Underdrive Pulleys

 

From: Steve Hazard <SHazard@nhboston.com>
To: e36m3@Mailing-List.net <e36m3@Mailing-List.net>
Subject: [E36M3] U/D Pullys
Date: Tuesday, April 13, 1999 8:01 AM

I had installed last Wend.....Worth every $$$$ IMHO....noticeble increase in torque across the powerband.....I ran U/D's on my last 2 SHO's BTW....The biggest surprise is how much easier it is now to match revs on H/T work....the tach needle JUMPS NOW! No side effects to date.....If you have any questions feel free to EM me.......

I posted the above yesterday to the UUC board....I've done pullys on SHO's in the past with great results.....I understand some of you here on the board preaching going with the lighter flywheel but the labor and cost of that upgrade is quite expensive! IMHO I would wait till it's time to go in there for a clutch anyways...And Yes in my last SHO I had a lighter flywheel also....If anyone on the board is going to the Rockingham auto x this weekend with the Boston Chapter you have an open invite to drive my car......IMHO this upgrade produces results similar to being Sharked......and the engine revs up and down much more freeley....check out this site for dyno results......europeanracing.com/underdrive_pully.htm.................they claim peak HP 12 and peak torque at 23ft/lbs........of course that's at the flywheel......tah tah all

Senior Account Executive
New Horizons Computer Learning Center
5 Old Concord Rd
Burlington, Ma 01803
Direct:781-939-9515
Fax:781-229-9552
E-Mail:shazard@nhboston.com
The Largest Worldwide Computer Training Integrator SM
http://www.nhboston.com


 

From: Brian M Kennedy <kennedy@i2.com>
To: Steve Hazard <SHazard@nhboston.com>
Cc: e36m3@Mailing-List.net <e36m3@Mailing-List.net>
Subject: Re: [E36M3] U/D Pullys
Date: Tuesday, April 13, 1999 10:03 AM

Steve Hazard wrote:
>
> I had installed last Wend.....Worth every $$$$ IMHO....noticeble
> increase in torque across the powerband.....I ran U/D's on my last
> 2 SHO's BTW....The biggest surprise is how much easier it is now
> to match revs on H/T work....the tach needle JUMPS NOW! No side
> effects to date.....If you have any questions feel free to EM me.......
>
> I posted the above yesterday to the UUC board....I've done pullys on SHO's
> in the past with great results.....I understand some of you here on the
> board preaching going with the lighter flywheel but the labor and cost of
> that upgrade is quite expensive! IMHO I would wait till it's time to go in
> there for a clutch anyways...And Yes in my last SHO I had a lighter flywheel
> also....If anyone on the board is going to the Rockingham auto x this
> weekend with the Boston Chapter you have an open invite to drive my
> car......IMHO this upgrade produces results similar to being
> Sharked......and the engine revs up and down much more freeley....check out
> this site for dyno
> results......europeanracing.com/underdrive_pully.htm.................they
> claim peak HP 12 and peak torque at 23ft/lbs........

Make that:

http://www.europeanracing.com/underdrive_pulley.htm

======

A few on this list have *strongly* argued against this due to damaging the accessories by having them rotate too slowly.  I'd like to hear their reply to this:

BMW surely engineered those accessories assuming your typical timid driving, with revs in the 2K-3K range almost all the time.  Or perhaps even ngineered
them assuming people would let the car sit idling at 750 rpm for hours on end. Now if my average engine RPMs is 4000 or more, I should be able to underdrive the pulleys 2x to 4x and still have the accessories turning faster than they were engineered for.  Right?  Aggressive drivers should be able to underdrive the pulleys.

So, my conclusion is that the only side-effect of underdrive pulleys is that you need to be careful leaving your car idling for a long time.  And on that note, would it be possible to reset your idle to be at 1200 rpm without significant negative effects to the engine??  BMW already did similar by having the idle RPM higher when you turn on the A/C -- right.

A few questions questions for those knowledgable about the pulleys:

* Which kits not only change the gearing (underdrive), but also use lighter weight materials for the pulleys??

* Do any of the kits change out the A/C pulley such that the A/C is NOT underdriven or even overdriven???  (I have no desire to underdrive my A/C -- if I am racing, the A/C is off and thus has no effect; when I am baking in Texas summers, I'll gladly give horsepower to keeping my car cool.)

Thanks,

Brian



From: Jim Powell <jspm3@acninc.net>
To: Brian M Kennedy <kennedy@i2.com>
Cc: Steve Hazard <SHazard@nhboston.com>; e36m3@Mailing-List.net <e36m3@Mailing-List.net>
Subject: Re: [E36M3] U/D Pullys
Date: Tuesday, April 13, 1999 10:37 AM

2 things.

Some cars don't drive the A/C off this particular pulley.  It (the compressor) may be unaffected.

Second, voltage sags and such can do damage in quick order.  So, certainly, go out and drive your car hard and get everything to maximum temperature spec.   Then let it sit and idle to cool off with the hood up.  I know I'm NOT the only one that does this. Now you have components at maximum temperature being under driven.  Its your money, do whatever you please.

Just don't tell me that people who make these must be possessed of knowledge to ensure nothing screws up.  BMW should know how to make a profile gasket.   GM should know not to put gas tanks outside the frame rails.  The people who built the Edmund Fitzgerald should have known the keel would snap.  And people who put under drive pulleys on their street cars to go compete should know they're pushing their luck.  And now you do.

If you want to put these on a car that's driven easy and you just want a little more pickup now and then, maybe you won't have a problem.

