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  #1  
Old Apr 16th, 08, 03:52 PM
fjas70 fjas70 is offline
 
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Default BBC OR SBC for my 70

got a bone stock 70 nova, inline 6 w/powerglide...just doing my homework...looking to get about an honest 400-450hp motor, for a street driven cruisin car possibly daily driver...should i go with a SBC or BBC, what's a good motor to work with??? i know BBC produces a lot more torque but i've been told a BBC will sag in the front end due to the weight??? is this true what mods would i need to make??? what about fuel injected motors??? i'm on kind of a budget, 22 year old going to college and working, can't afford a full blown race car but just want something with some good power to cruise around...BBC or SBC???
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  #2  
Old Apr 16th, 08, 03:56 PM
SHIFTY4
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Default Re: BBC OR SBC for my 70

my suggestion would to get some notebook paper and make two lists...

sbc on one, bbc on the other... compare first what cores would cost, then parts... machine work should be a wash. i think you'll find you can almost build TWO sbc's for what a "Good" bbc will run.

but then... we all "Want" what we want so let that also be your guide... do what makes ya happy, don't let cash (or the lack of it) hold ya back... BE HAPPY


Dr. Johnny
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  #3  
Old Apr 16th, 08, 04:04 PM
fjas70 fjas70 is offline
 
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Default Re: BBC OR SBC for my 70

could you get a 400hp SBC to perform like a 400hp BBC??? i think the small blocks rev higher??? but big blocks produce more torque or am i wrong??? i've heard a 383 stroker is a good motor...what do i need to build a 383 stroker??? will a 350 block work or will i have to bore too much???
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  #4  
Old Apr 16th, 08, 04:22 PM
SHIFTY4
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Default Re: BBC OR SBC for my 70

i think you should research the $$$ first and then decide what exactly fits your budget...

don't take this wrong now... i've seen a lot of 10,000.00/500.00 cars... a ton of cash sunk into a car that's not worth the investment, then if/when the car is sold the person loses their butt on the deal. look at the car and make sure it's worthy of the high costs of a high dollar running gear. you might decide to take the budget and cut it into different slices of pie so other areas of the car get some input also... then the whole car's value is greater than just a car with a high dollar whiz-bang engine.


i've owned a few 10k/500$ cars and i've bought a few too... i don't waste my cash on someone elses valve covers. i buy/build my own.

look at the total costs vs value and make that decision accordingly. the cost/value of an engine does not translate to value of the car... it takes quite a bit more. now i'm not looking at your car, i don't recall seeing it in pics so i may or may not be on or off target, just trying to get ya ta look at the BIG picture of what you'll have when completed...

sometimes a lesser priced investment "here" and more investment "there" will bring the value up of the total package

i think when all is said and done you could have a 375hp sbc and be so happy ya don't know what hit ya.

HP numbers really mean nothing in real life unless yer dedicated to the drag strip... a nice street machine with some punch that's drivable is way more fun than some super-duper high HP engine that's hard to tune, costs a mint to build and ya can't drive it a block without finding that next weakest link in the system. the whole car is a package, the engine, trans & differential, brakes and suspension... and that's not including body, paint & interior


i wish ya well on your quest, best of luck to ya


JR
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  #5  
Old Apr 16th, 08, 06:07 PM
Big Dave Big Dave is offline
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Cool Re: BBC OR SBC for my 70

Horse power is horse power. What most people do not understand is that the BBC is famous for generating gobs of torque (what is actually measured to calculate horsepower). The SBC does indeed rev up faster and that makes for high peak horsepower (more peak horsepower per cubic inch than the BBC can dream of achieving). But what you want is average horsepower which is also known as a flat torque curve. This is achieved by a long stroke (things like camshafts and pan rails get in the way of crank throws that are stock in all big block motors) and the corresponding cubic inches.

You can get 450 peak horse power out of a SBC 302, and it will happily run all day long pumping out that level of power. Problem is that power level only occurs above 8,000 RPM which is not within the gear range available within the standard automotive transmission. The gears ratios and the total number of available gears (typically only three forward) are designed to accelerate a 3,600 pound object from 1200 RPM to about 5,000 RPM. We can install steeper rear gears which allows us to side step the clutch at levels above 4000 RPM to get our car up and running but this will usually attract undue attention from the police.

Now consider the ZZ502 BBC it makes 450 horse power at 2,200 RPM and stays above that level up to 5,800 RPM were it "peaks" at about 540 horsepower. The engine will rev higher but all the numbers are on their way down. The difference is the area under the curve, or average power. If you look at your average 810 cubic inch big block, it will pump out over 1200 horsepower, and do it on pump gas. It has more than enough power to accelerate your average Nova away from any stop light, (might be a bit pricey though).

Bang for the buck can best be decided on cubic inches. If you consider the 7.0 liter displacement to be the tipping point were one family will make more power for less money than the other. 7.0 liters is 427 cubic inches (430 actually). A SBC that size will cost about the same as a BBC of that size. Anything smaller in cubic inches think SBC, anything bigger would be cheaper built as a BBC.

