Big - Small Block or Small - Big Block Question

[Perlmudder]

I was watching passtimes last night, and one of the cars had a 468ci small block. Ken Herring said sometimes those don't perform well. Why is that? Why would you be better going with a 454bb then a bored out sb?

[Griswald]

i don't know about not performing well, but there are limits with big stroke and long rods in a small bore space

[fund razor]

I would rather spend less and have a mildly stroked 540 inch bbc that idles like my truck than spend more and have a hopped up hand grenade small block build.

[clayinaustin]

There is no replacement for displacement!

[glassdave]

i wondered that myself. These days you can get some pretty hefty cubes out of some of the aftermarket small blocks and some pretty stout internals are available as well. Has anyone done a comparison between equal CI big and small block?

[Sean Stinson]

small block high revver low torque
big block low revver high torque
Offshore boat torque is good

[ROGUE]

Keep in mind, hes talking cubic inches here not horsepower. a 454 small block can theoretically have the same torque as a 454 big block. The question was on longevity and cost I think.

[Perlmudder]

Keep in mind, hes talking cubic inches here not horsepower. a 454 small block can theoretically have the same torque as a 454 big block. The question was on longevity and cost I think.

haha well im actually not really sure what my question is. im sort of just curious about peoples ideas on the topic in general!

[Griswald]

I had a 434" SBC in my old drag car. For a "small" motor, it made 700hp and 630ft lbs at 6300rpm. Not bad for out of the box 23deg headed motor. On the gas it made right at 1200hp to the wheels. There's big power to be made with these motors.

Consequently, the particular block I was running was able to support 472" with .0625 overbore and 4.25" stroke.

[CarBiz]

I had a 434" SBC in my old drag car. For a "small" motor, it made 700hp and 630ft lbs at 6300rpm. Not bad for out of the box 23deg headed motor. On the gas it made right at 1200hp to the wheels. There's big power to be made with these motors.

Word on the street is Cornett Racing Engines in KY. Is building 500+ inch SBC's. I do not know the power BUT if they can last up to 1200 laps before a freshen up at 8000-9000 RPM i would think that it would last 400-500 hrs in a boat at 5800-6000. Hell our old 421 SBF (all alum) made 826 HP and 784 FT lbs at 7800 and ran 1400 laps before freshend

[Tony]

small block high revver low torque
big block low revver high torque
Offshore boat torque is good

DING DING DING.


With the right parts you can make big HP, and big torque out of a small block. However, a big HP small block in a marine application that runs in its upper RPM range for hours on end will not last very long. Fuel requirements and availability on the water is another thing to consider.

I would love to be able to fit bit blocks in my boat, its possible but I would be trading 10lbs of chit in a 5lb bag for 50 lbs of chit. Its just not worth the nightmare.

[CarBiz]

small block high revver low torque
big block low revver high torque
Offshore boat torque is good

I do agree Sean BUT it seems i need more HP and less TQ in my boat to spin my surface drives more rpm

[HaxbySpeed]

There's nothing wrong with a healthy small block if you use the right parts. It is definitely easier to make power with a big block, but sometimes the weight savings and size is enough to make the small block a better option. This one sounds pretty badazz spinning along at 6500 all day...

[stormrider]

I got a quote for a pair 383ci of 470hp & 470ft/lbs sbcs, closed cooled.
Reasonable pricing and would work real nice in 30ft or under.

[sledge]

How much does it cost to make a 454ci small block? How much does it cost to make a 454ci big block?

Do you want a motor that makes power between 3000-6000rpm (which just happens to be where most drives like to turn) and will last for 1,000hrs? Or do you want to have to turn it to 6k+rpm? And how long do engines and drives last at over 6krpm?

Oh yeah, to answer your actual question, a small block head is just physically limited compared to a big block head as far as port volumes and valve sizes go. Go ahead and build a 500ci small block....you probably couldn't find a set of heads that would handle the volume.

One last thought: peak numbers mean squat. Show me at what RPM those numbers hit, and more importantly "area under the curve". 4,000HP is a sweet number.....but it takes 18,000RPM to get there.

[Dude! Sweet!]

Weismann is running "Small blocks" in the boat they ran at the Salt-on-Sea Kilo this year. LS7s I believe. Boat ran over a hundred.

[Excalibur Racing]

Chevrolet small block LSX can do 500 Cu.In. they have blown one over 2500 hp, check out the new performance book or google LSX. Iron block will out perform the C-5 aluminum and it isn't $8500.

[HaxbySpeed]

Oh yeah, to answer your actual question, a small block head is just physically limited compared to a big block head as far as port volumes and valve sizes go. Go ahead and build a 500ci small block....you probably couldn't find a set of heads that would handle the volume.

A bunch of the 15 degree stuff will no problem, or for conventional 23 degree the new Brodix T1 233 flows over 300 intake and 240 exh. out of the box..

I'd take a 454 small block over a 454 big block any day, but a more accurate comparison might be 454 small block vs a 598 big block... and the big cubes are gonna win every time.

[CarBiz]

A bunch of the 15 degree stuff will no problem, or for conventional 23 degree the new Brodix T1 233 flows over 300 intake and 240 exh. out of the box..

Ya now what is really screwed up is my brother has a set of Dart Iron Eagles on that at ported that f'in flow 290 on the intake i am not quite sure on the exhaust. That is what the 11X Brodix Heads flowed out of the box. That is a dayum good Steel head. Now hed had the 11x's ported and well it is all over What a GREAT set of heads IMHO

[Dude! Sweet!]

A bunch of the 15 degree stuff will no problem, or for conventional 23 degree the new Brodix T1 233 flows over 300 intake and 240 exh. out of the box..

I'd take a 454 small block over a 454 big block any day, but a more accurate comparison might be 454 small block vs a 598 big block... and the big cubes are gonna win every time.

Those Kiwi ProAction 12 degree heads are supposed to flow like crazy! And my old 18 degree TFS head had really solid flow numbers too, right out of the box.