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Do big(ger) strokes exacerbate the stock block problems? #3094291
11/15/22 08:23 AM
11/15/22 08:23 AM
Joined: Dec 2021
Posts: 810
Loudoun County, VA
Brad_Haak Offline OP
super stock
Brad_Haak  Offline OP
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Loudoun County, VA
Wondering if stroker engines are more likely to break a stock RB block than stock-stroke builds. "Hypothetically"... is a 512 build making 700 HP and 650 torque limited to 6500 RPM more or less likely to break the same block than a 451 build making 700 HP and 600 torque limited to 7000 RPM?

Or, to put it a different way, what is the general consensus -- if such a thing exists -- on what increases the likelihood of a stock block experiencing main webbing damage?
- RPM?
- Torque?
- HP?
- Detonation?
- High(er) compression?
- Piston speed?
- Curses by gypsies?
- All, or some specific combination, of the above?

shruggy

Last edited by Brad_Haak; 11/15/22 08:38 AM.

2021 Challenger 6.4L Scat Pack 1320 (2022)
100% stock: 1.680, 11.894 at 113.75 (DA 175 ft)
wheels, tires, air filter: 1.714, 11.833 at 115.80 (DA 310 ft)

1973 Challenger 452 ci street/strip (2008)
pump gas, DOT radials: 1.454, 10.523 at 126.44 (DA 514 ft)
Re: Do big(ger) strokes exacerbate the stock block problems? [Re: Brad_Haak] #3094292
11/15/22 08:27 AM
11/15/22 08:27 AM
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Posts: 1,734
NW Indiana
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fbs63 Offline
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In my opinion yes. Longer strokes with the same length rods have more rod angle therefore more side load on the cylinders. A bad tune will kill ANY engine though.

Re: Do big(ger) strokes exacerbate the stock block problems? [Re: Brad_Haak] #3094293
11/15/22 08:41 AM
11/15/22 08:41 AM
Joined: May 2004
Posts: 12,124
Taxes & Virus's R-US, NY
Dragula Offline
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Taxes & Virus's R-US, NY
Just tore down our oldest 512RB. We have been racing one for 15 years, and we just pulled it apart, the hone was gone, and a valve lock/keeper was broken, and it was about to drop a valve....No other issues we could find. Everything else was really good....So no, I don't think so. Last pass on that engine at the end of the season was 10.76 at 125mph....

The motor was always well tuned, and rpm generally kept in the safe zone....But we ran a lot of timing, and a 1050 on her, so it saw a lot of fuel and was generally shifted between 6k-6.5k....Super consistent round to round, and just a beast. Quickest pass on it was 9.70 at 138.5mph...

Last edited by Dragula; 11/15/22 01:12 PM.

'70 Cuda,...605 Hemi Street Car (6.20 best pass, 1.33 60ft)
https://www.youtube.com/watch?v=WYw6RA-k5Bk (6.25 at 108.75mph from inside car)
https://www.youtube.com/watch?v=3zQEb9uxFng (6.25 at 108mph from outside car)
https://www.youtube.com/watch?v=JCvfzsC4NgM (9.9)

'66 Barracuda AWB Stretched nose Blown 440 Car in build stage

'71 Duster Drag Car 400 Low Deck 512 best 6.002 at 115.44mph
https://www.youtube.com/watch?v=Znuo3jMUXTk
Re: Do big(ger) strokes exacerbate the stock block problems? [Re: Dragula] #3094298
11/15/22 08:58 AM
11/15/22 08:58 AM
Joined: Dec 2021
Posts: 810
Loudoun County, VA
Brad_Haak Offline OP
super stock
Brad_Haak  Offline OP
super stock

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Posts: 810
Loudoun County, VA
One of the things that got me wondering about this is a guy I know who ran a 4.15" stroker RB combo that ran in the same mid-10s range as my car did at the time. He said he loved the engine, but started hurting main bearings after switching to the bigger engine combo. As far as I know, he didn't have anything but main studs w/ a stock block and a Milodon deep pan... no idea if he did other oiling mods. But him not having bearing issues until going to the bigger crank seemed odd. AFAIK, he could have been running wrong bearing clearances, but you'd *think* he'd have addressed that if it was an issue.


2021 Challenger 6.4L Scat Pack 1320 (2022)
100% stock: 1.680, 11.894 at 113.75 (DA 175 ft)
wheels, tires, air filter: 1.714, 11.833 at 115.80 (DA 310 ft)

1973 Challenger 452 ci street/strip (2008)
pump gas, DOT radials: 1.454, 10.523 at 126.44 (DA 514 ft)
Re: Do big(ger) strokes exacerbate the stock block problems? [Re: Brad_Haak] #3094307
11/15/22 09:33 AM
11/15/22 09:33 AM
Joined: Dec 2013
Posts: 4,157
Wichita
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GY3 Offline
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My 4.25 stroke RB has been together since 2016 and it sees hard street miles (over 7,000) and lots of passes at the dragstrip. I doubt many people out there hammer their stuff like I do on a regular basis. It sees the dragstrip almost every weekend in the Summer.

