Explain: NST Underdrive & MI pulley

[evo165]

Hi all,

Currently I am on NST 10% under-drive pulley. I knew that NST have a problem with customer service etc. So far no mechanical problem on me yet. :biggrin:

I just need to know the exact different on the output of the 2 given pulley.

1. NST 10% smaller than OEM pulley size and light.

Since this is 10% smaller in size, It will reduce the engine load by 10%?

2. MI OEM size pulley. I read that this is a tad lighter than the NST 10% UD pulley.

Since this is OEM size, the loading to the engine is the same BUT just a MUCH lighter pulley? Am i correct?

Overall, what does each pulley can make the driver butt feel? Kindly enlighten...

[BEEF]

The 10% smaller pulley will run all your accessories 10% slower thus reducing parasitic drag on the motor. That being said, your water pump, alternator, and a/c compressor are all running slower than factory. There are gains to be had there but not 10%. I know guys that did this in larger trucks and saw a hp or two of increase but they were dynoing 300+ hp.

The fact that it is lightweight means that it is going to rev up faster meaning it will be more responsive. It is the same concept as doing a lightweight flywheel though the difference is not as significance (since you still have that heavy flywheel in there).

I have always heard that the weight difference is a bigger factor than the size. Some cars are very funny about running the accessories too slow (not sure about the yaris though).

I have the MI pulley myself and am happy with it. If I were you, I would leave what I had on there (unless you notice cracks in it... no seriously, check it). I do know that garm put a lot of effort into designing out some of the original flaws of the NST pulleys as they did have issues cracking and breaking. That being said, I have never owned the NST underdrive pulley so I don't have first hand experience.

hopefully this helps. I know there are guys on here that know way more about this than I do but I figured I would throw out a response.

[cali yaris]

Our pulley maintains OEM size while reducing weight. I like that combination, and I wanted to produce it that way; your accessories all spin according to the way Toyota designed them. Reduced rotational inertia is how you get increased throttle response. "Horsepower" is not the primary benefit of a lighter pulley (or flywheel, same thing but even bigger!)

As Beef says, I have not heard of any cracking or breakage with our design, so I think the changes we made worked. :smile:

[fnkngrv]

are you running or planning on running forced induction?

[evo165]

No sir... Currently i am still on NA set-up... Will stick to NA all the way...

I am asking as i need to know if i change from the NST to MI pulley. Will i be downgrading or upgrading due to the fact that NST is smaller therefore less loading to engine & the MI is a tad lighter than the NST pulley... ;)

[cali yaris]

^ There won't be any noticeable difference; they are both lightweight pulleys. The only difference is in design, and maybe peace of mind. That's an upgrade to my mind. :smile:

[fnkngrv]

Another thing to consider that this point is customer service reachability. I have the under drive pulley from NST. It has worked like a champ for me however in all honesty Mike (NST) is so busy with his business and racing it seems that he has become quite flakey in my opinion. I have called and left him 3 voice mails over the last 2 weeks with no response. Personally if I were you I would pick up the MI item and sell your NST just from a customer support perspective. MI'S shop 9 times out of 10 is pretty responsive on things. If they don't get back to you right away there is usually a solid reason. Not saying Mike doesn't have solid reasons, but his responsiveness has been quite wanting.

[cali yaris]

Anything we can help you with, Adrian?

[fnkngrv]

I will hit you up Garm when I have the chance. Thanks.

[justjesus]

Anything we can help you with, Adrian?

My Christmas Card from MI was lost in the mail !

I have been running the NST pulley for about 4.5 years, no problem. I would totally get the MI version, but I'm too damn lazy to do the swap!

[tk-421]

^^ ditto. :biggrin:

[Astroman]

If my NST pulley ever craps out I'll get the MI version.

[jpmck03]

My Christmas Card from MI was lost in the mail ! ...

Hey, what gives... I didn't get a card from MI either! :confused:


:wink:

[cali yaris]

LOL. Just for fun, we'll do Christmas cards in June this year. Why not, seems like they start playing the music that early now. :laugh:

[evo165]

Christmas card? Nope i never receive anything from MI... ;)