Underdrive pulley recommendations?

[Gary H]

I've also got Jakes UD Pulley - 2K miles, 2 track days (Spa and Nurburgring) and no issues. Interestingly I came back with an '03 986s (which I believe has 5bhp more?) Anyway, in a straight line, 50-130, I would pull maybe a car length every time - just about noticeable, but consistently noticeable.
The real difference is now in the in-gear pick-up - it's noticeably more brisk.

[chaudanova]

Originally Posted by Gary H

I've also got Jakes UD Pulley - 2K miles, 2 track days (Spa and Nurburgring) and no issues. Interestingly I came back with an '03 986s (which I believe has 5bhp more?) Anyway, in a straight line, 50-130, I would pull maybe a car length every time - just about noticeable, but consistently noticeable.
The real difference is now in the in-gear pick-up - it's noticeably more brisk.

You mentioned comparison to an '03 S...what model is your car?

Also, have you noticed any (even if slight) side effects during street driving with all accessories on?

[jhandy]

ok, here is what i have seen with my car. It may be different with someone elses...

The battery does not get a good charge with the 4inch pulley on short rides and at idle. I have accidently run my battery down by playing my radio while in the garage, and the car can drive fine, start fine, but if the battery is already crap, then the alt does not seem to recharge it quickly.
Now if I am not stupid and keep my battery to start the car and nothing else, it does just great.
There is no bad side when driving with all electrics on. I have measured the output while driving and at 1000 RPM and greater the charge is 14 volts.

So there is not a downside to a 4 inch pulley that i can see. Just dont run your battery down with the car off.

So... you meant an underdrive and a larger steering pump? why would you do that? I have not noticed any downside to the steering.

[chaudanova]

Originally Posted by jhandy

ok, here is what i have seen with my car. It may be different with someone elses...

The battery does not get a good charge with the 4inch pulley on short rides and at idle. I have accidently run my battery down by playing my radio while in the garage, and the car can drive fine, start fine, but if the battery is already crap, then the alt does not seem to recharge it quickly.
Now if I am not stupid and keep my battery to start the car and nothing else, it does just great.
There is no bad side when driving with all electrics on. I have measured the output while driving and at 1000 RPM and greater the charge is 14 volts.

So there is not a downside to a 4 inch pulley that i can see. Just dont run your battery down with the car off.

So... you meant an underdrive and a larger steering pump? why would you do that? I have not noticed any downside to the steering.

Hmmm, interesting feedback. So for short rides, do you find the battery doesn't get sufficient charge to the point where you might have problems starting the car afterwards, and how long do you mean when you say that the alternator doesn't seem to recharge it quickly?

And with the car off, how long does it take for you run your battery down now? Say you're waiting around, and have the car off, with the radio on. Are we talking like 15-20 minutes of that and the battery gets depleted, or much longer periods?

Yeah, from my understanding, the underdrive system... for the crank pulley, underdriving is accomplished with a smaller diameter (than stock) pulley. On the other hand, for accessory pullies, further underdriving of the power steering pump, for example... is actually accomplished with a larger than stock diameter pulley, rather than a smaller diameter. It would take more linear belt movement for each single rotation, and thus each engine revolution it turns less times than it would compared to stock. Hope that makes sense...

[Steve Tinker]

I installed the Raby pulley 6 months ago and have not encountered a single charging problem. The pulley unit fitted easily, gives more power at the rear wheels and runs the accessories quieter than the original !!
You have to ask yourself how often do you run the electical system @ 100% + capacity, at low engine revolutions (less than 1000 rpm) for long periods with a questionable battery.
If you answer NO to 3 of the above questions, you won't have a problem with the Raby pulley in real world driving......

[jhandy]

the pulley works fine and there is no noticable electrical problem.

One time while sitting at idle, I was on the phone and charging it , heater going, heated seats, lights and radio and after 20 mins, the car started to sound like it was going to stall, so a little tap on the gas and problem solved. Has not happened again.

My car, at idle, makes ~13 volts with electricals off. Before the pulley it was ~14.5.

at speed, it now makes ~14, and before at speed, ~15.

All that i have noticed, after buying a new battery, is that if I leave the lights on for ~15 mins, or play the radio for ~45 min, the battery has a hard time starting the car and some times does not.
If I drive a little, it is not noticeable, and the car seems to recharge it, until I do it again.
However the performance gains far outweight any issues.....