I had a 2.7 Heffner pulley installed today. While the GT was on the dyno, dialing in the tune, the pulley started "walking" off the shaft of the supercharger at approximately 6500 RPM's. Fortunately, the tuner noticed this happening and shut her down before anything disastrous occurred. The shop called Heffner and was told this may be a defective pulley and they plan on overnighting a new pulley. This shop is very experienced with pulley swaps and has never encountered this problem before. Has anyone experienced this issue or any thoughts or suggestions? Thanks, Bill
2.7 Heffner Pulley Problem
- Thread starter GT350H
- Start date
B O N Y
MODERATOR & FGT OWNER
analogdesigner
GT Owner
GT350H...I had a chance to call an engineering friend this evening. Long time background in S/C design. His opinion (and this in no way relects on any one or any company or it's products) the expansion rate and shrink rate of alum and steel are different. Aluminum will expand faster with heat then steel. If the blower shaft (steel) is at the low end of the tolerance scale when fabricated, and the pulley is on the high end of the tolerance scale when fabricated, there is a very good chance it will travel. The original pulley is of course steel.
Talk to you tomorrow GT350H.
It did make awesome power. AFR was flat as a board. Looked great.
Ron
Talk to you tomorrow GT350H.
It did make awesome power. AFR was flat as a board. Looked great.
Ron
Omega_man
GT Owner 2005 #248
Hi Bill, I have a Heffner 2.7 that has not been installed yet. The pulley ID is .7665. Do you know what the correct measurement is? I might need to call Jason to be sure mine is OK before we go through all the trouble to install it.
One other item to note that we saw on the dyno while tuning, were the MAF counts. Initially the tuning session was halted because the MAF hit 1023 counts. (maxed out) At that point the car began to lean out, which is normal when the MAF hits saturation. A MAFIA was installed which of course solved the problem.
Ron
Ron
Just some quick input. This is why we dry crank the cars every single time we put a pulley on. This is to make sure it is square before we even start the car. We have put on about 25 of these pullies and only had the issue with the one and that was caught before we even put the s/c back on the car.
- Feb 22, 2006
- 370
Hi Ron,
When I spoke to your installer yesterday I explained to him that of the almost fifty pulleys that we have sold and installed that this was the first issue of this sort. I also explained that it is highly unlikely that a defect in the pulley would have been the cause of this problem primarily because they are all CNC machined and not machined by hand. With that being said I felt that the easiest way to correct this situation would be to simply send out a new pulley, no questions asked.
Regarding Bony's car this is not at all what occurred. During installation of his pulley it started to press on slightly crooked which damaged the inside of the pulley. Rich and Dennis (The GT Guys), being the meticulous professionals that they are figured that it would be better to be safe than sorry and not install a pulley that was questionable. In this case as well I sent them a replacement pulley, no questions asked.
Pursuant to this issue every remaining pulley in inventory has been inspected and measured. I found no pulley to be larger in inside diameter than the factory 0.766" specification.
It is fortunate that the installer noticed what was happening prior to having any real issue. I regret that anyone may have been inconvenienced and firmly believe that there should be no cause for future concern.
Thanks,
Jason Heffner
When I spoke to your installer yesterday I explained to him that of the almost fifty pulleys that we have sold and installed that this was the first issue of this sort. I also explained that it is highly unlikely that a defect in the pulley would have been the cause of this problem primarily because they are all CNC machined and not machined by hand. With that being said I felt that the easiest way to correct this situation would be to simply send out a new pulley, no questions asked.
Regarding Bony's car this is not at all what occurred. During installation of his pulley it started to press on slightly crooked which damaged the inside of the pulley. Rich and Dennis (The GT Guys), being the meticulous professionals that they are figured that it would be better to be safe than sorry and not install a pulley that was questionable. In this case as well I sent them a replacement pulley, no questions asked.
Pursuant to this issue every remaining pulley in inventory has been inspected and measured. I found no pulley to be larger in inside diameter than the factory 0.766" specification.
It is fortunate that the installer noticed what was happening prior to having any real issue. I regret that anyone may have been inconvenienced and firmly believe that there should be no cause for future concern.
Thanks,
Jason Heffner
Last edited:
Omega_man
GT Owner 2005 #248
Thanks Jason for clearing this up. Mine at .766 (+/-.0005) should be fine. Install will go as planned.
B O N Y
MODERATOR & FGT OWNER
Thanks Jason, you peeled the onion and I appreciate the clarification.
I was thrilled with your pulley and out of the box tune,... but had to go Whipple.
More is better!
I was thrilled with your pulley and out of the box tune,... but had to go Whipple.
More is better!
Hennessey Performance
GT Owner
- Mar 15, 2006
- 767
Just to throw in my 2 cents - I would strongly suggest that any GT owner considering doing a pulley upgrade should have the work performed by a shop that has experience in installing GT pullies.
No offence to all the good shops out there who have not done this process but are capable of removing and installing a pulley. However, to the GT owner who seeks to have this done right the first time then I submit that you are assured of better results by using a shop who is experienced with GT upgrades.
No offence to all the good shops out there who have not done this process but are capable of removing and installing a pulley. However, to the GT owner who seeks to have this done right the first time then I submit that you are assured of better results by using a shop who is experienced with GT upgrades.
Just had my pully walk and strip the output shaft of the supercharger. It was professionally installed by bob ida and this occured after 12,000 miles of driving with the pully on. Any advice? Supercharger replacement is $4xxx from ford.
B O N Y
MODERATOR & FGT OWNER
Kenne Bell also makes a new case adapter/pulley drive that will allow for a pulley as small as 2.5".
cobrar1339
GT Owner
Ditto on the Kenne Bell snout. Sorry to hear about the pulley problem.
It will replace the snout you have that bolts to the body of the blower. Comes polished and allows easier pulley changes as it is not a press on design. Forum Vendor Accufab sells these. Lots of details on the Kenne Bell website. There are some other benefits beyond just easy change of pullies. I know Heritage Bruce and Not4re on this site are running that set-up. I believe these are less than half the amt you mentioned. The Whipple is a little more than 3x the amt you mentioned as I recall. Decisions, decisions.
Let us know how it turns out.
It will replace the snout you have that bolts to the body of the blower. Comes polished and allows easier pulley changes as it is not a press on design. Forum Vendor Accufab sells these. Lots of details on the Kenne Bell website. There are some other benefits beyond just easy change of pullies. I know Heritage Bruce and Not4re on this site are running that set-up. I believe these are less than half the amt you mentioned. The Whipple is a little more than 3x the amt you mentioned as I recall. Decisions, decisions.
Let us know how it turns out.