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If it was a stock 8.25 CR 454 short block, that increase sounds about right.
BTW I just ran some acceleration G calculations last night. SBC to BBC.
My old well built & factory stock solid lifter 350 LT1 / 390HP vs my new equally well built / period correct solid lifter 454 LS6 / 500 HP. (The TQ discrepency is even greater, more like 170ftlbs)
They both pulled 0.7Gs!!!
The 350 did it in first gear, and I have verified that with a g-meter years ago. Factory 411 CR Muncie car. Pulled hard.
But the 454 did it in SECOND gear!
(In first it was more like 1.0-1.2G ...uuhh .... traction dependent)
That's the difference in a SB to a BB. You have to compare apples to apples!
Put 50 year newer/better cylinder heads on both, and same results.
Cubic inches win!
The 350 stops pulling that hard up to the shift to second at 55 mph.
The 454 will pull that hard til the 2nd to 3rd shift at around 80mph.
Your choice!
I've been lucky enough to own a few BB's and lot's of SB's.
Love the 427-454 torque, but on a hot day in mid summer the heat soak into the cabin, really crappy fuel mileage, and hard starting when warm make me want to hop in a 350 with working A/C!
Just buy both!!
Its all relative. I still find it amusing that 427 and 'torque' are used in the same sentence. Horsepower? Absolutely? But torque? Having run nothing but Buick 455's and Mopar 440's, with the occasional Cadillac 500 thrown in, even Chevy 454's dont get to talk about torque. Torque over a Chevy 350? Again, absolutely. Further, stock for stock, there is a vast chasm... but there are a lot ov guys here that have built 383's, 400 smallblocks, maybe even 350's that could match or exceed that 427's torque curve and peak. Technology conquers all. A modern set ov heads and a roller cam and a 383/400 is gonna forget all about that 427 in a hurry...
Personally... if i had to stay Chevy old school in a Vette (i dont plan to), i'd build a VERY modern, all the tricks 350, or maybe a 377, a stock stoke 400 if i had to. I love the look ov a BBC, especially for that 'pop the hood' reaction, but weight is important too.
Its all relative. I still find it amusing that 427 and 'torque' are used in the same sentence. Horsepower? Absolutely? But torque? Having run nothing but Buick 455's and Mopar 440's, with the occasional Cadillac 500 thrown in, even Chevy 454's dont get to talk about torque. Torque over a Chevy 350? Again, absolutely. Further, stock for stock, there is a vast chasm... but there are a lot ov guys here that have built 383's, 400 smallblocks, maybe even 350's that could match or exceed that 427's torque curve and peak. Technology conquers all. A modern set ov heads and a roller cam and a 383/400 is gonna forget all about that 427 in a hurry...
Personally... if i had to stay Chevy old school in a Vette (i dont plan to), i'd build a VERY modern, all the tricks 350, or maybe a 377, a stock stoke 400 if i had to. I love the look ov a BBC, especially for that 'pop the hood' reaction, but weight is important too.
And what if you apply that same "modern" technology to a big block.......does it not make similar gains in performance? Even the weight factor goes down when installing aluminum heads and intakes on a big block. Of course, very soon when you start increasing torque on a big block,.......many other driveline mods are required, as well as sticky tires, or you just created a problem.
On my 77, I have built a very strong 406 small black, which is about to hit the road in a few months and I am hoping it makes my very strong 350 look weak. So, I do not disagree with your small block comments.
Last edited by Torqued Off; 01-17-2021 at 05:09 AM.
Its all relative. I still find it amusing that 427 and 'torque' are used in the same sentence. Horsepower? Absolutely? But torque? Having run nothing but Buick 455's and Mopar 440's, with the occasional Cadillac 500 thrown in, even Chevy 454's dont get to talk about torque. Torque over a Chevy 350? Again, absolutely. Further, stock for stock, there is a vast chasm... but there are a lot ov guys here that have built 383's, 400 smallblocks, maybe even 350's that could match or exceed that 427's torque curve and peak. Technology conquers all. A modern set ov heads and a roller cam and a 383/400 is gonna forget all about that 427 in a hurry...
Personally... if i had to stay Chevy old school in a Vette (i dont plan to), i'd build a VERY modern, all the tricks 350, or maybe a 377, a stock stoke 400 if i had to. I love the look ov a BBC, especially for that 'pop the hood' reaction, but weight is important too.
Sounds like a crate LS-7 would tick many boxes for you - 505 hp, torque of the devil, all ally construction so nice and light....
I love it when SB lovers bashes the weight of a BB. I love the SB, had two L48 for 6 years each and an LT1 for 27. But why bash the BB? And then they usually compare apples to oranges. True an iron head BB weighs 655 lbs. Those iron porcupine heads are really heavy. A comparable SB weighs 498, whether mild or LT1. So yeah stock iron ones are 157 lbs heavier. (Intakes will make that vary a little bit). A mild L48 350 at 300 HP is built very mild and similar to a mild BB 390 HP 427/454. So that's an apples to apples comparison. I'll kick my passenger out for that!
But many people compare a built SB to a mild BB, and that's not fair. Duntov loved the aluminum cylinder heads for a big reason, they drop 80-90 lbs off a BB. An aluminum head/manifold/wp BB gets down to 535 and that is only 37 lbs more than an all iron SB. And you still have the extra displacement, free flowing heads, 100 more HP, and 130-170 lbs of TQ.
