Krystal

True enough......but that Blueprint 427 from Summit is a "drop in" and go.....with a 3 year warranty attatched to it.

At $8,900 and change it's far from a "budget build" SBC....... but a crate motor BBC will cost you as much or more for sure and honestly.......that small block just fits better and is easy to argue as preferable in my opinion.

a little over a year ago I went with a very reasonably priced 383 with a very honest 455HP..........it took my car with a TCI Turbo 350 Super Street fighter auto trans down the quarter mile at a 12.8 sec pass.........better gears and traction it'd be easy to imagine a mid to low 12sec time slip. That 427 SBC with an extra 100 ft pounds of torque and 100 extra horsepower has to very easily put you into an 11 second pass with enough tire to contain the power.

Driving home on a twisty road and the car should be as good as possible for the chassis.......something no Big Block can ever claim unless made entirely out of aluminum. Chevy only built 2 of those in 1969.......I suppose you could attempt to acquire one........but WOW......talk about a budget breaker. Seems to me the LS swap is the move I'd make if more power was required anyway.......there is NO PLACE for the antiquated BBC in my world.

AT least no place other than that previously mention number matching museum quality restoration or survivor.

cv67

Only thing that keeps me from dropping a BB in mine is if I get the itch to put wider rubbber up front as i like to corner sometimes.
Im not impressed with the ls...they have thier place but look wrong to me in any older car no matter how well done they are.
Gen 1 power is a cakewalk to make these days besides you can only get so much to the ground the rest is just waving a dyno sheet around big deal.

Little Mouse

nothing looks like a bbc when you open the hood it's the wider heads and valve covers that look far better then sbc. To me best looking engine chevy built was the 67 427 with the higher manifold height trypower the tryangle thin looking air cleaner really good looking, second is the 65 327/375 that fuel injection unit looks great and the 327 in any form my favorite sbc, a close to second but third is the cross ram 302. Also having a 7 in your engine size is good luck, without it you are cursed. Lol

cv67

I hear ya...like the look, exh note all that too. Blocks are too much these days and weight conscious.Its never enough

leigh1322

I don't get the BB bashing, And believe me I loved my LT-1 I drove for 27 years.
But lets compare apples to apples please. Lets compare similarly built engines.
An AL head/intake/w.p SB is about 488 and a BB version is about 565. Only about an 80 lb difference.
That's not going to make it understeer like a pig, you need to do a little chassis tuning, as with any C3.
The AMA sheet says my car is 49% front/51% rear wt distribution. 3380 lbs all stock. No dieting. We'll soon see.
So with a BB you basically get a 100 extra cubes at the same build level, and 100-150 lbs more torque, with a battery sized weight penalty. I can live with that.
I am building my 1970 LS6 engine much like my 1970 LT-1. And it should be 560HP vs 410, and 580 tq vs 420. Both with era correct heads.
I'll like it, not because it is better than my LT-1, just because it's different.
One'll rev better, and one'll have more torque.
I'll have $9k into it, the same as the 427 blueprint engine, with more HP & TQ.
And my engine builder said I left 100+ HP on the table, for free, by going with the original 454 crank vs a 496, and 50 year old L88 snowflake alum heads vs new AFRs, since I was buying all the parts anyway as I started with nothing.
And that's exactly what they did in the blueprint engine didn't they?
So that would have been around 650ish. vs 540 for the Blueprint.
Why can't we just love all the C3s, SB or BB?
There's not much around that revs like a good SB. And 510 ft lb at almost idle has to be felt to be appreciated.

cv67

The ones that rave about a solid lifter Lt1 would chit driving a solid lifter 454 its just that much better only you dont need rpm/gearing to do it.
Just crack the throttle

leigh1322

Agreed. 1st & 2nd in a SB feels like .... well... 2nd & 3rd in a BB

So what does 1st in a BB feel like?
Depends on how much traction you have, 1st & 2nd may feel the same. 1st may be traction limited with a BB

Little Mouse

Your on the freeway with your sbc at 80mph and a bbc is beside you the race is now on. All you will see is taillights of the bbc and they will get harder for you to see the longer the race goes on. I like sbc I even go by little mouse but you can not compare the two and the situation today is worse today now with the really huge rats easy to build today. Your stuck with a punny 4.185 cylinder bore in a sbc and you still have to pay someone to bore it that far, you just use a 4.60 cylinder dart bbc and it comes that way. You get 300 to maybe 340 airflow for an aftermarget sbc 23 degree head you feel like you have done good, hell that's just a starting point for a bbc. You could come up with a 440 cfm all out racing head for a sbc but then the big block 550 to 600 cfm. all out head. Just a losing battle trying to compare the two engines. Your rich money not a problem you can buy a 1000 cu. BBC already built for you.

leigh1322

How about an "even" apples to apples comparison?
SB vs BB
427 vs 427
As similar as we can make it, head flow,CR, cam, carb, etc
HP vs Price, Torque, Weight etc
Interested?
Surely someone in this group has built at least one each of a similar enough combo that we could compare.
What parameters would you suggest for a comparison?
A max - street effort? or all-out?
CR?
Head Flow?
Cam Duration?
Carb size?

Little Mouse

the bbc will still have a big advantage in the heads that can be used and it's easy to lighten the rotating parts to take away advantage the sbc has. I like big bore short strokes engines. Me if I were going to build another bbc I would like to do a 4.60 bore 3.76 stroke. When I first read about the new LS engine it was disappointing to read they kept the old 4.45 sbc bore centers in a 100 percent remake of the engine. If they would have done a 4.50 bore center and it would have maybe been 1 inch longer, the extra weight either in iron block or aluminum would have been very small amount. Then you could at least have 4.250 cylinder bores.

