Flying Finn

Has anyone done write up about it?

I though there was one but couldn't find it...

Randy M

Can someone offer why the RS setup is better? My shop said something about my car needing a belt update so if the RS setup is somehow different and/or better than maybe I would consider doing it as well. <img border="0" alt="[thumbsup]" title="" src="graemlins/bigok.gif" />

Flying Finn

Randy,

This is different that 'normal' belt pulley update.

This will replace two belts with one, resulting that alternator turns slower which gives slighly more hp & responsiveness being lighter.

Randy M

Will this setup keep the battery charged adequately?

Flying Finn

</font><blockquote><font size="1" face="Verdana,Tahoma,Helvetica">quote:</font><hr /><font size="2" face="Verdana,Tahoma,Helvetica">Originally posted by Randy M:
<strong>Will this setup keep the battery charged adequately?</strong></font><hr /></blockquote><font size="2" face="Verdana,Tahoma,Helvetica">It won't charge the battery as much as with the normal system (remember, this is the RS pulley thing not the update I believe your mechanic is talking about) so if you're using lot of appliances that take a lot power, it might 'fell short'.

Robin 993DX

Wouldn't it more simple and cheaper if you just add a circuit to disconnect any charging from the alternator to the battery so that it just free spins when you are at WOT to free up the horse power when you needed?

Flying Finn

</font><blockquote><font size="1" face="Verdana,Tahoma,Helvetica">quote:</font><hr /><font size="2" face="Verdana,Tahoma,Helvetica">Originally posted by Robin 993 DX In Atlanta/Miami:
<strong>Wouldn't it more simple and cheaper if you just add a circuit to disconnect any charging from the alternator to the battery so that it just free spins when you are at WOT to free up the horse power when you needed?</strong></font><hr /></blockquote><font size="2" face="Verdana,Tahoma,Helvetica">I have no clue about that... <img border="0" alt="[ouch]" title="" src="graemlins/c.gif" />

But it seems to me that if you do that you're still spinning that extra weight (even though you're not charging anything) and that doesn't give any responsiveness (which I'm sure is very minimal but still something...) and the main thing: it's not from RS...

Bill Verburg

Bill Gregory(#151) did a write up in this forum in Dec. on the install in his 964. The 993 is slightly different but definitely an easy DIY.

On the 964 the crank pulley is not changed, on a 993 it can be changed or not, your choice. The pieces are a bit pricey so many do not do the crank pulley.

Here is a pic of the setup on my 993RS spec engine

tom_993

</font><blockquote><font size="1" face="Verdana,Tahoma,Helvetica">quote:</font><hr /><font size="2" face="Verdana,Tahoma,Helvetica">Originally posted by Robin 993 DX In Atlanta/Miami:
<strong>Wouldn't it more simple and cheaper if you just add a circuit to disconnect any charging from the alternator to the battery so that it just free spins when you are at WOT to free up the horse power when you needed?</strong></font><hr /></blockquote><font size="2" face="Verdana,Tahoma,Helvetica">Race cars often do just that. In fact, they have a switch to turn off the alternator. Run most of the race with it on, then at the end, if you need a couple extra HP to pass that one guy for the lead, turn it off.

Tom
’95 993

FlyYellow

so there are two things at play here. the first is the RS Hub and the second is the RS pulley down below.

the rs hub will remove a belt from the system.

the rs pulley removes the A/C.

so you can reduce a 3 belt car to 1 by doing both or you can reduce to a 2 belt by just doing either or.

am i wrong here?

cheers,
boris

viperbob

Boris,

Here is a quote from Bill Gregory in December on the subject.

"On the 993, using the RS hub, you can use either the RS crank pulley w/o a/c (993.102.050.40) or RS crank pulley with a/c (993.102.050.41), both using stock alternator pulley halfs, shims, and stock belt on the alternator shaft".

Flying Finn

So the easiest would be leave the crank pulley as it is and just change the alternator pulley. Although then you'd still have some extra mass turning around there...

Thanks guys!

Bill Verburg

</font><blockquote><font size="1" face="Verdana,Tahoma,Helvetica">quote:</font><hr /><font size="2" face="Verdana,Tahoma,Helvetica">So the easiest would be leave the crank pulley as it is and just change the alternator pulley. Although then you'd still have some extra mass turning around there...</font><hr /></blockquote><font size="2" face="Verdana,Tahoma,Helvetica">Yup! The extra mass of the stock 993 crank pulley is negigable.

Sloth

Another benefit of a smaller drive pulley is to allow the belt driven accesories to spin at a slower speed. This helps the accesories last longer in a race car that stays closer to red line. It does reduce the work load on the engine b/c it does not have to work so hard to spin the accesories, but the power increase is insignificant IMHO.

Flying Finn

</font><blockquote><font size="1" face="Verdana,Tahoma,Helvetica">quote:</font><hr /><font size="2" face="Verdana,Tahoma,Helvetica">Originally posted by Sloth:
<strong>Another benefit of a smaller drive pulley is to allow the belt driven accesories to spin at a slower speed. This helps the accesories last longer in a race car that stays closer to red line. It does reduce the work load on the engine b/c it does not have to work so hard to spin the accesories, but the power increase is insignificant IMHO.</strong></font><hr /></blockquote><font size="2" face="Verdana,Tahoma,Helvetica">I also had that in my mind.

To add more to Randy's question: I think if I compare my driving (cruising b/ween 2600-3700 and faster at track, not dragging around in low revs) i.e. typical tiptronic drivers, especially if driven a lot in traffic (very low rpms), with my kind of driving & RS pulley, I'd propably be charging more that tip driver.