To keep things equal, You can make up some of the weight diff by putting aluminum heads on the SB, but they don't help it as much as the BB. You could maybe get it down to 412-422 or so for a 120lb diff. But that limits you to 383-400 SB cubes.
The HD Dart block that will make 427 cubes is heavy and takes the weight back to 470. So that winds up being a 65 lb diff and then you can't go any higher than 427 easily. But if you built a stroked BB that way it would be either a 496 or 535 cube monster. So you are still 100 cubes short. If you want the cubes, and the TQ, and the strength, you have to have a little extra weight for the strength, whether SB or BB.
Mine's only 37 lbs heavier than a SB. I can live with that! I'm even gonna "go wild" and put 77lbs of AC in it.
I love it when SB lovers bashes the weight of a BB. I love the SB, had two L48 for 6 years each and an LT1 for 27. But why bash the BB? And then they usually compare apples to oranges. True an iron head BB weighs 655 lbs. Those iron porcupine heads are really heavy. A comparable SB weighs 498, whether mild or LT1. So yeah stock iron ones are 157 lbs heavier. (Intakes will make that vary a little bit). A mild L48 350 at 300 HP is built very mild and similar to a mild BB 390 HP 427/454. So that's an apples to apples comparison. I'll kick my passenger out for that!
But many people compare a built SB to a mild BB, and that's not fair. Duntov loved the aluminum cylinder heads for a big reason, they drop 80-90 lbs off a BB. An aluminum head/manifold/wp BB gets down to 535 and that is only 37 lbs more than an all iron SB. And you still have the extra displacement, free flowing heads, 100 more HP, and 130-170 lbs of TQ.
To keep things equal, You can make up some of the weight diff by putting aluminum heads on the SB, but they don't help it as much as the BB. You could maybe get it down to 412-422 or so for a 120lb diff. But that limits you to 383-400 SB cubes.
The HD Dart block that will make 427 cubes is heavy and takes the weight back to 470. So that winds up being a 65 lb diff and then you can't go any higher than 427 easily. But if you built a stroked BB that way it would be either a 496 or 535 cube monster. So you are still 100 cubes short. If you want the cubes, and the TQ, and the strength, you have to have a little extra weight for the strength, whether SB or BB.
Mine's only 37 lbs heavier than a SB. I can live with that! I'm even gonna "go wild" and put 77lbs of AC in it.
Is there a reason why many people don't build aluminium block BBs? I stumbled upon a Brodix ally block earlier and I anticipated that would shave a lot of weight of. BB motor? You could build an all AL BB I guess?
Cost mainly. If I win the lottery I would go that route. I have seen a couple of engine builders say that there is some horsepower loss due to the bores moving around and losing ring seal but I think that only applies to the really high horsepower builds. For a street build it would be negligible.
I had a chance to pick up two World Industry’s aluminum blocks.
They were new in the box and I thought one would be really cool in my C3.
I talked to my local speed and machine shop who told me the cost to build one would be outrageous and realistically un-advisable for the street.
I will have to respectfully disagree with them. From what I know, and I'm not a professional engine builder, there isn't too much difference in machining practices between aluminum and cast iron. Maybe since the World blocks were rough machined and would need a lot of finishing? I agree that it would have been a cool power plant for your car. It sounds like, for whatever reason, they didn't want to do it, which is a shame
They have been building racing engines for over 50 years, know their business and the blocks were in their warehouse.
I could have gone for it, but the cost of the block and the total amount to build one was out of my budget.
I’ve had several big blocks and they are awesome. Even a stock low compression big block still has authority that you know it’s a big block.
I have a bbc in mine, but if I had a non bbc corvette and wanted to build a motor, id probably build a 406 sbc and have a nice day. 11 second power and an easy fit engine bay.
I would really like to see a correct LS engine weight. The two I found were 412# with accessories and 454# LS7 w/ flywheel & clutch.
So say around 390-400 w/o all that stuff?
Anybody know?
FWIW that only makes it 10-20 lbs lighter than a gen I SB w/ AL heads. (no flywheel)
It's hard to get good numbers. One source says a LS block weighs 110# bare, and a Gen 1 350 block weighs 200# Another source says 148#
So what's correct?
So you can't believe everything you read on the internet. Surprise. LOL A bare SB block only weighs 148 and a bowtie version 178 while a LS block weighs 107 and a BB 218 and a Bowtie BB 270.
So an LS motor saves a whopping 41 lbs vs a std. SB!! WOO-HOO. I just don't get it. I could change the rear spring and save that.
Is there a reason why many people don't build aluminium block BBs? I stumbled upon a Brodix ally block earlier and I anticipated that would shave a lot of weight of. BB motor? You could build an all AL BB I guess?
It only makes sense if you're doing track days on a road course where lighter front weight helps cornering and braking ability. If you're on a straight track (drag strip, Bonneville, etc), it's makes more economic sense to just build a larger displacement, high horsepower iron engine that will push the extra weight of the vehicle.
I have both and without a Doubt Big Block cars are the BEST. They are just unreal Power all over the place. Simple proof... EVERY successful C3 Corvette SCCA or Lemans car was a Big Block
I have both and without a Doubt Big Block cars are the BEST. They are just unreal Power all over the place. Simple proof... EVERY successful C3 Corvette SCCA or Lemans car was a Big Block
01-14-2021, 05:53 PM
If it was a stock 8.25 CR 454 short block, that increase sounds about right.
