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OT***AUTO TURBO QUESTION***OT

Discussion in 'Uncategorized Threads' started by Bvr Tail, Sep 20, 2008.

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  1. Bvr Tail

    Bvr Tail Well-Known Member

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    A question for you gearheads out there.......

    My son is playing around with a '86 Monte Carlo, stock 305 engine.

    He got the urge to put a turbo on this thing, and with the help of some friends, has it properly installed and running.

    It has a stock tranny, no added stall converter, but he will change this when he gets the turbo right.

    I know little about these, but it has that terrible "Turbo Lag" on take-off.

    Once it gets about 10 lbs of boost, it really takes off and will light the tires all through 2nd gear, but we need to fix the lag. We can not adjust the waste gate by conventional means. When he stalls it to a point the tires start smokin' and the boost is up, it really screams.

    He wants to get the turbo as close to right before he drops in the new motor and trans,' then make whatever adjustments needed for the new set-up.

    Any help or advice? Drop the X's from the e-mail address, or discuss on here.

    Thanks.....Danny
     
  2. motordoctor

    motordoctor Shoji Tabuchi in Branson

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    make sure the timing is correct. it might be retarded. Try about 12 degrees initial and total about 34 degrees. May have to go more initial and less total by adjusting the distributor like maybe 15 BTDC. You may have to change the weights or stops in the distributor. It is possible that you have the wrong size turbo and not getting it to spin fast enough initially. Converter is wrong--you say--which will not allow engine speed to ramp up fast enough. motordoc
     
  3. M-16

    M-16 TS Member

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    Turbo's will always have some lag due to it use's exhaust to spin and make boost. Some use a short shoot of nitrous to fill the void. You want instent get a blower
     
  4. motordoctor

    motordoctor Shoji Tabuchi in Branson

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    221 has good ideas. you can wrap the exhaust system, turbo and plumbing leading in with insulation wrap to hold the heat in. might be able to get it from summit auto or check someof the turbo sites.
     
  5. TOOLMAKER 251

    TOOLMAKER 251 Active Member

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    Before he drops his new motor and trans in I would suggest he put after market higer strength head bolts in to prevent head gasket failure.
     
  6. StonewallRacing

    StonewallRacing Well-Known Member

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    Check out TurboBuick.com

    Lots of Turbo techies hang there.

    http://www.turbobuick.com/forums/

    SW
     
  7. backfenceata

    backfenceata TS Member

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    Been there,done that. We ran the Buick Grand Nat. turbo in a rear engine dragster(engine supplied by BUICK,) with great sucess. My 16 year old then added twin turbos to his 350 street truck. Soon to follow he went to the race track, of course turbo lag killed him. Short story--add stall converter(3000) and trans brake!!! Is you sons a blow thru ,is the carb ahead of turbo ( terible lag) or presurized (limited to 7 / 10 lbs boast) Let me know what your son intends to do with his car(street,strip or both) and I will be glad to help. Kirk (kirks auto- kirks@hamiltoncom.net) Kirk
     
  8. M-16

    M-16 TS Member

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    221 Heat is a limiting factor for a turbo, but does NOT drive it. A turbo simply is a shaft with a fan blade on each end were the exhaust gases flow [not heat] turns the fan and the shaft turns the 2nd fan to force air into the engine. Yes more gas makes a bigger combustion in turn makes more gases flow and the byproduct is HEAT. The time it takes to get the gas into the engine, combust and get the exhaust gas past the turbo and get it spining to make boost is the lag time.
    Heat is used to determin how much fuel you can put to the engine for more HP.
    Temps over 1400* for much time can/will melt or deform the turbo fins/fan causing failure$$. Also to function properly with a computer controlled fuel system the computer should be reprogramed or chiped for a turbo. As the program for my turbo diesel will send extra fuel to the motor to get the boost up, and also will limit fuel for over boost andif the EGT's go over 1300* to avoid damage. Much better info out their especially in a turbo form over a shooting one.lol
     
  9. Brian in Oregon

    Brian in Oregon Well-Known Member

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    A smaller exhaust turbine impeller and shell will "spin up" faster. Most turbos have the exhaust and compressor matched. But by the time the compressor is fully spun up the engine has relined well before then. Swapping out the exhaust "snail shell" for a smaller one can help spin up the compressor sooner. Most turbos are designed to that they can use different shells on the same impeller. Most turbo makers have charts showing this relationship. One drawback is that a wastegate will have to be properly set up. But when it is, the compressed air charge will be consistent over a larger RPM range.<br>
    <br>
    Delving even further into this, two small turbos are often more responsive than one large turbo. The drawback here is cost and complexity of the installation.<br>
    <br>
    The biggest mistake is using a turbo that's way too large for the engine and vehicle combination. They just become unresponsive at low RPMs. Bigger is not better with turbos.
     
