Just like a 383 stroker makes a 350 SBC better, so does stroking a BBC.
427 or 454 or 496 take your pick! It's just a bigger crank, in a stock block. So why not?
Torque is fun!

 

Torque is KING, it is not just "fun". Torque RULES on the Roads and gives you that G-Force of being held back into your drivers seat while accelerating hard. I LOVE Torque as it is easy to make with the right parts.

I chose not to stroke my 427 but instead went with high compression which makes torque like a diesel locomotive. After driving around with the power of the 427 BB, it is hard to get back into lower torque cars and be comfortable with them.

Compression is the easiest way to make torque and you can customize the compression based on the fuels that are available for you. The 11-1 for the 1970 LT1 was okay but they started pinging pretty soon after the 1971 year showed up with the reduced compression. I ran 93 octane Sunoco gas in a 1970 LT1 and it was happy until the engine got really hot and then you "might" hear some pinging. The cooling system on the 1970 LT1 was enough to really keep that engine cooler and that made the car perform like it did and still does. The higher compression engines work better when they have a very effective cooling system that kept it cool enough to avoid the issues with high compression.

 

Torque *is* fun – but so is rpm! I’m in the process of going in the opposite direction. Previous engine was a pump gas 565 (4.60 x 4.25) that made over 800 HP. Great engine but honestly had too much low end torque – traction was problematic, especially with just 255/60R15 drag radials.

First step to address this was to section rear frame and wheel wells for more back spacing. This enabled 275/60R15 drag radials.

2nd step was a new engine – all aluminum 535 (4.613 x 4.00) based on a Brodix block and using the same heads and induction system from 565, with a slight bump in CR (11.5 to 12:1). Still in process of dyno tuning but best run so far has yielded 830 HP at 7100 rpm – 400 rpm higher than previous 565 peak HP w/ a slightly smaller cam. The peak torque difference was only ~ 14 lb-ft at a similar rpm; the largest torque delta was 36 lb-ft below peak torque rpm. Curious to see final tuning results w/ a different cam.

Both approaches have their attributes – high winding vs low end grunt. The beauty of the BBC is its versatility and ability to exploit the best of both approaches.

 

I love your high rpm BB build.
I too am going the opposite way.
From a 7000rpm LT-1 to a 468 LS6 torque monster.
TQ 400# to 550#
Should be fun!
TQ peak 400# @ 4800 to 550# @ 3500...much earlier and a third stronger
Redline: 6700 rpm vs 6200 rpm - oh well

I autocrossed the LT-1 for decades, and once I got used to the power, and could use all of it, I found myself waiting for 3500+rpm, far too often!
It would hook pretty solid, in 2nd, even at WOT. So I just floored it, and it stuck. (10" Street slicks aka autocross specials - DOT "0".)

Pretty sure the LS6 is going to need at least one more gear to "stick em" And without good tires, that may not even work.

The LT-1 was pretty weak at 3000, so the new one might be twice as strong at that point!
You know what I mean..."roll-on" TQ zone

 

Are you making any suspension (or other) changes to account for the added weight of the big block? Will you be autocrossing w/ the new setup? Very different engines - and I suspect a very different driving experience. Curious to hear your thoughts comparing the 2 after completion.

 

Yes. Very different driving experience. And that is exactly what I am looking for.

I have driven some strong BBCs occassionally, just never owned one of my own. I have owned lots of cars that revved to the moon, and desire something very different. My first new car was a Cosworth Vega. 8k rpm was fun too, but no TQ to it. Drove a 4 ft wheelstanding 650 HP 10 sec chevelle drag racer a couple times, it was certainly more "explosive". I considered and test drove a 500HP 427 C6 Z06, '12 supercharged CTS-V coupe, and honestly those two were fast, but too smooth. too quiet, too daily driver like. Not for me. I want the old school style, noise, racket, header ring, piston slap, lifter purr, reminders. And the driver will have to be the anti-lock and anti-skid control "module". It will demand driver skill, no nannies onboard, no novices allowed.

