Underdrive pulley recommendations?
 

I've been wanting to put a new pulley on and wondered if someone can recommend one.
I looked around Flat6 but didn't see anything there. I see a few out there for sale but would prefer a word form someone who has experience with one.
Thanks
Chris

I am still testing our 4" pulley in real world conditions to see how it effects the operation of the charging, power steering and A/C subsystems. Its the smallest pulley on the market and so far has out performed every other I have tested back to back in the performance category.

I have not added them to our site yet because they haven't proven themselves thoroughly enough as of yet. I hope to have them on line by the beginning of the new year.

I have almost 8K on the test pulley in my 996 and 14K on the unit in the Boxster test car.. I want to see how they perform in cooler weather.

That's a very tiny pulley! How cold does it get in GA? I'm in CT and would be dealing with Zero temps sometimes.
Chris

Dragon

you can go to boxsterspec.com and do a search for under pulleys, a lot of the spec boxster guys are starting to use them. One the members, Chris Amond, has his own design that I put on my car and I have been very happy with it so far

I have the RSS UDP. Got it from stuttgartperformance.com Seems to be good.

We see single digits here in the dead of winter, BUT the other cold weather data will be gathered by LN Engineering on their Boxster test car that I built the engine for in March of 09. They will certainly see temps well below zero.

In the heat of the summer this pulley did awesome both on the track and the street.

now what is the threat here with the smaller pulley? the belt will move... slower and so affecting subsystems how?

I installed BBI Autosport's latest light weight UDP. I am very pleased with it. Its difficult to qualify any performance gain since it was installed along with some other upgrades. However, the car feels great, and there is plenty of data to suggest that it adds hp. :)

Thanks for all the replies. I put my stock headers back in and likely my stock muffler this weekend. I never got dyno data but car feels exactly the same. I had the original maxspeed headers. Now it makes the muffler sound lousy so back to stock till I can find a decent PSE. I want the pully and likely Pedro's techno torque instead.

Chris

I am running the Mantis pulley at the moment with no ill-effects save some power steering pump wine on full lock while parking.....It is suppose to give 7hp. I did notice a difference when I first put it on...the engine felt it was now free to give! The car pulled just a bit hard on full throttle...this is all subjective feel of course.

This one works pretty good.
 

Have not had any problems with this 4" pulley.

Chris

Me either ;-0

on a 2.7L 5 speed - would insalling this pulley create a noticeable difference in acceleration? would engine rev up faster... even if just a little bit..would it be enough to notice?

given the relatively modest price of a pulley - it might be a worthwhile mod if it didn't hurt anything and could actually make some gains that could really be noticed...

I guess it depends on how sensitive your butt is. The pulley will add about 10hp.

So far these pulleys have proven to give me the best improvements in real performance. They bolt on more than an ECU flash or a 3,000.00 exhaust system.

I apologize in advance for the newbie question, but is there a noticeable increase in vibration? I threw an UDP on my 4 cylinder commuter and although I was happy with the small power gain, I do notice some resonance in the cabin.

Ques - when you say Underdrive Pulley and HP gains, are you assuming w/o A/C?... or still have A/C connected?

Would there be more HP gain w/o driving A/C?

thanks,

kj

yes no A/C would "gain" you more HP, if you were to remove the whole system also some weight would be lost giving you even more...

however, its more along the lines that you will just have more HP that the car makes already available to you.


correct me if im wrong.

Correct. They pulley does not create horsepower it only reduces the factors that rob hp from the motor. Another way to think of it is that the motor is just an air pump. It sucks, bangs and blows. If you don't change the amount of air it sucks or how big the bang is or how it blows you do no "create" hp.

That said all we really care about is how much hp we have at the wheels not how we get it, and the pulley does work.

... sorry, I asked the question the wrong way. I know it doesn't create HP, I was just surprised at the estimate of 10 extra available to the drive train... that's pretty darn good for just an external pulley change.

I've been thinking about the pulley and instead of full A/C delete, just go with the shorter belt and eliminate the A/C drag from the equation. This pushes me a little farther along.

You're right about the weight, that compressor feels like it weighs 20 lbs. alone... the whole system ought to net 40ish?... no?


thanks,



kj