Is a Modern Hemi a big block or a small block?

[Markp]

Don't we need a larger displacement engine to compare it against? Technically wouldn't the 392 be a big block since Dodge does not offer a larger modern motor?

 

[coolblue]

Nope.... the hemi is marketing only now (and the hemispherical heads were found to not be that efficient anyway - thanks to more modern modeling and computers)

Agree with this statement but there is a caveat. The hemi chamber is not efficient at low rpm. Wing that baby into the stratosphere and its plenty efficient. There's no quench area so low rpm torque isn't that great (esp. on the old carbureted hemis) That's why they added edges to the chamber and cut off the full hemi design on the street Boss 429 Ford. Todays Mopar hemis also have a vey shallow roof for quick burn instead of the full hemispherical shape that would make it look like 1/2 a softball (like the original's).

 

[coolblue]

@moparjim,
@coolblue Chevy had a 400 cid small block

That is true, but it was always referred to as a 400 small block and was a POS in stock form. It was a bastardized version of a 400 c.i. engine. They shortened the rods (from standard SB) and cut the heads on the rod bolts half off, to clear the cam. The rods were so short (the rod/stroke ratio was LESS than 1.5). It had Siamesed cylinders with bores so big for small block they used to run hot and they had to put steam hole reliefs in the block to the head. They also put a 396 size (3.76 in.) stroke crank in it, which would make over 400 ft lbs of torque at low rpm and would literally crack the main webs in the block when under full load in a heavy vehicle or towing situation, even at 8:1 compression. Again not sayin it couldn't be or wasn't done, but on a well engineered platform generally it needed a bigger block or much stronger and more exotic building materials.

 

[Jimmy N.]

Don't we need a larger displacement engine to compare it against? Technically wouldn't the 392 be a big block since Dodge does not offer a larger modern motor?

There's always the 6,423 cc engine.

 

[moparjim]

@moparjim,
@coolblue Chevy had a 400 cid small block

That is true, but it was always referred to as a 400 small block and was a POS in stock form. It was a bastardized version of a 400 c.i. engine. They shortened the rods (from standard SB) and cut the heads on the rod bolts half off, to clear the cam. The rods were so short (the rod/stroke ratio was LESS than 1.5). It had Siamesed cylinders with bores so big for small block they used to run hot and they had to put steam hole reliefs in the block to the head. They also put a 396 size (3.76 in.) stroke crank in it, which would make over 400 ft lbs of torque at low rpm and would literally crack the main webs in the block when under full load in a heavy vehicle or towing situation, even at 8:1 compression. Again not sayin it couldn't be or wasn't done, but on a well engineered platform generally it needed a bigger block or much stronger and more exotic building materials.

I didn't say it was one of the better choices. LOL

 

[Mike L.]

From what I have read by certain experts; the Hemi and the LS don't fit either one. Guess they are a hybrid of sorts. I remember the Olds rocket block, which was a tall deck small block Chevy could be punched out to almost 500 ci. It was for racing only.

 

[Hpindy]

Don't we need a larger displacement engine to compare it against? Technically wouldn't the 392 be a big block since Dodge does not offer a larger modern motor?

The original 392 was also a small block ....

Sent from my BBF100-2 using Tapatalk

 

[coolblue]

From what I have read by certain experts; the Hemi and the LS don't fit either one. Guess they are a hybrid of sorts. I remember the Olds rocket block, which was a tall deck small block Chevy could be punched out to almost 500 ci. It was for racing only.

Wow. Never heard of that.

 

[Demoniccat]

@Hpindy...there was no 383 RB that I am aware of, all were "B" blocks. If you ever tried to fit an intake from a "RB" to a "B" you will quickly understand the difference.

Exactly, the deck height on a 413, 426 wedge 426 hemi and 440 were all .750”. 3/4” higher that brought both intake and exhaust manifolds up higher. Although like Pontic “ouch” a lot of the internals could be mixed to get more displacement.
case and point. Hot swaps are 400” low deck with a 440 crank thrown in is the hot set up especially the ones with thick main web castings. I think some 73 or 74 years had em.

There is I believe one caveat that allows a low deck factory intake to go on a RB block, that would be the the 383, 413 cross ram, AKA long Ram manifolds because they were a 2 piece manifold with opposing runners feeding opposite cylinder banks see attached

imagine those long runners with our power chillers and a couple of laughing gas NO2 plates under each AFB carb

 

[SublimeIsLife]

Small block. The epa decided we can't have big,burly, manly, 100% testosterone big blocks anymore since the vortec 8100 stopped being produce.

I'd stuff a big ass gen 2 hemi or stroked out 440 magnum in my hellcat if it'd fit and there weren't any stupid emissions laws

 

[Mike L.]

Ford is the only company that makes a big block ( 7.3 ). Seems it will fit between the frame rails of the small block compartment. So, what is it?

 

[Magnified]

I grew up with a lot of old big block engines and I have to say I actually prefer the massive tuneability and cleaner running of the new engines. You can't wrench on them as much (or as thoroughly) without learning tuning or getting to know a good tuner, but the results, reliability, and efficiency are off the old charts.

 

[Jungle Cat]

I would say it’s a Smig Block!

 

[mopar madness]

wasn't the only true full hemi design the ones from the fifties, I believe even the 426 street hemi of the sixties and seventies was compromised to fit in the engine bays.