Jim Powell



From: Brian M Kennedy <kennedy@i2.com>
To: Jim Powell <jspm3@acninc.net>
Cc: Steve Hazard <SHazard@nhboston.com>; e36m3@Mailing-List.net <e36m3@Mailing-List.net>
Subject: Re: [E36M3] U/D Pullys
Date: Tuesday, April 13, 1999 11:13 AM

Jim Powell wrote:

> Some cars don't drive the A/C off this particular pulley.  It (the compressor) may be unaffected.

Some E36M3's do and some don't?  Which ones?

> Second, voltage sags and such can do damage in quick order.

I wouldn't expect voltage sags with a good condition battery and a normal number of electrical accessories.  Now if you are idling your car at night with lights
on blaring your 800watt stereo.... but I don't do that.

> So, certainly, go out and
> drive your car hard and get everything to maximum temperature spec.   Then let it sit
> and idle to cool off with the hood up.  I know I'm NOT the only one that does this.
> Now you have components at maximum temperature being under driven.

This is a good point.  I've noticed that doing that actually results in water temperature rising a bit.  So usually I sit in the car and rev the engine to about 1000 rpm for a while to keep the water pump flowing.  (Maybe two or three minutes.  After that the bulk of the heat seems to have been dissipated.)   Clearly, such procedure will be even more critical if I were to underdrive the water pump.

Brian



From: Steve Hazard <SHazard@nhboston.com>
To: Jim Powell <jspm3@acninc.net>
Cc: e36m3@Mailing-List.net <e36m3@Mailing-List.net>
Subject: RE: [E36M3] U/D Pullys
Date: Tuesday, April 13, 1999 11:31 AM

Jim Powell, I had JC bump my idle up....I see no dimming of dash/headlights with the new idle.....I put 150,000 miles on the last two SHO's with more
aggressive Pulley setup BTW....No accessory damage...1 dead battery at 80K in my 94 SHO because the battery WAS NOT Being charged 100% at idle....both those SHO's had a rev limiter at 8500 ......and both saw the track several times over the years and 3-10 auto x's a year...... Jim this is the 1st time I have to disagree with you.....This is a very conservative pulley setup for the M3.....

 "And people who put under drive pulleys on their street cars to go compete should know they're pushing their luck. And now you do."

 "Then let it sit and idle to cool off with the hood up.   I know I'm NOT the only one that does this.  Now you have components at maximum temperature being under driven. Its your money, do whatever you please."

Jim after lapping an Auto X course, or 20 minutes of tracktime I   do a cool down lap and sit in my car and keep the idle at about 1.2K-1.3K and turn on
the AC......That tends to cool the motor down just fine BTW......

If anything does happen I'm ready to ante up take my lumps and put the stock one back on.....and be the first to tell the boards what happenned.....Somehow I don't think that's going to happen......

Senior Account Executive
New Horizons Computer Learning Center
5 Old Concord Rd
Burlington, Ma 01803
Direct:781-939-9515
Fax:781-229-9552
E-Mail:shazard@nhboston.com
The Largest Worldwide Computer Training Integrator SM
http://www.nhboston.com



From: Jim Powell <jspm3@acninc.net>
To: Brian M Kennedy <kennedy@i2.com>
Cc: Steve Hazard <SHazard@nhboston.com>; e36m3@Mailing-List.net <e36m3@Mailing-List.net>
Subject: Re: [E36M3] U/D Pullys
Date: Tuesday, April 13, 1999 12:24 PM

See comments in **** below:

Jim

Brian M Kennedy wrote:

> Jim Powell wrote:
> >
> > Some cars don't drive the A/C off this particular pulley.   It (the compressor) may be unaffected.
>
> Some E36M3's do and some don't?  Which ones?

*****
I don't know, I was speaking in generalities about BMWs in general.   I've only owned 1 M3 so thats all I could go look at.  I have looked at a couple of other series and some drive the aircon off the main pulley, some don't.
*****

> > Second, voltage sags and such can do damage in quick order.
>
> I wouldn't expect voltage sags with a good condition battery and a normal number
> of electrical accessories.  Now if you are idling your car at night with lights
> on blaring your 800watt stereo.... but I don't do that.

*****
Its not the voltage sag to your cars systems I was talking about.   Its the sag out of the alternator which will be running slow.  this will stress the alternator itself and the regulator.  Both will be at high temperature and you won't be doing it any good.  Remember BMW UNDER BUILT THE FRICKIN ALTERNATOR ALREADY! THAT'S WHY IT HAS AN AIR DUCT.  There now I feel better.
*****



From: Land Shark <lndshrk@xmission.com>
To: Steve Hazard <SHazard@nhboston.com>; Jim Powell <jspm3@acninc.net>
Cc: e36m3@Mailing-List.net <e36m3@Mailing-List.net>
Subject: RE: [E36M3] U/D Pullys
Date: Tuesday, April 13, 1999 12:45 PM

At 11:28 AM 4/13/99 -0400, Steve Hazard wrote:

>I put 150,000 miles on the last two SHO's with more aggressive Pulley setup BTW....No accessory damage...

Your SHO's also have 1/5th the number of sensitive electronic control units that your BMW does.

People.. you have to understand 'murican vs. German mentalities when it comes to engineering.

American: Well billybob: let's see the input voltage could be from 11 thru 16 volts.. so let's overvolt protect it, reverse polarity protect it, regulate it down to 5v just in case, and use 5v as the internal power.

German: Zee input Voltage ist 12.00000v Dumbkopf!!

OK, it's not that bad, but the truth is that the electronics in German cars are much less tolerant of voltage surges and screwups.  Hence jump car == blown DME sometimes!

Hey, it's your car.. do what you want.

Forewarned is forearmed

Jim C.