RPM's and Torque Delivery: Big Block vs Small Block

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

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.

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.

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.

440 Source doesn't list any aluminum rods on their website.

My bad, could have sworn I'd seen those

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".

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
Gus

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

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

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.

You can get traction control. Just go FAST EFI

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

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.

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?

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

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

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.

Have you considered a 3rd Gen Hemi? They can easily make to power you are looking for.

I did actually, and I love those new motors, but I'm looking for a classic Mopar powerplant with this build. I'm planning to buy a new Challenger at some point, probably a Scat Pack or SRT 392, and I don't see any sense in having two of the same motor in different platforms.

I didn't realize FAST had it but Holley and Megasquirt do. I believe they run a few strategies, the most effective one uses two speed sensors, one on a front wheel on and one on the driveshaft or rear wheel. It can retard timing, reduce boost or nitrous, or kill cylinders to get back to the target slip percentage.

Here is a really cool video of a Megasquirt MS3Pro system working on an 8 second car...on the street. Watch the difference in wheel speeds on the top and the timing down on the bottom on the screen.

https://youtu.be/FembJNagxOE

big block torque is going to be harder to manage driving around town

Try that pedal under your right foot.

I've been eyeing the 426 Chargers, the Daytona R/T 426 has the sweet spot of options for me. I've got some financials to clear up, so next year I'm hoping to pull the trigger on one.

If you're referring to the modern Chargers, they don't have the 426 available as a factory option (yet). But there is a lot of information coming from Mopar insiders that suggest one is coming soon to replace the 392.

That's pretty cool, I'll definitely have to consider that.

Yes, getting ahead of myself I was thinking of the 6.4L

Lol, the 6.4 is a great motor but I'm really looking forward to the rumored 426 Hemi. I may hold off on buying a new Challenger until it's confirmed or debunked.

I installed an all-aluminum 426 Gen 3 Hemi in my E-body in 2015 and have been tracking it ever since. I'm a dealer for Prefix Performance who builds similar race engines for the TA2 series as well. In my opinion an all-aluminum Gen3 is a great compromise with small vs. big block and super reliable 500 rwhp. Save your pennies though as they are not cheap around $20k

My advice, as I have been there before with my `Cuda, is to make a solid plan and to not deviate from it. I also had intentions of putting all the latest tech in my car but that eats up any budget fast. I was going to replace the `Cuda's 340 with an all aluminum 572 Predator 800hp engine but all the custom fabrication made it that if stuff broke great expense and wait times will mean less seat time at the track where it matters and most importantly having fun, the most. In the end I was able to sell my Predator stuff at about 75% of what I paid and saved enough for the 426 Gen3 Hemi that had just been released at the time. I build for reliability & durability, to me they are more important than horsepower.

I was enlisted in the USMC as well and being in the military will allow to to save up a decent budget if you are smart about it. Have fun!

I appreciate your input, and thanks for your service

Oh man. i'd love an All Aluminum gen 3 Hemi!