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Discussion Starter · #1 ·
me and my dad got into a heated debat . he thinks the 396 is capable of more hp than a 400 . i obviously think the 400 sbc can match the 396 bbc hp and torque or better it.:boxing: what do you guys think.
 

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Several magazines years ago had this same battle. The Rat motor took the mouse motor to school on the dyno and the track. The BBC is capable of more airflow than the SBC due to it's canted valve heads and airflow is power.
 

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Power is in the heads and BBC's have an advantage in that department.

Also a stock 396 bbc block can handle more max power as compared to a stock 400 sbc block.

However, a BBC will get 25% less MPG as compared to a similarly built SBC.

Plus a BBC is a tougher fit and puts an extra 150 pound on the front end.

And a BBC is more expensive to build.
 

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I have a 1967 Camaro that I bought in 1997. I rebuilt a 1971 454 engine for it. The compression ratio was about 11:1 and I mixed 93 octane pump gas with turbo blue 50/50. Well I got the idea to replace it with a 383 mechanical roller motor to use all pump gas and set my big block up on an engine stand for storage. Man, was I disappointed. Don't get me wrong it had power but not the the torque the big block had. A couple years later I ordered an Eagle 4.00" stroke rotating assembly with pistons that gave me 9:1 compression and rebuilt the big block again and reinstalled it. I sold the 383 and will keep the big block in it.
 

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Add one more vote for the BBC.

When I was looking to repower my 66, replacing the buzzin' half dozen, I took a look at some HP/TQ graphs and decided to go with the rat.
The HP/TQ peaks just looked very sharp on the SBC, and so much broader on the BBC.
I reasoned that I could make a lot more dependable power at significantly lower RPM's, and lose very little power between shift points.

Well that, and simply going for a ride in my brother's 69 GMC with a 427 in it. It was just a weapon!

The sound of a big-breathing BBC trying to suck air past closed throttle plates on decelleration was a factor!
 

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Properly matched parts in a small block or big block makes no difference.If it runs good it sounds good.Close your eyes they sound the same.Powerful engines sound great,doesnt matter what block holds the parts together.
 

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454 c10
However, a BBC will get 25% less MPG as compared to a similarly built SBC.
show me the math please?I dont understand that part of your post
Over the years, I have put in 396, a 454, a 350, and a 400 in my truck (all in the same truck). And BBC's get 25% worst mileage, that is it. In fact, the 454 got slightly better mpg than the 396. (+0.5 mpg)

It is no secret that BBC heads are very inefficient. Plus the blocks have more energy losses (more bearings surface and more rotational mass) as compared to a SBC.

here is some data BSFC data that might help.
http://www.strokerengine.com/NGPCT.html
 

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If you compare SFC based on fuel burnt per horse power produced,you will find that there is very little difference between small and big blocks.You cannot directly compare a 350 hp 350 to a 350 hp 454.MPG is dependent on gearing and other factors.A 454 that makes the same horse power as a 350 will make more torque,there fore to compare MPG the 454 can use a taller gear because of the higher torque output so should be operated at a lower rpm for fuel economy.Both engine convert the same fuel to heat,,,, If you get down to the technical differences then the BB will lose some efficiency due to the heavier crank and reciprocating weight,slightly more friction because of bore,extra few horses required to move the extra 100 pounds.
again horse power is a part of the power formula,torque is also a part to consider.High performance engines require similar pounds of fuel to create similar power outputs.If you compared a 700 hp 350 to a 900 hp 454,the pounds of fuel burnt per horse power create would be very close.
 

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Well, I have ran BBC and SBC in the same truck with the same drive line and I promise you a BBC gets a lot worst MPG than a SBC.

Very inefficient heads and more internal losses makes the BBC a gas hog, plain and simple.
 

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396BBC vs 400 sbc

454 c10
However, a BBC will get 25% less MPG as compared to a similarly built SBC.
show me the math please?I dont understand that part of your post
The car is a toy not driven daily. I put the big block in the car as a perference over a small block. As long as I can run pump gas (93 octane) I will spend the difference. It is the cost of racing gas that I didn't want to spend.
 

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Well, I have ran BBC and SBC in the same truck with the same drive line and I promise you a BBC gets a lot worst MPG than a SBC.

Very inefficient heads and more internal losses makes the BBC a gas hog, plain and simple.
you answered your own problem..
same driveline..
to get good mpg out of a big block you have to gear to use the low end..
I had a mid 80's monte ls with 2.14 reargears and got 17 city and 29 highway.. with a vac 2nd carb.. efi , so I'm told would even do better.
 

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My truck has a 3.08 gear. I can drive it to work and not go over 2000 rpms. Yet it still gets 8 mpg. The sbc in the same situation gets around 11 or 12. Seems like enough gearing to me.

It's no mystery that a BBC is not an efficient engine. I'm just letting the original poster know that BBCs are thirsty. However, since it is not a daily driver it will not matter that much.
 

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ok the old man is right . but i still like the 400 sbc more especially with the new big stroker assembellys available today. thank you for your info.
You do know they make some killer BBC stroker kits now too? These days, life starts at 496 for the big block guys. And personally, I wouldn't trust many of the 400 blocks left around these days, they've been pretty picked over. And, many prefer the 2 bolt main version to the 4 bolt.
 

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Discussion Starter · #17 ·
well i have a virgin 509 blockn thats been maged and hot tanked got it for a 100 dollars. got a new eagle crankshft for 130.00 and scat procomp rods 6" for 195.00 . i dont have really have the cash for a big block. it is going to be a daily driver. so fuel milge and performance will be in consideration.
 

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build the heads,get them ported and flow tested.2.02 valves may not be required,,,when you have flow numbers you can piece the rest together. pre determine what you want for fuel economy first though???
 
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