at what ci does a block become "big"

88LX5.Oh · Feb 12, 2013

What Gearhead was saying is that displacement IS cubic inches. The displacement of an engine is measured in cubic inches (or also liters)

93project · Feb 12, 2013

gearheadboy said:
So a 396, 366, 350, etc are not big blocks I guess.

Well, to me anyway.. I've always thought of big blocks as 400 up, 429, 454, etc.. Aren't most 396, 366 stroked 351's? I'm not sure

MikeySmikey · Feb 12, 2013

Something I always urge people to consider before looking at displacement or big/small block is what they want out of their engine. Small blocks do some things better than big blocks and visa versa. It's all about goals and objectives.

For me, give me a Cleveland, let me update the oiling system and slap on a pair of quench Aussie heads and I'm a happy camper.

f8tlfiveo · Feb 13, 2013

gearheadboy said:
"They don't base a SBC or BBC off of CI, but they base it off of displacement." WHAT? REALLY? cid= Cubic inch displacement. Its the same thing.

Yeah I was thinking the same thing..

CarMichael Angelo · Feb 13, 2013

My .02?
It's an old adage. Used back in the day when there were displacement limitations because of block architecture.
Big blocks were just big assed chunks of cast iron that could displace whatever their external dimensional limitations allowed based on what internal bore/stroke combination was applied. I.e. a 352 became a 360, became a 390, became a 427, became a 428. (and if you were crafty back in the day, a 428 crank used w/ a 427 bore, became a 454.) Regardless of the displacement though, every one of the c.i.'s listed above all lived w/i the confines of the same block architecture.

Just think of it as a big box built extra large so as to accomodate multiple purpose design intentions.

It was really always a Chevrolet coined phrase anyway, when the 396 showed up in the middle 60's, they needed a new catchy way to differentiate the standard boring little turd from the new bigger one.

Modern strokers have dispelled any rule of it being a size thing based on displacement, as it is now possible to get up to 490+ inches in a SBC, and what? 460 out of a aftermarket Windsor SMALL block?

srtthis · Feb 13, 2013

93project said:
Well, to me anyway.. I've always thought of big blocks as 400 up, 429, 454, etc.. Aren't most 396, 366 stroked 351's? I'm not sure

so whats the 450" motor in the race car?

90lxwhite · Feb 13, 2013

hm I thought it'd be more cut and dry than this

srtthis · Feb 13, 2013

90lxwhite said:
hm I thought it'd be more cut and dry than this

nope... you can make "big block" inches in a small block pretty easy these days.

you can make a 461" small block ford with a 4.157 bore and a 4.25 stroke

ford made a 460" "big block" also

90lxwhite · Feb 13, 2013

MikeySmikey said:
Something I always urge people to consider before looking at displacement or big/small block is what they want out of their engine. Small blocks do some things better than big blocks and visa versa. It's all about goals and objectives.

could you give an example?

NIKwoaC · Feb 13, 2013

Semantics. /thread

85_SS_302_Coupe · Feb 13, 2013

Cubic inches have nothing to do with it. If anything the term "big block" more likely came from the family that an engine belongs to. Ford produced the 335 series FE big blocks that started at a mere 332ci big block. That engine family went on to be further bored and stroked to 352, 360, 361, 390, 406, 410, 427 and 428 before it was replaced by the 385 series FE engines which also came in 370, 429 and 460 versions, but I believe was also even manufactured in a 351ci version but wasn't used in a production vehicle (could be wrong though). These days the term is pretty much a marketing tool right along side "hemi", since we've seen small engines with big cubic inches and hemispherical combustion chambers more times than we could count since the two terms were coined.

NIKwoaC · Feb 13, 2013

SO ask yourself, is the DOHC 4.6, which is physically larger than a BBF, technically a big block? LOL!

85_SS_302_Coupe · Feb 13, 2013

NIKwoaC said:
SO ask yourself, is the DOHC 4.6, which is physically larger than a BBF, technically a big block? LOL!

That's exactly my point. It's just as big as many big blocks but is only 281 cubes. I'm not familiar with the physical size of some of these 6+ liter engines out these days but I would assume they're not much bigger than a mod motor.

NIKwoaC · Feb 14, 2013

srtthis · Feb 14, 2013

NIKwoaC said:

thats pretty cool! never knew the 9.5 deck windsor was that close to the FE motor height wise. but the FE is much wider.

NIKwoaC · Feb 14, 2013

srtthis said:
thats pretty cool! never knew the 9.5 deck windsor was that close to the FE motor height wise. but the FE is much wider.

I do not know exactly how accurate that is, and I have no idea if the mod is supposed to be 4.6, 5.4, SOHC or DOHC. Anyway, I saw it before on another site and thought it was interesting.

Noobz347 · Feb 14, 2013

Back in the day, folks said BIG BLOCK or SMALL BLOCK to differentiate the physical characteristics of the engine you were using. Not internal characteristics but EXTERNAL. So folks were on the same page as to what cross member, bell housing, exhaust, etc., that was needed to mate up to the engine block. It had nothing at all to do with internal displacement... and then there were mid-blocks.

Bullitt347 · Feb 14, 2013

gearheadboy said:
Once again, that has 0 to do with big block or small block. And if every small block had a 3.5" stroke and a 4" bore, they would all be 350's. Well, depending on the rod.

This must be cleared up............the length of the connecting rod has NOTHING to do with displacement, period. ONLY bore and stroke make up the differences in displacement. Rod length only effects relative piston speed and dwell time of the piston at TDC and BDC. I can make a long rod 302 by moving the piston pin closer to the top of the piston, and I can make a 302 with a short rod by moving the piston pin further down from the top of the piston. In both cases, the 4" bore and 3" stroke determine that it is indeed a 302 cid engine.

90lxcoupe · Feb 14, 2013

is are this thread really good at win

90lxwhite · Feb 14, 2013

rod lenth...

at what ci does a block become "big"

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