MPI crusing AF

[kinger]

I know everyone looks for cruising AF's to be in the 13-14 range but I can never get that mine are always 11-12, mainly 11's. Light load crusing at say 60-70 mph I'm always in 10lbs of boost, WOT I'm at 10 lbs and the AF drops to low 11'S

I know that the benefits of a turbo are at light loads your not in any boost. So is my AF appropriate and it should be like that for a SC machine?

I have talked about ways to dump boost and try to get my MPG up a little bit but never bothered with anything. Probably explains why a turbo on the trail can muster 11-12 vs my 9-11 mpg.

 

[gsxr]

ADD A BYPASS VALVE , ADJUST THE FUEL CONTROLLER , FIXED

 

[kinger]

I have a vortec BOV

 

[quebecmoutainrider]

I m no expert but my sled drops off..unless at WOT..when the sled gets crusing the boost drops.just crusing Im pretty sure yours should drop off too..ridding around with my wife I see alot of only 4-5 psi at 50 mph..even lower if I feather the thing..

 

[rxrider]

With a SC engine rpms will determine boost, not engine load. Take away some fuel, your wot is way rich, shoot for 11.8-12.0 at wot.

 

[quebecmoutainrider]

thanks Jan-O..

 

[kinger]

Why should I take away fuel? It runs flawless that is my question. I just dont like that its always in 10 psi above 65mph.

 

[TurboMatt]

Apparently its not "flawless" if you on here complaining about fuel mileage. Listen to what they are saying, all good ideas

 

[miner]

Throttle position and rpm control boost on a centrifugal compressor, unless the gauge is in front of the throttle. Hook the gauge behind the throttles for usefull indications.

 

[insane]

Throttle position and rpm control boost on a centrifugal compressor, unless the gauge is in front of the throttle. Hook the gauge behind the throttles for usefull indications.

I tried this and the mapping was all over the place because of the vacuum, but I didnt't mess with it, I just put the 3 bar map air line back into the intercooler. I have a vortech bov that I have tied in behind the throttle plates on the t/b's. Should the 3 bar be tied in behind the plates as well? I also have a rich issue at low throttle(cruising) and I have pulled fuel and it didnt seem to help. I thought the A/F at wot should be 12.5-12.8???

 

[tapex_07]

12.5 would be great. 12.8 is closing in on playing with fire. I would say 11.9 to 12.6 is "ideal"

 

[kinger]

tapex_07 that is exactly where I am at. I'm going to leave it. I still get 10-11mpg which isn't horrible.

 

[tapex_07]

Can you adjust your fuel per throttle position vs rpm. like say at 15% throttle @ 7500 its "X" amount of fuel? That would be the way to tune in the mileage..

 

[kinger]

No the GEMS only has adjustment akin to a carb, a needle adjustment, main adjustment and a boost enrichment adjustment. Nothing tied to RPMS or TPS.

One of the limitations but it runs so clean throughout the RPM band, it doesn't spit fuel out the back or smell like other un tuned turbo sleds I have been behind. It just starts and runs like a mad man everytime so I'm not willing to dink with it for 1-2 mpg.

 

[gsxr]

add a bypass valve , you can adjust to bleed off some boost until you want it !