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Shot me 3 deer!!!
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hey all,

I was just reading on the FJ and found this post.

I'm quoting.

"The formula is simple and I'll explain it for my PowerWorks blower on my SVT because I know exactly what the specs are. It will translate whatever size pulley you use on a JRSC.

On my SVT the stock crank pulley is 5.2" in diameter. The PowerWorks blower pulley is 2.8" in diameter.

Multiplying diameter by pi gives you circumference.

5.2 x 3.14 = 16.328. The crank moves 16.328 inches of belt per revolution.

2.8 x 3.14 = 8.792. The blower needs 8.792 inches of belt to turn it one revolution.

Now we find out how many revolutions of the blower we will get when we turn the engine one revolution. Simple gear ratio.

16.328 / 8.792 = 1.857142. The ratio is 1:1.86 roughly.

Now we want to find the blower rpm at a given engine rpm. So we multiply the ratio by engine rpm. I'll use 7000 engine RPM.

7000 x 1.857142 = 12999.994

So at 7000 RPM my PW blower spins 13000 RPM with a stock crank pulley and a stock blower pulley.


Class dismissed.



-edit-

I gave you guys the lengthy version. You can also just divide the crank pulley diameter by the blower pulley diameter and multiply by engine RPM. Same answer. But it's intersting to do it my way because them you can determine belt speed. At 7000 rpm, a stock SVT moves 9524 feet of belt length per minute. That's pretty close to two miles.

Before I forget, there is no linear correlation between blower speed and manifold boost pressure. There are WAY too many variables to calculate that with good accuracy."

anyways, the JRSC max rpm is suppossed to be 16000 rpm w/o overspin, so by these calculations, you get.

BBK w/ stock crank pulley. diameter of stock crank pulley is 5.1875 in. and bbk pulley is 2.5 in. so 5.1875/2.5 = 2.075 so at max power for the jrsc, you get 16000/2.075 = ~7711 rpm

BBK w/ 5.7 inch dia. OD crank pulley = 5.7/2.5 = 2.28 so 16000/2.28 = ~7017 rpm.

so is my logic correct here? i may have pulley sizes off but i did some searching and i found those numbers.

so i can safely go w/ a 5.7 OD pulley and be fine?? of course this is w/ a proper tune.
 

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Shot me 3 deer!!!
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Discussion Starter #2
o, and this is assuming the IAT temps are safe!!! this is only the idea about overspinning the sc!! i will be using WMI.
 

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You wont be able to haul enough WMI to keep it cool.

You can spin the JRSC to stupid rpms but your never really going to make any more power due to its small size, inefficiency and lack of cooling.... basically when you start to overspin the JRSC it just becomes a heat machine.
 

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Shot me 3 deer!!!
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Discussion Starter #4
i thought the jrsc started overheating w/ the need for wmi at 16k, not w/ just the bbk.
 

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So you think the 2.4" snout pulley w/ the CFM 5.7" crank pulley @7k RPM would be too much for the PWs?
 

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Oscar once told me that the SVT JRSC/BBK had a little head room before it would be at max efficency and that the ZX3 JRSC/BBK had no head room and should not be spun any faster. He also touched on his thoughts about WMI and how he thought the water molecules took up volume that does not compress like oxygen. Like Orange said, overspin equals heat machine, equals blown motor.
 

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Shot me 3 deer!!!
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Discussion Starter #7
god i wish there was an intercooler for the JRSC!!!! lol
 

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I've been researching an intercooler for the (SVT) JRSC on and off for a little while now... nothing concrete yet, though.

As I mentioned on FJ, the Powerworks kit and the SVT JRSC kit both use Eaton M62 blowers, but the JRSC/BBK pulley is 3", and the Powerworks kit is available with a pulley all the way down to 2.4". It seems that even Oscar agrees that there's room to spin his kit, and I think that's proven with the Powerworks. All that's needed is sufficient cooling.
 

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Shot me 3 deer!!!
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Discussion Starter #9
ya, but unfortunately, there isn't much in the way for the m45 other than WMI!!
 

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Even though the JRSC and Powerworks are M62 blowers, they are not the same. The JRSC is a version 4 and the Powerworks is a version 5. Each version has about 10%-15% improvement over the previous version. I`m hoping that Eaton makes a direct replacement for the M62 with their newest line of blowers.
 

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god i wish there was an intercooler for the JRSC!!!! lol
couldnt you just buy an intercooler and get some piping fabed up? in my mind thats all you would have to do, but i havnt even seen a JRSC in person so it might not be doable.
 

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The blower sits directly on the intake manifold... you'd have to fabricate an intercooler unit between them (requiring a longer belt and bypass tube), or integrate cooling tubes into the manifold itself. I'm looking into the second option.
 

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yea you should really take a look at one because that is absolutely impossible. Its a roots blower, it sits ontop of the intake manifold. The only intercooler possible would have to be an air to water unit that sat between the blower and the intake mani.
 

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ah you beat me!
 

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It's not impossible to do air-to-air with a front mount; just highly impractical.
 

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lol that would be some kind of weird contraption. would there even be space under the hood to get two sets of pipes between the jrsc and the IM. Either that or relocate the blower altogether....
 

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Weirder things have been done. I'm pretty sure someone even attempted it on a Focus using an M90... never finished, I believe.
 

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Supercharged
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What about a top mount intercooler? We actually have 8-10" of room between the blower and the hood
 

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The blower sits directly on the intake manifold... you'd have to fabricate an intercooler unit between them (requiring a longer belt and bypass tube), or integrate cooling tubes into the manifold itself. I'm looking into the second option.
That's exactly what they do at LHT, I know they've been around for awhile and I believe are still in business. Granted they seem to only do Honda kits but I'm sure it could be adapted to our kits.

http://www.lhtperformance.net/Superchargers/Parts/intercooler_pics/interc.build.html


Also, anyone remember what happened to Frush? I believe he was pushing like 16psi and didn't even make 20whp more than the regular BBK.
 

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Supercharged
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That's exactly what they do at LHT, I know they've been around for awhile and I believe are still in business. Granted they seem to only do Honda kits but I'm sure it could be adapted to our kits.

http://www.lhtperformance.net/Superchargers/Parts/intercooler_pics/interc.build.html


Also, anyone remember what happened to Frush? I believe he was pushing like 16psi and didn't even make 20whp more than the regular BBK.
Yes, his engine puked oil all over itself...[vommit]
 
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