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1998 4runner trd supercharged recently installed a 2.2 pulley from urd but i dont see more than 7 psi at max rpm there are others who at sea level make up to 9-10.5 psi on the 2.2 pulley. i'm also at sea level and the belt tensioner has maybe 3k miles on it and the belt has pretty good tension and the pulley is brand new i changed the bypass valve butterfly gained 1 psi from 6 to 7 as far as ive checked there are no leaks. i dont know where else to look or what to check the guy i bought the supercharger from said he rebuilt it but it has some play in the pulley shaft front to back and it makes a rattling sound that i do not belive is normal but im not sure if that could play a part with the boost numbers. thoughts?
 

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Mambeau / Admin
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It's conceivable you've got some sort of pressure leakage inside the supercharger body itself, but I'm not sure how you'd go about checking it. The play in the pulley shaft doesn't seem like a good sign to me.

Your 4Runner isn't the original vehicle the S/C was installed on. Was it originally installed on another 4Runner?

Are the folks who allegedly get up to 9 - 10.5 psi gains also running 4Runners with basic URD kits?

As far as I recall URD sold a single basic S/C kit for both the Tacoma and 4Runner back in the relevant timeframe. I'm just wondering whether there were tuning / ECM / accessory differences between the two vehicles that might help to explain your results.
 

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Discussion Starter #3
the supercharger originally came off a Tacoma. As for the guys claiming those boost numbers they also have the 1st gen supercharger with same fuel setup and pulley size as I have.
 

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1998 4runner trd supercharged recently installed a 2.2 pulley from urd but i dont see more than 7 psi at max rpm there are others who at sea level make up to 9-10.5 psi on the 2.2 pulley. i'm also at sea level and the belt tensioner has maybe 3k miles on it and the belt has pretty good tension and the pulley is brand new i changed the bypass valve butterfly gained 1 psi from 6 to 7 as far as ive checked there are no leaks. i dont know where else to look or what to check the guy i bought the supercharger from said he rebuilt it but it has some play in the pulley shaft front to back and it makes a rattling sound that i do not belive is normal but im not sure if that could play a part with the boost numbers. thoughts?
Your asking too much?! Low boost means low. LCengineering highboost Kit only gets 8psi.
 

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Check the accuracy of the boost gauge. Often it's not the supercharger at all but a boost leak to the gauge or an inaccurate gauge.
 

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Hey just thought I’d chime in I have a pulleyboys 2.2” pulley and it generally makes about 7-7.5psi and I’m at 2300ft elevation. I bet it would get up to 8psi max or so if I pushed the engine to its redline. So your not too far off on ur 7psi mark.... remember it’s all proportional to the rpm speed.

just got back from a street tune. Installed an ame AFR gauge and I’m finally tunning the 7th injector system. I was perfectly happy with gadgets “from the factory” tune for a while but I’m getting the itch for more power. Running about 11.3-12 AFR at wot.

I’m considering getting the 2.1 pulley to gain another 1.5-2psi in boost but I think I need the methanol injection for that?
 
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