It depends on racer throttle control to have decent mileage. Me myself only get 8+ minutes with 4btt engine so to get that extra minute would be a myth

Is your clutch slipping a lot?

So we get over 10 minutes with my modified version being driven by some seriously fast racers..

my advice is as follows... 9886ss/41001 7.5 mm insert, even a 41001 on your 9901 will help, remove 0.1 -0.2 mm head shim from the engine... all these will improve efficiency but at a loss of smoothness as this setup will make a pile more power.. use a #6 plug if you remove 0.1 mm shim and if you remove a 0.2 mm then you can a 6 or even a 7 plug

I always thought that the bent headers were less efficient than the smooth headers. As well as the the larger Venturi. I guess if the engine makes more power, I won't be full throttle as often. In terms of the head shims, if I remove remove the smallest one, would I be able to run 30% nitro? I usually run 25% anyways but just wondering if it would still be safe.

I thought that may be the case. I was using the 4 shoe losi clutch with 2 aluminum and 2 composite shoes with all green springs. I recently switched to the aluminum prebuilt losi clutch, same shoes except the aluminum springs have one step stiffer springs. Could not tell any difference in fuel mileage

I know assumptions can easily cause misunderstandings, but usually people with this kind of extreme mileage issue, will have a very fat bottom end tune, which causes them to be on the throttle much more than they should. This lowers runtime significantly.

Check that all your exhaust seals are good, then make a new attempt at tuning it, with the goal of having a crisp, clean bottom end. An excessively lean top end can mask a fat bottom end. So before you tune the bottom end, open up the top 1/4 turn (or more if needed!).

The seals are good and the tune seems good as well. However, I'm still gonna take your advice and check seals and retune it to see if there is anything left in the bottom to lean out.

I'm not experienced with the losi clutch.

However, I would look at a softer spring for the 4 port motor over the 5 port. This should also help with mileage, though it isn't going to be some miracle that'll give you an extra 2 minutes.

Truth be told, there's no single miracle cure. It's in car setup, throttle control, track size, and then it will fall back on mechanical things.

Personally? I'd be happy with 7-8 minutes. 1 less pit stop is only advantageous if you never crash. A single crash and you've lost your advantage.

I realize that there is not going to be any miracle that is going to make my engine 20% more efficient, there is just no way that's possible. However, any advantage I can gain with fuel efficiency would be nice. Just the peace of mind if being able to pit at 8 minutes without sweating would be nice.

How much fuel through the motor? My novarossi's got much better fuel mileage around the 3 gallon mark if I did the break in myself. After that, I refused to break a motor in and just send it to rcrenew and have it lapped and then broke in.

Engine has just over 2 gallons. But you are right about the 3 gallon mark. Happened with my p5.

turns out this motor is the old max power max racer .21 3 port

well your following the conventional wisdom with your current setup and its giving you terrible mileage and probably less then stellar performance !

And yes you can remove 0.2 mm from a stock Nova and still run 30% fuel...just run a colder plug like a C7TGC

Pipe/header/Venturi are on there way. I'm excited to try your recommended setup. I have a ton of c6tgc plugs, so if I remove .1mm I would still be able to use the c6?

Yes the #6 will work

Also venturi will be something to play with some...there is a ideal balance between its size and the size of the track... I know my largest Mizer insert makes nearly the same power as a 8 mm , better runtime , but narrower tuning window and a loss of trigger smoothness....