wh7702

Whats typical run time on a P5X?

I am usually in 20min A mains, and so typically everyone will push the window and pit twice. once at 7min and the second time at 14 minutes. I usually just BARELY make that on run time (usually pulling in on fumes). Others do not seems to struggle with it as much as I do. Does anyone have some advice on extending fuel millage for this motor? Different Pipe? Change in carb? Different Plug? Lay off the trigger finger a little?

Motor: Novarossi P5X
Pipe: JP3
Plug: McCoy 59

Thanks for any advice!

WH

GRANT ED

Do you use a carb insert?

wh7702

It has a stock one. The P5X dosnt come with swappable ones like the P21-5.

WH

RBMike

Put a restrictor in the carb, like 7mm and get a better pipe for run time, say RB2045.

lsurber

Just cut a sub-piston induction port in the exhaust side of the piston skirt like I did! You'll get almost double the mileage!

claudacio

My Feedback: (9)

+1

wh7702

How about a NR9886 and a new carb insert?

Anyone recommend Innovative Designs Velocity Carburetor Inserts?

WH

Jerseyboy

Post some pics of your mod.

gtsum

The Nova 86 pipe will give you better runtime as well. I am not a big fan of the JP pipes (I have the 1 and 2), and I swear they suck the mileage out of most all engines they are used on...

lsurber

[link]http://www.rcuniverse.com/forum/m_6145208/mpage_3/key_/tm.htm[/link]

Here is a link to the thread with photos added on page 3

This port will give you a conservative 50-60% more runtime depending on the size of the opening!

gubbs3

My Feedback: (1)

I know a few people who run that motor with a variety of pipes and can't get much more than that for run time. If you're not running dry and flaming out I wouldn't worry, you are in the right ballpark. A smaller carb restrictor would help somewhat.

Here's the real deal though... If you are running 20 minute mains and can make the two 7 minute stops without running out of fuel, that's fine. You will not be gaining ANYTHING unless you can make it a one stop main. That means that unless you can run 10 MINUTES between stops, it's pointless to worry about mileage.

wh7702

I agree 100%. I'm not looking to make the 10min mark on pit stops, my problem is I'm trying to make the 7min mark!!! I don't want to pit three times... Sometimes at 6.5min mark, I'm pulling in with the motor leaning/cutting out because its literally on fumes.

I would be absolutely ecstatic if I could go like 8min!

Codeblack

What are all the reasons for bad millage?

gubbs3

My Feedback: (1)

There's nothing that's ever 100% of the cause for less than average mileage. The greatest factor is the engine itself. Then all other things like pipe, fuel, weather, needle settings, driving style, track layout and traction, gearing, etc. all contribute to the overall run time. Something as simple as throttling back a little bit can really help extend run times. I almost never hold the throttle wide open down the straights. 80% is about all I pull it. Top speed doesn't change much but you will notice probably an extra 30 seconds of run time per tank.

Codeblack

ooo, nice. Funny you mentioned pipe because I know I have an air leak in mine, could that be a significant factor in bad millage? also gearing. Do you get more run-time geared up or down? does the engine have better millage at high resistance+low rpm or high-rpm+low resistance? Would really like to know the answer to this[]
thanks a ton

gubbs3

My Feedback: (1)

A leaky pipe will generally rob power since the tuning effect gets screwed up and the back pressure is reduced. It also creates very erratic running/tuning which is common for any type of air leak.

For gearing it is a double edged sword. Too low and your engine will be screaming around the track sucking fuel very quickly. Too high and you will have the trigger buried much deeper and longer which again, will consume lots of fuel.

Codeblack

thanks so much gubbs, lots learned today and yesterday

relay8039

Get a second engine or build a procedure for tunning, but for the Q races use 30% for the power and speed. But because of the nitro content you need to run a little richer. On longer races, use 20% fuel because you will be able to lean out the engine a little and get an extra few minutes. Depending on driving style I also look to change the gearing to compensate for the reduced power of the 20% fuel. I have a p5x and get about 8 minutes on a tank with 30% fuel and about 10minutes with 20% fuel. After re tunning. I lean out the mixture about 5 hours when I switch from 30% to 20%. It works for me. Oh check for air leaks around the carb. Once I had a great reduction in the milage because I was tuned too rich because of the air getting in from around the carb. I had a blown O-ring from removing and replacing the carb. Once replaced I have been able to get 8 minutes on 30% fuel. 20min mains are two stops. On 20% I can almost make it in one.