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Thread: Help me decide which trans to use...

  1. #1

    Help me decide which trans to use...

    I'm hoping to finish my 84 Regal soon. I'd like to hear some opinions on which transmission to use. The car will be a toy I take to the track about once per month. I might even try my hand at bracket racing. I want to go as fast as possible, but be reliable. The choices will be a Turbo 400 or a Powerglide w/ stk 1.76 planetaries. The trans will be built with good cluthes and a transbrake. I have a BTE 8" C100+ converter that will be used, should stall around 5500 RPM.

    I'll list as much info on the car and engine as I can. If you need more, I'll try to answer.

    CAR
    84 Buick Regal
    approx 3400 lbs
    bolt-on stock suspension
    double adj upper/lower control arms
    anti-roll bar
    29.5 x 10.5 slicks on 10" wheels
    9" w/ 4.30 gear

    ENGINE
    BB Chevy 4.375 x 4.000 481"
    12.25:1 CR
    6.135 rods
    990 heads with 2.25/1.88 11/32" valves
    bowls blended, short side radius reworked, and chamber unshrouded
    flow numbers are for #6 port(bad port?) & no pipe on exhaust
    .100 72/59
    .200 143/113
    .300 215/139
    .400 261/165
    .500 290/186
    .600 306/204
    .700 323/213
    .800 333/216
    Howards solid roller 7/4 swap
    ADV 314/322
    050 278/287
    200 187/196
    110 LSA/108 int CL
    lobe lift .439/.430
    valve lift .790/.731
    rockers 1.8/1.7
    Weiand 4150 Team G with 2" 4500 adapter
    opened up (still has some venturi) and blended on intake side
    #9375 1050cfm Dominator (stock non-HP style)
    intake has no port work to plenum or runners
    Hooker super comp headers for G-body
    2" x 30" primary
    3 1/2" x 10" collector
    3 1/2" Bullet mufflers

    It should make about 650-700 HP. Shifts will be around 70-7200 RPM. What trans should I use? Any thoughts on what the car might run?

  2. #2
    n20racer,

    That is a nice BBC you have there. In most cases if a car will only see the strip once a month I would usually recommend the Turbo 400. But it depends on what your goals are. If you want 1/4 mile ET's I would go with the P/G trans and that's because your BBC will keep the car in it's powerband from a 1-2 shift and the 4.30 gear is enough where you don't run out of engine with say a 5.13 gear or steeper gear for launching, especially if a 5.13 gear is behind a 350 SBC making 400 HP

    However, that being said the Turbo 400 is a stout unit, it is cheap and it makes a better street trans than the Powerglide. I would go with the turbo 400. :mrgreen:

    I have 4.10 gears in my car now and let me tell you it $*cks over 50-55 MPH. The problem is the GM overdrives other than the 4L80E will have a hard time handling the power you are making.

    Since this is more of a street trans, that stall steep would be crazy high wih a Powerglide and you still could run of out of RPM.

    Just my 2 cents.

    P.S. check out www.turbobuick.com Look at the cars on their home page on the left side. There are five 1980's Buick GN's/T-Types. All five run turbo 400's. Either way is fine, but for your application I like the Turbo 400.

    P.P.S. On my first 1969 Camaro, that car had a P/G from the factory. Nice trans! But eventually it was replaced with? A THM400

    Good Luck!!

  3. #3
    Member JUNIOR BUILDER
    Join Date
    Jan 2004
    Location
    Wisconsin
    Posts
    65
    For your application, the turbo 400 will work the best for you. But you have a converter issue with that 8" BTE. Not the right converter for your application at all. I would call BTE or contact Oldani in the trans section here. He is also a BTE dealer. Either one will help you with the correct converter.

    Looking at your motor specs you posted. That cam is to big for what your doing. The heads are OK, but you will not see any benefit from that big of cam. The heads do not flow enough for that cam! Nor were they designed for that big of lift. They are very porus, and you may pull the stud right out of the boss. You have alot of spring pressure with that big of lift. In this case BIGGER is NOT BETTER. Contact Ed @ edvancedengines in the motor section, or cboggs.

    Dave

  4. #4
    Thanks guys for the replies. I'm sorry that I didn't give more details in the original post.

