Advice with 144 blower combo--500hp goal

Discussion in 'High Performance Modifications' started by L-82kid, Mar 9, 2010.

  1. L-82kid

    L-82kid Veteran Member

    108
    0
    Mar 8, 2010
    Ct
    Whats up,

    I just picked up a B&M 144 blower for a good deal and its in great condition. I'll be doing a 357ci motor with it and its going into my corvette. My vette is a stick with 3.73 gears. weights 3650lbs with me driving.
    Heres my car:



    So far I have:

    144 blower (5.8psi pulleys-will swap to 7psi 2.86 top pulley)
    357ci block machined with GM forged Crank
    forged gm "pink rods"
    new 1.6 roller rockers-harland sharp
    750cfm speed demon mech carb (not boost referenced)

    I was thinking of getting:

    Forged pistons
    AFR 195cc eliminator heads
    850cfm blower carb
    hyd roller cam with split duration and 113LSA
    MSD boost retard system( i have HEI with re-curve kit and MSD coil and 6a box now)


    Looking to make as much power and torque as I can with the mini blowerin the idle-6200rpm range for street/strip driving. I want be close to 400rwhp/400'lbs of torque if possible. I wanna spins tires for a roll but also have plenty of mid-upper rpm power.


    My car buddies tell me I'm wasting my time with a mini blower and they dont make power so I'm trying to prove them wrong. I have connection at local dyno shop so it will be tuned once completed.



    My questions:

    Should I get a blower carb or can my current carb be boost referenced? Is 750cfm fine for my power goals or is 850cfm a better match?

    need options on cam size? i thinking of something like a nX288HR comp nitrous roller cam:
    288/315 236/248 .555/.576 113/108 2500-6500rpm....cam will be too big in N/A 357ci but will the blower keep low end torque up and cam will make power in upper rpm?


    Will a mech fuel pump work to support blower motor? have a high vol carter mech pump now.


    need opinions on decent priced forged pistons?- looking for 8.5.1 CR (75cc heads, blocks not decked)




    combo wont be rushed and I'm opened to all suggestions and opinions.
     
    Last edited: Oct 24, 2011
  2. Damon

    Damon Veteran Member

    12,865
    9
    Nov 16, 2000
    Philly area
    I just typed out a whole long thing and then lost it. Here's the shorter version:

    You're at the limit with that blower hitting the 500HP level. Doable, but at the limit.

    Overall, it's a good plan, but I'll make a few suggestions from my experience of what works:

    1. A little too much cam. I like the cam family you've chosen but you're about 10* too big. Notch down 1 step. High revs are not in the cards with these little blowers (efficiency falls like a stone as RPMs rise) and you can't waste what little airflow they're capable of by blowing any of it straight out the exhaust with a big cam. Sub-6000 RPMs is what you're looking for since the blower's efficiency drops quickly in the higher RPMs. You have to build the combo around the blower, not the other way around. Unlike a big X-71 blower there is very little "headroom" to pulley them up. The old rule about the COMBINATION of parts being more important than any single part alone.

    2. A little too much compression. You're going to want to be down in the 8:1 range or a little less. Boost is much more important to making power than compression is. And you don't want to flirt with detonation in a blower motor- it can destroy things very fast. Nothign exotic- just a set of forged SpeedPro pistons will work fine. Do the math on which ones will get you down in the 8:1 range or even a little lower.

    3. Just changing the top pulley won't get you to your goals. You need the bigger 7" bottom pulley and maybe the smaller top one with it as well.

    A 750 carbs is good enough to get your going but is marginally too small for your goals. Can't say if your existing carb can be boost referenced but most Holley carbs can. This isn't the first place I'd look to drop big coin, though. If buying a big new carb already set up for a blower was going to impact your ability to afford those really good AFR heads, I wouldn't do it (just as an example). But if you can afford both, do both.

    The 383 in my Malibu lays down 390HP at the rear wheels along with 420+ ft/lbs of torque (factoring out converter flash spikes which are well over 500). I have worse heads (older AFR 190s and 8:1 compression), a tiny flat tappet cam (214/224* on a 112* LSA) and I use a home-tuned QJet carb (no boost referencing) along with a near-stock HEI distributor (no box, no boost retard, just careful ignition curve timing). I'm running the 7" bottom pulley and stock 3.07" top pulley, yielding about 5PSI of actual observed boost. Converter is a Redneck unit built for a blower with a stall around 2700. Rear gears are highway 2.73s.

    Peak power is at 5500 and falls off rapidly past 6000 (I never take it over 6000 for that reason). Peak torque is so low I can't measure it on a chassis dyno with the converter effects at the low end of the RPM range. Real peak is probably right around 3000-3500.

    Low end torque is absolutely unusable on street tires. I can spin violently ANYWHERE in 1st gear, including from almost a 40 MPH roll (downshift into 1st). 2nd gear is marginal traction for about a second or two after the shift as well. Quite frankly, it's a silly-stupid combo to try to hook up on the street. But silly-stupid fun as well.

