which would make more power. if they were set-up as close to one another as possible.

I mean I know that the big-block is a legend all in its own but how can you have a 396 big-block and a 400 amall-block?
What are the differences between the two?
Would the 396 make more power even though in theory its smaller?
what is the comparison of bore/stroke between the 396BB and the 400SB?

thanks for anyone who can clear this up.

 

The BBC would make more power. Even though the bore and stroke are almost the same, the BBC heads are much better. The smallest valves in a BBC are bigger than the large SBC valves. The ports are bigger so more air can get into the engine.

It's easier to get more power out of the 396 with better heads or port work than with the SBC.

The classification between a BBC and a SBC is bore spacing. The center to center of each cylinder is larger with a BBC. BBC = 4.84", SBC = 4.40" The extra distance allows for larger bores without having thin cylinder walls. A 400 SBC is almost out to the maximum bore. It can be safely bored .030 over. A 396 was bored .030 over from the factory and rebadged as a 400 but later called a 402 to avoid confusion). A 396 BBC can be bored out to a max of .125" over if there is no core shift.

 

Well im opting out of the poll part but, 396!
There really is no comparison between a 396/402 and a 400sb. 396's/402's are sick! (sick as in bad@ss) Your automaticly getting tourqe by adding cubes and 396/402's make power at ungodly rpm if setup right. SB 400's make tourqe but no where near the amout a 396/402 makes. 400's come with dishes pistons very similar to LG4's 396/402's have great designed domed pistons stock! You could use the stock bottem end of a 396/402 get the good stock BBC heads cam it put a descent intake/carb and be around 500hp. The one good thing a 400 has going for it is the dished pistons because with a blower, good heads and a cam can make some power but 1/2 of the cost of that will make more power with a 396. The difference between a 396 and a 402 is just .40 over the funny thing is a stock 350 pistons is roughly the same size as the 396's.
I'm sure 5.7 is going to give you some more on this subject.
SSC

 

did the exact test. They built 2 motors using the same cams from comp. They started with dart and merlin heads and had both ported.

The BB made like 40more hp (and 22ft/lbs more torque). They also took both motors and ran them in the same 70camaro with 4.10 gears. The bb went like .27sec and 3mph faster.


But, not only did the bigblock cost more (almost 1K) it weighed 140lbs more.

If the money the bb cost over the sb was used (to increase the rpm and airflow) it would have easily been able to make up the difference (possibly on something as easy as a looser converter for the small block)

Not even mentioning all the other parts that will need to be bigger/upgraded for the bigblock.

ps, i did not vote.

 

yeah i don't think that the cost would be worth it for the 396.

 

I think the cost for the BBC and SBC was only about $400 difference in the test I read about, don't recall which mag it was in. Also, I think there was more to be had in the BBC, wasn't there? IIRC, they did some carb jetting with the SBC in the car, but bolted the same carb on the BBC and only had time for one jet change.

 

Give me a complete 396 and $1500 and I bet ya I could make an engine that would spank the bejesus out of every N/A stroker or 400 owned on this board, yes its that easy.
SSC




Edited for spelling: Damn split keyboard.

 

Ya know, thinking about it, it's not a "real world" poll anyways, right?

I mean who would actually think "hey, I'm gonna install a new engine, should I go with a 400 SB or 400 BBC?"

No one.

If you're gonna go with a bigblock, why not 454 or 502? 454's are probably easier to come by than 396's anyways.

I can understand the mag article..they answered some old questions of "what make more power", but in the real world, if you had a BBC, no way you'd swap to a SBC, and if you had a SBC, no way you'd look intoi a 396 BBC for your install...unless ofcourse that's what you had layiong around, but instead you'd head to a wrecking yard and pull a 454 and get busy...right?

 

There's nothing really wrong with a 396 but nothing beats cubic inches and the 454 makes it easier to get more HP with more displacement. Keeping the same external dimensions a BBC can go to 540 CID.

I knew a guy with a 396 in a 69 camaro. Rectangular port heads, solid cam, tunnel ram and 2 4 barrels. It had a full cage since it was running in the 10's and he drove it on the street.
As I mentioned before, heads are the key. The more air you can get into the cylinders, the more power you can make. Good SBC heads are usually around 220cc and rarely get over a 2.100" intake valve. Typical BBC oval port heads are between 225cc to 262cc. Rectangular port heads are 290cc to 327cc. Those are the factory heads. Aftermarket can be even larger. While most BBC heads use the smaller 2.06/1.72 valves, most can have 2.19/1.88 installed. There's room in the open chamber heads for massive 2.30/1.88 valves.

With these combinations, but still limited to the 400 cid displacement, the 396 can easily make more power than the SBC.

I also read the magazine comparison. Although it only really showed how similar the 2 engines were, they didn't really get into potential of each.

One more thing to consider is if you had the choice of a 400 SBC or a 396/402 BBC, what are you doing and what did you have before? Ripping out a tired 350 that had headers, intake manifold etc and dropping in the 400 is easy and cheap. Many of the parts could be re-used. If you went with the 396 BBC, you would need to buy everything again and that would add to the cost. When I first built my 454 I budgeted for $5000 to drop the engine in. $8000 later I fired it up.

 

Since I have about $2200 in my "mild" 396, and am spanked by about 2 seconds in the quarter by a fellow '57 Nomad 383 racer, I think I'd take that bet.

When the 396 was sitting on the engine stand back in '97, I'd see those big ports staring at me every morning and dream. But, with more expensive parts and a 140 pound penalty, added to Stephen's points about actually getting one into an engine bay, I'd have to go with the 400, all else being equal.

 

Oh, the bore/stroke question:

396 BBC = 4.094" bore, 3.76" stroke for 395.97 cubic inches.

400 SBC = 4.125" bore, 3.75" stroke for 400.92 cubic inches.

0.030" over, the 396 is 401.80, and the 400 is 406.77.

Back to Stephen's heads: The 396 has notches for the 2.09 intake valve on closed chamber heads. Aftermarket heads are all open chamber (at least the good ones), and the larger valves would require even more notching. We always hear criticism of the 305 for the inherent valve shrouding, you think a big-valve 396 would be any better off? You'd also need massive piston domes (and stock are already domed) to maintain compression.

I'm sure I can close the gap between me and that Nomad with some pocket porting and gears, but I'd still have to vote for a 400.

 

well I like big power from a little source. plus you can tell everyone its a 305