912 IS retrofit in Kitfox?

[jrevens]

Regarding a kit to add fuel injection to to a 912/914 -
1. How much weight does it add, if any?
2. Are there potential HOT start issues?
3. What does it cost? (I agree that the $3500 figure is very reasonable)

I know that the 912is seems to be considerably "busier" in the engine compartment, as well as heavier all up. I'm not sure you're going to see any increased power. Better fuel economy, yes, but I'd like to see legitimate testing results of any power claims.

[Esser]

Our setup weighs much less than the carbs but we are putting a second alternator on so I think we are going to be about 4 lbs heavier in the end. I can confirm this later when we actually move everything around.

Hot starts can be an issue depending on how you route your injector lines. Basically if you go straight to your injector as a dead end then you will probably have issues. The way we are doing it is one fuel line "Loop" per side of the engine with short 3/4" tees off of that loop to the injector if that makes sense.

You are able to buy complete kits for under $4000 so I think it is a good way to go.

http://www.sdsefi.com/rotax3.htm

[Esser]

This is what I mean by a loop.



I think this setup below would give you hot start issues as you have to clear the vapour all the way down.

[Kurt.A]

Icefox,
I have done several automotive conversions and all have turned out to be far superior in cold start up as compared to the carbureted original. I have yet to do a conversion on a Rotax to see if the results are similar but will be doing mine in the near future. I have no reason to doubt that the Rotax would cold start and idle like your modern day family vehicle when set up properly.

[Kurt.A]

Regarding a kit to add fuel injection to to a 912/914 -
1. How much weight does it add, if any?
2. Are there potential HOT start issues?
3. What does it cost? (I agree that the $3500 figure is very reasonable)

I know that the 912is seems to be considerably "busier" in the engine compartment, as well as heavier all up. I'm not sure you're going to see any increased power. Better fuel economy, yes, but I'd like to see legitimate testing results of any power claims.

John,
Hot start issues if any would relate to plumbing issues as stated in Essers reply. Also I would add that Intake Air Temp sensor location is critical to hot start issues as well as state of tune in the ECU. I am sure that some weight will be added but the differences will depend on the installation configuration. A well thought out system would be minimal difference. With regards to power production, there is a magazine out called "Eng Masters". They have proven several times that a fuel injected system will produce more power on the same carbureted eng every time. The same accuracy of the fuel curve that provides the better fuel economy is also responsible for the better power curve. It really depends on how far off the fuel curve that the current carb set up is. What I have seen for test results on automotive engs is with both systems tuned ideally there will be a 2-5 hp increase with EFI. These increases are usually seen in areas of the power curve that the carb is transitioning from one circuit to another.