SB vs BB who wins?

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Mean416

Mean416

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Ok so this is one I've been pondering for a bit. Just to preface, it's purely an academic exercise to see if I can learn something.

So, take a stroker SB of choice. Call it a 408. Could be 390, or 416. Now take a 383/400/or 413. No stroker big blocks, that's not in the spirit of the experiment.

Top these engines off with a decent set of heads. Nothing wild and exotic, but a good set of well prepped heads your typical dude might run. Appropriate and fairly equivalent supporting valvetrain, intake, exhaust, compression etc.

Which series engine would better, in terms of power and torque production, and why?
 
Since it’s hypothetical…I think the 400 with its 4.34 bore, shorter stroke and higher flow potential heads (for the mid level you mentioned) will have the top end advantage…albeit it weighs more.
 
So, you're wondering which would come out on top on a dyno; given similar strokes, bore sizes, valvetrain (I assume by that you include similar cam specs), similar "decent" aftermarket heads, and overall displacement in the same general range... They're going to perform pretty similarly.
Sounds like NASCAR.
 
Professor Fate said:
So, you're wondering which would come out on top on a dyno; given similar strokes, bore sizes, valvetrain (I assume by that you mean similar cam specs), similar "decent" aftermarket heads, and overall displacement in the same general range... They're going to perform pretty similarly.
Sounds like NASCAR.
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Yeah, Im with you. But there's enough of a difference in a real comparison using real off the shelf parts that there would be differences. I'm curious what those would be.
 
A 408 with trick flow 190s, vs a 400 with trick flow 270s, both cnc, both off the shelf and available, similar cam, carb and compression..... I'd take the big block.
 
Yeah figures. So it basically comes down to head flow capabilities and nothing else?

Which one makes more torque?
 
Mean416 said:
Yeah, Im with you. But there's enough of a difference in a real comparison using real off the shelf parts that there would be differences. I'm curious what those would be.
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When you drop them in a vehicle, there will be differences; since weight comes into play and the supporting hardware will out of necessity be different. But since you were talking purely in terms of "power and torque production', and barring anything exotic, I still say they'll be pretty similar.
 
400 every day of the week and twice on Sunday.
too much bore for the 408 to overcome.
 
In theory... big blocks have wider bore spacing so bigger bores and room for bigger valves and bigger ports. Bigger and heavier parts to move but air flow matters most in the end. SBM is a newer design than the BBM by about 6 years so the head architecture is a bit better but with similar parts my vote goes for the BB.
 
Mean416 said:
Ok so this is one I've been pondering for a bit. Just to preface, it's purely an academic exercise to see if I can learn something.

So, take a stroker SB of choice. Call it a 408. Could be 390, or 416. Now take a 383/400/or 413. No stroker big blocks, that's not in the spirit of the experiment.

Top these engines off with a decent set of heads. Nothing wild and exotic, but a good set of well prepped heads your typical dude might run. Appropriate and fairly equivalent supporting valvetrain, intake, exhaust, compression etc.

Which series engine would better, in terms of power and torque production, and why?
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So, stroke the small block all you want and limit the big block to stock stroke? Nope. I ain't playin this ridiculous one sided game.
 
With basic off the shelf non trick heads like trick flows sbm 190 vs bbm 240/270 the sbm gonna be in the 500s hp with pump gas and street strip cam and the bbm 600-700 hp.

And torque the a larger piston has more surface area for the combustion pressure to apply force to and be multiple by crank and since most the force is applied in the top half of the stroke the force is gonna have more time per stroke on the shorter stoke but will have less multiplying effect.

So at the very least they have similar torque capability but I'd give the bbm the slight advantage.

But the advantage is the bbm has large bore for large valves, larger structure for larger ports to be able to spin the similar torque to higher rpms for more hp, at 5252 rpm tq and hp is the same above hp is always more Eg.. 6565 rpm hp is a 125% of torque and 7878 rpm is 150% and 9191 rpm is 175%. etc.

The breathing available to the big block should smoke the small block.

