496 vs 511 vs 525 - Chevelle Tech
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post #1 of 57 (permalink) Old Nov 8th, 18, 8:06 PM Thread Starter
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496 vs 511 vs 525

If you’re buying a rotating assembly, crank, rods, and pistons, why wouldn’t you build the largest displacement practical.

Considering the same compression, appropriately sized cam, wouldn’t the longer stroke make more average power?

496
4.25
6.535
1.12 C.H.
9.78 deck height
-3, 112cc, 9.07


511
4.375
6.535
1.06 C.H.
9.7825” deck
-3,112cc, 9.31


520
4.5
6.48
1.06 C.H.
9.79 deck height
-3cc, 112cc, 9.55

It seems like a 525 would be a nice torquey cruiser to pair up with a 3.08 gear and have a decently smooth idle and still run 11s on 87 octane.

I’ve read plenty both ways, thoughts on what you seen?

Canton 13-30 pan, pay attention to windage of course, extra drain holes in front and back of block, reduce oil draining down the oval openings while keeping open for air.

Heads will be AFR290. Cam choice open right now but not huge. 250-260 HFT or 243 HR. Airgap intake, max power by 5800.

Proving every day hindsight is 20/20.
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post #2 of 57 (permalink) Old Nov 8th, 18, 9:20 PM
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Gary
 
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Re: 496 vs 511 vs 525

i dont think i would go beyond 4 3/8 stroke with a stock block with the pan rail main oil galley. atleast check to make sure you have enough meat
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post #3 of 57 (permalink) Old Nov 8th, 18, 10:01 PM
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Jeff
 
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Re: 496 vs 511 vs 525

if stock block have it sonic-ed and go as large bore as it will allow. then I think a nice 4.375 stroke 511 would be all I would try, that or look for a used 502 block and go same stroke and a 4.500 bore that would make a nice 556.

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post #4 of 57 (permalink) Old Nov 9th, 18, 6:15 AM Thread Starter
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Originally Posted by Jebchevelle View Post
if stock block have it sonic-ed and go as large bore as it will allow. then I think a nice 4.375 stroke 511 would be all I would try, that or look for a used 502 block and go same stroke and a 4.500 bore that would make a nice 556.
The main reason for going extra long stroke is this engine, while raced for a year or two in a car with 3.42 gears(‘81 Malibu wagon), will likely end up in a cruiser/show car that has 2.56 gears (‘70 MC). If the engine could pull a 2.56 gear, with low stall, and chug 87 octane, that’s even better.

Eventually, I’d love to build a 532 with 3.70 gears to run 7500 with my wagon.

I chatted a little with my machinist about the 525/4.5” stroke, standard deck build and he said he’s built a few for pulling trucks and he generally uses a small block rod - not sure which small block rod but my best guess is a 6.400” rod.

Proving every day hindsight is 20/20.
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post #5 of 57 (permalink) Old Nov 9th, 18, 8:44 AM
 
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Re: 496 vs 511 vs 525

Quote:
Originally Posted by Dragginwagon467 View Post
If you’re buying a rotating assembly, crank, rods, and pistons, why wouldn’t you build the largest displacement practical.

Considering the same compression, appropriately sized cam, wouldn’t the longer stroke make more average power?

496
4.25
6.535
1.12 C.H.
9.78 deck height
-3, 112cc, 9.07


511
4.375
6.535
1.06 C.H.
9.7825” deck
-3,112cc, 9.31


520
4.5
6.48
1.06 C.H.
9.79 deck height
-3cc, 112cc, 9.55

It seems like a 525 would be a nice torquey cruiser to pair up with a 3.08 gear and have a decently smooth idle and still run 11s on 87 octane.

I’ve read plenty both ways, thoughts on what you seen?

Canton 13-30 pan, pay attention to windage of course, extra drain holes in front and back of block, reduce oil draining down the oval openings while keeping open for air.

Heads will be AFR290. Cam choice open right now but not huge. 250-260 HFT or 243 HR. Airgap intake, max power by 5800.
The more stroke, the shorter the life expectancy of the engine. Look at GM's to largest stroke production enngines, 400 and the 8.1 Vortec, both in production for only 10 years.

Budget. The more stroke you put in an engine the larger oil pan you will need and the larger header. A 496 at 6000 rpm needs a 2" Header. A 525 CID with 4.500 stroke need a 2.250" header at 6000 rpm.

Power gain. Most don't look at HP per cube. A good pump gas engine makes 1.3HP per cube. Going from 496 CID to 525 CID equates to about 37.7HP gain. Factor that gain with the cost of the "supporting" parts needed for the additional CID and see if the added power is worth the added cost.