Big Dave
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  #6  
Old Apr 16th, 08, 06:39 PM
Veno Veno is offline
 
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Default Re: BBC OR SBC for my 70

funny thing here is you mentioned torque ..... a 396/402 and the 427/440 use the same crank stroke of 3.76...... while the 383/400 use a stroke of 3.75.... the bore on a 400 sbc is 4.125 while a 396 bore is 4.094 a bored .020 396 = 406 and a .030 over 400SBC is a 406....

so stump pulling 396 bbc tq can be had in a 400 SBC..... the difference is heads.. a good set of heads for the 400SBC is required.... while factory BBC oval port heads will produce the power level with minor mods IE; valves and porting...

you can make an easy 500+ hp with a 400SBC just like you can with the 396... the difference is space in the engine compartment and weight... the SBC will save you 200lbs on the nose of the car.... then again like dave said.... 540 ci is hard to ignore....
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  #7  
Old Apr 16th, 08, 06:40 PM
jays64II jays64II is offline
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Default Re: BBC OR SBC for my 70

i think a better question is why the 450 horse magic number and what are you intentions for the car and dare i say "budget" for the entire project ?

also remember the weight difference between a sbc and a bbc.

dollar for dollar , pound for pound build the largest bore longest stroke sbc you can afford to build using good parts.

450 horse on motor on pump gas is easy to do with either a sbc or a bbc but 9 times outta 10 you will spend more to build the bbc.

torque is what you want either way you go and for a good street motor you want peak horse and torque to be the same and the curve to be flat with an optimum rpm window of operational efficiency

all of this is meaningless talk though if you don't have the rest of the car's combination worked out for the optimum. By this I mean drive line multiplication through proper torque conv. and gearing along with the right trans and it's gearing.
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  #8  
Old Apr 16th, 08, 07:49 PM
WILMASBOYL78 WILMASBOYL78 is offline
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Post Re: BBC OR SBC for my 70

Quote:
Originally Posted by fjas70 View Post
got a bone stock 70 nova, inline 6 w/powerglide...just doing my homework...looking to get about an honest 400-450hp motor, for a street driven cruisin car possibly daily driver...should i go with a SBC or BBC, what's a good motor to work with??? i know BBC produces a lot more torque but i've been told a BBC will sag in the front end due to the weight??? is this true what mods would i need to make??? what about fuel injected motors??? i'm on kind of a budget, 22 year old going to college and working, can't afford a full blown race car but just want something with some good power to cruise around...BBC or SBC???
You mention "possible daily driver"...since you live in CA where the gas will soon go over $4.00/gal fuel economy might be worth considering. How nice is the car..??? solid body...?? nice paint and interior..??? believe it or not these should all be considered before dumping $$$ in driveline....post some pics for us to see for reference. If you are looking for any kind of performance you won't be happy with the Powerglide tranny...so there is some more $$$...providing the car is worthy of the investment....a mild small block and TH350 trans is a bolt in swap and will probably be the most economical setup....if you get some big torque monster under the hood you will need better suspension, brakes and rear....more $$$...getting the idea..?? you should be able to put together a nice package of SB 350, TH350 tranny, exhaust, odds and ends for under $5k...you might be able to locate this setup used and save some money...just be sure you buy it from someone who is reliable...might even get a few bucks for the old 6 cyl and glide

Good Luck, wilma
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  #9  
Old Apr 16th, 08, 08:39 PM
ovrdrive ovrdrive is offline
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Default Re: BBC OR SBC for my 70

Why don't you go ahead and build / swap a TPI motor and ovrdrive tranny into it and just cruize arround. I think Wilma hit the nail on the head with the price of gas going over $4 to possibly $5 dollars a gallon... We've all seen the BBC and pro-street cars selling on E-slay for high dollar. Why? Because they can't afford to chuck up the duckets for the gas tank.

Build yourself a nice 350-375hp motor, back it up with a 5-speed manual or 200/700 overdrive auto tranny and be happy... Just some food for thought..
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  #10  
Old Apr 17th, 08, 04:34 AM
fjas70 fjas70 is offline
 
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Default Re: BBC OR SBC for my 70

as of now there's not set budget on my car, it's more of a project that i can drive around and fix up on the way. I plan to keep the orig 6cyl but add th350 and drive it around, do a 4 wheel disc brake conversion, fix up my suspension, throw a nice posi, or limitied slip diff., then go with different engine and may consider a 200r4/700r4 or manual transmission swap later. do you guys think the LS1 motor swap is worth doing or can i get the same results with a tpi motor???
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  #11  
Old May 2nd, 08, 04:05 PM
SSavon69 SSavon69 is offline
 
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Default Re: BBC OR SBC for my 70

Lsx
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  #12  
Old May 22nd, 08, 05:55 PM
Jimmy71Nova Jimmy71Nova is offline
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Default Re: BBC OR SBC for my 70

Big Dave is 1000% correct in what he said.
If you do go with a BBC remember that parts for them are much more expensive than a SBC.
I am finding this out the hard way.
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