It makes 600 n/a and we have sprayed it with 100 shot all the way up to 250 shots of nitrous to it in the last couple of seasons. I've probably put a dozen 10 lbs. bottles through it.

I was concerned last Winter about what the bottom end would look like so I pulled it out and did a wellness check.

Honestly, the rod bearings looked good enough that I could have re-used them but put new ones in anyway. Mains looked good so they stayed. Stock mains and ARP studs. No oiling mods! It does have a balance job on it by a very good local shop.

It has a Molnar crank, 7.1" rods and Mahle pistons, so it makes for a pretty lightweight rotating assembly. This combined with the rev limiter at 6500 (and almost never bouncing off of it) and being conservative with timing is, IMO, what keeps it alive.






'63 Dodge 330
11.19 @ 121 mph
Pump gas, n/a, through the mufflers on street tires with 3.54's. 3,600 lbs.
10.01 @ 133mph with a 250 shot of nitrous an a splash of race gas. 1.36 60 ft. 3,700 lbs.

Re: Do big(ger) strokes exacerbate the stock block problems? [Re: Brad_Haak] #3094316
11/15/22 10:08 AM
11/15/22 10:08 AM
Joined: Nov 2015
Posts: 735
Missouri
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jwb123 Offline
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Missouri
Do some reading on rod stroke ratios and piston speeds. couple years ago I built a 540, it has a better rod stroke ratio and therefore less piston speed than the 500 inch engine it replaced. If you pay attention to rescpicating weight and rod stroke ratios, the engine will last and perform very well.

Re: Do big(ger) strokes exacerbate the stock block problems? [Re: Brad_Haak] #3094321
11/15/22 10:29 AM
11/15/22 10:29 AM
Joined: Jan 2003
Posts: 30,213
Oregon
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AndyF Offline
I Win
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Oregon
It would require some super computer time to figure out the answer to that question. My guess is that a really high quality 4.250 stroke rotating assembly will last longer than a low quality 3.75 stroke rotating assembly. I've seen this at the engine shop over the years where guys with super high dollar rotating assemblies just come in every few years for a ring change and everything looks perfect. But the blocks with the cheap Chinese rotating parts are usually beat to heck. Bearings beat up, main caps beat up, studs loose in the block, etc. The cheap stuff seems like it destroys itself over time while the Callies and better parts just spin like watches.

Not sure I can provide a technical explanation for that, but I've seen it many times.

Re: Do big(ger) strokes exacerbate the stock block problems? [Re: jwb123] #3094322
11/15/22 10:30 AM
11/15/22 10:30 AM
Joined: Dec 2021
Posts: 810
Loudoun County, VA
Brad_Haak Offline OP
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Loudoun County, VA
jwb123 - What are the bore / stroke / rod length for each combination? I'll take a s.w.a.g. the 500 was 4.380", 4.15" and 6.76"...


2021 Challenger 6.4L Scat Pack 1320 (2022)
100% stock: 1.680, 11.894 at 113.75 (DA 175 ft)
wheels, tires, air filter: 1.714, 11.833 at 115.80 (DA 310 ft)

1973 Challenger 452 ci street/strip (2008)
pump gas, DOT radials: 1.454, 10.523 at 126.44 (DA 514 ft)
Re: Do big(ger) strokes exacerbate the stock block problems? [Re: Brad_Haak] #3094333
11/15/22 11:21 AM
11/15/22 11:21 AM
Joined: Jun 2006
Posts: 5,121
CT
GTX MATT Offline
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CT
I think detonation kills them, and all of the things to turn them into “torque motors” increase detonation. Detonation starts long before its audible. I think the idea that RPM will break the block is a myth (like losing torque with bigger ports) and sends people in all of the wrong directions. Peak torque is peak VE and thats where detonation is most likely.

Also, people like flat timing curves and the engines pick up power at 36-40 degrees so people run them there even though they lose peak torque. How many dyno sheets have you seen where they run a timing sweep and 33-34 makes the most torque but 36-40 makes the most horsepower?

Its apples to oranges, but look inside the bottom end of a Mitsu 4G63, regarded by many as one of the greatest engines of all time and 1000 HP capable, and tell me if it looks familiar. But they do also have much less swinging mass as well.

I believe there was a member on here making north of 1000 HP with a turbo on a stock block with a knock sensor.

Last edited by GTX MATT; 11/15/22 11:38 AM.