    You'll probably quickly tire of the 3.73 gears out back without an overdrive. It's not going to be a high revving combo and hooking up with steep gears is going to make your traction situation even worse than mine on street rubber. The little blowers make MOUNTAINS of low end torque (much more so than your would think from just a half dozen pounds of boost) and just don't need very much gear to pull you away from the line.
     
  3. theflash

    theflash Veteran Member Lifetime Gold Member

    10,990
    6
    Feb 27, 2004
    Podunk, CT
    Welcome to the site. What part of CT are you from?


    Damon knows his stuff when it comes to the baby blowers ;)
     
  4. L-82kid

    L-82kid Veteran Member

    108
    0
    Mar 8, 2010
    Ct

    Thanks for response, sucks the first post was lost but thanks for taking time to redo it. sounds like your combo is making good power and torque. The 383ci probably helps out with torque also, with my 357ci I'll probably be under you numbers.

    For cam I was thinking of having a custom grind made. keep duration lower then posted cam like in 226-230, 236-240 range and on a 112/107 or 113/108? Going hyd roller

    I should have enough in budget for both AFR heads and blower carb. I'm thinking an 850cfm mighty demon blower carb with annular boosters. Then I'll sell my current carb.


    As far as gearing I'm gonna have to keep the 3.73s, rear is new and a custom built 12bolt. I'm thousands invested in it and it only have about 100miles on it so far. However, I was planning a 5spd od swap in future.

    As far as boost, will it be hard to make 7psi of boost with good flowing heads? I was told on a few other forums to expect 5psi even with swapping pulleys because heads flow too good to get higher boost. chart in instructions shows 2.86 top pulley with 6" lower will be 2.11 drive ratio and create 7.2psi of boost with 357ci, Whats the advantage of swapping to 7" bottom?





    .
     
    Last edited: Mar 10, 2010
  5. L-82kid

    L-82kid Veteran Member

    108
    0
    Mar 8, 2010
    Ct
    Thanks,

    I'm from wallingford, ct
     
  6. theflash

    theflash Veteran Member Lifetime Gold Member

    10,990
    6
    Feb 27, 2004
    Podunk, CT
    Cool, they're building a Sonic there soon, I'm psyched, lol.

    I used to go to the Wallingford Walmart cruise a lot, back when BJ's was a walmart. I still head down to Heavenly Donuts in Derby on Sundays. I'm anxious to get the car out for the season soon.
     
  7. Blown Camaro

    Blown Camaro Veteran Member

    892
    0
    Dec 13, 2009
    Deltona, FL
    I've got a 355 with a B&M 144 blower I race all the time so you can copy my setup if you like:

    4 bolt main
    Speedpro forged 4 valve relief flat top pistons.
    X-rods
    Steel crank
    Dart Iron Eagle 200cc heads with 72cc chambers
    Holley 950hp carb
    Hedman 1 3/4 headers
    2 1/2 exhaust w/2 chamber Flowmasters
    Performer RPM cam + 1.6 rockers
    Mallory Unilite LOCKED distributor set to 34 degrees total
    Mallory HyFire VI box

    1.61 60 foot still sprinning - too much bottom end. Went 12.07 @111mph last time out. The car weighs 3500lbs.

    Have fun!
     
  8. L-82kid

    L-82kid Veteran Member

    108
    0
    Mar 8, 2010
    Ct
    The old walmart cruise nights were the best. They were the 2nd and 4th sat of the month, i used to go all the time.

    Ive heard local rumors that the Sonic is being delayed because of issues with zoning laws. Rt 5 is too close to the build site and they cant move it back from road because of railroad tracks behind lot. A few people are saying that it might not even happen at all now!!!

    we'll just have to wait and see.
     
  9. L-82kid

    L-82kid Veteran Member

    108
    0
    Mar 8, 2010
    Ct
    thanks man, Do you have videos of you car or sound clips?

    I've seen another 144 blower combo with the RPM cam in an S10, that set up made around 400rwhp 420'lbs. whats your Shift rpm with that cam and heads? rear gear ratio?

    Whats your CR with the flat tops and 72cc heads? how much boost is the blower set up for?

    My short block with me similar to yours: I have a 4-bolt block with GM forged crank, X rods, and I was thinking of speed pro forged pistons.
     
    Last edited: Mar 10, 2010
  10. L-82kid

    L-82kid Veteran Member

    108
    0
    Mar 8, 2010
    Ct
    Blown Camaro

    I called Weiand and they recommend a lunati flat tappet cam:

    303/315 234/244 .488/.509 112/107

    Your cam is very close: Rpm cam

    308/318 234/244 .488/.510 (.520/.544 w/1.6) 112/107

    duration at .050" is dead on recommended and so it LSA/ICL


    how does that cam idle? I enjoy a rough idle for that muscle sound.
     

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