- yeah, listen to Chuck - this guy really knows his stuff. Also, I've been beat by a midyear vette with a 327 (setup for racing) against my big block '68 ! :eek:

The small blocks really are more 'reliable' although my BB is holding up pretty well these days.....and the BB gas consumption is ~well~ just awful.
:(

Anyways - on the street - torque is king & the Big Block guys have always bested the 'stock' small blocks.......but with some $$$ and elbow grease - you'll run with the best of 'em ! :cheers:


[Modified by verskel, 4:08 PM 11/4/2002]

 

I'm a member of a third gen f-body club here in So Cal. One of the guys in the club has a 91 Z-28 running a 350 sb with ported and polished Vette aluminum heads, a lt4 hot cam, SLP headers, large base, big mouth runners, and ported and matched plenum in a speed density tpi with a custom chip. His combo made 331 hp at the rear wheels, and 417 ft.# torque on his last dyno pull. It also is smog legal for ca. His dad just built a 350 with Vortec heads, a Scoggin-Dicky base, and large runners, ported plenum in his 92. It also has a custom chip. The engine just went in Saturday. It hasn't been to the dyno yet, but should do better yet because the Vortecs flow better than the Vette heads. Finally, I just saw an artical in the current issue of Car Craft where they built a 350 with Edelbrock E-tec heads (aluminum vortecs), Edelbrock vortec manfold, and a Demon 850 carb. They used a huge cam because they had too much compression, but they got 529 hp and 485 ft# torque.

 

I do think it is fair to compare the weights of a BBC with aluminum heads, intake, and water pump to the stock SBC with iron heads, intake, and water pump. That makes sense, but to talk about an aluminum block does not... it's very expensive.
So can anyone offer some real world data/numbers for the handling penalty for the heavier BBC?
Anyone care to offer an actual number for the weight difference of the above?
Sometimes a swap to BBC could be justified. In my case, the SBC has a cracked block when I got it. So I would need a new block, and would probably upgrade the intake/heads/rods/crank while I was at it anyways. The cost is a little more for BBC stuff but not hugely so. I realize, that the BBC swap necessitates a new radiator and brackets, where staying w/ the SB doesn't.
Additionally, I wanted to build an EFI engine, and the after-market stuff is about the same price for SB and BB (although a stock TPI is quite cheap).
Now I'm concerned w/ handling as well, but the thought of building a mildly modified engine capable of 400+HP/400+ftlbs is appealing without going radical.

 

75 BBC Stingray,

The handling penalty due to the weight of a BB as you described vs. an all iron small block is negligible. What does seem to be a detractor for such BB's is the excessive torque available. It takes a great deal more skill to drive a car with enormous power compared to one with modest power. I think 67 Heaven has the article, but I recall the 69 LT1 promo car out performing the 69 ZL1 on a road coarse on a press event. The ZL1 was lighter, but its greater power was above the skill threshold possessed by any of the drivers that day. A humbling experience to be sure.

Chuck

 

To compare an aluminum head, intake, waterpump equipped BBC to a iron head, intake, waterpump isn't an accurate comparison unless you're simply trying to convince yourself that the weight difference between a BBC and an SBC isn't as great as it really is.

A complete SBC typically weighs around 550-600 lbs, while a similarly equipped BBC is around 750-800 lbs. Of course it depends on what material is used for the various components mentioned, as well as the year of the block. Older small blocks for example weighed much more than those used towards the end of the SBC's life. GM trimmed the weight down from almost 200 lbs to close to 150 lbs in an effort to improve overall vehicle fuel economy. The same is true for production cylinder heads.

 

Monty,

I think 75 BB is on track with his statement. My L88 with aluminum heads, water pump, intake, 11" flywheel is only about 60# more than my L46 350/350. Using an aluminum radiator and headers vs. big brass radiator and cast iron exhaust manifold cuts this difference in half. I don't think anyone but a truly professional road racer could feel such a small weight difference from behind the wheel.

Greater horse power is subject to the laws of diminishing returns. A ~100hp Pinto engined formula Ford is not that much slower in lap times than the ~200hp V6 engined Formula Atlantic's which are not that much slower than the 800+ hp Indy cars.

I find the BB to be a bit more fun than the SB; but, I don't kid myself for one second that driver skill will be the primary determinant over who will win a road race.

Chuck

 

BB wowBagger

 

Wow... Truly an incredible amount of information here.

In light of some recent financial problems, I won't even be able to get the car until at least spring, probably more like summer of next year. I think this is for the best, though. Perhaps instead of buying a complete junker and rebuilding from scratcher, I'll go with something that's in better shape, that there won't be any problems driving stock for a while. It may be a long while before I can afford to dump some serious money into a corvette now. Perhaps when I buy it, I'll bite the bullet and get one that is in good condition, drive it for six months, then put it away for the next few years for a huge overhaul, and go back to drivin' a regular ol' car.

