Inferno with Hyper 21 tuning solved !

[Bad Inferno]

After installing a Hyper 8 port (with OS carb) in my Kanai I could never really get the acceleration tuned correctly and had to lean out the LSN way tooo much. Well today I finally figured out why.

It seems with a full tank of fuel (nearlly all the way to the top) the car just "bogs" down when trying to accelerate, too rich. I stumbled accros this as the buggy had been running really well before I added fuel. When I think about it all my pre tunning was done with full tanks of fuel.

I have a short length of fuel line between the muffler and fuel tank (2" and next time I take it out I will put 6" line on and see if it allows me to fill the tank.

Seems like the fuel tank was being over pressurised on a full tank. I can now back out my LSN to what is a more normal setting now I know not to fill the tank all the way !

Maybe a trap for new players thought I would share this with you....anybody else had this trouble !

 

[niggle]

AFAIK every nitro car with a reasonably large tank is affected in the same way (it certainly affects me).

I suspect that the weight of the "head" of fuel in a large tank has more effect on the syphon pressure than exhaust line pressure. This problem is less pronounced on 1:10 cars with smaller (75cc) tanks.

This is something that most 1:8 buggy owners just live with and tune for safety at around 1/2 - 2/3 empty.

More elegant solutions might be some kind of fuel pressure regulator (expensive and difficult to source) between the tank and the carb or a "header tank" positioned above the HSN to provide a more constant gravity feed to the carb. A large fuel filter mounted vertically neat the HSN union might work as a "header tank".

Lengthening the pressure line between the tuned pipe and the fuel tank delays the point at which pressure builds up and richens the part-throttle mixture.

 

[Bad Inferno]

I have been running for the last 4 months, so new to the sport and read quite a bit about tuning...I cannot remember being warned against trying to get your car tuned with a full tank. It caught me...and as it turns out, I thought as I was tuning the car it was getting better however in reality it was the fact that I was just running the car for 1-2 minutes and nownot got a full tank.

When I fill it up to just below the cenntre partition its fine...it was just that last bit of fuel I was trying to squeeze in !