Help Me Plan the Race Build: Twin Turbo 455

Discussion in 'Race 400/430/455' started by TheEternalDance, Jan 15, 2021.

  1. TheEternalDance

    TheEternalDance Well-Known Member

    Hello Buick Brethren -

    I am hoping all of your expertise can help me begin planning for a serious street/strip engine. I want to be able to drive to the track, make a number of passes (sub 10 seconds?), and drive the thing home, still running in one piece.

    Recently picked up two running 1975 Buick 455s that I am in the process of tearing down. First thing will be sonic check and magnaflux - need to know I have something sturdy to start with.

    Came across an even better deal on 10/10 indexed crank, TA sportsman rods, and some Wiseco 4.362 pistons. Hoping enough wall thickness to stuff these pistons in, fingers crossed. If not, will likely go the .038 over route to grab more readily available parts.

    The car came with 2 Garrett 66 mm turbos, with all the fittings/plumbing to bolt up to TA's Stage 2 TE heads, which both will be part of the build. I plan to run a girdle on mains but would like to think I wouldn't need a lifter girdle - don't plan on outlandish lift or crazy spring pressures. Plan to run between 10-20 pounds of boost to keep things happy and living a long life. Will end up with a blow-through carb at some point, previous owner ran a CSU - anybody have preference to ability/brand of blow-through carbs?

    On that 'living a long life' thing, I don't want to push so hard the thing isn't streetable - I'm passionate about keeping this thing a street running machine, but also want the ability to turn up boost at the track. Was thinking to run a hydraulic roller up to ~.600" lift, but have no idea on specs or considerations when running boost. Any cam/rocker ratio suggestions? Lift, duration, LSA...? Also will need guidance on deck height/static compression, too, because I have no experience running boost. What I've found to be the common theme is to run lower static compression with forced induction. Somewhere in the neighborhood of 7 - 9:1 SCR? Sounds logical to me.

    In the much longer term I have dreams of throwing (most of) this rotating assembly into a Tomahawk block, or KB's new cast block. Do people here have a strong opinion which may be better suited?

    Anybody with boost experience that can help point out things I should stay away from? Or, should tend towards? How far off base am I with things?

    Thank you Buick community for the knowledge/guidance!
    Andrew
     
  2. Bens99gtp

    Bens99gtp Well-Known Member

    I'm no boost expert here, but keep in mind when you figure your valve spring pressures out. If on average wr have spring closing pressure say 150lbs......when you have a valve size say 2.250 and 20 psi of boost.....you have about 70lbs of pressure trying to push the valve open when it should be shut.....so you loose almost half your holding force....150 keeping it closed and 70 trying to open it at the same time.......so you forces on the lifter bores with the higher spring pressures needed will be much much higher than that of a NA motor with a very similar cam profile.

    I wouldn't skimp on the needed support in these areas.....the slightly extra overkill could be alot cheaper than finding out you were wrong
     
    bobc455 likes this.
  3. TheEternalDance

    TheEternalDance Well-Known Member

    Thanks for the insight, Ben. I’d rather error on the side of too much support than not enough.. like you say, it’d be better to have some overkill in precaution than finding out I was wrong..
     
  4. Bens99gtp

    Bens99gtp Well-Known Member

    I'm surprised the ppl who have experience with boost hasn't replied about about a few things they have learned that will all apply to motors in general, things that fet over looked
     
  5. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD" Staff Member

    Twin turbo? Why? No stock block will survive for very long with 10 pounds of boost or above. Just ask John Csordas Jr. I suggest you start off with a Tomahawk block. That is what John had to do to make it live. I don't know how many blocks he had to go through before he finally went with the Tomahawk. Up to that point, he was using a filled block and some sort of girdle. I remember him having a problem with oil temperatures if he tried running it on the street.

    I would talk to Jim Weise.
     
    Last edited: Jan 18, 2021
  6. sean Buick 76

    sean Buick 76 Buick Nut Staff Member

    I would use a custom camshaft specced by Scotty Brown
     
  7. TheEternalDance

    TheEternalDance Well-Known Member

    He was actually my first message! We spoke only briefly, but his sentiment was so long as I wasn’t “overdoing” the boost, I should be fine. I mentioned 10-20 pounds to him, but would more realistically be living in the 10-15 pounds neighborhood. He didn’t seem to mention that was overdoing it.