For a short term project, I'd be inclined to go with the 383, but in the long term, like I said before... If I'm investing years, and thousands, into a car, I'd like to do it all out with a 454. Perhaps I'll still stick with the 383, time and money will tell.

Truly a lot of issues to flesh out I guess... Time to start making a plan!

I'll be posting more! :D

Thanks everyone for the help. I think I'm just as indecisive as I was before I posted this, but a lot more educated now to make some decisions.

Adam

 

Chuck,

It just seems to me that the comparison is based on skewed criteria to prove a biased point. It's like comparing my small block's power and torque to that of a NA big block, in my opinion. It's an argument I would never make because the comparison isn't indicative of the real world.

I wan't really intending to add fuel to the fire, but I do have to admit that I get a chuckle out of the claims that there's no replacement for displacment or that small blocks can't produce 'big block like torque" etc. 500 ft lbs or what ever is still 500 ft lbs regardless of whether a big block is making it or a small block. My only point is that the comparisons should be apples/apples, oranges/oranges....

 

well you could go with the merlin 632, 1000hp NA hp is hard to beat, wait, you said you wanted handling and mpg and didnt have money? damn, its 35k :lol: :lol:

 

Monty,

I once had my SB built to about 500hp. It was a beast! The L88 has only a little more hp, but more torque. What 75 BBC was saying with my agreement is that if you now have a stock L48 or L48 and you want to go with a BB, there is not much of a weight penalty if the BB is fitted with light weight parts as I listed. You could do the same with a SB and save even more weight; but for me, as long as I was going to be spending $$ on new parts, I might as well get the ones for a BB.

It is much simpler to get more power from a larger bore motor than a small one. You have much more power from your TT SB; but, you also had to go to extremes to do so. With simple straight forward over the Chevy counter engines, the LT1 (with 2nd design off road factory racing cam) and the L88 are not much different except for their size. For only a 60 pound weight penalty, the L88 is the better choice for power.

If you go a more complicated route with roller cams, turbos, etc. on an LT1, you would have a proportional increase if you were to do the same to the BB.

But as I said earlier, if I already had a decent SB, I would readily consider a good roller cam and perhaps a few other enhancements instead of BB transplant if $$ were important. This would be a much simpler solution with great rewards!

Chuck

 

Yup.:D

I chose to do both, 383SB in the 88, 454 BB swap in the 75. Both have 10lbs of liquid refreshment as well.:)

 

Chevy High Performance built two motors, a 408 small block with dart heads and a 408 big block with merlin heads. Both had the "same" XE284 cam and the same brand and type manifold. The small-block made 443 lb-ft of torque at 4,600 rpm and 423 hp at 5,700. the Rat made a peak of 464 hp, but at a relatively low 5,400 rpm, with 465 lb-ft of torque at 4,600 rpm. Times for the small block: 12.18 at over 110 mph; for the big-block 11.91 at 114.14 mph in the same 70 Camaro w/auto. "It would cost about $850 more to build this big-block compared to the small-block, and that’s worth roughly $300 per tenth of a second. But for the purpose of this story, on the dyno and in the same car, the big-block is king!" Joe

 

I saw that too but find flaws in the comparison mainly being head, intake and header flow. The bb heads, intake and headers flow more because they are bigger. What needs to be done is have a big block and small block with the exact same everything: bore, stroke, comp, head volume, valves, etc. Would be hard to do but would yeild a better comparison.

 

You could also look at it the other way. You could build a much bigger big block than a 408 for the exact same price, and then the power differential would be huge. To make both engines identical, you would have to use the largest, high performance SB heads and the smallest, smog big block peanut port heads to get similar port sizes. Not exactly apples/apples. IMO, all these comparisons are too flawed to be much use. Fortunately, they are good entertainment! :lol:


[Modified by Flareside, 3:51 PM 11/7/2002]

 

The sad thing about that comparison, regardless of which side of the SBC/BBC fence you are on, is that both the SBC and the BBC engines used are dogs. It's pretty sad when one of the better magazines can't even make 1.2hp/ci (490hp for a 408ci engine)which is pretty much the minimum standard for a decent high-performance aftermarket engine. There are probably a dozen or more guys on this forum alone with 383's making more power and torque than that. Most good engine buildups these days are approaching or exceeding 1.5hp/ci, which would yield approximately 600+hp in either case.


[Modified by Monty, 3:16 PM 11/7/2002]