Installation and Review: Mountain Performance Inc, Stage 1 & 2 Supercharger

judger101 · Dec 22, 2013

i have an mcx low boost turbo kit and I REALLY noticed this boost chatter. I put in a thistle lighter spring and I know that I can feel a difference, plus yes it sounds better. I am not even close to an expert on turbos or superchargers, but I cant imagine that that type of chatter noise is "normal", after seeing the difference after I made a change to my spring.

irondave86 · Dec 22, 2013

Matt@MPI said:
The supercharger also has a built in blow off valve inside. That sound you heard is completely normal. The 2 examples in these videos both have the filter sticking up through the hood. This makes the internal BOV chatter more prevalent. We also have had a new design BOV for the last 1 1/2 years that gives you that rush sound that everyone wants to hear. I'll post some pictures tomorrow. Years ago the Apex also didn't have a BOV in the kit standard. But has been standard for the last 6 years.

100% BS! There is no "built in" BOV in the blower. And the sound heard in the video is compressor surge and it will damage the blower.

MotoPsycho · Dec 22, 2013

We send the sheet out that I have attached to this post with every one of our fuel controls...

It is printed on a bright yellow sheet, and it is wrapped around the OUTSIDE of the controller instructions...

The sound is not "normal", and we take it VERY seriously.

christopher · Dec 22, 2013

Matt@MPI said:
The supercharger also has a built in blow off valve inside. That sound you heard is completely normal. The 2 examples in these videos both have the filter sticking up through the hood. This makes the internal BOV chatter more prevalent. We also have had a new design BOV for the last 1 1/2 years that gives you that rush sound that everyone wants to hear. I'll post some pictures tomorrow. Years ago the Apex also didn't have a BOV in the kit standard. But has been standard for the last 6 years.

Ok Matt, your going to have to educate me a bit on this one. How in the heck does the supercharger have an INTERNAL blowoff valve and where is it?? I handled that unit pretty extensively during the install and I sure as heck never saw a BOV on it??

As for the Apex. Aren't there stories of the early super chargers on the Apex blowing the manifolds off because they had no BOV?

Sent from my iPad using Tapatalk 2 pro.

A.Granath · Dec 23, 2013

Is the standard MPI BOV that comes with the kits constructed to bypass air from the charger when pressure after throttle bodys are at negative reading?

How can i check this? i got the feeling that it does not do that...

MotoPsycho · Dec 26, 2013

Mr G. It's more of a "differential" actuation. When charge pressure is greater than the pressure down stream of the throttle plates, AND overcomes the internal spring pressure of the bypass valve, it should open.

Generally, the springs are much too stiff - intentionally. The valves are of an inferior design and tend to leak boost without a very firm spring. Cold temperatures exacerbate the problem, as the diaphragm stiffens, and slows actuation even further.

Try backing your preload out as far as possible, ride, note any differences. Remove the spring entirely, ride, note differences.

None of these tests will "fix" a valve, but may help you understand how they work.

Sent from Moto's iPhad

christopher · Dec 26, 2013

So whats the STRUCTURAL differences with the "Moto BOV" compared to the MPI ?

MotoPsycho · Dec 26, 2013

Our valve utilizes a billet piston with o-rings, rather than a diaphragm. It also one sensing port, rather than 2.

Sent from Moto's iPharce 5
PsychoSled.com - Got snow?

christopher · Dec 28, 2013

Think I will give this a try as well.

christopher · Dec 29, 2013

So, apparently there have been some changed to MPI's BOV..

It seems that I have the "older" 2 port style that they no longer produce.
About a year ago they changed their BOV to a single port, they are made from 100% billet and made in-house now. And a little bird said they are supplying several other "Powersports Manufacturers" with the BOV under private label.

So I am going to try and talk MPI out of one of the new ones to do a "Compare and Contrast" against the old one.

Might be this is something those of us running MPI Turbos or Superchargers should all be considering as an update??

Monster Max · Dec 30, 2013

I had the first if the new batch of valves. It has that constant flutter that moto was talking about.

christopher · Dec 30, 2013

I am going to get one of each and compare them side by side.
In the end, thats really the only way for us to know the differences between them.

christopher · Dec 30, 2013

christopher said:
Just ordered Moto's "Super Secret Squirrel" clutch kit.

Moto's "Bridge" controller solved a WORLD OF PROBLEMS with my fuel controller, so I am more than a little optimistic that his clutch solution will work every bit as well!!

Clutch Kit has arrived.
Will start a new thread on the install.