68/70Vette

After many, many years, I hoped to build up my Keith Black aluminum big block with it's aluminum Brodix heads. However, I recently had an A&A Centrifugal supercharger installed on my stock 6.2 liter 08 Corvette. The 08 is 378 cubic inches and it's a LS3 engine. Stone stock rated at 436 hp at the flywheel. With an A&A supercharger, it dyno'd at 580 rear wheel horsepower.

My Keith Black big block has a Keith Black billet crank and is configured for 454 cubic inches. This was a big displacement when I bought it 25 years ago. For today's standards, I have plans for have the sleeves bored for 502 cubic inches. With pretty much open Hooker header side pipes and a non-too extreme cam, it looks like with 502 cubic inches I can get 600 to 650 FLYWHEEL HP...not 580 hp REAR WHEEL HP like my supercharged 2008 6.2 liter engine. For people with a LS7 engine, the current Z06 427 cubic inches car which has a window price of an additional $20,000, you can be looking at about 700 REAR WHEEL horsepower with a supercharger. So... it looks like with a traditional big block, I'm going to be making less power than a much smaller displacement engine and to build up my less powerful 454/502 I'm going to spend a lot of money. (I know that a BB has low engine rpm power and also a sound that modern engines can't match). My 580 rear wheel hp 08 HP car, has a quiet idle, gets good gas milage and is very docile to drive on the street. It's only when you get the rpm above 2500 that you can feel the power.

The obvious thought is to put a supercharger on the big block. This is an engineering challenge. Currently I have Small Block Serpentine brackets on the BB with adapter plates to make them fit. Trying to fit a centrifucal or roots blower will be a custom installation and probably too expensive for me. Selling the 454 cubic inch Keith Black engine and buying a new LS7 engine also has a lot of problems, notwithstanding some custom frame work for the LS7 motor mounts and then there's the LS7 computer wiring worries.

I guess, the answer is to go for a 600 to 650 flywheel hp build on the BB and just enjoy it as it is. With 10 inch tires on the back maybe that's OK, maybe with more HP, I'll just spin the wheels . PS. I have a Tom's rear end with a super 10 bolt diff. 30/31 spline half axles.

Comments???? Thanks

tfi racing

If you were starting with nothing,but a huge pile of cash-then the blown LSX combo would be the way to go.But- you already have one of those,since you already have a pile of cool parts,why not go in the opposite direction with the C3 and have the best of both worlds?

bobbarry

If you were interested in maximum horsepower, then no question an LS motor would get you there more elegantly than a Mark IV motor.

If you want plenty of unusable horsepower for the street, you can certainly build the motor you have for a lot less, and still retain some of the original look and feel of an original Stingray.

It's all a matter of preference and wallet-size.

cv67

We know how awesome the LSx series motors are but really..


To pop a hood on a C3 and see a KB aluminim BBC in there? Ultimate cool factor. You can get plennnty more power out of it than that too.
There are sbcs around doing that. Nice tech in aftermarket heads/cams out that make it real easy

oldalaskaman

I vote for this one, ultimate cool factor is good

jim2527

I vote for the BBC with an EZ-EFI kit.

Markhudson

Ive Kinda been thinking in the same arena as your post. I have an 82 with a SBC with a little work done to it and yes it has some power but i'd guess somewhere around 350hp and thats after the PO had sunk $3500 in it for heads, intake and a rebuild. I stopped by a Shop yesterday and talked to some guys who hop up corvettes and saw a few they had in there 2008 to 2012 and heard some of the HP ratings there getting out of them by changing the Cam and computer tweaking and i was amazed. I was thinking in order to get the same HP in my 82 I'd have to spend around $20,000 I would think and have an Engine Sticking out of the Hood higher than the Roof...Cool Looking but Just not for me. I think I'm going to keep the 82 as/is and start looking to buy a 2008 with the LS3 in it and from there see which one I enjoy the most. I guess thats why you see Guys with one from every year in there garage

Les

I have an 08 Z06 and a 69 with a 427 that's putting out fairly close to the same power of the LS7. Neither approaches what you already have or what you're talking about building. I love the 69 as much as the 08 but even at my power level I have to be smart about it when I drop the hammer in that 69. Remember, the suspension in your older Vette is about 40 years old. Unless you have a plan to upgrade what's under that car, including wheels and tires, you'll need to be very careful when you want to use all that power. You won't have traction control or suspension nannies to save your butt. You'll need to run drag radials out back to have any hope of hooking up that power. That being said, there's something special about a pumped old school big block and I would never trade mine in the 69 for a modern motor.

uxojerry

You could build your big block and add a procharger and easily get 800hp. All of the modern fancy boost equipment is largely available for BBC motors. If you are going to sleeve the block, why stop at 502? Why not build a larger displacement NA motor with 800hp?

One difference between BBC motors and LS motors is low end torque. The older design motors build much more low end torque than an LS. Your block alone is worth $4k, heads another $2k. Everyone worships Gen 4 LS motors. If the Gen 5s are drastically different, LS motors will be yesterdays news much like the Gen 3s.

Add a modern EFI to your build and you can have fuel efficiency also. A cool efi would be the FAST dual quad set up. A single FAST EFI can handle 650hp. The twin set up doubles capacity.

