Tuning opinions

Discussion in 'PSI Superchargers Tech Questions' started by PROMOD63, Apr 2, 2009.

  1. PROMOD63

    PROMOD63 Member

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    I have a pro mod deal it has a hemi with a littlefield it ran 4.40 on a soft pass with 28% over and 750-800 degree egts and 20 lbs of boost i imagine that i will be changing pulleys to up the boost i need this car to go a low 20 or a high teen which would be the best way to go lean the motor or change the pulley ?
     
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  2. BLOWN INCOME

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    Yes,you can change pulleys but i would get your egt up to around 1000 + ...what rpm at the shift ? What and how old of blower ? How are you leaving the line ?
     
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  3. Mike Canter

    Mike Canter Top Dragster
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    Is that max boost at what RPM or boost at 8000 RPM. Either way that is pretty low boost at 28% OD if that is max. It would suggest that it maybe time to re-stripe the blower which is no big deal. If you re-stripe the blower and get the boost up then the car will lean out and the EGTs will go up. Does the guy that is selling it have some data on past performance on a fresh blower and what the boost was at what RPM and what the EGTs were?

    You should get the serial number of the blower and call Littlefield and make sure that blower does not have the K-8 rotors in it. The K-8 rotors had a horrible habit of cracking and coming apart. When that happens it destroys the case and the blower is trash.

    What fuel pump is on the motor and when was it flowed last?
    How many runs on the rods?
     
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  4. PROMOD63

    PROMOD63 Member

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    I leave at 5000 and shift at 8000 that is total boost the blower is fresh or was supposted to be and it looked fresh it has a 990 pump on it the motor is 540 inches would that make the boost lower?
     
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  5. Mike Canter

    Mike Canter Top Dragster
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    At 8000 RPM I think the boost of 20 lbs is low at 28% OD. Somebody jump in here but I think you should be around 30 to 32 lbs of boost.

    How old is the 990 pump? When was it flow checked last. Ask for the flow sheet.
     
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  6. PROMOD63

    PROMOD63 Member

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    No way to get flow sheet........... Would boost be at this level on a 540 inch?
     
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  7. Mike Canter

    Mike Canter Top Dragster
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    Yes, I lowered it a liitle for a 540 motor. Even if a little off we are talking at least 10 lbs low on boost if that 20 lbs was at 8000 rpm. This is probably why the EGts are low because the fuel system is set up for higher boost.
     
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  8. Flyboy68

    Flyboy68 Member

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    Maybe he's got huge ports! : ) Does your blower have standard or hi helix rotors?
     
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  9. PROMOD63

    PROMOD63 Member

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    It is hihelix rotor
     
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  10. Kevin O'Dell

    Kevin O'Dell Member

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    It is a 14-71 isn't it?
     
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  11. Kevin O'Dell

    Kevin O'Dell Member

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    Mike,
    Was it the K8 or K9 rotors that had the issues?
     
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  12. SoDak

    SoDak Active Member

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    I thought many many k8's were made and a limited amount of k9's:confused:
     
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  13. Mike Canter

    Mike Canter Top Dragster
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    I was under the impression it was the K-8's and the crack along the top half of the lobes where the strips/screws are and then come apart. The K-9's and K-11's are OK. I watched one blow apart during a burnout. It made me a believer of blankets.
     
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  14. G Martin

    G Martin Member

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    20 lbs of boost at 28 over sounds low. We run a 14-71 Mert Hi Helix Retro with K11 rotors on a 518 in fuel headed hemi on alcohol in a funny car. We are getting around 30 lbs of boost at 22% over. The car has a centrifugal clutch so it leaves at idle, shift at about 7800, and goes through the lights under 8000. A friends car with the same K11 14-71 blower is making about 38 lbs of boost at 28% over.
     
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  15. BLOWN INCOME

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    Listen what mike said ! More boost will get your egt's up because it's leaning it out more...the boost is way off ! Our old 10 year blower put out 30 lbs. @ 34 over our new littlefield puts out 42 @40 over all at 8000rpm...8500rpm will or should pick you up around 2 to 3 more..check your serial # and call littlefield...my serial #1996 and its almost 3 seasons old..
     
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  16. secondwindracing

    secondwindracing top alcohol

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    the k8's were a breed of there own..they make 0 as in no parts for them..dave
     
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  17. Les Mellows

    Les Mellows New Member

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    Power ... or Lack of ??

    The boost is way low , You need to investigate other options to get the boost up (it can get expensive ) and yield lower results with a Littlefield . Having said that, there are compensatory changes mechanically you can make to help the engine create a satisfactory power curve to run your 4.1-4.2 range , but i believe ratios and gearing will help also on low power applications .
     
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  18. PROMOD63

    PROMOD63 Member

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    Thanks for all the input!!!! It is very nice to have people with so much knowlage at my fingertips!!! I have lived my life with the idea of surround yourself with great people and i feel as i have hit the nail on the head with all you guys!! I am going to up the pulley and see if that helps if not i will call it super charger problems and work from there......... I do have a 980 whipple setting on the shelf that i bet will cure the low boost problem
     
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  19. Mike Canter

    Mike Canter Top Dragster
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    Changing the OD will not help. It needs new stripes. Take the belt off and see how is it is to turn with your hand. There is probably little to know resistance.
     
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  20. AnimalCrew

    AnimalCrew New Member

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    Mike is right. You won't build much boost if the strips are worn out. That blower should do better. When we ran the Littlefield on our 526, we made 35# at 8000 RPM at 44 over. Replace the strips and see what it does for your boost. That should lean it out some then after you know your safe there, put a smaller pulley on it and dial in your tune. There's a point where the increased boost won't improve performance because it's heating charge. We seemed to be good to about 50 over with our littlefield but the gain between 44 and 50 was minor...

    Troy.
     
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