upper pulley install?

[SecondZ28]

Originally Posted by JANNETTYRACING

You are installing larger injectors with this 18% pulley correct?

It is much better to upgrade the crank pulley and leave the stock upper.

Ted.

If replacing the isolator, doesn't it make sense to do at least a 2.5 pulley anyway?

[JANNETTYRACING]

Originally Posted by SecondZ28

If replacing the isolator, doesn't it make sense to do at least a 2.5 pulley anyway?

No, why induce belt slip with a smaller pulley?

Change the lower and keep the stock pulley up top and keep max belt traction.

You have not said if you plan to change injectors.

[Roadking107]

Originally Posted by JANNETTYRACING

You are installing larger injectors with this 18% pulley correct?

It is much better to upgrade the crank pulley and leave the stock upper.

Ted.

Yes larger injectors and upgraded HX. Griptec pulley and changing out the isolator

[SecondZ28]

Originally Posted by JANNETTYRACING

No, why induce belt slip with a smaller pulley?

Change the lower and keep the stock pulley up top and keep max belt traction.

You have not said if you plan to change injectors.

ID-1050’s

CTS-V’s have been running with a 2.4/2.5 upper for years; with the right belt and a 100mm idler. I’ve seen some report slip with a 2.38/2.40/2.45 but the 2.50/2.55 seem to do fine.

It also setups up for future headers with a 8.6/2.5

[JANNETTYRACING]

Originally Posted by SecondZ28

ID-1050’s

CTS-V’s have been running with a 2.4/2.5 upper for years; with the right belt and a 100mm idler. I’ve seen some report slip with a 2.38/2.40/2.45 but the 2.50/2.55 seem to do fine.

It also setups up for future headers with a 8.6/2.5

Belt slip is not something you can detect with a boost gauge.

We used Laser RPM sensors on the crank and supercharger pulley to determine slip and it is real, you can also pick up traces of black belt dust around the throttle body which comes from the upper pulley.

Great choice on the injectors.

[robrocketanski]

I have never believed that .05 to .1 inch difference in pulley is all it takes to make it go from no slip to slip. As in, 2.38 to 2.45 might slip but 2.5 doesn't. I used a 2.75 upper for 2k miles and there is black coloring on my water pump below the upper pulley.

Whether the slip is that big of problem is a matter of opinion I guess but there probably is some.

[JANNETTYRACING]

Originally Posted by robrocketanski

I have never believed that .05 to .1 inch difference in pulley is all it takes to make it go from no slip to slip. As in, 2.38 to 2.45 might slip but 2.5 doesn't. I used a 2.75 upper for 2k miles and there is black coloring on my water pump below the upper pulley.

Whether the slip is that big of problem is a matter of opinion I guess but there probably is some.

Any slip is lost performance.

Ted.

[RobZL1]

Originally Posted by JANNETTYRACING

Any slip is lost performance.

Ted.

Spinnin' ain't winnin'.

[Can'tHave2MuchHP]

Originally Posted by RobZL1

Spinnin' ain't winnin'.

Or is it Slippin' Ain't Winnin' in this case?

[RobZL1]

Originally Posted by Can'tHave2MuchHP

Or is it Slippin' Ain't Winnin' in this case?

I'll meet you halfway with Slippin' It Ain't Whippin' It

[JANNETTYRACING]

Originally Posted by RobZL1

Spinnin' ain't winnin'.

Originally Posted by Can'tHave2MuchHP

Or is it Slippin' Ain't Winnin' in this case?

Originally Posted by RobZL1

I'll meet you halfway with Slippin' It Ain't Whippin' It

Good stuff here LOL.

[d454brisson]

I tried to get the back supercharger bolts off but could never get to the last 2 without drilling.

Some will hate this but I had just enough clearance (with a little prying force) to slide the snout out.
I cleaned and clearanced the area that would rub with a file and grinder (top under hat, cannot be seen and lower portion of snout plenty of sealing area left) and now can Remove / Replace the snout without loosening the intake bolts.
The crankcase vent tube bent a little and had to be straightened but once clearanced its pretty easy now to get the snout off for bearing changes, porting, swaps etc.

[silversleeper]

Originally Posted by d454brisson

I tried to get the back supercharger bolts off but could never get to the last 2 without drilling.

Some will hate this but I had just enough clearance (with a little prying force) to slide the snout out.
I cleaned and clearanced the area that would rub with a file and grinder (top under hat, cannot be seen and lower portion of snout plenty of sealing area left) and now can Remove / Replace the snout without loosening the intake bolts.
The crankcase vent tube bent a little and had to be straightened but once clearanced its pretty easy now to get the snout off for bearing changes, porting, swaps etc.

I can't envision where you are talking about grinding. I already ground some on mine to get the front fuel rail bolt off. If it doesn't look too bad or affect reliability and it's not a perfect original show car why not. Could you post a pic of what you did?