Which style of groove is better for us PD users?

[Mighty Thor]

The grooves that spirals or the one that goes side to side on the pulley?

[John_D.]

My vote would be the type that goes all the way around. I've seen spikes of 13 psi at the top of 2nd with mine. 5 grooves.

I think the benefit comes from having a place for the air to go. With side to side grooves, there are sections where the air can still get trapped under the belt.

A while back I looked at all the results I could find from the grooved pulley guys that went ahead of me, and the ones that went all the way around were getting the higher boost numbers. I posted all those numbers in one post somewhere...

[98GREENGLOW]

Defiently all the way around......

My side to side dose a good job and dosent slip, but Ive never seen more than 10 psi with it.

My old 6 pounder with the grooves going all he way around would spike at 10-11 pounds when the belt was really tight.

I remember for a few months I was getting 7-9 pounds of boost from it.

So my vote goes to my spiral for over all boost, but to the side to side for slippidge reliability.

I havent put ony belt dressing or done any retightening to my side to side pully since I put on the intercooler a month or two ago and I still see 6-7 psi with the ocassional 8.

Considering the loss through the intercooler, thats really about 7-8 with the occassional spike of 9 so I cant really complain.

But Im happy you brought this up....

Both desighns seem to work and have there advantages /weaknesses.

So when I order my custom 2.6 pully from ASP racing in a few months I will be sure to tell them that I want my side by side grooves that he dose so well and also 5 sriral grooves of equal depth going all the way around.

It would be very interesting to see what the results would be with this double groove pattern.

But for now Ill just sit back and enjoy the slip free goodness.

BTW...We are always quick to blame the pully but I beleave that the belt is the evil one.

My 103 inch dayco elt could barely fit over the pully when new. It was a tight belt with out even adjusting the tensioner pully.

NOW my tensioner pully sits all the way down and almost touches my PD. Theres a few mm between them. The belts stretch like crazy.

That belt has really stretched a few inches!!!!

[John_D.]

My goodyear is still in the middle of the range of adjustment. It had some initial stretch, then it settled in and stayed put....

[AllTheGoodNamesAreGone]

hmm.. intesresting.. anyone have pictures of the two?? i am kinda confused.

[John_D.]

The one that goes around, imagine the pulley is turning with no belt on it, and you were to hold a pencil up against it while it was turning... Or like the ribs on a stock pulley.

The one that goes side to side on the pulley, each one would be about a 1" long groove. If you were looking at the pulley on the engine, the groove would be in a line from the front of the car to the back of the car. There would be 4 or 5 of these equally spaced around the pulley. Kind of like the grooves on the edge of a dime (but further apart).

[AllTheGoodNamesAreGone]

Originally posted by John_D.:
The one that goes around, imagine the pulley is turning with no belt on it, and you were to hold a pencil up against it while it was turning... Or like the ribs on a stock pulley.

The one that goes side to side on the pulley, each one would be about a 1" long groove. If you were looking at the pulley on the engine, the groove would be in a line from the front of the car to the back of the car. There would be 4 or 5 of these equally spaced around the pulley. Kind of like the grooves on the edge of a dime (but further apart).

OK.. thats what I figured.. who makes teh spiral pully? how bad will that eat up a belt?

[John_D.]

I took mine to a local machine shop and they did it with a file for $10.

It's not any worse on the belt than the smooth pulley was.

I heard of someone running a ribbed pulley one time, and it shredded the belt pretty quickly. But a grooved one should be fine.

[98GREENGLOW]

THE GROOVES DO NONTHING TO HURT THE BELT.

You pretty much have to groove the pully or youll be lucky to hold 5-6 pounds of boost....

Some people did.....But most didnt....

Judging from Johns and my boost.....I think it's pretty conceivable that we could get a 2.5 inch pully to work and run a constant 13 psi.

Im gonna attempt the 2.6 with both grooves and see what happens.

Only problem with this is eventualy some ones powerdyne is gonna break.....

It's SUPPOSSEDLY not suppossed to go over 9 pounds.

But there are alot of people breaking that boundery and so far none of them have had that problem.

[ssms5411]

I'm using a dayco poly cog 103.8 belt, dayco makes different types of belts and I find this one to be the strongest and doesn't stretch that much. I tightened my belt today and it is about midway on the tensioner.