Pulley Question

[nealskilling]

Hi,

I've recently caught the modifying bug and now I'm saving all my spare pennies to get new parts for my MCS. I've just installed the Promini air intake and I should have a Milltek exhaust soon. After that I'm planning on changing the pulley. I'm not sure whether to go for a 15% or a 19% pulley. Most people seem to have a 15% one, but I would have thought the a 19% offers the biggest bhp gains. Could anyone give me some advice please on which pulley to get and the advantages/disavantages of going for a 19% pulley over a 15% one.

Thanks in advance.

[Keith]

My understanding is that a 15% pulley puts the supercharger near its designed max speed at 7,000rpm. That means a 19% pulley is running the supercharger 4% faster so could be putting more strain on it when you are at the red-line. Having said that, if I was to do it again I would probably get the 19% as I want it for power during daily driving - I am rarely at 7,000rpm so I don't think there is much of a reliability problem.

[bkwalker]

I am looking at doing very similar mods.

keith:
how do you find your car drives with all those mods?
what hp range are you in? about 190?
do you lose traction much?

Thanks

[Keith]

Quote: Originally Posted by bkwalker

I am looking at doing very similar mods.

keith:
how do you find your car drives with all those mods?
what hp range are you in? about 190?
do you lose traction much?

Thanks

I think I am in the 190-195hp range and the car is a blast the drive. The pulley made the biggest difference and is noticable right through the rev range. It is easy to spin the wheels when starting off which makes DSC kill power so turning DSC off is a must for max performance. The sway bar was also a big improvement when cornering hard - no more understeer at the limit.

[AmRov]

I got the 15% pulley, and I am loving it. (I also got a cold-air intake at the same time.) The boost in power was immediately evident, and for under $500 total (installed), these mods were a great bang for the buck! Now my MCS runs like it should. Before, it felt like it was being held back.

I've read elsewhere that a 19% may be too much of a strain on the supercharger, so I was reluctant to go for that one. I knew the 15% had been tried and tested for a long time, with good results. I figured if the 19% later proved to be worth it and safe, I could always change out later...

[bkwalker]

cool!
think im gonna do it!

what pulley and intake did u buy?

[AmRov]

I went for the Alta pulley and intake. So far, great!!

[Mini Tike]

i have a brand new three piece pulley w/belt from mini mania for sale. interested??
e-mail me @ mjwong6@yahoo.com

[MiniTiger]

Quote: Originally Posted by Keith

My understanding is that a 15% pulley puts the supercharger near its designed max speed at 7,000rpm. That means a 19% pulley is running the supercharger 4% faster so could be putting more strain on it when you are at the red-line. Having said that, if I was to do it again I would probably get the 19% as I want it for power during daily driving - I am rarely at 7,000rpm so I don't think there is much of a reliability problem.

Just a technical nit...
The max operating limit of the supercharger is 14000RPM
Eaton Supercharger Model 45

The 19% pulley was designed to operate the supercharger at that limit at engine redline.

The way the 19% vs 15% was explained to me...
If you plan on doing mostly street driving/ racing (for lack of better word) the 19% may be better for you.
If you plan to be on the track a lot or high rev'ing a lot, then back down some on the pulley reduction.

Of course, one of the side effects of the supercharger compressing the air is heat. So if you are constantly rev'ing high you'll be raising your intake temperature. The standard ECU goes into full rich mode above certain point. I don't have exact number, but I did see this effect on my dyno runs (didn't have good fan setup for intercooler). See my thread 19% pulley dyno'ed

A lot of the gains with the pulley are at mid-range RPM'S.

If you are racing on the track, or rev high significant amount of time with 19% pulley, you will most likely force ECU to go full rich and defeat purpose of pulley mod. Go with lower % pulley reduction.

If you are mostly driving on street, and want the little better accel performance for on-ramp, green light go power, consider 19% pulley.

My 30000 cents worth (cost of my pulley upgrade)

[nealskilling]

Thanks MiniTiger, that's really helpful. In that case I think I'll go for the 19% pulley as I'm not planning on taking my mini on the track. I really just want to be able to beat my mates Integra Type R. I think he's got about half a second on me at the moment. Not for long though!!!