Can a BBB survive a procharger? What will it take?

Discussion in 'High Tech for Old Iron' started by GoldBoattail455, Dec 12, 2012.

  1. GoldBoattail455

    GoldBoattail455 462 -> TH400 -> Posi

    I don't like to be a skeptic but let's face it, the BBB is a great motor in stock applications. Outside of stock form, its apparent that the BBB has some areas that need improvement. But with weaknesses, what says that we can make improvements to extend the life of the engine. My next build is going to be procharged.

    I'm very interested in keeping the build Buick. What stock parts are you guys reusing? What parts need to be upgraded, pistons for starters, block girdle, studs for the mains and cylinder heads? Are cylinder heads still the biggest area for improvement since now were going to shove that much more air through the engine?

    I've got a stock '74 455 that I've set aside for this purpose. The block would receive the standard oiliing mods, plus the rear cam galley line to the oil pump. Forged pistons are a must, but is one brand really better than another. SpeedPro vs say custom Diamond pistons?

    I'm looking for some guidance on where to start the build.
     
  2. pmuller9

    pmuller9 Well-Known Member

    Rob

    I'm presently working through this problem for a boosted BBB build.
    This will be for a serious street application using more than the typical 6 to 7 lbs of boost.

    Our biggest problem is finding a 455 block that doesn't have thin areas in the cylinder walls.
    We have sonic tested 2 cores so far, a 73 and a 76 and are not happy with either one.
    The 76 has thicker walls overall than the 73, but still has some areas that are too thin.

    For boosted application displacement is not an issue since the BBB is horsepower limited even with a girdle
    so looking at thicker walls with a smaller bore is a good option.
    Looking at the 430 block would be my first suggestion.
    The second is sleeving the 455 block down to 4.250" using ductile iron sleeves.

    The block will have a girdle installed.

    Cylinder heads are still very important. The more they flow the less boost it takes to make the target horsepower.
    The less boost, the less the intake air is heated and the overall engine efficiency is better.

    Also the cam profile can be milder.
    A roller cam with high lift and short duration was chosen for this build.

    A custom piston will be needed because of the large dish volume for 9:1 compression with aluminum heads.
    The piston will be at zero deck for good quench.
    The other reason for the custom piston is so we can use longer than stock length rods to reduce side loading of the pistons.

    Speed Pro pistons are only set up for press pin fit which limits you to the TA/Crower rods or the modified press fit Pontiac rod.
    The Speed Pro dish volume is not enough for low compression if you zero deck them.
    There are 3 other reasons for not using the Speed Pro pistons. I sent a set back yesterday for credit.
    They are the cheapest of the BBB forged pistons but they are not a bargain!!

    Would this be for street use or racing only?

    How much power are you looking for?

    Paul
     
    Last edited: Dec 13, 2012
  3. offbrand Racing

    offbrand Racing Platinum Level Contributor

  4. Staged 1

    Staged 1 GS restoration in progress(Finally)

    Yes, it can live. No, I would not make a race car with one:Dou: The biggest problem is, as others have stated, the strength of the block. You can make enough power to destroy it with out boost, so why add a turbo or procharger? Because it is different:TU: If you had an aftermarket block then everything would be ok. But most of us cant afford to build one of those. My car has been together for around 10 years. I know it had some problems in its early days. But it was higher compression back then too. I don't race the car, for the reasons stated above. I do not however, baby the thing. It gets driven like any muscle car should be. I am not afraid to have fun with it.
    If you would like more info on it, look me up. I am not far from you. Are you a member of the Chicagoland GSCA? I am at most all of the meetings/events.

    DSC03510.jpg DSC03508.jpg
     
  5. ken betts

    ken betts Well-Known Member

    If you are going to use a pro charger then you can probably afford a TA block! Let these guys know what HP you are trying to achieve! By the time you put all the girdles and machine work on a stock block it is about a wash. Good luck, it is going to be a great project.
     
  6. Todd69GS

    Todd69GS Silver Level contributor

    I was just thinking the same thing. Plus piece of mind has to come into the equation too. Once you cross the 900-1000hp threshold on a stock block it becomes a crapshoot to say the least. Some might say that # is even lower.And with a blower that # comes very easily.
     
  7. 73-462GS

    73-462GS GS Mike

    I think Bob Makley (Sp?) runs a serious procharged BBB in his 72 GS. Car runs mid to low 8's if I remember right. He is out of Michigan. Finishline Performance is him. Mike D.
     