Now I need to pin those needles, got to feel that heat
Hear my motor screamin while I'm tearin up the street
Re: Do big(ger) strokes exacerbate the stock block problems? [Re: GTX MATT] #3094345
11/15/22 11:43 AM
11/15/22 11:43 AM
Joined: May 2019
Posts: 539
Lake Villa Il
INTMD8 Offline
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GTX MATT- Good post. Also makes me cringe when I see timing full in 30+deg at very low rpm.

I always run less timing at peak torque (of course a bit more difficult with a distributor)


69 Charger. 438ci Gen2 hemi. Flex fuel. Holley HP efi. 595rwhp 475rwtq.
Re: Do big(ger) strokes exacerbate the stock block problems? [Re: GTX MATT] #3094348
11/15/22 11:52 AM
11/15/22 11:52 AM
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Posts: 4,157
Wichita
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GY3 Offline
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Originally Posted by GTX MATT


I believe there was a member on here making north of 1000 HP with a turbo on a stock block with a knock sensor.


It's hard to find people that push stock blocks or maybe it's just hard to find people that are willing to talk about it? There have been a few on here like MoparBilly.

There are, however, lots of people with little to no experience (more so on Facebook than here) that are more than willing to regurgitate a number they've heard on what one will hold. I've heard 600, 700, 750, etc. rolleyes


'63 Dodge 330
11.19 @ 121 mph
Pump gas, n/a, through the mufflers on street tires with 3.54's. 3,600 lbs.
10.01 @ 133mph with a 250 shot of nitrous an a splash of race gas. 1.36 60 ft. 3,700 lbs.

Re: Do big(ger) strokes exacerbate the stock block problems? [Re: jwb123] #3094361
11/15/22 12:24 PM
11/15/22 12:24 PM
Joined: Oct 2007
Posts: 4,070
New York
polyspheric Offline
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better rod stroke ratio and therefore less piston speed
Piston speed is a direct function of stroke length, rod ratio not a factor: Stroke X RPM / 6 gives speed in feet per minute

Piston acceleration includes rod ratio:
Where Z = acceleration in feet per second per second
N = RPM
S = stroke in inches
n = rod to stroke ratio
Z = N^2*S*(1+(1/2n))÷2189


Boffin Emeritus
Re: Do big(ger) strokes exacerbate the stock block problems? [Re: GY3] #3094434
11/15/22 04:27 PM
11/15/22 04:27 PM
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Posts: 660
Central TEXAS!!!!
sr4440 Offline
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Central TEXAS!!!!
Originally Posted by GY3
Originally Posted by GTX MATT


I believe there was a member on here making north of 1000 HP with a turbo on a stock block with a knock sensor.


It's hard to find people that push stock blocks or maybe it's just hard to find people that are willing to talk about it? There have been a few on here like MoparBilly.

There are, however, lots of people with little to no experience (more so on Facebook than here) that are more than willing to regurgitate a number they've heard on what one will hold. I've heard 600, 700, 750, etc. rolleyes


I run this same 400 based 512 block and stroke since 11

Joe

Attached PDF document
512.pdf (14 downloads)
Last edited by sr4440; 11/15/22 04:28 PM.

Without Data, you’re just another guy with an opinion.
Re: Do big(ger) strokes exacerbate the stock block problems? [Re: fbs63] #3094441
11/15/22 05:08 PM
11/15/22 05:08 PM
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Posts: 4,070
New York
polyspheric Offline
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I agree, not only does a small rod ratio push the piston against the wall (more strongly than a higher ratio), but also pushes the crank in the mains in the opposite direction.


Boffin Emeritus
Re: Do big(ger) strokes exacerbate the stock block problems? [Re: GY3] #3094449
11/15/22 06:13 PM
11/15/22 06:13 PM
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Milwaukee WI
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TRENDZ Offline
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Originally Posted by GY3
Originally Posted by GTX MATT


I believe there was a member on here making north of 1000 HP with a turbo on a stock block with a knock sensor.


It's hard to find people that push stock blocks or maybe it's just hard to find people that are willing to talk about it? There have been a few on here like MoparBilly.

There are, however, lots of people with little to no experience (more so on Facebook than here) that are more than willing to regurgitate a number they've heard on what one will hold. I've heard 600, 700, 750, etc. rolleyes



That would be me. People taking it farther than I have like that orange procharged challenger with a 383, or the totally home built avenger with a turbo.

I preached the importance of ignition timing and benefits of distributorless programmable ignition for years on this board to be ridiculed and doubted by the vast majority of users on this board.
Now 15 years later, it has become acceptable here to embrace technology that has been available for years.
It was explained to me years ago by Kenny D that it’s real easy to keep an engine alive if you time it to keep the crank rolling forward instead of pushing it down. This is an easy rule to follow with a turbocharged engine. There is no need to maximize timing to make power. All you need to do is turn up the boost.
The weak link in my situation (400block/ 3.90 stroke 7000-7200 rpm shift) was the cylinder bores. They were shaped like beer kegs after years of making more power than I was told was possible. Still made good reliable power, but it ate rings every season.


