ka24de-r blower/pulley/boost calulations

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500hpKA240sx
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ka24de-r blower/pulley/boost calulations

Post by 500hpKA240sx »

Well its getting close to my blower project to being finished and have been doing some figuring/calculations and just thought I would share what I have come up with and see what you guys think and see if my calculations are accurate. Im going to put up a boost calculator equation and put some info needed for our engines to do the figuring.

also from what I found our valve overlap is like 21 degrees if anyone can confirm or rebut this please pm me and I will make changes.

Boost (psi) = (PR x 14.7 x V / C/2 ) - 14.7 - I

PR is pulley ratio, crank pulley diameter divided by drive pulley diameter. e.g. The stock Jaguar M112 pulley is 3 inches in diameter, therefore 5.5/3= 1.83

14.7 is the pressure of the air we live in, we don't live in a vacuum, we live in 14.7 psi.

V is the volume of the Eaton blower for one rotation. The M90 is 90 cubic inches or 1475 cc. The Eaton M112 is 112 cubic inches or 1835cc. Turn it once and it pumps out 1.835 liters of air.

C is capacity of the engine in cc : 4000 cc for the 1UZ-FE. The C/2 is C divided by 2 - because for one rotation, a four stroke engine is only half way through a complete cycle. When the piston is up the top and starts going down, air and fuel go in, then it gets to the bottom and goes back up and compresses the mixture. That's one rotation. Then the spark plug ignites the mixture and it starts to go down again, it gets to the bottom and then goes back up again pushing the burnt mixture out the exhaust valve and returns to the top to start over again. That's two rotations.

I (capital "i") is an allowance for boost lost due to valve overlap. All engines have valve overlap; the intake valve opens before the exhaust valve closes - the incoming fresh air and fuel pushes out the last of the burnt exhaust gases. The 1UZ-FE has a small overlap of only 9 degrees. Nissan's RB26DETT has 14 degrees, Subaru EJ20 has 16 degrees and the turbo EJ20 has 14 degrees. The allowance is quoted as 5% boost lost for every 10 degrees of overlap. So for the 1UZ-FE at 6 psi boost, perhaps boost loss is 0.05 x 9/10 x 6psi = 0.27 psi lost - it's not much.

KA24DE
crank pulley-Stock 5.875" / blower pulley size ex(2.8")
V-(m62-1035cc) (m90-1475cc) (m112-1835cc)
C-stock KADE 2389cc (bored .02 is 2416cc) (bored .04 is 2444cc)
I-10% boost lost ka24de with 21 degrees overlap

so by using the M90 blower with a .04 over bore KADE and stock crank pulley/2.8 blower pulley......

5.875/2.8=2.1x14.7=30.8x1475cc=45494.5/(2444/2)=37.2-14.7=(22psi)
-boost lost during overlap .1x9/10x22=1.98psi LOST so 22-2=(20psi)


one more lets use the more common M62 blower with stock displacement, stock crank pulley/3.0 blower pulley....

5.875/3.0=1.95x14.7=28.7x1035=29795/(2389/2)=24.9-14.7=(10psi)
-boost lost during overlap .1x9/10x10=.9psi LOST so 10-1=(9psi)


now this does not take in affect of a few things but does give you a close idea of boost. and also this calculator can be used with any blower with any engine as long as you have all the correct measurements from what I understand. so let me know what you guys think and those of you guy running the m62 if you wouldnt mind running your setups with this formula and see if what you get is accurate or not.

websites I used:
http://planetsoarer.com/boost/boost.htm
plus ka-t for our engine specs.
viewtopic.php?t=53160&postdays=0&postorder=asc&start=0

Paul Walker- 1973-2013 Race In Paradise. you will be forever missed
Niys
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Re: ka24de-r blower/pulley/boost calulations

Post by Niys »

Do you have a thread on your build???
bicer9
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Re: ka24de-r blower/pulley/boost calulations

Post by bicer9 »

^^ I agree, id like to follow your build thread if you're making one. Seems like a nice estimation formula though, I'm in the process of piecing components together for a KA-R right now but I'm sure ill be referring to this more often when I start trying to manipulate ratios, so thanks!
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shift_down
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Re: ka24de-r blower/pulley/boost calulations

Post by shift_down »

He has a build thread, its nice one too. Check it out in the picture thread section.
He hasn't been very active lately, but still good info on there.
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