Think of a 400 b engine as a mini pro stock engine with a 4.34-4.4 instead of a 4.7 bore but with similar stroke.
 
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RustyRatRod said:
So, stroke the small block all you want and limit the big block to stock stroke? Nope. I ain't playin this ridiculous one sided game.
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What got your panties in a wad? Sheesh.

One sided would be a 512 up against a 408. That would be the most retarded question ever.
 
The one with the better cylinder heads wins. JMO
 
85glht said:
The one with the better cylinder heads wins. JMO
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True, which one has more generally available high flowing heads with csa that can feed 400 ish cid especially in 6500-8500+ peak rpms range. Under 6000 it becomes more of a wash since your not asking a lot out of the heads, but bet generally most bbm won't nose over peak hp as hard as sbm stroker.
 
RustyRatRod said:
So, stroke the small block all you want and limit the big block to stock stroke? Nope. I ain't playin this ridiculous one sided game.
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But you don't have to spend the coin for all the stroker stuff. All comes down to heads, combination and the stronger block.
 
85glht said:
The one with the better cylinder heads wins. JMO
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I think it's a bit more nuanced than that.

Just spit balling a bit, what are some advantages the BB offers over the SB...

1. Bigger bores, bore spacing
2. Heads will generally have significantly larger valves that can also work with the bigger bores.

Are there other smaller yet still significant factors favoring the BB? What about lifter angles, pushrod pinches etc?

Are there items favoring the SB?
 
Mean416 said:
I think it's a bit more nuanced than that.

Just spit balling a bit, what are some advantages the BB offers over the SB...

1. Bigger bores, bore spacing
2. Heads will generally have significantly larger valves that can also work with the bigger bores.

Are there other smaller yet still significant factors favoring the BB? What about lifter angles, pushrod pinches etc?
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Doesn't the big block have a better valve angle too? 15 vs 18 degrees ?
Mean416 said:
Are there items favoring the SB?
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Guessing mainly size, weight inside and out, bearing size ?

Sbm does have a lot of decent heads that will make enough power to keep most people happy especially at the rpm ranges most want to build in Eg. under 6500 rpm, the differences are less, but the bbm should be able to make 100+ hp over the sbm if both are built with logical parts Eg sbm trick flow vs bbm trick flow but probably at higher rpm depending on efficiencies. But if building both with similar head capability for similar rpm and tq/cid than out come should be similar but then are just really handicapping the bbm.
 
Mean416 said:
I think it's a bit more nuanced than that.

Just spit balling a bit, what are some advantages the BB offers over the SB...

1. Bigger bores, bore spacing
2. Heads will generally have significantly larger valves that can also work with the bigger bores.

Are there other smaller yet still significant factors favoring the BB? What about lifter angles, pushrod pinches etc?

Are there items favoring the SB?
Click to expand...
I believe that the small block heads have the valves at the centerline of the cylinder bore vs. the big blocks... less valve shrouding...

Also money comes to play... the more you have to spend the faster you will go
 
B3422w5 said:
Me too. 500 inch motors in light bracket cars that run 10.60’s. Ultra common
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It’s actually pathetic to watch at times. Guys are shocked I have a small block and often say wholly crap so n so has a 512 cubic inch engine and runs 10.70’s. A few guys mentioned about the best head wins and they are totally wrong. The best “combination” usually wins. And notice I said usually.
 
273 said:
Doesn't the big block have a better valve angle too? 15 vs 18 degrees ?

Guessing mainly size, weight inside and out, bearing size ?

Sbm does have a lot of decent heads that will make enough power to keep most people happy especially at the rpm ranges most want to build in Eg. under 6500 rpm, the differences are less, but the bbm should be able to make 100+ hp over the sbm if both are built with logical parts Eg sbm trick flow vs bbm trick flow but probably at higher rpm depending on efficiencies. But if building both with similar head capability for similar rpm and tq/cid than out come should be similar but then are just really handicapping the bbm.
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+100 HP? That's a lot. If that's all coming from Headflow then the heads would really have to be a whole lot better. I mean, we're talking better than 50 cfm right?
 
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