single pulley worth it on 3.6 conversion?

[MuffinMan]

I'm planning some of the last details on my 3.6 conversion, which leads me to the "single pulley" debate. I've read that it spins the alternator slightly slower, yielding a small gain in power. It's also lower rotating mass, which should help, as well. The 993 cup cars have single pulleys.

Nevertheless, is it worth it to do this mod? It's ~$129 for the part, and I'm told a few hours of labor. Words of wisdom are appreciated.

[MuffinMan]

doh! I just found the archived thread discussing this:

pulley thread

[Mike Feinstein]

Opted for single pulley at alternator only. Cleans things up a bit too.

[Embs]

If you don't have a single pulley conversion and you lose a belt, YOU could be in big trouble because your engine could cook quick and the belt minder (if still there) is dead.

[Embs]

So Mike, how fast are you going when you hit the redline in 1st? Or does it happen so quick that you don't really know.....

[Mike Feinstein]

You know....I knew someone had asked me that and by the time I checked, I had forgotten who it was. Thanks for reminding me. Hard to be exact but it was around 37 mph. Gearbox is G50 with 8:31 r and p. Why do you ask? Is yours much different?

Also, looking at your engine pic, is that the vacuum canister for the Vram mounted near the rear left bracket (presumably where the heater blower once lived)? Looks better than having it tie wrapped to the intake spider like mine. Any problems relocating and mounting it there?

Not sure I understand your explanation about the single pulley setup being better for avoiding catastrophic engine damage in the event of a broken belt. Please explain. And, am I safe in assuming that the inside belt is 10mm x 776mm (need to get a spare)?

Could have PM'd but thought others may be interested in your setup.

[Embs]

Originally posted by Mike Feinstein
You know....I knew someone had asked me that and by the time I checked, I had forgotten who it was. Thanks for reminding me. Hard to be exact but it was around 37 mph. Gearbox is G50 with 8:31 r and p. Why do you ask? Is yours much different?

I am close to 45-50 before I have to shift into 2nd. 915/67

Also, looking at your engine pic, is that the vacuum canister for the Vram mounted near the rear left bracket (presumably where the heater blower once lived)? Looks better than having it tie wrapped to the intake spider like mine. Any problems relocating and mounting it there?

None at all, made a bracket and put it there

Not sure I understand your explanation about the single pulley setup being better for avoiding catastrophic engine damage in the event of a broken belt. Please explain. And, am I safe in assuming that the inside belt is 10mm x 776mm (need to get a spare)?

before the single pulley conversion, one belt turned the fan and one the alternator, the fan spun on it's own sealed bearing. If that belt would have broken you wouldn't have known via indicator. With the single pulley conversion, the fan and alternator are connected and turn together and if your belt breaks your alt light comes on.

[Bill Verburg]

I did both on mine, its only money and the Porsche gift certificate took most of the sting away. I agree that for a t/p where the belt minder light isn't hooked up it's a nice safety measure.

[Mike Feinstein]

Bill and Todd,

Looks like both of you have a clean looking spacer to replace the outer alternator pulley. Did you fab this, or is it available somewhere? Dr. Timmins used a couple of spacers on mine.

Also, is that belt 10 x776mm?

[Bill Verburg]

Mine top and bottom are the factory 993RS parts.

[Embs]

I used Patrick Motorsports

[widebody911]

I guess I'm way behind the curve here; looks like it's time to upgrade to a varioram engine!

[Embs]

Originally posted by widebody911
I guess I'm way behind the curve here; looks like it's time to upgrade to a varioram engine!

If you haven't driven one, you won't believe the difference. It really sneaks up on you though especially in fourth & fifth. Without doubt one of the most unique powerbands I have ever experienced. In a way, it's like an electric motor you launch, then before you know it your going well over 100 with no surge, no turbo feel neck snapping stuff. It's really smooth.


I was initially dissapointed with the Vram (I thought) then I looked down at the speedo, felt like I was going about 85 but instead I was going 140.

[code7rpd]

If you have a factory belt the size should be imprinted on it. I found that mine was a 10mm by 776mm and they also make a 10mm by 760mm.

[widebody911]

Originally posted by Embs
If you haven't driven one, you won't believe the difference. It really sneaks up on you though especially in fourth & fifth. Without doubt one of the most unique powerbands I have ever experienced. In a way, it's like an electric motor you launch, then before you know it your going well over 100 with no surge, no turbo feel neck snapping stuff. It's really smooth.

So how is that different than a normal well-built 3.6L?

[Mike Feinstein]

One word.........torque.

[Embs]

Originally posted by widebody911
So how is that different than a normal well-built 3.6L?

I can't think of any other adjectives for the Vram maybe Bill V will provide his insight. All I can say is that you will notice a difference and you will like it.