Is there any issue on mounting a 2T or 4T engine upside down, in case it optimizes the space in the cowl?

Regards,

Nilo

What's most important is the carb to tank relationship. The tank should be slightly lower than the centerline of the carb. Inverted engines generally run fine, but they are more prone to a flame-out due to wet fuel landing in the plug. They are also more prone to hydraulic lock if you flood the engine when starting it. None of these things are a big deal if you know what you're doing and you get the engine set up right (mixture controls).

Also, you can use an onboard glow igniter to help keep the plug hot, but usually it's not necessary.

The two references would be the carb center line and the chunk inside the tank, is this right?
In case the correct alignment doesn't happen (Carb below chunk), would a fuel line manual valve a good idea to shut off the line when not running?
I guess the concern here is the fuel not flowing by gravity to the carb, right?

Thanks for the reply!

Nilo

Fuel is drawn into the carb due to the vacuum created inside the engine. However, in your setup with the tank above the carb, the engine has an easier time drawing fuel. When the plane is inverted, the tank will be well below the carb and lean out - possibly dying. you could use pump to make the flow more consistent.

Hi Nilo,the center line on the carb should read the spray bar on the carb, also the center of the fuel tank should read the center of the fuel tank to 3/8"below center of fuel tank in relations to the spray bar,hope this clears up the question.

Yes, I made myself unclear.
I was saying that we should make sure the fuel doesn't flow by gravity from the tank to the carb, otherwise it could happen alone without the engine running and make a mess, flood the carb, wet the plug and put fire when starting the engine, so on. Then I suggested to add a fuel line switch to cut the line when not flying.
If the tank is going to be below the carb when flying inverted, it would also happen in the suggested configuration for a normal fligh(tank below carb).
1)Wouldn't it also kill the engine, following the same thought?
2)Isn't the vacuum from the engine enouth to suck the fuel?
3)Is there any rule of thumb about this maximum diference in level that the engine can suck?
4)What about using pump?How it works?

I'm getting confused here![&o]

Nilo

Hi Nilo,#1 when the engine is inverted if the spray bar is on the fuel tank center line all stays the same,if inverted and the spray bar is a little below the tank center the engine will be a little rich #2 very seldom with glow engines,the pressure from the muffler pressurizes the tank #3 probably but I don't know,the big problem is as the planes goes inverted and there is a large difference in tank/spray bar relations then the engine can get to lean causing damage,or get to rich causing a dead stick,also some engines have problems getting fuel if the fuel lines are more than 12" long,#4 the pump helps in the distant from the tank to the engine ,but not the height of the tank from the spray barHope this is a little help if not ,check back ,someone else might explain it a tad better.

Yes, thanks a lot.

Nilo