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RPM's and Torque Delivery: Big Block vs Small Block #2511045
06/20/18 09:05 PM
06/20/18 09:05 PM
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Spartan040 Offline OP
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We all know that the big blocks have a lot more power potential than the small blocks, but I've seen some small block stroker motors in the 408-426 CI range that really scream, edging around 500 HP and torque numbers around the same figure (I've even seen a few go as high as 600). Given that they're lighter and far less expensive than big blocks, I've had to at least reconsider the idea of using a small block stroker versus sticking with my plans to build a lightweight aluminum 440 stroker in my planned Challenger build. So, my question isn't about power levels so much as how do the two engine types deliver power to the ground differently, and how do they rev differently?

As I understand it (although I could be wrong, I'm still learning), the big blocks have a lot more low-end torque and you get a much larger kick in the pants than you would with a small block, whereas the small blocks have a more even torque delivery throughout the powerband which makes it easier to launch them without going sideways and boiling tires, and to have more consistent torque delivery throughout the RPM range, similar to the Gen 3 Hemis. Am I correct here? Or way off?

I'm also fairly sure that the small blocks rev higher and faster than the big blocks, topping out somewhere in the low 7k range versus the big blocks that top out around the mid to high 6k range. While revving faster could be an advantage, is it really a benefit to rev higher if your peak HP and torque numbers were a good ways below that?

I realize the SB vs BB debate has been going for a long while, but I just thought it might be fun to throw a little gasoline on the embers grin

Last edited by Spartan040; 06/20/18 09:10 PM.
Re: RPM's and Torque Delivery: Big Block vs Small Block [Re: Spartan040] #2511062
06/20/18 09:48 PM
06/20/18 09:48 PM
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With the light pistons in most stroker combos, they all rev faster than stock....In the old days the 451 BB stroker was called the BB that revved like a small block....With 5 bolts per cylinder and opposed to 4 the BB is always easier to keep head gaskets in.

Yes low end torque is largely a function of cubic inches...so BB's also win here too.

Last edited by HemiRick; 06/20/18 09:50 PM.

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Rick
68 Coronet R/T 440 & 68 Charger 528 Hemi,and 5 Challengers! 6 cyl, 318, 360, 383, 451
Re: RPM's and Torque Delivery: Big Block vs Small Block [Re: Spartan040] #2511066
06/20/18 09:55 PM
06/20/18 09:55 PM
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A 400 inch SB is going to have very similar numbers to a 400 inch big block given the same head development. The SB will have a smaller bore size and a longer stroke so the torque curve might be a little bit different than a big block, but I doubt you would notice it.

If you are aiming for something in the 400 inch range then a SB will fit the bill. If you want something in the 500 inch range then a BB will be the easy solution.

SB engines get expensive to build once you start buying the good parts for them. An 800 hp W/R type of SB is going to be more expensive than a 800 hp big block with stock block and Indy heads.

Re: RPM's and Torque Delivery: Big Block vs Small Block [Re: Spartan040] #2511074
06/20/18 10:13 PM
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The displacement size doesn't matter all that much to me, I'm just interested in what performs best and lasts the longest. I'm slightly concerned that big block torque is going to be harder to manage driving around town or doing something like an autocross course. But maybe I'm over-worrying, I'm planning on either adapting a Corvette C6 IRS with the kit from Dobbertin Performance (it's a really interesting concept), or get a custom built Art Morrison Multilink IRS (I'm leaning more towards the former for the sake of cost and OEM support, unless the Morrison is just far and away superior and worth the extra $), and IRS's generally help keep better control of torque delivery and aid in handling while improving ride quality. And yes, I know that rear gears also have a lot to do with torque delivery too. I'm planning on using either a Keisler A41 or a TCI 6X Overdrive automatic, so I'm thinking either 3:55 or 3:73 gears. No need for 4:11's. I also plan to use a square 295 or 305 tire setup.

And the big block stroker kit I was looking at from 440 Source makes use of forged aluminum pistons and rods, so I'm sure that would help it rev better, but I'm not too sure about the long-term longevity of the aluminum parts.

