New Buildup! 448ci STG 2 SE Hyd roller.. an MPG motor

Discussion in 'Street/strip 400/430/455' started by Jim Weise, Jul 27, 2012.

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  1. elagache

    elagache Platinum Level Contributor

    Rear-end ratio intended for MPG (Re: 448ci STG 2. an MPG motor)

    Howdy SilverBuick, Jim, Bob, and V-8 Buick assertive engine fans, :3gears:

    Uh well, right now there is a 2.78 ratio differential that came from a donor Pontiac Tempest because the whole rear end housing was damaged and leaking. However, it wasn't intended to be permanent.

    The plan is to upgrade this to a positraction differential to cope better with the torque. Last time I checked the numbers I was still hoping to go to a 3.08 ratio . . . because, that would keep the engine RPM down and allow for better fuel economy. . . . . . .

    That is the goal in this case - remember? :grin:

    Thanks Jim for answering this question. I have to admit I was also curious about the difference.

    Although in this particular case sticking to the STG 2 heads results in a huge performance advantage . . . . cuz otherwise the darn engine won't fit in the car with the exhaust headers!! :Dou:

    Cheers, Edouard :beer

    P.S. Stay tuned for the inevitable . . . . *SURPRISE* we found something that doesn't work!! :error: questions which I'm sure will come once the engine installation gets underway!!
     
  2. Edouard,
    I have a set of 3.08 gears and a posi carrier that will fit your wagon if interested. Bob
     
  3. LARRY70GS

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

    Doesn't the goat have a 2004R? That will make final drive 2.00, about 1500 RPM at 60 MPH. I think I'd want more like 3.23 or 3.42's Edouard, is the biggest priority gas mileage, or do you want to have fun at the track at some point?
     
  4. elagache

    elagache Platinum Level Contributor

    Need to review rear-end situation (Re: 448ci STG 2. an MPG motor)

    Hi Bob, Larry, and V-8 Buick rear-end experts,

    Well, I might . . . . but I haven't gotten that far ahead to confirm I want the 3.08 versus the 3.23 . . . as an example:

    Uh well, not exactly . . . there is a 200-4R sitting on the floor in Orinda Motors collecting dust!! [​IMG]

    Actually, we've had this discussion before and there is a nagging problem I haven't had a chance to look at again. I started this project simply trying to restore the car. So the car has really wimpy tires on it (205/70R14.) Worse I put on beautiful Buick Rally 14" wheels . . . not knowing better. :( I can probably be talked into replacing the tires, but the rally wheels . . . I don't think so!! :bla:

    With the existing tires the RPM at about 65 mph ends up at about 1700. However, you've given me a recommendation for better tires and I've looked into it but . . . . to be honest have lost it! :Dou: So I need to go back and try to find this. It was one of the threads I lost during the V-8 Buick forum software upgrade last winter.

    So Bob you do you see my reluctance to jump on your rear end? :Do No:

    Afraid I'm missing the "drag racing" gene . . . I'm just not the competitive type and speeds does nothing but give me fear. So I'm not trying to get any drag-racing capability. However, I would like to give the car a reasonable towing capability and the tires on the car now clearly won't do.

    So I need to look back into all these things again. Larry if you can recall off the top of your head what you suggested for 14" rims that would give me a start!

    Thanks, as always, for all the help!! :TU:

    Cheers, Edouard :beer
     
  5. LARRY70GS

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

    P225/70R-14 closely approximates a G70-14. It is 26.40" tall. With the 2004R, and it's .67 overdrive, you get 3.08 X .67 = 2.06, and 1573 RPM at 60 MPH in lock up

    ...............................................................................................................................................................3.23 X .67 = 2.16 and 1649 RPM

    ...............................................................................................................................................................3.42 X .67 = 2.29 and 1749 RPM
     
  6. D-Con

    D-Con Kills Rats and Mice

    Hey Larry, if Eduard uses 3.08's, what will the car's speed be at 6000 RPM in OD?
     