  10. M-16

    M-16 TS Member

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    Very true Brian on biggers not always better. Charts and computer programs have made sizing turbo's properly a lot easier. Plus better machining technogy has made repeatabiliy better and more choices of turbine blades. Seen in the 80's were two turbo's were the same but had 2 diffrent charitoristics[spelling]
     
  11. claybrdr

    claybrdr Well-Known Member

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    This also is OT: never buy a turbo Volvo.
     
  12. M-16

    M-16 TS Member

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    221 here are some FACTS air expands or contracts 1% for each 5 degree's from a 60* base, and also compresses base pressure + 14.4 divided by 14.73 = compressiblity factor. So yes if you flooded the area with cold water and your turbo was at 1300* and it cooled the gases inside to 1000*. the gases would contract thus lowering the volocity of the gases past the turbo blade. If heat was all that you needed though you could put a turbo in a oven heat it and it would spin, but it won't. I tried to keep it basic and still recomend for better info go to a turbo forum not a shooting one.
     
  13. M-16

    M-16 TS Member

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    221 you must work graveyard too! Yes the light under the fan works heat rises causes air to circulate. Yes I agree losing heat to the turbo will lesson the proformance until it gets to 1400*, and now it is limiting you on putting more fuel to the engine or you could ruin the turbo from excess heat.
    [ agree'd] "Oven" if the air entering was low and leaving high heat would cause a draft and air would circulate thus would spin the blades. As the old kitchens used a fan in the chimmely to drive their equipment. A oven has no intake or exhaust just as taking a rosebud tourch to the turbo on the engine will not cause the turbo to spin due to no air curents/ drafts. I see your points do you see mine? In my case I'm looking at the top end in my truck and car and heat limits how much HP I can make. Thanks this shift is going fast to night
     
  14. Quack Shot

    Quack Shot Active Member

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    Heat is only partially right. It is the rapid expansion of exaust gasses that make it work. The more rapid that expansion, the more power you will aquire. Heat is only one part of the story. Changing the housings and rotors can help to decrease the lag, but it would take a lot of trial and error. The turbo's manufacturer should be able to offer some helpful advice and recommendations. Wastegate adjustment might not be a solution, unless it is seriously out of whack to begin with, or a variable device that is way out of calibration. Since you are apparently developing the pressure, it may well be that the wastegate adjustment won't help much for the issue.

    Getting the timing and fuel delivery up to snuff is one part. Check the manufacturer for a recommendation. They have it down to a science. We developed turbo kits for everything from a stock VW to an overbored Big Block. Ran them on the track, street, and water. Engine modifications that would help a naturally aspirated engine's performance may actually inhibit performance with a turbo. A 15 minute conversation with a factory rep would go a long way to getting you pointed in the right direction.
     
  15. M-16

    M-16 TS Member

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    Very true Quack shot. Theirs a lot more info out there today. Had a turbo off of a small 6cyl diesel and put it on a 289 .030 over after a few turbo blade change outs had it working pretty good until a screw from the holley throtle plate came out. Needless to say their went $200 quick. Not a lot of help back then for oddball stuff your pocket book was your guide. Lucky though the motor spit it through and never hurt a valve, piston, or the cylinder. Ran two fuel tanks had the secondarys on racing fuel to stop detenation with 50# boost. Then just ran premium in the main tank for normal driving. I think 221 and I are just trying to say awake on minight shift.
     
  16. motordoctor

    motordoctor Shoji Tabuchi in Branson

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    ok guys. information on this. the new setup for a viper or corvette is twin turbo's in the back of the car and tubing running both ways. they say no lag. but with allthat we are discussing how well does that system work.
     
  17. Bvr Tail

    Bvr Tail Well-Known Member

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    My son has read all of your comments and thanks you.

    He tells me he has the initial timing at 8 degrees BTDC, because he is afraid of burning a piston, with total around 34 degrees.

    He is in the process of building a 350 Turbo with a trans brake, and shift kit, but is a 3000 stall enough?

    Without a lot of trial and error, what would be a good rear end ratio for the 1/4 mile with 30 in. street slicks?

    The temperature stats are interesting!

    Danny
     
  18. motordoctor

    motordoctor Shoji Tabuchi in Branson

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    kick up the timing but make sure to not go over about 34 degrees. it might be that the timing is causing a lag. change the weights to maintain the total. you can buy kits to do that. I used 10 in the distributor which is 20 on the crank and 14 advance. it works pretty good. message me if you need help on the distributor motordoc
     
  19. omahasportingsupply

    omahasportingsupply TS Member

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    TTT for Turbos!
     
  20. steele

    steele TS Member

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    I'm a little skeptical at some of boost you guys are listing. 50#, 125# & 275# are just not realistic in a poppit valve motor. Indy cars are only running 20-22# on alcohol. With 50# boost creates over 150# of pressure on the intake valve of a 2.02 valve. Now add 275# of boost & you have over 850# of pressure, which would easily overpower valve springs, keeping the valves from closing. 5# in a street engine is realistic, 15# maybe, 50# & up, you better get Sasquatch to drive it, because there will be two urban legends.
     
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