Re: RPM's and Torque Delivery: Big Block vs Small Block [Re: Spartan040] #2511120
06/20/18 11:25 PM
06/20/18 11:25 PM
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Originally Posted By Spartan040

And the big block stroker kit I was looking at from 440 Source makes use of forged aluminum pistons and rods, so I'm sure that would help it rev better, but I'm not too sure about the long-term longevity of the aluminum parts.
440 Source doesn't list any aluminum rods on their website.

Re: RPM's and Torque Delivery: Big Block vs Small Block [Re: Skeptic] #2511122
06/20/18 11:27 PM
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Originally Posted By Skeptic
Originally Posted By Spartan040

And the big block stroker kit I was looking at from 440 Source makes use of forged aluminum pistons and rods, so I'm sure that would help it rev better, but I'm not too sure about the long-term longevity of the aluminum parts.
440 Source doesn't list any aluminum rods on their website.


My bad, could have sworn I'd seen those

Re: RPM's and Torque Delivery: Big Block vs Small Block [Re: Spartan040] #2511146
06/21/18 12:20 AM
06/21/18 12:20 AM
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I REALLY like the torque my 605 makes. How's 764.3 ftlbs@ 3527rpm, (the start of the Dyno pull and it peaked at 818.4ftlbs@4818. I don't think a naturally aspirated sb will ever compete. As the old saying goes, "There's No Replacement For Displacement".

Re: RPM's and Torque Delivery: Big Block vs Small Block [Re: Spartan040] #2511150
06/21/18 12:28 AM
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With an autocross type of deal that you are going for just a stroked smallblock will do the job. Weight distribution is an issue so you would want something light over the front wheels to get near that 50-50 number twocents
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Re: RPM's and Torque Delivery: Big Block vs Small Block [Re: Spartan040] #2511178
06/21/18 02:02 AM
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If everything is set up perfectly for (just for example) a 600 hp 408” SB, then it’ll be as quick as a perfectly set up 600 hp 512” BB in the 1/4 mile. Deviate from the perfect set up, the BB will maintain more of its performance than the SB

Re: RPM's and Torque Delivery: Big Block vs Small Block [Re: WO23Coronet] #2511186
06/21/18 02:09 AM
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It’s kinda fun beating up on big blocks with our little blocks. I love them both but boy are the small blocks easier to work on in tight spots


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5.984@112.52
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5.982@112.56 mph
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Re: RPM's and Torque Delivery: Big Block vs Small Block [Re: Spartan040] #2511189
06/21/18 02:12 AM
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Just out of curiosity, I know there aren't any aluminum small blocks but how much would aluminum heads, water pump and housing, and manifold reduce the weight of a SB?

I'm still leaning more towards a BB because I know I can lighten that thing to around 475 pounds with enough aluminum, and as someone else said there's no replacement for displacement. I just thought I'd entertain the idea of a SB as well. Then again though, it would be easier to find space for the power accessories, Classic Auto Air system, and XV engine bay brace if I went with the small block, nevermind it being easier to work on in the engine bay....ah, decisions, decisions.

All that being said, I don't want to get too crazy with the power on either of them, there's no traction or stability control in these cars like there is in the modern Challenger.

Last edited by Spartan040; 06/21/18 02:20 AM.
Re: RPM's and Torque Delivery: Big Block vs Small Block [Re: Spartan040] #2511206
06/21/18 04:36 AM
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You can get traction control. Just go FAST EFI

Re: RPM's and Torque Delivery: Big Block vs Small Block [Re: FastmOp] #2511229
06/21/18 09:58 AM
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Originally Posted By FastmOp
You can get traction control. Just go FAST EFI


Really? They have that? How's it work?

