnt where you are going to break anything. The cylinder wall is likely to be the weak link.

The Mahle pistons have 1.5/1.5/3.0mm rings. Use a GNS or hellfire top ring and life will be good.

1/16" = .0625"
1.5mm = .0591"

Are we really think .0035 is a game changer in the ring pack durability? No, it's not.

And lastly, Andy mentuoned he removed the 451 manifedto from his site because it was obsolete with the parts available in 2022.

My juice cam 451 dyno'd at 500/500 hp/tq with big valve 906's at 9:1cr. It made 572whp through the manifolds on a 175hp n20 shot. The standard plasma moly rigs look perfect after 50 bottles. It had to come apart due to a split cylinder wall that showed up when it was idling in the driveway.

All of the above are facts that I know first hand. Aka not internet expert speculation lol
Click to expand...
:popcorn:
 
Not arguing, just pointing out the facts of why rings have been getting thinner.
For someone who's been carrying on here like a ring expert, you don't seem to understand the simple physics behind it.
If anyone is interested, they can read this.
Why Do Piston Rings Keep Getting Thinner?
 
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