    I picked up two 455s that were otherwise heading to the junkyard and figured $600 for two running 455s is one 0 less than a start up Tomahawk - too hard to pass up to get my race car moving.

    The Tomahawk block is the front runner for long-term build. I plan to build a big stroker twin turbo, but my timeline is sufficiently out far enough I’m half holding out for the KB cast block.

    Twin turbo because it came with the car, and the intercooler, fabrication, fitment, etc is all figured out and drop in ready - it’s plug and play.

    Any thoughts about provisions to make a stock block live longer under boost? I’ll be running girdles, but anything else, apart from a stronger short block, to consider?
     
  8. TheEternalDance

    TheEternalDance Well-Known Member

    Thanks for the note - heard of him, but never worked with. Are you familiar with specs on grind for boost?
     
  9. TheEternalDance

    TheEternalDance Well-Known Member

    I hear you. Thought I’d get more attention from the turbo folk, but that’s okay. I’ll update you all with what I find out - for better or worse!
     
  10. 436'd Skylark

    436'd Skylark Sweet Fancy Moses!!!!!

    What does the car weigh?

    There was a block listed with a girdle already machined for a decent price. I'd buy that up..
     
  11. TheEternalDance

    TheEternalDance Well-Known Member

    Car will be roughly 3800-3900 pounds with me driving.

    Saw that listing, but if I’m remembering correctly it was BC and local pick up? Was thinking similarly, though. Just tough to pay probably close to the cost of a block in shipping for me
     
  12. Bens99gtp

    Bens99gtp Well-Known Member

    The problem with that block is its in Canada......I've been trying to work out a way to reasonably get it here but shipping from the west coast is crazy high with fastenal not shipping from West to East.

    I had it worked out to get it into the states, someone to pick it up and get it to fastenal, then I found out they pulled cross country shipping
     
    TheEternalDance likes this.
  13. hugger

    hugger Well-Known Member

    20181030_163720.jpg Set comp at 9.0 to 1 to 9.5 for pump gas 93
    Set comp at 10.5 to 11.0 for e85

    If you wanted to be extra "safe" set it at 8.8 for 93 pump

    Cam grinder will spec the springs leave that to them

    You bought the Green Buick that was good combo and working car,. What you have is very good stuff

    I wouldn't bother with a girdle,..the rpm range and type of load will not hurt a stock block you can get one Rob's halo girdles

    Get or build a nice high efficiency intercooler,..coupled WITH a Meth injection setup

    Ring gaps only need slightly more clearance at the boost level you will be needing

    Timing should be 24 to 28° to be safe with e85 you can push it up to 30 to 32
     
    TheEternalDance likes this.
  14. hugger

    hugger Well-Known Member

    That intake can be bought CHEAP,...if you want to really get people's attention
     
    TheEternalDance likes this.
  15. TheEternalDance

    TheEternalDance Well-Known Member

    What a bummer. I didn’t go to that length, but figured it’d be rather steep to get delivered.
     
  16. TheEternalDance

    TheEternalDance Well-Known Member

    Thank you for all this!

    Yes, the Green Skylark was really well setup. No girdle? David had the car before me and he didn’t run a girdle, but only reported pushing 10-12 pounds.

    Car came with a very stout intercooler, but I’ll look into the meth injection.

    Appreciate the tips
     
  17. hugger

    hugger Well-Known Member

    If you truly want to do an aftermarket block then I wouldn't worry with a girdle

    I would keep the rpm below 6200 and boost around 8 to 10 ,..put some nice rods on a stock crank and have fun. I myself am not convinced hanging a 88lb billetbcrank off the stock mains is the best idea,..the stock piece is very good
     
  18. hugger

    hugger Well-Known Member

    I'm going to do 400 or a 430 block for my next boosted build,...the thicker walls with a half fill and a halo is my plan,..only looking for 700~750hp but with a 871 20201115_105446.jpg
     
    m louk likes this.
  19. Bens99gtp

    Bens99gtp Well-Known Member

    Is that a modified offer 360 lower intake ethan
     
  20. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD" Staff Member

    10-15 lbs. of boost is overdoing it for sure for a stock block. Girdle for sure. 8 lbs. is safer. Some block fill at least. You have to watch oil temps though.
     

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