Re: RPM's and Torque Delivery: Big Block vs Small Block [Re: Spartan040] #2511341
06/21/18 03:00 PM
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My biggest beefs with teh BB are the pain in the but to work on simple things like spark plugs, tighter header clearance, plus the extra weight and then add on the fact these stroker SBs make so much TQ now it is hard to hook them on the street much more that an 818lb TQ is fun it can be dangerous and hard to control on the street like most of the stuff I get to build now being so far from a track. A stock 5.9 magnum block is a cheap easy roller cam, can handle as much HP as a 440 block, better valve placement on a common head, better weight distribution, much better plug placement for burn and working on, the SB is a bolt in factory installed in many more aplications... I just see limited use for the BB in street cars like original BB cars or all out race cars where your running big indy heads big strokes and big money in the car to make it hook. I cant get the 410 SB in my dakota R/T to hook on the street for anything and am always trying to kill some TQ, I have even considered selling the motor and going back to a 360.


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Re: RPM's and Torque Delivery: Big Block vs Small Block [Re: Spartan040] #2511348
06/21/18 03:15 PM
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Who told you there are no aluminum small blocks? You can order one today and have it in a week if you have the money.
You got $7500 laying around? grin


"use it 'till it breaks, replace as needed"
Re: RPM's and Torque Delivery: Big Block vs Small Block [Re: TRENDZ] #2511455
06/21/18 07:15 PM
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Originally Posted By TRENDZ
Who told you there are no aluminum small blocks? You can order one today and have it in a week if you have the money.
You got $7500 laying around? grin


I just assumed there weren't because I couldn't find any online. $7500? The big aluminum blocks are surprisingly $2000 cheaper

Re: RPM's and Torque Delivery: Big Block vs Small Block [Re: HotRodDave] #2511456
06/21/18 07:18 PM
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Originally Posted By HotRodDave
My biggest beefs with teh BB are the pain in the but to work on simple things like spark plugs, tighter header clearance, plus the extra weight and then add on the fact these stroker SBs make so much TQ now it is hard to hook them on the street much more that an 818lb TQ is fun it can be dangerous and hard to control on the street like most of the stuff I get to build now being so far from a track. A stock 5.9 magnum block is a cheap easy roller cam, can handle as much HP as a 440 block, better valve placement on a common head, better weight distribution, much better plug placement for burn and working on, the SB is a bolt in factory installed in many more aplications... I just see limited use for the BB in street cars like original BB cars or all out race cars where your running big indy heads big strokes and big money in the car to make it hook. I cant get the 410 SB in my dakota R/T to hook on the street for anything and am always trying to kill some TQ, I have even considered selling the motor and going back to a 360.


Weight isn't a huge concern to me since I'm banking on using an aluminum block, but I didn't know about the other stuff. And I'm only planning to make around 500-600 torque in a 500 inch stroker, which is a fairly mild build for an engine of this size. Part of me just has an emotional connection to and desire for a super cool aluminum big block, but if it's truly too much of a disadvantage I'll reconsider

Re: RPM's and Torque Delivery: Big Block vs Small Block [Re: Spartan040] #2511497
06/21/18 09:53 PM
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Google “mopar performance A8” this will get you to the “available now” aluminum small block that mp sells for sprint cars. Many special parts are needed.
Or contact Ernie Elliot race engines for thier own aluminum casting to be used with P7 heads.
If you have money you can get a new aluminum small block.


"use it 'till it breaks, replace as needed"
Re: RPM's and Torque Delivery: Big Block vs Small Block [Re: TRENDZ] #2511515
06/21/18 10:32 PM
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Originally Posted By TRENDZ
Google “mopar performance A8” this will get you to the “available now” aluminum small block that mp sells for sprint cars. Many special parts are needed.
Or contact Ernie Elliot race engines for thier own aluminum casting to be used with P7 heads.
If you have money you can get a new aluminum small block.


I think I'll consider an aluminum block for the 440 only, it's just too expensive and more difficult for the small block.

Re: RPM's and Torque Delivery: Big Block vs Small Block [Re: Spartan040] #2511527
06/21/18 10:52 PM
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Have you considered a 3rd Gen Hemi? They can easily make to power you are looking for. twocents

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