  8. sailbrd

    sailbrd Well-Known Member

    About 1400 hp TA block.
     
  9. sean Buick 76

    sean Buick 76 Buick Nut

    Have you considered a Buick 350? Much stronger deep skirt design with more meat where it is needed. Even the stock rotating assembly is very durable and can handle low boost.

    I built a nice simple 350 with ported heads, Diamond forged pistons, Hershe forged rods and no need for a block girdle. This engine will be about 400 HP NA and I should be able to make about 600 HP without too much boost.

    Here is a Buick 350 built by Bobb Makley's 16 year old son. It was about 420 HP NA at 8:1 compression and then 630 HP with jsut a few PSI of boost from a procharger. Since this dyno run they cranked up the boost so it should be making about 720 HP now. No block girdle or bandaids... Iron heads.

    http://www.youtube.com/watch?v=zktYYQhCtqU
     
  10. theone61636

    theone61636 Well-Known Member

    It depends on how much power he's going for. With a stock late year 455 with low compression pistons, decent heads, and proper oiling mods I think he'd be fine to bolt up a procharger with the low boost pulleys and be happy living with 5-6lbs of boost and 500-500hp.
     
  11. pmuller9

    pmuller9 Well-Known Member

    Rob

    You haven't replied to any of our questions
    How much power would you like to make using an iron block?

    Paul
     
  12. GoldBoattail455

    GoldBoattail455 462 -> TH400 -> Posi

    I apologize for the delay. Haven't had the time to sit down like I would like to and put things on the drawing board.

    The car will be race only. Ideally I would like to build an O.E. block up rather than dish out the coin for an aftermarket block. The TA block is nice but it has some pretty big pitfalls; everything around that block is going to be custom. That means an engine north of $12k. I really wish the TA block was setup to take a Chevy crank, it would be so much cheaper for all of us. Instead its custom crank, custom rods, pistons, cam etc. The Chevy aftermarket is already established. The block would still be a "Buick" block and work with replacement applications from mild to wild.

    To answer Paul's question, there isn't a specific number I'm shooting for in the engine department. I still have yet to find a suitable race car (thinking Skyhawk). I would want the combination to live, hence why I started this thread. Anyone can spin a BBB up and make a 1000hp but for how many runs or run? It would be great to build a BBB to say 800hp and then tune it down to live all day long at 700hp. But that is probably wishful thinking.

    The topic of durability is where the LS series engine rears its head. But I want to entertain keeping the build Buick. Sean is the cheerleader for the SBB and he brings up great points. I know I could find a SBB with very little sleuthing. That may be the ticket since were talking Skyhawk and power adder. More reading is definitely needed on my part.

    Since you bring up the 430 having thicker walls than the 455, does a 400 have anymore meat to its cylinder walls than a 430? Do the block or lifter girdles really help? Wouldn't you want to let the block flex and return?
     
  13. pmuller9

    pmuller9 Well-Known Member

    Rob
    I had the same thoughts about having the TA block set up to fit the BBC crank. I'm sure it was looked at as a possibility. It's worth investigating.

    The present plan for the twin turbo project we have is to sleeve a 76 455 block down to 4.185" using BBC sleeves with a lip on the top.
    The OD of the sleeve will only require an .060" overbore and will not break into the water jackets.
    Because this will be a street application we wanted to sleeve instead of doing a block fill so it will run cooler.
    For race only you can do a high block fill or go with Methanol and do a complete fill.

    The 400 and 430 blocks should have thicker walls assuming the cylinder OD is the same as the 455 blocks.
    You will need to sonic check each block to be sure.
    You need at least a 4.185 bore if you want to clear Stage 1 size valves.

    The weak area is still the main webs under the main caps.
    Here is a block from one of the members here that broke during a run.
    The main caps were held on by a Halo girdle which kept things in place.
    The clue to the failure was the loss of oil pressure.
    Notice how thin the webs are that support the main caps.

    block%20004.jpg block%20001.jpg


    We will be installing a full block girdle.
    The full girdle is designed to apply downward pressure and support to the main caps by way of the pan rails.
    Don't know what the limit is with a full girdle and what a failure would look like but minimum amount of damage would be cracked main webs with loss of oil pressure.

    Here is some reading about block help and more examples of block failure.

    http://www.v8buick.com/showthread.php?82399-How-to-increase-BBB-engine-longevity!

    Paul
     

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