You have a 7" crank pulley? SOS kits come with a 5.45"

So (5.45/4.5)*3.61*8400=36,725

I'm running (5.5/3.0)*3.61*8400=55,500

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No, I have a 5.45" crank pulley. camuman was asking a general question.

 

Shouldn't the gear ratio should be 3.45?

 

Shouldn't the gear ratio should be 3.45?
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I was just assuming 3.61 was correct...I always look at my email from me to SOS when figuring out max rpms.

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Unless I heard incorrectly from Paxton over the phone, the internal step ratio for the 1200 is 3.61:1.

 

I'm a bit confused at the max impellor speed and max psi the 1200 is rated for. Paxton says this blower is good for 21psi, yet if your seeing max impeller speed at just 16psi, what’s going on? Why are the two ratings not lining up? I realize psi is relative rather then absolute like an impellor speed, but 16psi is quite a difference. I'm trying to decide which blower to upgrade to 1200/1500 to get 500+ whp wile having the least parasitic loss and efficiency over the entire rpm range. The new 1200 blower appears to be more efficient, the 1500 is rather outdated at this point, but Paxton says the 1500 good for 26psi, yet an even lower impellor speed at like 52k if I remember correctly, so with my long winded example here, how do these figures correlate with one another? I plan to max out the psi on what ever blower I get, but not if I’m being limited by the impellor speeds.

 

The way I understand it. Our motor is way more efficient air pump then the typical motor. So psi ratings can't be looked at for generic stuff like that.

His belt is slipping up top. He said he should see 18 psi at redline. I can see 3 psi loss cause of our motor eating air better then others.

 

I saw 18psi on my f22 with a 3.0" and 22psi with my RR 2.8" so I don't know why others only see 16psi

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I see, so stick with common thought and aim for max impellor speed and what psi I get is what I get....

I thought there was a few guys running the 1200 in the 20-22psi range though, maybe they were over spooling? I'm going to be running a 9:1 comp motor if all goes to plan, so I’ll likely see even less boost.

 

Were you over spinning the blower with the 2.8"?