My Gen 1 SBC 427 has 565hp using an Inglese 8 stack EFI. My 427 could be tweaked for another 75hp. An LS7 is capable of 50-75hp above my Gen 1. 700hp is about max for an NA LS7 using pump gas. 650hp is much more common.

Lastly, an LS7 runs 11 to 1 compression, it is not safe to add a blower to the car without other mods. You are probably looking at a $10k project, above the purchase cost of the motor.

cv67

Lsx motors best sb conversion to date they do much well.
But one day they too will be outdated.

Remember the TPI/LT1 transplant craze? Be hard to get rid of one of those cars now. not that they are bad they arent but its now outdated tech. Something to think about.

TimAT

Bore that 454 block .060 over, add a 4.25 stroke crank, some good rods and forged pistons, and it's an instant 496 with very little if any grinding inside the block.
No replacement for displacement. I don't know about your block, but the GM aluminum BB's with aluminum heads, the weight was close to the original Gen 1 SB with iron heads.
The new LS technology has just about wiped the slate clean as far as driveable horsepower. With a careful selection of parts, you can make big power with them. Same can be said for a BB too.

richiev88

But, is it really about the numbers?? or seat of the pants fun?
I love the old school, grumyness of BB engine, for me its the character of the beast!
Big block still make big torque and big hp built right.
Nothing like the sound of 700hp naturally aspirated big block running through side pipes!
And with modern heads/ cams you can have 700hp on pump gas
Love the modern muscle cars and LS engines but nothing beats old school for a weekend warriors.

Solid LT1

I made a decision 2 months ago to abondon my 377 cu/in gen1 build and go for a LS3 swap. $4.50 gal has prices helped in my decision. Our C6 Z06 knocks down 26-28mpg at 70 mph cruise. I want to still be able to drive my C3, so my decision was to keep with my gen1 build and add EFI or go to factory engineered set up. Plowing around 100lbs of weight off the front of the Vette won't hurt in the handling department either. Finding a reasonably priced dry sump LS3 with only 2K miles put me over the edge.
I will say that project is already $2K over budget but, will be worth while in the end.

Solid LT1

For people looking forward to Gen5 motors, I have already lived through the big problems of direct injection gasoline motors. The GIANT problem of debris build up on the back sides of intake valves has yet to be solved.
In my long since sold B7 Audi RS4 "wunderkar" that build up of deposits would kill airflow enough to drop HP 5% after only 20K miles and cause misfires after 40-60K miles. I think direct injection is better left to my DuraMax diesel pick up.

TheSkunkWorks

I vote for an alum head, intake and water pump BB with mini-starter, and throw in an alum block if you're bucks up.

That said, whatever type of mill you decide to build, I'd suggest you give a bit of thought to available traction. Drifting or drag racing on slicks or drag radials aside, if you're otherwise into "spirited performance driving" or ever plan on getting into AX/RR tracking, having an engine that produces a huge amount more thrust at the drive tires than they can possibly handle won't likely be as much fun as bench racers make it seem. Aborted a 496 in favor of another 427 over this concern myself when I started looking at the maths. Just some food for thought...

TSW

gdh

Just add a flux capacitor, case closed.

riggs 74

Is there a thread I could follow? I would love to see your progress.

Riggs

Solid LT1

So would my wife, just lots of preliminary stuff going on right now like cam change, rod bolt swap and rocker arm trunion conversion. When I start building the headers, I'll shoot some photos of that task.

Gale Banks 80'

The new engines are more advanced than the Old Engines. So lets take the new engine tech and apply it to the old engine. Leave the CI alone and add some modern heads and a Blower Turbo setup and let a ECM run the show and I think the performance won't be all that far apart. The BBC's mamoth Square Intake Ports arn't going to produce the drivability of the modern engine. However the latest LS engines ports are copies of the BBC. The main reason I would go for the BBC is beacuse of the way it looks, everybody knows its a BBC, when I see a LS motor in a Kit car I have to ask, "what is it?"

Little Mouse

The small intake runner heads and punny valves " left the building " when the LS 7.0 liter came about with 7000 rpm capabilty. It was now a real engine all that punny sh-t runners and valves had to go just like the earlier big runner heads big valve's in the 427 BBC. They even came out with big runner heads on the much smaller 6.0 liter LS 2.

The LS is only really modern in that it has computer management. It is still an antigue two valves per cylinder pushrod engine. Of course if you start putting boost to any engine power goes way up thats been done forever.

Jesus man if you already have an aluminum block and good aluminum heads simply stick some boost to it with fuel injection. No need for more then 454 cubes.

427 hot rod has 850 hp out his 540 with no boost with his stick sift car he probably has at least 700 + at the rear. You build a 454 with todays even better airflow heads for BBC. With even low amounts of boost you will equal that or be close.

Why bust your backside to switch over to a glorified slightly more modern SBC when you already have good parts for a superior engine. Skys the limit on a BBC 632 cubes no problem. Plenty money 4.9 5.0 bore center blocks 800 plus cubes. LS or LSX your still stuck with 4.4 bore center SBC nothing has really changed.