Yes suspension mods will be many and are basically done.
Basically a street and slalom type package, big front sway bar, factory rear, ridetech delrin bushings, 480# front springs, 330# monoleaf rear, single or double adjustable shocks, wheels 18*9 or 18*10 Aluminum Ralleys, pilot sports or nittos. I pulled 1.3G's in my solo car, with some even stickier tires. But the LT-1 didn't "launch". Only 13.9s but at 106. And a custom torsion bar valved borgeson box by Turn One for 48 in-lbs feel at the steering wheel. 5* caster. I probably forgot a few things. V-S delrin diff locator kit etc. TKX 5 speed, double-disc clutch, blue-printed tuned cryo'd diff posi. Headers, Pypes 2-1/2" undercar exhaust, Magnaflows. It will look pretty stock, from say ~5 feet. Unless you have a sharp eye. L88 heads, LS6 carb, intake, etc. Just like a factory 71 LS6, but "optimized". Custom H roller cam for a slightly lower rpm TQ peak than stock LS6, without changing RPM potential. I could have easily stuffed another 100HP in this one, but figured that would ruin the original LS6 "look" and 500/550 was enough for my goal and a different feel than the SBC. It's gonna have traction problems already under 60 on street tires anyway right? Life is all about compromise.

An aluminum head BB is only 40# heavier than a stock all iron 300HP SBC. With all the TQ I am not worried about that, or the weight from the A/C, or "ruining" the handling according to the naysayers. Lack of traction will be the biggest effect on handling below 60.

I promised myself I would not get addicted to autocrossing again (~27+ times a year before, for 20+ years), but it will be very capable and will likely find it's way out there once or twice, and a couple dragstrip runs too.
After all it'll need to be "tuned" right?
It's a driver, not a show car!

The goal is a very well rounded street car, low 12 sec? car, that turns over 1+ G, and is comfortable enough for a Power Tour or a coast to coast drive, which is planned. Hence the adjustable shocks, moderate springs, and Vintage Air. It should stick with almost any newer Vette, except the king of the hill models. The low TQ peak, TKX O.D. and a well tuned Holley should give it 18+MPG cruising potential. Somewhat less when on the throttle!

Thanks for asking!

 

468s are fun, lot of traction issues when I had it under the hood...but they were fun issues.

 

When the engine on my '68 built I very specifically didn't want a high revving engine. Wanted to retain 3.08 rear, M21 and 27" tall rubber and have good street manners. The aftermarket oval port heads and dual plane inlet with mild(ish) hydraulic cam have achieved that. The torque figure at 2400 rpm is similar to the peak torque figure for a stock L36 engine. 6200 rpm and its all done. With a torque peak of 606 ft/lbs at 3850 you have the choice of driving 'on torque' or dropping a couple of gears for fun and letting it rev a little.
And, yes torque is most certainly king!

 

Of course there's always my version......

4.25" stroke...555"......when N/A it peaked HP (871) around 6800-6900. It had 742 lb ft of TQ. Shifted it at 7600-7800 regularly.

Now I've added boost....still shift at same RPM range..cross the line at 8000 RPM.

Big engines can rev too!! No one has ever complained about a lack of bottom end or "waiting for it to come up on the Tq curve"....LOL

JIM

 

With a Holley EFI system I have been toying with the idea of "just a wee bit o' Nitrous" with a 12.25-1 Compression ratio tweaked BB 427. Everything is Forged and ready for some action according to what we did building the bottom end.

The Holley EFI systems are able to handle the extra fuel requirements and you can use just dry Nitrous with a few solenoids on the Holley EFI system. That might be fun to play with at lower levels (like 50 hp shots), not starting with a 250 hp shot and needing a new engine right away.

After replacing the turbo on my Brothers Merkur XR4Ti it felt like you were hit by a truck when that boost came on. Turbo's and Superchargers are still not in my box of toys. I did meet a local engine builder and racer car driver once, he looked at my little 427 and all the room around it and then told me to leave the car and $10k with him and he wanted to install a sequential turbos on my 427. I don't know if my Car's frame could take that much fun and still survive, for that matter whether I would survive...

 

I have a question for you 3-4 BB guys.

I have only driven a BB vette gently, they weren't my cars. I like 'em.
My LT-1 would not take full throttle in 1st gear. Even when rolling into the throttle gently, once it got near the power peak, the tires went up in smoke..
And that was with 10" Hoosier Autocross slicks.

In second gear it was fine, and would hook pretty darn well, as long as you did not drop the throttle too fast.

My BB "problem" is almost double the TQ, say a jump from 300 lb-ft to 500 lb. From a 2500 rpm roll-on.
I won't ever have to worry about being caught in the wrong gear again!


Now that is exactly the driving experience I am looking for.... I certainly will not have to wait for the revs to build....but ....

Question:

Is there any hope of the tires holding full power in 2nd gear?

