Underdrive Pulley + Blitz - Toyota Yaris Forums

47_MasoN_47 · 08-21-2013, 09:35 AM

It just occurred to me to ask.. Since I have one of the old NST 10% underdrive pulleys installed, am I also underdriving my Blitz? Would I be better off getting one of the MI OEM sized pulleys to swap in?

CTScott · 08-21-2013, 09:45 AM

Do you have a boost gauge, as that would let you see any effect from the underdrive. The Blitz seems to be internally limited to 6 psi, so the only effect you would see is the boost being developed 10% later.

47_MasoN_47 · 08-21-2013, 09:51 AM

Boost gauge usually shows about .7kpa

So it would just delay the boost slightly rather than giving me 10% less boost? That makes sense actually.

cali yaris · 08-21-2013, 10:28 AM

You are getting less boost, and later. You're S/C pulley is now turning more slowly at all times than it would with an OEM sized pulley. 10% is the diameter. You'd probably have to do some wicked math to convert that to the difference in rpm's.

You should get the MI pulley and enjoy full on-demand boost AND lighter weight with your s/c.

Scott, how is the blitz blower limited to 6psi? I'm unfamiliar with the inner workings I have to admit. We know of at least one user who had a fixed underdrive pulley made for the Blitz, and another had an overdrive crank made for it. Both increased horsepower.

CTScott · 08-21-2013, 10:42 AM

Quote:

Originally Posted by cali yaris

You are getting less boost, and later. You're S/C pulley is now turning more slowly at all times than it would with an OEM sized pulley. 10% is the diameter. You'd probably have to do some wicked math to convert that to the difference in rpm's.

You should get the MI pulley and enjoy full on-demand boost AND lighter weight with your s/c.

Scott, how is the blitz blower limited to 6psi? I'm unfamiliar with the inner workings I have to admit. We know of at least one user who had a fixed underdrive pulley made for the Blitz, and another had an overdrive crank made for it. Both increased horsepower.

I have no idea as to how it is limited, but once it gets to 6 psi the boost gauge never climbs any further. It may be some type of internal wastegate or it may just be something to do with how the paddles work.

47_MasoN_47 · 08-21-2013, 11:50 AM

I'll have to snag one of those MI pulleys. Ugh at having to redo those freaking belts again, lol.

08-21-2013, 09:35 AM	#1
47_MasoN_47 What I thought I'd do was View User's Garage Drives: 09 Yaris Sedan Join Date: Aug 2009 Location: Northwest Alabama Posts: 1,140	Underdrive Pulley + Blitz It just occurred to me to ask.. Since I have one of the old NST 10% underdrive pulleys installed, am I also underdriving my Blitz? Would I be better off getting one of the MI OEM sized pulleys to swap in? __________________ My Nissan Hardbody (D21) 4x4 build log Check out my YouTube channel (mostly shooting) - http://www.youtube.com/user/47MasoN47

08-21-2013, 09:45 AM	#2
CTScott ULTIMATE View User's Garage Drives: 09 5dr LB, 2x 08 3dr LB Join Date: Oct 2008 Location: USA, CT Posts: 13,460	Do you have a boost gauge, as that would let you see any effect from the underdrive. The Blitz seems to be internally limited to 6 psi, so the only effect you would see is the boost being developed 10% later. __________________

08-21-2013, 09:51 AM	#3
47_MasoN_47 What I thought I'd do was View User's Garage Drives: 09 Yaris Sedan Join Date: Aug 2009 Location: Northwest Alabama Posts: 1,140	Boost gauge usually shows about .7kpa So it would just delay the boost slightly rather than giving me 10% less boost? That makes sense actually. __________________ My Nissan Hardbody (D21) 4x4 build log Check out my YouTube channel (mostly shooting) - http://www.youtube.com/user/47MasoN47

08-21-2013, 10:28 AM	#4
cali yaris ULTIMATE View User's Garage Drives: 07 Yaris Turbo Join Date: May 2007 Location: Canoga Park, CA Posts: 14,859	You are getting less boost, and later. You're S/C pulley is now turning more slowly at all times than it would with an OEM sized pulley. 10% is the diameter. You'd probably have to do some wicked math to convert that to the difference in rpm's. You should get the MI pulley and enjoy full on-demand boost AND lighter weight with your s/c. Scott, how is the blitz blower limited to 6psi? I'm unfamiliar with the inner workings I have to admit. We know of at least one user who had a fixed underdrive pulley made for the Blitz, and another had an overdrive crank made for it. Both increased horsepower. __________________ Micro Image forums, online store and shop are now closed. It was a great eight year run, but it was time to focus on other things. I'm still selling parts on eBay under micro*image seller ID and customers can still make requests for anything specific.

08-21-2013, 11:50 AM	#6
47_MasoN_47 What I thought I'd do was View User's Garage Drives: 09 Yaris Sedan Join Date: Aug 2009 Location: Northwest Alabama Posts: 1,140	I'll have to snag one of those MI pulleys. Ugh at having to redo those freaking belts again, lol. __________________ My Nissan Hardbody (D21) 4x4 build log Check out my YouTube channel (mostly shooting) - http://www.youtube.com/user/47MasoN47

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