    The car is for drag racing only. All of my racing will be 1/8 mile. I will be using nitrous in the future. The 8" converter is for HP runs and I have a 9" for nitrous runs. Steve O. and BTE both agreed that this converter would work great on HP. My peak torque should be right around 5500 RPM.

    As for the camshaft, I selected something that would work with the natural RPM range of the rectangle port heads -- 5500 to 7500 RPM. I chose the big lift to get as much curtain area flow as possible to help with the velocity of the big ports. I have a 4340 crank & rods w/ L19 bolts, so the high RPM shouldn't be a problem.

    I have decided to go with the PG. The 4.30 gear should work well on the bottle. I may build another center section and try a steeper gear like a 5.14 or 5.29 for HP runs. This would allow me to have a gear and converter set-up to run HP or nitrous. I don't plan on spraying a ton on it, around 250 HP or less.

  5. #5
    Senior Member MASTER BUILDER
    Join Date
    May 2003
    Location
    Owingsville, Ky
    Posts
    157
    Sounds like you have a pretty good setup to have fun with. With the smaller tires and stock style suspension, I think that the powerglide was the better choice for being able to hook. With that said, you do need to put some upgrades in the trans to make it live. I would suggest the dual ring servo, billet servo cover, kevlar band, hardened input shaft, steel hub for 6-7 clutches, drum drilled with holes under the band, and have the front drum cut for the front roller bearing.

    I think that those heads will work for the naturally asperated up to about the 7200-7300 that you stated, but will be a little small for the nitrous. I am going to take a guess that the ET could be about 10.20's in the quarter and about 6.50 in the eighth.

    Good luck,
    Bill M

  6. #6
    The port volumn of the intake runners per NHRA specs are 323cc stock. With the bowl and shortside work, I'm guessing closer to 330cc now. I don't know for sure as that was never checked. Do you think they are still too small for nitrous?

    I am buying a transmission from a friend. It was built by a local racing transmission shop. It has stock 1.76 planetaries, pro brake, and 8 clutch high gear. It was living behind a 505 in a 2400lb car running 4.90's.

    What do you think about running more gear for 1/8 mile racing on HP. I talked to BTE this morning when I ordered a std length pilot for the converter.The guy told me I could expect between 55-6000 RPM on the stall and that is what they would've recommended if had bought a new one.

  7. #7
    Senior Member MASTER BUILDER
    Join Date
    May 2003
    Location
    Owingsville, Ky
    Posts
    157
    I used to run a 468 with the steel 990 heads that I had reworked some and the flow numbers were similar to yours. The car was 2700lbs and ran 9.50 with tunnel ram and dual 750's. I changed to a set of Dart 320's and was disappointed to only pick up about 1/10th, but the Dart heads were better on the 468 and you have a 481. I did additional work on the Dart 320's and was able to get the 468 to run a best of 9.19. So based on that, I would think that with nitrous you would need a bigger head. It should still run good, but could possibly run better.

    The transmission sounds good. It has things in it that it needs to live. If you are running only 1/8th mile, you could change the gear on up to help move the car quicker. With the 7200rpm, 29.5 tall tire, and figure max of 125mph in the 1/8 (allowing for the nitrous), you could go up to about 5.00. So on the conservative side, I would go with the 4.86. It will have more of a tendency to spin with the steeper gear, but it sounds like you are doing everything right on the car.

    Just some thoughts,
    Good luck,
    Bill M

  8. #8
    real race cars have clutch's. LOL 8)

  9. #9
    Junior Member SHOW GUEST
    Join Date
    Jul 2007
    Posts
    7
    I'm waiting for someone to suggest the built, 200R4..... I've tested Hemi's & 429's w/ 800+ HP with them.... One car is a '66 Dodge Coronet with a new 426 Hemi, and a Mustang with 750 HP.

    Just a thought

  10. #10
    Senior Member RACING JUNKIE
    Join Date
    May 2006
    Posts
    2,044
    I had a friend that built a mid eighties cutlas and put a old 500 cube caddy motor in it.
    He called it the cutlac...lol
    It ran 720's 1/8 . Stock motor with a performer intake, holley carb homemade headers as the only upgrades, that thing had to be making around 500 plus ft pounds torque or more and he ran a welded up 7.5 rearend and a 200R4 trans, ran it that way for four seasons without a single failure. I couldn't believe it.
    ***IN GOD WE TRUST***


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