Or do I just have to wait til 3rd gear?

 

With my 502 and a 3.36 rear gear 2nd gear struggles. It will start to hop if I stay in it.
Tires are also 275 and I can't imagine what would happen to a 225 tire.

 

Perhaps soft front springs, drag shocks and some weight transfer off the line could be 'your friend' for improved traction?

 

Thanks ddawson!
That is the kind of feedback I was looking for.
I can deal with my right ankle being traction control.
As long as it sort of hooks.
That is reason I am going with 285s.

Thanks Rosco.
That's the reason for the 285 Nittos.
But I will keep the suspension a little stiffer for handling first.
And then as much traction as I can get.

 

My buddy across town has a 468 in his C3. HOLY ****!! That thing pulls like a frickin' freight train on steroids! You jus gotta love a BBC.

 

I originally had 285/40/18 Toyo's on the rear when the 489 was installed (and still have) - they were surprisingly good in terms of traction back then (but 'gone-off' in grip terms more recently) - oddly my car had the F41 suspension installed from new - but didn't realise the F41 specific dampers had been replaced with cheapo softly valved Gabriels (or similar) front and rear.
Off the line the front-end would rise-up high - rear end would 'sit-down'. Never had traction issues through 1st, 2nd and intially 3rd with the M21/3.08 rear gearing - it was only up around 80 or so that things could go 'squirrely'. Once some firmer gas shocks were swapped-in the front-end would stay-down and off-the-line traction decreased - but perhaps age-hardened rubber is a contributing factor. I'd like to know how good a pair of MT ET Street's are compared with the best radials like Nitto or Michelin. They are very expensive here in UK (and probably set to get more so in future!
This photo was a few years ago not too long after engine install. Trailing the camera car at 20 or so mph and hitting hard in 1st.

 

Funny!
I had a similar experience. 650HP 468 in a 2700 lb car. Got to drive that one in "anger" . Needle on a gauge was flying across the dash. Almost afraid to look. Thought it was the tachometer. Turned out to be the speedo. I was counting the metal seat ribs with my backbone. Swore a locomotive was trying to rip the car out from under me with a chain or something. 95MPH on a 30mph road, in just seconds. Coolest ~5 seconds ever. Holy ****


Rosco:
That is one impressive pic!
You are convincing me I need double adjustable shocks now.
So I can switch back n forth.

Hey!
Aren't you on the wrong side of the road? LOL

 

Rosco you got me thinking about the softer traction oriented suspension:

My LT-1 (top) and your BB (2nd) actually had similar total TQ in 1st & 2nd due to gearing differences, but mine did not stick in first cause it was autocross stiff, where yours did stick cause when it had lift, and spun when stiffer.



But with the deep 1st gear of my TKX, I think it's hopeless in first gear W.O.T. no matter what!
Even 2nd gear til 75mph will be bad if I keep it stiff.
Just like Dawsons.
Oh well.
Maybe I can tune the shocks to get it to stick in 2nd, past 50mph!!

DDawson has even more TQ in 2nd (~3900), with his gearing, and his comment was it "struggles" in 2nd on good street tires.
I guess that is where I'll be.


Our deeper 1st gears, and rear gears, than Rosco, put 1st gear well past the will hook up stage, in first gear, at WOT.
But they do make it more lively at half throttle.
I have a buddy George with 411s, a TKX, and a 427, so an awful lot of first gear, and it drives great at half throttle. Never saw it a WOT.

Thank you for the driving feedback guys!

I doubt I will ever have to wait for 35+mph for the power to "show-up" any more!

 

I have a 468 in my 70 backed by a TKX wide ratio going through a 3.08 rear. with the 3.27 first gear in the trans and the 3.08 rear it launches hard through the gears. Since its a new build I have yet to push it hard as I believe the drivetrain will suffer. Mark Jones built the motor and it has over 550 both on torque and HP. With the overdrive it cruises at 70 mph at only 2200 rpm.
I do have coilovers at all four corners as well as most Vansteel suspension upgrades.
I was worried about the wide ratio trans but Jeff at Silversport highly recommended the wide ratio and it has worked out just fine.
Long live the big block

 

Nice pic! There is a whole lot a squat going on there, do you have 90/10s in front? I run M/T ET Street R drag radials all the time now on my 82. At the track, I air em down to 18lbs and just dust em off. They bite rather well and launch the 82 well with a 1.70 60' best launch. I really like them for sure and they aren't nearly expensive as others.