CFI fix with injector placement?

[Norway]

Wanted to ask this in other threads, but it`s sorta outside their case.

I`ve been following lots of pro/dragon threads about the engine headaches and just have to ask:

Cant we make that engine live better with injectors in the throttlebody, just two of them?

It would mean injector + ecu change on CFI-4, and moving the injectors on the CFI-2.
With this move you can cool the engines internals and lubricate through fuel, and no more transition trouble for the dragons.

How do you turbo-people feel about this? You`ve set up these engines with secondary injectors so hardware should not be an issue.

And I know Polaris should fix it and not us, but it`s my sled so leave that choice to me.

 

[jetski]

i think its a pretty good idea... if you look at the rings that come out of the pro and cfi motors that have the injector in the boost port, the ring face is flaking off, i beleive that is from tempurature shock, plus you look at any good fuel injection system, they dont point the injector 3/8's of an inch from a flat peice of aluminum (the backside of the cylinder wall).

 

[Norway]

Ok, I'm no motor builder, what did I miss?

120 views and 1 comment, in these fix-the-pro days. I see possible hickups in placing the injectors correct, including angle into the airstream, and timing of fuel delivery.

Just seems to me that with blue small ends on the rods and no oiling the bottom through fuel, this would be something that someone would do??

Please enlighten me if you can, thanks!

 

[Boyko]

Well the big issue I know about is the piston clearance up to 2010, last one I seen it had .015” with a cast piston that should be .0035 There are a few “fix kits” for that problem. I am working on boosting 2 800 pros now a 2011 and 2012. The piston clearance on them was .006 which should not be a issue, not ideal though. The 2011 had 600 miles on it and the reed were starting to chip, this is a bone stock sled.

One thing that is important is to make sure your engine is up to operating temp before you bag on it or it could end up giving you problems down the road. Cold shock is nothing new to snowmobiles, it is just more noticeable with the Polaris gauge package

What you are proposing is costly and involving. I do not know what issue you are trying to fix with it. That might be why there has not been a lot of action on this thread.

 

[allblowdup]

Ok heres the deal with the dragon 800 engine and cfi 4. Wrong injector placement for sure. Wrong ex valve calibration for sure. Wrong fuel calibration for sure. Pistons to loose of fit for sure(this was an attempted bandaid because of all the other wrong things done).
First the injectors need to be placed in an area that the fuel can fully vaporize. This was not done. If you do that it is much easier to get good emissions without having to run the engine to lean. Then you don't have to hold the ex valve closed so long so that the engine will try and burn the unvaporized fuel and overheating the piston because the ex vale is holding heat in the engine.(double edged sword). The you can set your piston clearences proper so that you don't get knife edging and get better heat tranfer to the cylinders.

You could get the Dragon engine to run good but you needed to make a few changes. Namely a fuel controller of some sort. Remap the ex valve opening time.(pretty much just plug the vent hose and make sure you have the proper spring in it. Run the engine a little cooler 10-15 deg. I did this on a 2010 Dragon and the difference was amazing. Before it had a stumble had a weird running issue in midrange and i was always scared of it. After it ran flawlessly. No stumble at all, mid range was good. WOT was great. I ran it for 1000 mi and the performance never changed. The neat thing was I looked in the cylinder throught the ex and the pistons did not have the ex valve outline stain on them like every other Dragon I have seen has. I am sure that the pistons would still start to knife edge and wear out early because of the clearance.

As far as the Pro engine they have pretty much done most of that and it's amazing. It works.

That is my experience.

 

[Boyko]

The dealers installing the piston fix kits (there are a few different kits out) on the cf-4 are all saying they had no failures with them. One thing I did not mention is to go back to the 2008 flash on the ecu

 

[allblowdup]

Did anyone on here get to ride the pre production dragon 800's. They had none of the issues. The reason was because pre production units do not have to meet emission certifications. just FYI

 

[Norway]

Thank you for good input!

The problems I think of are as mentioned here and I would sum them up like this: Polaris tried to make a lighter 800 and got a double task with emission criteria. The CFI-4 was born, but would not live AND give power.

So they "lean it and loose it", go leaner on fuel and looser in piston/cylinder clearance. Still, there is this transition thing that I don't feel qualified to disect at all, never ran a Dragon. But hardware and software is thrown at it, to SOME success.

Enter CFI-2; No staged injection, porting tuned more towards bottom end/midrange and a MUCH lighter package that somewhat hides the lower max output (compared to Cat/Doo). Still sloppy pistons and not enough meat in the cylinder skirts. Also no lubing the lower end except what the oilpump feeds the crankshaft, nor can the internals be cooled by fuel since the injector sits in the transfer port only.

Back to my question:
I'm thinking there would be a benefit in getting the fuel sprayed in earlier in the airstream, cooling the piston/rod and oiling it to.
You could also increase oil by mixing in the gas and not just benefit the top piston ring.

I see billet intakes for turbo use with mounts for auxilary injectors and clamp on throttle body adaptors, so the hardware (less some details) to move your injectors is pretty much there (know nothing about wiring and fuel lines!).

Now, IF this would take us to an engine that would operate like a "normal" or traditional 800 engine, then we could tighten up the clearance so it won't beat itself to death and still not squeek the pistons = something to work with!

Nuff said, I just wanted to ask the question. When I started to roam thes forums and learned engines the latest and greatest had "Y2K" in its name. Get it? Back then there was a lot of carbs still running around and every gallon of fuel consumed by sleds had to pay a visit to the lower end before it could "get to the penthouse".

Mad ramblings over..

 

[pus1100]

Rune,have you heard of any PRO's with squeeked pistons.OEM or aftermarked?cast or forged?I have not yet.

 

[Norway]

Rune, have you heard of any PRO's with squeeked pistons.OEM or aftermarked?cast or forged?I have not yet.

No, I have not. Hence my words "wont beat itself to death and still NOT squeek the pistons".

 

[pus1100]

i guess the clearances on aftermarked forged pistons are tighter than OEM.have not heard of anyone who has squeeked yet.dont understand the problem here?if you have loose OEM pistons,swap them out for wiseco,the fix kit or RKT/wossner and ride.

 

[diamonddave]

Did anyone on here get to ride the pre production dragon 800's. They had none of the issues. The reason was because pre production units do not have to meet emission certifications. just FYI

You are right. I rode a trashed Dragon and couldn't believe the HP. That thing was stomping everything, except 900's.

You guys are all correct. The one big difference we are seeing with the CFI-2 is the ring flaking. And all of the CFI-4 comments are dead on correct.