EFI Sled engine

[fz1mini]

k-fab -does that k&n system use a wide band o2 sensor?can you datalog to a laptop while driving so you can replay your run time?

[K-fab]

Originally Posted by fz1mini\";p=\&quot

k-fab -does that k&n system use a wide band o2 sensor?can you datalog to a laptop while driving so you can replay your run time?

It's the basic cheapie O2 sensor. *Nothing special. *Works for what I'm after, though. *Has a set of LEDs on the gauge, tune to keep the one in the middle lit.

I'm not sure about the data logging (I'm assuming you're talking about the Power Commander).

Since it's in a desert car, I'm not worried about trying to log. *It wouldn't really help me. *On a track, sure, but out in the desert - nah. *My main concern is just getting the EFI mapped out so that the engine's a happy unit and will run all day w/o any trama or drama.

Using the K&N to keep an eye on throttle settings and response and then tuning w/the Power Commander will let me get everything dialed in eventually.

[opsled]

I've looked at jetting charts in a few of the Yamaha service manuals I have for different Yamaha 2 strokes and they all read about the same. They have jetting requirements for temps that range from -22 F to +70 F and altitude requirements from sea level to 8000ft. My Vmax 4 750cc needs a 133.8 main at -22 F and 8000ft of eleivation. At sea level it requires a 138.8 main at +70 F. Sea level at -22 F is a 140 main. This engine actually needs more fuel at sea level with warm weather than at 8000ft and sub zero temps. 2 strokes always need more fuel in cold weather than in warm so I think this is telling. These numbers show me that altitude is a much larger factor than air temperature when talking air/fuel mixture and we know that 2 strokes are much more finicky than 4 strokes.

The Yamaha Phazer 500 EFI owners manual says that NO adjustments other than clutching are needed for high elevation riding. Quote {Your snomobile utilizes an electronic fuel injection system that delivers the optimal air/fuel ratio required by the engine. Therefore, the fuel injection system does not need to be adjusted, even for high altitude.} They don't have any language in there about air temps so I assume there is nothing needed there as well.

* We all know that snowmobiles are made to run in cold weather so air/fuel specs for summer (warm weather) are not going to be available from the factory but I would conclude the following with what I know.

*1 - If 2 strokes are more finicky than 4 strokes on air/fuel mixture warm weather running on a 4 stroke will be less of a problem to start with.

*2 - If altitude plays a larger roll in air/fuel mixture that air temperature and these Yamaha injection systems can compensate for altitude they should have no trouble compensating for the higher air temps you guys will normally be running in.

*3 - *So if these injection systems can adjust themselves for temps from -22 F to +70 F and altitudes from sea level to 8000ft I don't see them having any problems being able to properly adjust for the conditions you guys are running in. From what I can find they can adjust themselves from sub zero at sea level to +70 at 8000ft and probably more which should more than enough to handle your needs.

I also had a conversation with a friend of mine this morning who is very knowledgable on modern fuel injection. He owns an automotive repair shop but builds many different customs with fuel injection. His forklift is running a 3.0 Chrysler fuelie engine and he builds ultralight helicopters with gas turbines in them as a hoby. He has even set up and run one of these turbines with an automotive type fuel injection system in order to make it more efficient. It didn't pan out but the guy really knows is $hit. I talked with him on this question and he said that it should not be a problem to run these sled EFI 4 strokes in warm weather. He said that air temp is the least important imput to most systems and that coolant temp, RPM and throttle position play a much larger roll in fuel managment. He also said that O2 sensors for the most part only imput at part throttle and are there to fine tune the mixture to get the proper ratio for the CAT to work properly. He said that at most systems don't read the O2 at 75% throttle on up and that it goes into what he called "open loop mode". When in that mode the computer is only reading coolant temp, throttle position and RPM for the most part and that O2 imput on an application that is being run without a CAT and at mostly open throttle would be useless to the computer which is why they are not on most of these types of applications.
*
*I am far from any kind of an expert on any of this stuff and might not have all of this right but I thought I would pass along what I know and have been told in hopes that it might help answer some questions.

* *My 2 typing fingers are cramping up so I have to go. * Phil (opsled)

[minibajaman]

Thanks guys that is basically what I thought I just wanted to double check that it would be ok. *Now if I could only decide on and find an engine to use...