    Max Damage likes this.
  7. over the legal limit :Brow:
     
  8. TheSilverBuick

    TheSilverBuick In the Middle of No Where

    I wouldn't be afraid of 3.23's, particularly with towing in mind. I did some fairly light towing (my little camp trailer) with 3.08's, 26" tires, .64 OD and 25%-30% less HP/TQ potential and it towed just fine even through the hills, though I did down shift to 4th a few times just so I didn't feel like I was lugging the engine.
     
  9. LARRY70GS

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

    Just solve the proportion, 1573/60 = 6000/X

    X =228.86 MPH.:laugh:
     
  10. BillA

    BillA Well-Known Member

    Re: Rear-end ratio intended for MPG (Re: 448ci STG 2. an MPG motor)

    Uh well, right now there is a 2.78 ratio differential that came from a donor Pontiac Tempest because the whole rear end housing was damaged and leaking. However, it wasn't intended to be permanent.

    The plan is to upgrade this to a positraction differential to cope better with the torque. Last time I checked the numbers I was still hoping to go to a 3.08 ratio . . . because, that would keep the engine RPM down and allow for better fuel economy. . . . . . .

    That is the goal in this case - remember? :grin:

    Edouard,
    Aren't you going with a 2004R tranny? If so you might want to go with a numerically higher gear in the rear. I'm turning about 2,000 RPM at 70 MPH in my car and that is with a 3.73 gear and 26" tall tires. With a numerically lower gear my cruising rpm would be below the range of where the cam is making power, especially at speeds below 70. Make sure you consider that when selecting a gear. Of course, you could always leave it in 3rd gear but that defeats the purpose of an overdrive. Also, a 2004R can be sensitive to cruising rpm. If too low it can buck and surge as it decides if it wants to be in 3rd or 4th gear.
     
  11. elagache

    elagache Platinum Level Contributor

    Tires and lowest "safe" RPM? (Re: 448ci STG 2. an MPG motor)

    Howdy Larry, Adam, Bob, Silver Buick, Bill, and V-8 Buick RPM calculation specialists,

    Ah, this is indeed where I remember the previous discussion and the problem I ran into therein.

    A P225/70R-14 is a rare beast. The only one that I could come up with in a relatively short Internet search was this: BF Goodrich T/A RWL - 225/70R14. That wouldn't be my first choice for the admittedly vain reason that I was hoping to stick to more period authentic whitewalls (for the homey wagon look.) Anybody have a better source for particularly unusual tires?

    The largest whitewalls I found find at Coker were these: BF Goodrich 3/8 Inch Whitewall - 215/70R14. If I crunch the numbers right, those are 25.9" tall. However, when I run the RPM calculations, I'm getting larger numbers than you're getting for the P225/70R-14 :error:. I just checked my spreadsheet and it looks okay. So how do you crank out them RPM numbers Larry? :Do No:

    Another reason I was aiming toward 3.08 versus the 3.23 with the small tires I've got now was to take into account the tire compression under the weight of the car. If you assume the tire radius is reduced by 5%, that's enough favor the 3.08 (at least if my computations are correct.)

    All this raises another question that Bill was nudging me about:

    So where is that magic lowest reasonable RPM where the engine would be still providing sufficient torque and horsepower to be comfortable, but still save as much fuel as possible? As I understand it, Overdrive is literally for cruising - the engine shouldn't be producing a lot of power - just enough to overcome mechanical friction and aerodynamic drag.

    Jim describes the cam as:

    The dynamometer graph (from Jim's post) is way beyond the cruising RPM ranges suggested here but sure hints the engine can run comfortably at low RPM:

    [​IMG]

    I've never found the car to really be a slug and the stock engine could only do 210hp tops.

    So my instinct remains to go as long a rear end ratio as I can safely get away with. Since this engine produces oodles of torque, the best way to save gas it of have it work harder each turn so that needs to turn less per mile.

