SoCal Jet Boats

Tech Talk => Jet Pumps => Topic started by: bigred88 on July 31, 2014, 05:53:46 PM

Title: impeller help
Post by: bigred88 on July 31, 2014, 05:53:46 PM

hey guys gotta newbie question here I've had my boat for couple years now finally blew up so what started out as just rebuild turned into stroker, heads, etc and just having engine built so now I have my first legit non junk yard build engine I wanna freshin the pump i have a 12JG with supposed to be an A I haven't got a good explanation on how to calculate impeller I kno JBP has the calculator but what do I need to kno exactly it's a lake cruz/ local race night boat engine goin to dyno in week or so I kno I need dyno info also I seen a chart does this mean anything to someone that knows what there lookin at? Long post sry guys

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Title: Re: impeller help
Post by: bigred88 on July 31, 2014, 05:59:07 PM

engine is 500 inch 10.8:1 single carb bbc

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Title: Re: impeller help
Post by: Riverrat81 on July 31, 2014, 06:32:38 PM

When you dyno the motor you will know what RPM peak HP is . If you have an A cut already run it at see where it wants to rum rpm wise . If the a. It is not letting it run enough rpm go with a smaller cut impeller if it runs to high of a rpm go with a bigger impeller. You want it to run wide open at peak Hp Rpm.


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Title: Re: impeller help
Post by: Flusher on July 31, 2014, 10:57:47 PM

Make sure you get uncorrected HP numbers.

Also, a bigger/heavier boat will need a larger cut impeller.

Cheers,

Joe

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Title: Re: impeller help
Post by: Blown R/T on July 31, 2014, 11:36:39 PM

Quote from: Flusher on July 31, 2014, 10:57:47 PM

Make sure you get uncorrected HP numbers.

Also, a bigger/heavier boat will need a larger cut impeller.

Cheers,

Joe

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What's the difference between corrected and uncorrected HP?  And why would he want that instead of the other?


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Title: Re: impeller help
Post by: GT Jets on July 31, 2014, 11:45:40 PM

Corrected simply means that the current conditions are taken out of the equation and calculated for sea level. So that being said if the dynomometer is in your "neighborhood" you would have accurate data for how it will run at those actual conditions.

Both numbers are valuable, but the "corrected numbers" will almost always be a bit higher and can bite you in the buttocks if too extreme. Especially if you have a set expectation of what it will do at "home".

GT

Title: Re: impeller help
Post by: Blown R/T on August 01, 2014, 12:30:20 AM

As always, thanks for the info Glenn...  Also, thanks for the info on the races this weekend, hope to see you out there on Sat


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Title: Re: impeller help
Post by: bigred88 on August 01, 2014, 07:31:26 PM

River rat when u say smaller cut is that a B bein smaller than A? I'm gonna see how it acts with what it has now but want the whole combination to wrk so I'm just preparing myself yo buy impeller cause everyone knows how it goes building these things

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Title: Re: impeller help
Post by: Riverrat81 on August 01, 2014, 08:04:46 PM

Quote from: bigred88 on August 01, 2014, 07:31:26 PM

River rat when u say smaller cut is that a B bein smaller than A? I'm gonna see how it acts with what it has now but want the whole combination to wrk so I'm just preparing myself yo buy impeller cause everyone knows how it goes building these things

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AA is larger then an A cut . B is smaller then an A and so on ...


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