Chris Straub
Mfg Performance Parts

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Why is it we never have time or money to do it the right way in the beginning but we always have time and money to do it over again?
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post #6 of 57 (permalink) Old Nov 9th, 18, 9:23 AM
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Rick
 
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Re: 496 vs 511 vs 525

Why not a 454 or even shorter stroke 427 - 440. Keep the torque down at lower RPM and raising the HP in the upper RPM. It costs a lot of $$$$ to support a big inch engine through out the rest of the vehicle.
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post #7 of 57 (permalink) Old Nov 9th, 18, 11:20 AM
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Re: 496 vs 511 vs 525

I would go 4.250 crank if you are not using an aftermarket block. You can take it to 511 size but thats a big bore but a lit of block can go there. 496 is a nice motor i think you will be more happy and less fuss.
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post #8 of 57 (permalink) Old Nov 9th, 18, 11:29 AM
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Re: 496 vs 511 vs 525

Long stroke cranks do not work well with stock type blocks and oil pans. Even in my 4.25 combos, a stock type oil pan lost oil control due to windage at 6500 rpm. A pan with a passenger side kickout and bigger front half was needed to stabilize the oil pressure.
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post #9 of 57 (permalink) Old Nov 9th, 18, 2:02 PM Thread Starter
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Originally Posted by cstraub View Post
The more stroke, the shorter the life expectancy of the engine. Look at GM's to largest stroke production enngines, 400 and the 8.1 Vortec, both in production for only 10 years.
Both great engines, the 400 in particular. I suppose from a mileage perspective there’s no denying you’re fighting additional friction compared to their shorter stroke brethren. My 406 lasted well to me.

Quote:
Budget. The more stroke you put in an engine the larger oil pan you will need and the larger header. A 496 at 6000 rpm needs a 2" Header. A 525 CID with 4.500 stroke need a 2.250" header at 6000 rpm.
Is a 2” header on a 525 really going to cost much average power on a street/strip car? The additional low end torque will be there all the time, even without a high stall converter. The car could sound more “stock” and still run very well.

Quote:
Power gain. Most don't look at HP per cube. A good pump gas engine makes 1.3HP per cube. Going from 496 CID to 525 CID equates to about 37.7HP gain. Factor that gain with the cost of the "supporting" parts needed for the additional CID and see if the added power is worth the added cost.
I certainly considered the additional costs per HP and torque, The only additional supporting parts I considered were than the pan and windage related items. Headers...1.625” worked good on my 406, maybe not ideal, but certainly didn’t feel like it was held back.

Great feedback, I’ll comment more later.

Proving every day hindsight is 20/20.
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post #10 of 57 (permalink) Old Nov 9th, 18, 2:17 PM Thread Starter
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Originally Posted by mrpaticular View Post
Why not a 454 or even shorter stroke 427 - 440. Keep the torque down at lower RPM and raising the HP in the upper RPM. It costs a lot of $$$$ to support a big inch engine through out the rest of the vehicle.
For the final destination of this engine, a ‘70 Monte Carlo, I don’t think it would be as enjoyable as feeling that big torque all the time.

I imagine my final engine for the wagon will be a 4.6 bore x 4.0 stroke in a Big M block. Assuming we still have gasoline at that point.

Proving every day hindsight is 20/20.
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post #11 of 57 (permalink) Old Nov 9th, 18, 2:19 PM Thread Starter
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Originally Posted by RickyHill View Post
I would go 4.250 crank if you are not using an aftermarket block. You can take it to 511 size but thats a big bore but a lit of block can go there. 496 is a nice motor i think you will be more happy and less fuss.
511 is only 4.310” bore x 4.375” stroke.

It is hard to argue with 496 but there really isn’t much hard cost difference to 511” or 525”.

Proving every day hindsight is 20/20.
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post #12 of 57 (permalink) Old Nov 9th, 18, 2:21 PM Thread Starter
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Originally Posted by bracketchev1221 View Post
Long stroke cranks do not work well with stock type blocks and oil pans. Even in my 4.25 combos, a stock type oil pan lost oil control due to windage at 6500 rpm. A pan with a passenger side kickout and bigger front half was needed to stabilize the oil pressure.
I plan on running Canton 13-330 pan and a couple more odds and ends. I have the Moroso 20408 pan now.

Proving every day hindsight is 20/20.
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post #13 of 57 (permalink) Old Nov 9th, 18, 2:34 PM
 
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Re: 496 vs 511 vs 525

Quote:
Originally Posted by Dragginwagon467 View Post
Both great engines, the 400 in particular. I suppose from a mileage perspective there’s no denying you’re fighting additional friction compared to their shorter stroke brethren. My 406 lasted well to me.



Is a 2” header on a 525 really going to cost much average power on a street/strip car? The additional low end torque will be there all the time, even without a high stall converter. The car could sound more “stock” and still run very well.



I certainly considered the additional costs per HP and torque, The only additional supporting parts I considered were than the pan and windage related items. Headers...1.625” worked good on my 406, maybe not ideal, but certainly didn’t feel like it was held back.

Great feedback, I’ll comment more later.
It will lower max HP by 400-500 rpm with a 2" on a 4.50 arm engine.

Chris Straub
Mfg Performance Parts

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post #14 of 57 (permalink) Old Nov 9th, 18, 5:26 PM Thread Starter
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Originally Posted by cstraub View Post
It will lower max HP by 400-500 rpm with a 2" on a 4.50 arm engine.
What size 4.5” stroke engine?

What is the critical rpm?

I’m of the understanding manifolds kill power too; the higher the rpm (flow), the worse the hindrance. It will be the same for 2” vs. 2.5” primary, right?

Of course you’re sacrificing scavenging (a bigger problem with naturally aspirated engines), which is affecting quality of your inlet charge. Assuming the problem is worse at higher flows.

Proving every day hindsight is 20/20.
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post #15 of 57 (permalink) Old Nov 9th, 18, 6:37 PM
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Re: 496 vs 511 vs 525

Mild 421 sb will get you 11's in that Monte.

Jim

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