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MPI crusing AF


Sorry I use the terms interchangibly and i shouldn't I knwo the difference.

I have the vortec maxflow bypass valve.

Looks like the adjustment is for how many inches of vacumn to open at and this wont do anything for me because with the Sc it never sees vacmumn at 70+mph unless I stab the brakes and the rpms drop.
 
If you have a bypass valve it has 2 hoses.
one vacuum , one pressure .

As long as you have the right spring in the valve for the min boost you want to run , thread out the adj screw all the way , it will go there. Then you can thread it in to increase boost.

You can't adj below spring pressure !

So for 5 lbs , 5 lb spring , adj all the way out !
 
Hey Kinger, I'd be happen with 10mpg. I'm running 5psi and getting 5-6mpg (I don;t even want to think about $/km). I'm in hills and deep pow and I know I'm running way rich but with a little adjusting I'd by way happy with 7mpg!
 
Why do you guys run the GEM boxes?
The RapidBike and PowerCommander have real adjustability to them. Adjust whatever you like, boost vs TPS and RPM, fuel vs MAP and RPM.
They cost a bit but the adjustability is way better them any gems type box IMO. Even the MCX Display Box has these capabilities and 6 hours of logging all kinds of parameters to boot.
 
I am guessing that they run the gems because it is easy. Also it sounds like it handles the fueling just fine. It is just a matter of the supercharger being a constant boost dependant of RPM. I think maybe the clutching or gearing may help the fuel mileage more. You can't reduce fuel when boost is present.

If you gear up one or two teeth on the top I would assume you will still have the power and at say 50 MPH your rpm should be a little lower therefore lowering the boost. Also you could maybe lower the engagement rpm.

The only other smarter way would be to have a control box that could know if you were at steady cruise (not in and out of the throttle) that would controll the Bypass valve. Think of it kinda how the GM 6.0 can drop to 4 cylinders with the right conditions. This control box could sense if the rider is agressively hammering the throttle or if it they are jsut out for a smooth drive through the woods. And say dump the boost ouf the bypass. It would probally be best to not vent this excess to the atmosphere either. Just vent it to the intake side of the supercharger.

Well that box is no where near my electrical capabilities! I wish I could build half of the electrical stuff I can dream up.

But you could put a swtich in line for a bleeder to your Bypass valve that if you so desired would allow you to dump the boost. Possibly also you could run a swtich off the throttle lever as well that under a certain Throttle position it will dump the boost.

These are just a few of my thoughts. Everyone on here has always helped me out and I hope I can return the favor!
 
You're probably right on that one... clutching and gearing is the key when it comes to SCs :)
As it has boost off engagement; load the inner hole of the clutch weight to the max, use a helix with taller start angle to make it shift to a taller ratio thus beeing able to run the same speed on the trail at a lower rpm. Just my .02
 
I was just doing some more reading on your post as well. I see that you said your air/fuel runs quite rich on cruise. You may want to turn down your fuel pressure regulator a little bit and reset your gems settings to the new fuel pressure. Most likely to much fuel pressure is not letting you turn the fuel down in the cruise setting.

That and some different clutching for fuel effiency should do the trick.

I know that there is quite a difference in 10.5:1 afr to 12:1 in terms of fuel useage. The difference in power though is not as noticeable. The sleds will run pretty well rich under boost.
 
A mbc in line to the maxflow should do the trick to bleed off boost with the bypass valve. It is all about a diferential in presuure. If you can fool the top top side of the bypass valve it will not have enough pressure to hold it shut. If this works you could put the MBC in a line that is connected in parallel to the current line and put a solenoid valve in that line that is normally open so if you want to cruise at on low boost you could just press a switch on the handlebars and it would lower the boost to what the MBC is set at and then you could hit it again for full boost.

THis works in my head. I think it would be best to vent it back to the intake side of the supercharger though to maintain some of the volume and help the supercharger scavenge air, making it more efficent.

I can draw you a diagram if you would like.

Or wait i just got a really crazy idea. This would take some work but I will throw it out there. I variable speed belt drive to the supercharger. Could be manually controlled to ramp up the speed or slow it down. Haha now that is going a little to far. Would be sweet though if it was made by MPI and tested and R&D'ed by them.
 
All good suggestions what I have never got a good awnser on is this. On SC's ONLY when your crusing at say 8000+ rpm its making 10 psi, what AF should you be at when on light throttle. 13-14 seems way to lean for 10 psi even with light loads. I'm running at 12.5-12.9.

At WOT it goes down to 11.5-11.9


I like the idea of a MBC in line to the BOV I could see that working however with as much as I am on the throttle off the throttle I would never hit the switch LOL Its one of those things where i am crusing at that speed for say 30 sec to a min then brake turn, repeat, etc.

I can plumb the boost to the filter side of my BOV and it will level the boost in half at 5 psi and I may try that although my clutching will be lugging the engine and again I wont have my 10 psi unless I turn the valve to shut off the boost line and open the atmospheric line.

Your right on the Rapid Bike no way I want anything that complex, I would be messing with it every ride and that zaps the fun. The GEMS is stupid simple it works good enough and I rarely look at it, in fact its buried under the hood and I have only adjusted the idle AF a couple times in two years otherwise I haven't touched it.
 
I have a ball valve on my charge tube coming out of my compressor, when i need mileage I open that up to take me down to 5 psi from 13 psi....instant mileage and less things that can go wrong, we have enough moving parts on these things stock let alone adding 100-150 hp!!!
 
kinger...just got back from spending another 875 $ on my S.C...they told me to run it at 12.4-12.8.WOT.this is what the tec told me..his name is Francis..and he holds the speed record for the yammie at G-Force..Changed some weights and now...WOW...it is 30-40 percent better.Had to change pullies..was getting 17 psi on pump 94..rode a tank like that..nothing happened.it runs great..so can you run it that high on pump..did it..but wouldnt ever again..back now at 14psi..he also told me..if you see 15 A|F and its just for a sec..its ok..it has to stay there for a bit..only take note of the numbers you see constant..thats what he told me..bigger smile than before. ;)! .lol..
 
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