Whipple Bypass?

[StangLoveR]

Hey all. Need an opinion. I've got a 2.3L Whipple on my 5.0, with just a few thousand miles on the setup (road course duty). Everything's been just fine with it, until now:

I just installed a slightly smaller pulley and swapped injectors, new tune, etc. I understand the data logs are spot on, but I'm having a problem. Sometimes, when I lay into the throttle (not necessarily WOT), there is a bit of a lag/delay, and then all of a sudden the car takes off like a rocket.

I'm told (and this makes sense to me) that my bypass valve may be sticking.

Has anyone had this happen to them? I don't know what else it could be.

Has anyone replaced a bypass on this blower? I'm wondering how involved it is.

It would be disappointing if that's what failed after just a handful of hours of use.

Thoughts? Thanks!

 

[stangn]

Not sure that's the trouble. Have you pull the vacuum line to the valve and drove it to see if there is a change?

 

[StangLoveR]

Not sure that's the trouble. Have you pull the vacuum line to the valve and drove it to see if there is a change?

I have not, but, that test won't determine anything if the bypass is only mildly acting up, e.g. sticking - no?

 

[debit_free_2010]

You can test the valve , It doesn't take much vacuum for the plunger to move.

If r&r'ing the BPV on the Whipple is like the TVS, You have to remove the blower to get the arm out and back into of the butterfly.

It could be sticking but there's not much in it to stick, usually the diaphragm goes bad and it just stops working.

 

[NickSezz]

There are a few possible causes for this effect you are describing.

1) The tune you are running has the throttle opening too quickly. Too much throttle response on your set up will cause the bypass to lag behind the throttle body movement causing it to surge when the valve finally closes and you see boost.

2) The valve is having trouble closing quick enough because it is only routed to see vacuum. Rerouting the vacuum lines so the bypass valve sees boost helps the valve close quicker and also helps keep it shut or from fluttering. They tell you not to rout it this way but we do this on all of our installs including my own car that has the Whipple 2.3.

3) The fuel isn't coming on as quickly as the throttle is opening. Again possibly needing a slight tuning adjustment in the throttle/injector tables.

 

[StangLoveR]

Thanks for the responses guys. Hmm...I can talk to my tuner (Lund) and have them re-check, but they've already reviewed the logs with this in mind, so I would think that's not the problem (though anything is possible).

That leads us to possibility #2. However, I can only assume that the overwhelming majority of people running this setup have the bypass setup the way the manual suggests (fair assumption), and, I don't see that there are gobs of complaints similar to mine. So that alone concerns me. I'm not saying re-routing won't solve the problem, I'm just saying it's odd that I'd be one of the few that had to do such a thing.

BTW, I'm also still running a pretty big pulley, should only be making ~10 lbs of boost.

Just to give a bit more detail on the problem (though it may already be 100% clear), here's a prime example of what I'm experiencing. Drop to third gear and hold steady rpm's (say 3,000 or so) and then apply some throttle - it hesitates and then takes off hard. Also relevant is that this occurrence is intermittent.

To the extent I'd benefit from re-routing, does anyone know where I could find some details on what I'd need to do?

Again, I appreciate the help!!!

 

[stangn]

I think I'd listen to JDM they are on the ball. Going to check my bypass valve after work thanks Nick.

 

[StangLoveR]

Anyone able to give a run-down on how to re-route the vacuum lines? I'd appreciate it!