Little Mouse

the bashing its like over in the chrysler camp. You either have a hemi or you don't and your looking for excuses to not have it. Lol

427Hotrod

Anyone who thinks a 540+ cube BBC won't rev quickly have never ridden in one. Trust me...mine revs quick as you want and it's never shifted under 7500 RPM...and crosses the line at 8000. And it's been doing it for 19 years so far.....and been very reliable.

JIM

Little Mouse

I reved my factory stuff 454 to 7600 all the time with 3/8 rod bolts and a two bolt block. You might want 4 bolt mains if you were going to do that for hours like old nascar engines did but you sure don't need them in most cases. To me a smart build on the not high cost is just go get 454 pickup truck engine bore it at least .060 throw in say a forged scat rotating kit some better aftermarket heads. To me that's a far better plan then spending 12 to 15 grand beefing up a sbc to be reliable then you have a bbc wanna be that cost ridiculous money. The truth of the matter if you happen to have decent experince porting some heads just port the pickup truck head and you can be right at what people spend more then couple grand trying to get airflow for a sbc then it would cost you almost nothing. I also doubt with some porting the head would not crack all to hell like the sbc did. When I messed with heads in the machine shop the guides always a mess to fix. Then the 2.02 160 valve heads would be cracked in between the valves. The same head 1.94 1.50 almost never cracked. The original sbc design started with maybe 170 intake and 150 valves . Then they kept pushing things till it got to 2.02 ,160 another example of trying to stuff 7 lbs in a 4 pound box. That's what large sbc are. I would bet money and win I could build a 454 pickup truck engine make 650 hp reliable as all get out with nothing more then things like cheap in cost solid flat tappet cam. would half the money in it of most large sbc builds.

cv67

x2
I dont care what some peak dyno # is on a stroker sbc it will never be the same as a big block.
Dyno and street are two different things. Have a pretty stout sbc but id do a BB in a hot second if I had the $ theresnothing like it.

Drive a 600hp sbc/bbc the difference is obvious.

leigh1322

I am really curious though if there would be any difference in power or torque, for two Equivalent cubic Inch motors, one SBC one BBC.
What do you think?
427 SBC vs 427 BBC
Wouldn't that be interesting?

C3 Stroker

Two equivalent cubic inch motors, say 427 SBC vs. 427 BBC, if equivalent in peak horsepower (ex. 600 hp), in similar cars would E.T. the same. Each would have to be optimized as far as gear ratio, though. The BBC would have its peak torque at a lower RPM, while the SBC would rev higher. Both would cross the finish line at about the same time. The BBC will feel quicker at first because of the neck-snapping low end torque, but would get caught at the end.

427Hotrod

There's a lot of variables in the comparison. That 600 HP small block would have some serious aftermarket parts while the BBC would be able to do it with iron oval ports. The peak HP might be similar but the torque band could look a lot different. No doubt the small block would run hard...and of course unless you equalized weights it could be a mismatched race. The better aftermarket parts in the small block might do better everywhere also if the combo was built right.

My old 427 big block was run hard for 20+ years in 3 different cars and I still have it. 2 bolt main, 3/8" rods, forged pistons, flat tappet cam, iron heads. Ran anywhere from 11.70's in mildest form to 9.90's with some tweaks and some N20. In the middle was a real nice combo with a small street roller cam that made 423 RWHP at only 5850 RPM...yet was only down 6 hp at 7000. Had an incredibly wide powerband and walked away from many a car that dyno'd higher. Today..it could be made a lot quicker with some different parts pretty easily.

The beauty of the big block is for the same $$$ you can make BIG cubes at any price point whether it's low buck or mega. Those added cubes are an advantage in a street toy and a heck of a lot of fun!

JIM

txfatboy1

I ended up having to replace the BB in my 71. The block was not original to the car and was not worth trying to fix/rebuild. The crank journals looked like someone had polished them with 50 grit sandpaper. I was able to build a very nice running 498 stroker with aluminum heads and a Lunati solid flat tappet cam for less than $5k. I don't have a clue how much power it makes. It pulls like a freight train, sounds bitchin, doesn't overheat, and starts and idles every time I turn the key. Unfortunately, now I have to build the TH400 because second gear is pretty much wiped out....

cv67

11;5:1 bbc and sbc
427
220 and 265 afr
240 hr sbc 260 bbc
single plane
tell me they are the same lol

leigh1322

Theoretically, if the two engines have the same Cu. In. and had heads that flowed the same, why would one make more power, or one make more torque?
But I do know of two variables you'd probably never be able to fix:

1. BBC cranks are heavier, maybe by 15-25 lbs?
2. BBC probably has a wider bore and shorter stroke, at that Cu. In., so it should un-shroud the valves more..

But I do strongly believe at that it would be much easier to build Hp to a certain level with a BBC, and use less exotic parts, and be less expensive overall, even at the exact same cubic inch.

Update: Can equivalent heads even be found?
A very quick search looks like some heavily ported SBC bowtie heads can flow almost as much as stock BBC oval ports. But the port volumes are still not comparable: 220 cc vs 270 cc. And one is a 50 year old design and ones state of the art off the flow bench. Can an "equivalent" pair of heads even be found? The original OP question was all about valve size. But is it? Isn't port flow and volume just as or even more important?