Lemming

Stephane,

With stage 2 pulley and normal crank pulley the boost was around 6 lbs at redline (6500 rpms). I don't remember what that is in impeller rpms, but there is a calculator on Carl's website that you can use. If you search my user name in this forum, you will find a thread that I started on my car when I had the SC installed. It has a number of dyno runs posted.

Tim

STEXIER

Thank you Tim,
I will look at your thread

Steph

edz968s

Here`s the link
http://www.928motorsports.com/servic...tingpulley.php
Diameter of oem crank pulley, plus the size of the s/c head unit pulley you have fitted will give you the impeller speed
I`m running the S1 kit

STEXIER

Yes I have done it, I have round the information that I reached
I'm looking now for a picture (from Carl?) with the big crank pulley to see it integrates on the engines

Stephane

Carl Fausett

Does anybody have a 968 near me (Wisconsin) that they want to drop off for a little bit? Now that I have the larger crank pulley and an underdrive alternator pulley in stock, if I had a 968 here I'd like to take another shot at redesigning to use a two-sided serpentine belt...

Jfrahm

Hmm, you might be able to figure it out with a junkyard 944NA motor. I have used my 951S motor to help figure out my double sided belt setup.

Carl Fausett

Thats a thought. Still, would rather have a car so I know the locations of radiators, coolant tanks, and hoses. But thanks for the idea.

edz968s

You found double sided 6PK belts? Who`s make.
If I get a ribbed pulley and a double sider, that would be the final solution

STEXIER

Gates do a 6DPK 1710
With à small modification on the supercharger black puley support can use it

edz968s

I`m using a 6PK1570 belt, single sided. Whats needed is a double side 6-rib, so as to fit a 6 grooved pulley and thus eliminate all belt slip.
I Take it the 'D' means double?
It`s a lot of slack to take up with that length belt (1710mm), what mod have you done to use this length?

STEXIER

Yes "D" is for double
To use the 1710, you must do a new support of the black plastic pulley on the Raptor to move it for 5-6 cm by report of the actual position, that's enough
and rebuilt a new supercharger grooved puley off course

Jfrahm

I have been working with the DK060674 Corvette belt (68.5" long) and the Dayco 6060724 (72.44") Volvo fitment double sided belts.

With an additional idler in between the alternator and the crank I was able to use these longer belts but the loss of adjustibility was a pain. I did get a lot more crank wrap. I still saw slip at 5psi or so regardless of what I did. I suppose it could have been slipping on the crank pulley but I did have a lot of belt wrap there.

When I get around to trying again I might try the idler farther inboard from the one on the alternator bolt. I was going to set up to build boost early and limit it to 4psi to prevent slip. I liked how the car ran with lots of boost in the midrange.

edz968s

They are long belts, I have 61.8" fitted.
Do you have a link to the belt supplier, can`t find one anywhere and especially the 6DPK1750

andys-944

Here's a link to the Gates web site;

http://www.gates.com/automotive.cfm

Carl Fausett

I have this 968 coming to our shop in March. It has our Stage 1 kit on it, and the customer is letting me use it to develop a double-sided solution for our Stage II kits.

While it is here, I will also be installing an Tec-GT engine management system, and taking it to the dyno. We will end up with solid numbers on what our New Stage II kit can produce.