Toothed belt kit vs Ribbed belt kit

[Fifress]

As the title says, I currently have the 5pk kit with a 61mm or less size pulley, not quite sure.
I have the possibility of buying a toothed belt kit, however, with a 55mm pulley...

How reliable will this be? And worth it?

Price is peanuts like we say here


I know i've been busting balls far too often lately, i do apologize eheh

[kwijibo_coupe]

The toothed belts are better than the ribbed ones as the toothed ones allow no slip at all.
55mm pulley though, that will kill a G40 charger pretty quickly.

[Fifress]

The toothed belts are better than the ribbed ones as the toothed ones allow no slip at all.
55mm pulley though, that will kill a G40 charger pretty quickly.

That's what I feared, what sizes most people use? to max the performance out of the charger and still maintain some reliability

[Jezza-7]

The majority of people use 65mm, myself included.

If i remember correctly someone did run 55mm pulley what was rebuilding it every 3k mile or so. The general guideline for servicing with a 65mm pulley is every 20k however, it can go longer depending on a few things. For one, i ran a standalone oil supply which actually allowed me to take my R1 charger to 25k miles before it needed a rebuild which is considered good. Also i do a lot of drag racing which was included in the use.

If i was going to run a 55mm i would have a spare standard supercharger and run that to see how it goes. The whine they make from 55mm is a lot more than a 65mm and sound good.

[Fifress]

Great stuff!
Always good to get feedback like this.
The kit comes with a 55 pulley, but bartek offers a 60 or 65 pulley separately. So I might get it and then switch for the bigger pulley...
I'm changing the charger's belt and apex seals as soon as it arrives. Is this what you mean by rebuilding every x miles? Or are you talking about full rebuild? I've had my g40 for 4 years approx. and never did anything to the charger, went from stock to ribbed belt 65 mm kit, daily driven, occasionaly pushed it... Only now it feels somewhat weak and reads around .7 bar at higher revs

[Jezza-7]

I think that is standard boost pressure, with 65mm you should see at least 1 bar.

When i talk about rebuild that is everything including bearings.

Some people have done a lot more mile than the recommended milage, also VW said its a seal unit and doesn't need servicing so i guess some people never got it done. When i bought my G40 it had 83k on it and the 2nd owner who had it from about 40/45k never had it done.

When you start loosing boost pressure its normally the apex seals.

[Fifress]

Then I am in need of apex seals...
By using a 55mm pulley it will just spin faster, does that bring danger to having it physically destroyed? Or just faster wear on bearings etc
The unit is completely stock, should be balanced from factory

[ereeiz]

I can't remember the maths off the top of my head (I'm on my lunch break so haven't got time to work it out now) but I'm sure I did a bunch of calculations and posted on here some time ago (it could be 3-5 years ago, not been on here much the last year or two) stating the differences in pulley size.

If the supercharger pulley is smaller then it means that the supercharger is spinning faster than it would be with the larger, standard pulley. There is a point where the G40 physically cannot flow anymore air through it but I can't remember what speed the supercharger needs to be spinning at in order to meet that point. Anything over that point and the charger is producing no more boost. Pushing it further (ie making it spin even faster) will just result in breaking parts, leaking seals, bearings, etc.

Take a look with the search function from the main forum menu. I seem to remember something about 1.2 x crank speed, although no idea if that's to do with this or something else entirely. Also, try looking up Andy and yoof, they've done a lot of work on G40's and can be a great help!

If you do sit down and work it all out, post your findings on here as a reference!

[Fifress]

I Searched but only found 2 posts mentioning this.
I read the standard pulley gives out a 1.6x speed multiplier on the charger and 60 or 65 toothed belt around 2x speed.
Problem with running higher rpms on the charger is, as Pete explained, the top bearings (i assume these are the countershaft sealed bearings) run outside the higher rpm range they are designed for. Thus resulting in gripped bearings and kaput. One dead charger.
However, he found some bearings that were suitable for the 60 or 65 toothed belt mod, also some seals that handle higher temps. Will be talking to him to get these.

Funny how on one post someone said that in Portugal a common upgrade was a 58 toothed pulley and how we (i'm portuguese) got away with it....can't really cover this as I live outside mainland (Azores) and in my island I'm the only one running G40's daily...

[Jacque]

The toothed belts are better than the ribbed ones as the toothed ones allow no slip at all.
55mm pulley though, that will kill a G40 charger pretty quickly.

I dont know if toothed is "better", imo, if it wants to slip, at least it can.. while running toothed might put more load on your charger? (no expert on these things though)

better for building boost, it probably is, but if a ribbed belt is tensioned correctly, it wont slip.. (at least not on my G, i used to run 68mm, now running stock pulley)

[kwijibo_coupe]

I tried both the ribbed and the toothed belt kits and I preferred the toothed belts. The noise was the main factor, nothing else sounds like a G40 on toothies. But I found with the ribbed belts up the higher RPM the boost used to drop off which must have been the belt slipping. But with the toothies the boost stays strong. The only downside I found was if you accidentally hit the rev limiter then the toothed belt strips. But you shouldn't be hitting the limiter in a G40 anyway.