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14-71 questions

  1. #1
    B.A.M aka "Black Azz Mike 396_Ways_To_Spit's Avatar
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    Default 14-71 questions

    How much boost can these guys produce? Do they work well on smaller motors?
    G H E T T O F O E L I F E
    Quote Originally Posted by cave View Post
    They bout shit themselves when yelled in Messican, "No brakes no brakes."
    I showed them all the sticker on the side that reads "Driver Ricky Bobby" They just looked at me and nodded yes yes
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    Some peeps just build it 1 part, 1 week, 1 paycheck at a time

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    They usually are able to make a little more boost than your motor can take. I do like big blowers on all sized motors. I have a 'budget' combination using a 440" Chevy BB and a 14-71 that will run/win in the 8.00 class in a runnerbottom. Yes the offset dist and all the 'up front' costs seem large, but the power and motor life (IMO) is worth it.

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    Half a bubble off jrork's Avatar
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    Hey George. What about for a smaller motor that is not a max-effort type motor? Is there a point where the additional effort to turn a 14 is not worth it unless you're spinning it enough to make some boost to offset? Sorry, crappy way to ask a question of "unless you're spinning a 14 to make X lbs of boost, the parasitic loss of the blower is too great and you'd be better off with a smaller blower?".
    Make sense what I'm asking???

    Sorry for the thread jack Mike....john

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    Senior Member TwinTurbo540's Avatar
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    Quote Originally Posted by jrork View Post
    "unless you're spinning a 14 to make X lbs of boost, the parasitic loss of the blower is too great and you'd be better off with a smaller blower?".
    You nailed it John!!

    Main reason for going with a bigger blower like a 14 is if you are planing on making some big big power or you dont want to spin the blower any harder but want to go with more cubes. More cubes will require a bigger blower to make the same boost at the same drive ratio. In theory anyway, every engine set up is different!

    Travis

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    Thumbs up 14-71's

    A Roots blower should be sized to the engine.

    14-71 vs. 8-71 with the same boost pressure in the manifold. The 14-71 will make a tiny bit more power at wide open throttle. The smaller blower spun faster to produce the same level of pressure has more air leakage than the bigger blower turning slower. This additional leakage heats up the air/fuel charge a little bit.

    The 8-71 will work better down low and through the mid range RPM. It will respond to throttle better and build torque faster.

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    With our blower shop hi-helix 14- 71s and billet inner coolers on our Dart headed 565ci mills we have seen as much as 16 lbs and have now run an honest 14 lbs on pump gas and methanol injection for several seasons.
    18% over driven.Busted several dry sump 6 drives as well!
    Hope this helps!
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  9. #7
    Senior Member VDRIVERACING's Avatar
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    Quote Originally Posted by Wildwarrior View Post
    With our blower shop hi-helix 14- 71s and billet inner coolers on our Dart headed 565ci mills we have seen as much as 16 lbs and have now run an honest 14 lbs on pump gas and methanol injection for several seasons.
    18% over driven.Busted several dry sump 6 drives as well!
    Hope this helps!
    Nice blowers, but I'm puzzled that you still use the Kuhl in-line carb plates... (sorry for the hijack!!!) We found 40HP (dyno) by going sideways directly over the blower opening.

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    Quote Originally Posted by VDRIVERACING View Post
    Nice blowers, but I'm puzzled that you still use the Kuhl in-line carb plates... (sorry for the hijack!!!) We found 40HP (dyno) by going sideways directly over the blower opening.
    Thanks!
    We had the in line carb adapters from another set of engines so we used them.

  11. #9
    Senior Member junkyard's Avatar
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    If a 14/71 putes out 10 lbs of boost and a 8/71 putes out 10lbs of boost are they going to make the same HP? Is the lbs of boost pritty much the same betweetn diferent blower.

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    Pounds of boost is the same no matter which blower you use, a pound is a pound.

    The VOLUME of air changes. A 14-71 will put a larger volume of air/fuel into the engine versus a 8-71.

    The reason for using the larger Blower would be that you don't need to spin it as fast to equal the same boost as the smaller blower.
    At the lower RPM the larger blower will deliver a larger volume of air/fuel equaling the same boost level as the smaller blower.
    Last edited by FLATMVN; 01-28-2009 at 05:14 PM.

