on my ppwerdyne, but should be similar in other systems. going from approx 2.9 to 2.7. I removed the bolt on the pulley, am faced with a rectangular keyed bolt hole. The new pulley is similarly keyed. I just need to know how to get the old one off, with a puller? Thanks, Mark

 

Maybe its just stuck on the key. I haven't tried this myself yet. So I can't offer any experience.

I would try a two-jaw puller carefully and see what happens.

Are you sure you really want to spin the blower that fast?

That pulley combination will put your impeller speed at 42700 rpm at only 5400 crank rpm.

I'd be concerned going over 40,000 impeller rpm which would occur at just over 5,000 rpm with said pulleys.

The LT1 powerdyne guys seem to like either a 6" crank and 2.7" blower pulley or 7" crank and 3.12" blower pulley for 6-7 lbs of boost."

7" crank and 2.7" blower pulley might be pushing it.

I'd probably opt for the $495 upgraded billet impeller from 928 motorsports instead of overspinning the blower.

It is supposed to be worth 20% more boost and 20% more flow at the same rpm as the current impeller.

 

dont know about powerdyne,but some units (paxton) have a loctite compound applied between the shaft and pulley to eliminate vibration. this requires heat to remove the pulley. i'd call powerdyne custtomer support and ask.

 

Hi Pat

Thanks. ill give her a shot on the puller.

Im looking to see what effect the pulley change has. remember im a newbie. i too am interested in the 928 turbo optional impeller etc. Have you heard from anyone using it? Love to hear of your concerns on the pulley size. I sent the injectors off for testing and cleaning to rich at cruizen, also doingthe hood prop relocation and the parallel fuel feed.

mark

 

Mark,

Just like you, I'm a newbie at this also.

The impeller rpm concern is just what I've picked up from the rebuilders websites, and from info obtained from CamaroZ28.com and SuperchargersOnline.com etc.

Everyone seems to be cautioning against high impeller rpm. From what I've read 40,000 rpm seems to be the max practical rpm. 36,000 rpm is considered to be safe and reliable. 40,000 for a bit more boost and more frequent rebuilds. Finding the right compromise is the key.

Apparently it can go up to 42,000-43,000 maximum rpm, but the efficiency drops and the likelyhood of cooking the bearings or having the impeller come apart and frag the motor increase.

IIRC you already have the ceramic bearings so they should help somewhat.

The improved impeller and upgraded shaft and bearings etc. that available may increase the safe operating range.

I'm only regurgitating what I've read, so take it for what its worth.

There is a Youtube video of a guy in Australia running the improved impeller. They're claiming 60 hp and and an ET reduction of about 3 tenths on a mid high 11 car and there is at least some discussion on SuperchargersOnline.com in the Powerdyne Tech area regarding the new impeller.

I'm sure I will try this impeller as a future upgrade, maybe next year since winter is coming and the vette season is almost done here in Michigan.

I'm still looking for a deal on 38-42 lb. injectors. So this is also limiting my use of the car and blower for now.

 

never mind. slid right off with leverage. i was just concerned about screwing it up somehow.

 

Mark,

Here's a rebuild link that may be helpful. This guy says to use a 3 jaw puller on the pulley. I see now that you already got the pulley off.

I didn't register to check out the pics, but they may be useful.

http://forums.bimmerforums.com/forum...d.php?t=758459

 

Great link! Thanks. read from end to end.