    Any pearls of wisdom on this one? :Smarty:

    Cheers, Edouard :beer

    P.S. What speed would you'all take as your base-line cruising speed? 65mph is now fairly standard in the USofA and there are considerable stretches were 70 is legal. On California's freeways, you'd better be doing at least 65 . . . or your a roadkill waitin' to happen!! :eek2:
     
  12. LARRY70GS

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

    That engine will make enough torque to deal with the 2.06 final drive.


    RPM= 336/tire height X Final gear X MPH The 2004R has a .67 OD The 3.08 will be 3.08 X.67 = 2.06

    Your P215/70R-14 is 25.85" tall

    336/25.85 X 2.06 X 60 = 1606 RPM

    BTW Ed, this engine will scare the crap out of you the first time you lay into it, no matter how you gear it.
     
    Last edited: Jul 31, 2012
    Max Damage likes this.
  13. Jim Weise

    Jim Weise EFI/DIS 482

  14. D-Con

    D-Con Kills Rats and Mice

    If you're planning to travel about the west, I wouldn't target a cruise speed of less than 75, and you might keep up at that speed in much of CA. As for using the 3.08 with the OD, my friend's 87 Cutlass with I think the Olds V8 came stock with 3.08 gears and the 200-4R and I know you have way more torque than a 307 Olds! He traded me for my 2.41's! (I think he decided that was too much afterward).
     
  15. elagache

    elagache Platinum Level Contributor

    Started new thread on rear-end question (Re: 448ci STG 2. an MPG motor)

    Hi Larry, Jim, Adam and V-8 Buick assertive engine lovers,

    Uh, I made a mistake and actually measured the tire height and that opened up a new can of worms . . . Rather than further hijack this thread, I decided to start a new thread: Which rear end (and tires?) for my JW powered 65 Special Wagon? Please do continue helping me out of this puzzle!! :pray:

    *GULP*!! :eek2: That's what I'm afraid of!! I sure hope the Orinda Motors fellow can manage to get the car out of the shop without breaking anything. I've had my fill of body work! :rant:

    Cheers, Edouard :beer
     
  16. TheSilverBuick

    TheSilverBuick In the Middle of No Where

    A couple months ago I started a thread about lift and longevity because I was thinking about getting a new cam to pull my RPM power band down below 5,500rpm by reducing duration (and then increase lift while I'm at it), and looking at this engine's cam I like what I'm reading! My current cam has 232* @.050 duration on the intake and exhaust, and this engine's at 215* @ .050", that's a heck of a reduction whill having around .05" more lift, which put's it in the ballpark I was thinking of. I was told "Lift" for horsepower and "Duration" to increase RPM. A friend of mine recently built a 454 Chevy with what he called "an all lift" cam for his '70 Caprice to make a torque monster. I might get a new cam and some roller rocker's for Christmas =P


    Again, thank you Edouard and Jim!


    http://www.v8buick.com/showthread.php?249048-Going-high-miles-with-a-high-lift-cam&highlight
    (I thought I had more responses on this thread, I guess I got more info from PM's with pmueller, another forum and from some people I've talked too including Jeff Smith at CC)
     
  17. pmuller9

    pmuller9 Well-Known Member

    Don't forget that half the magic with the cam Jim chose for Edouard's engine is the matching port and chamber work.
    A lot of attention around the bowl area to help with the high velocity that the high lift is trying to develop.
    Also higher lift is less of a problem with the aluminum heads because they have hard valve seats.

    Paul
     
  18. TheSilverBuick

    TheSilverBuick In the Middle of No Where

    You've also got me thinking about porting for Christmas too... With it getting painted I'm running out of things to do to the car :Dou: j/k!
     
  19. TheSilverBuick

    TheSilverBuick In the Middle of No Where

    Jim, what timing did you settle on? 32*? 34*?
     
  20. Jim Weise

    Jim Weise EFI/DIS 482

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