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    I like the large blowers for a few 'good reasons'. How much crankshaft power is used to make the CFM and boost. Internal blower speeds VS mechanical heat and harmonics. Low (engine) RPM intake velocity and fuel mixing ability. I see so many guys turning smaller blowers 'way too fast/hard, and some have 'way too small' of a top. (carbs?) No blower will make any 'clean boost' with small carbs. The blower must have a large air inlet on the top to make boost (CFMs) You can spin any blower very fast, but it also MUST HAVE a large enough inlet (carbs, hat, EFI) to allow the blower to make the air flow. "Sizing the blower" (to me) consists of "how much money do you have?" The bigger the better, smaller blowers just limit your CFMs and so too the boost/heat level you can safely maintain. This ain't normally asperated, this is blowers, and I know the big ones work better. If you are going to tell me that you "just want 5 lbs of boost", fine, go big with little/no overdrive. (sizing?) You can always 'slow down' a big blower with good results. BUT speeding up a smaller blower most often leads to 'high intake temps' and 'tune up' problems.

  14. #12
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    Quote Originally Posted by VDRIVERACING View Post
    Nice blowers, but I'm puzzled that you still use the Kuhl in-line carb plates... (sorry for the hijack!!!) We found 40HP (dyno) by going sideways directly over the blower opening.
    Really??? What do you suggest??

  15. #13
    B.A.M aka "Black Azz Mike 396_Ways_To_Spit's Avatar
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    Quote Originally Posted by GFINISHLINE View Post
    I like the large blowers for a few 'good reasons'. How much crankshaft power is used to make the CFM and boost. Internal blower speeds VS mechanical heat and harmonics. Low (engine) RPM intake velocity and fuel mixing ability. I see so many guys turning smaller blowers 'way too fast/hard, and some have 'way too small' of a top. (carbs?) No blower will make any 'clean boost' with small carbs. The blower must have a large air inlet on the top to make boost (CFMs) You can spin any blower very fast, but it also MUST HAVE a large enough inlet (carbs, hat, EFI) to allow the blower to make the air flow. "Sizing the blower" (to me) consists of "how much money do you have?" The bigger the better, smaller blowers just limit your CFMs and so too the boost/heat level you can safely maintain. This ain't normally asperated, this is blowers, and I know the big ones work better. If you are going to tell me that you "just want 5 lbs of boost", fine, go big with little/no overdrive. (sizing?) You can always 'slow down' a big blower with good results. BUT speeding up a smaller blower most often leads to 'high intake temps' and 'tune up' problems.

    Who is this guy????? I like what he has to say I read that 6 times and it makes 100% sense to me!
    G H E T T O F O E L I F E
    Quote Originally Posted by cave View Post
    They bout shit themselves when yelled in Messican, "No brakes no brakes."
    I showed them all the sticker on the side that reads "Driver Ricky Bobby" They just looked at me and nodded yes yes
    Quote Originally Posted by Kyle View Post
    Some peeps just build it 1 part, 1 week, 1 paycheck at a time

  16. #14
    B.A.M aka "Black Azz Mike 396_Ways_To_Spit's Avatar
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    Quote Originally Posted by Wildwarrior View Post
    With our blower shop hi-helix 14- 71s and billet inner coolers on our Dart headed 565ci mills we have seen as much as 16 lbs and have now run an honest 14 lbs on pump gas and methanol injection for several seasons.
    18% over driven.Busted several dry sump 6 drives as well!
    Hope this helps!

    Please tell me more about this methanol injection. My manifold has provisions for nozzles. I wouldnt mind running some water or methanol(small dose). Please tell me more!!!!!
    G H E T T O F O E L I F E
    Quote Originally Posted by cave View Post
    They bout shit themselves when yelled in Messican, "No brakes no brakes."
    I showed them all the sticker on the side that reads "Driver Ricky Bobby" They just looked at me and nodded yes yes
    Quote Originally Posted by Kyle View Post
    Some peeps just build it 1 part, 1 week, 1 paycheck at a time

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