"use it 'till it breaks, replace as needed"
Re: Do big(ger) strokes exacerbate the stock block problems? [Re: TRENDZ] #3094456
11/15/22 06:33 PM
11/15/22 06:33 PM
Joined: Dec 2021
Posts: 810
Loudoun County, VA
Brad_Haak Offline OP
super stock
Brad_Haak  Offline OP
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Loudoun County, VA
Decided to check out the price of aftermarket blocks as a tangent to this topic: https://billmitchellproducts.com/product-category/engine-blocks/mopar-big-block-2/

OK, anybody else surprised that the Mopar / Callies cast iron blocks are $400 more than the BMP aluminum blocks? And that's for about 170 lbs more weight, too.

Last edited by Brad_Haak; 11/15/22 06:41 PM.

2021 Challenger 6.4L Scat Pack 1320 (2022)
100% stock: 1.680, 11.894 at 113.75 (DA 175 ft)
wheels, tires, air filter: 1.714, 11.833 at 115.80 (DA 310 ft)

1973 Challenger 452 ci street/strip (2008)
pump gas, DOT radials: 1.454, 10.523 at 126.44 (DA 514 ft)
Re: Do big(ger) strokes exacerbate the stock block problems? [Re: GY3] #3094467
11/15/22 07:00 PM
11/15/22 07:00 PM
Joined: Feb 2005
Posts: 19,653
PA.
pittsburghracer Offline
"Little"John
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PA.
Originally Posted by GY3
Originally Posted by GTX MATT


I believe there was a member on here making north of 1000 HP with a turbo on a stock block with a knock sensor.


It's hard to find people that push stock blocks or maybe it's just hard to find people that are willing to talk about it? There have been a few on here like MoparBilly.

There are, however, lots of people with little to no experience (more so on Facebook than here) that are more than willing to regurgitate a number they've heard on what one will hold. I've heard 600, 700, 750, etc. rolleyes





I ran 275 quarter mile 8.60@155mph passes with a stock block and 500 cubic inch 440source assembly but I was only 2500-2600 pounds. When I tore it down for rebuild I found a crack. That would be a lot of years for most on here. I feel my biggest mistake on that engine was using 440source steel caps.


1970 Duster
Edelbrock headed 408
5.984@112.52
422 Indy headed small block
5.982@112.56 mph
9.42@138.27

Livin and lovin life one day at a time




Re: Do big(ger) strokes exacerbate the stock block problems? [Re: pittsburghracer] #3094474
11/15/22 07:31 PM
11/15/22 07:31 PM
Joined: Dec 2021
Posts: 810
Loudoun County, VA
Brad_Haak Offline OP
super stock
Brad_Haak  Offline OP
super stock

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Posts: 810
Loudoun County, VA
Were thinking in retrospect that aluminum caps would have been a better choice?


2021 Challenger 6.4L Scat Pack 1320 (2022)
100% stock: 1.680, 11.894 at 113.75 (DA 175 ft)
wheels, tires, air filter: 1.714, 11.833 at 115.80 (DA 310 ft)

1973 Challenger 452 ci street/strip (2008)
pump gas, DOT radials: 1.454, 10.523 at 126.44 (DA 514 ft)
Re: Do big(ger) strokes exacerbate the stock block problems? [Re: Brad_Haak] #3094475
11/15/22 07:35 PM
11/15/22 07:35 PM
Joined: Feb 2005
Posts: 19,653
PA.
pittsburghracer Offline
"Little"John
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PA.
Originally Posted by Brad_Haak
Were thinking in retrospect that aluminum caps would have been a better choice?



That’s my thinking now too but I’ll never go down the stock block road again. Heck I have a keith black sitting here for 12 years doing nothing and sold a mega block and assembly last year

8CBDCF48-271D-4B9C-96EE-0A2EC58ADB68.jpegD17C39F8-036D-4F8D-9DF6-1296BD455C21.jpeg

1970 Duster
Edelbrock headed 408
5.984@112.52
422 Indy headed small block
5.982@112.56 mph
9.42@138.27

Livin and lovin life one day at a time




Re: Do big(ger) strokes exacerbate the stock block problems? [Re: pittsburghracer] #3094477
11/15/22 07:44 PM
11/15/22 07:44 PM
Joined: Jan 2003
Posts: 5,626
Hot Rod Ridge
FastmOp Offline
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Hot Rod Ridge
Tune-up, tune-up, tune-up twocents

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