mercfocus

iTrader: (3)

I've noticed on occasion my engine would start to lean out like it's running out of fuel and then shut off. I thought it was tuning like the LSN was just a little lean so I adj it but the lean sound would still happen occasionally and still sometimes die like it ran out of fuel but there's always anywhere from 1/4 to 3/4 tank.

I tested the fuel system and it's perfectly air tight. No leaks there at all.

Then I thought about the pipe so I loosened the set screw to see where the pipe sits comfortably. it's 13mm off. The pipe hanger was pulling the pipe out away from the tank. If it doesn't sit out that far, it would melt the tank and that's why I did that to begin with. But letting the pipe sit where it really wants to doesn't even leave enough room for the tank.

So I think I'm intermittently loosing tank pressure from the exhaust seals being stressed.

So my solution is the pipe header. This one on the JP1 seems to have a 3cm radius. If I could find one with around a 35 – 40mm radius, I can maintain pressure and keep it off the tank.

Have any of you guys had this problem?

If so, what did you do about it?

But mostly, I want to know if anybody knows of a header that will suit what I need to do here.

It's a Hyper 7 RTR Pro with a Nova Rossi/Mugen Beat 5 and a JP 1 pipe.

Thank you for any advice you might have.

imaxx21

iTrader: (1)

i think your problem is in the carb tuning

mercfocus

iTrader: (3)

I don't believe so.

It runs flawlessly 99.9% of the time or even more.

If it was tuning, the problem would be more consistent, like every tank and every time it warmed up.

The problem I'm seeing is while it's running, it sounds perfect, and then leans out like it's running out of fuel. I can back off the throttle a little and that will keep it going and then it's back to normal.

I think because the pipe is pushed out that far, the O-ring seals are barely sealing and than as the pipe gets hotter, metal expands and where the seal barely seals now leaks pressure.

So if it can leak a little pressure there while the engine is at higher RPM, it will continue to suck the same volume of air through the filter but with less fuel being pushed in causing that momentary lean affect.

The pipe was held out quite a bit and I can see in those seals where it wouldn't seal perfectly so my guess is the manifold.

Especially since engine tuning is not an issue for me. I had this engine in another car that allowed a lot more space between the tank and pipe so it wasn't under any strain and never acted like this in that car. Acts like this only in this Hyper 7 where I had to force the pipe to sit out away from the tank.

I have at least 4 maybe almost 5 gallons on this engine.

It's very well maintained. I put new ceramic bearings in it a couple gallons ago and recently changed the rod and wristpin.

I would be more inclined to suspect a carb leak than something like tuning.

This engine is very easy to tune and has always held its tune just fine.

Sideshow Bob

dunno if that motor is basically a new P5 but a few years back when i was running nova myself and another person at the track the the exact opposite happened. it would richen out slowly until it got to a point where is was to slow to clear jumps. both motors were apparently from the same batch. It turned out to be the LSN literally undoing itself as the race progressed. had to replace the LSN and orings. i remember how loose it felt...you could set it with your finger nail lol.
what im getting at is, like you mentioned as well - perhaps check the carb first for a leak or something. You could also try the expensive nova gaskets - red ones i think. they can handle more heat. i remember you get soem Hpi gaskets that are pretty thick..thicker than the norm...so the pipes go over very tight. it was purple.

EDIT: these http://www.hpiracing.com/en/part/87049

Hoese37

iTrader: (5)

You need a header like this one. http://rex-usa.com/MANIFOLD-41019-41019.htm

Juice1

iTrader: (16)

Jus simply spread your header open until the pipe reaches the mount. No need to spend money on a new one.

mercfocus

iTrader: (3)

That's the right idea right there.

It's one of the headers I've looked at so far but I don't have the dimension between the center of one opening to the center of the other opening.

Do you happen to know if that's any where near 70mm?

I just got a 9901 pipe from them last week. I'll have to call them tomorrow and see if they can measure it for me I guess.

mercfocus

iTrader: (3)

That's another idea I came across on FB from one of the pages there.

It has to be warmed up first?

This guy said he put his in the oven.

I'd rather get a different header that's already the size I need but if that's not even available, then this is what I'm doing.

Jerm13

iTrader: (36)

I had to do this a couple times a few years ago. Funny thing, both the buggy and truck were same manufacturer, and they just fit so much different. Pipe hangers were the same length and position, just the buggy was tighter than the truck. Had a JP header and put 2 larger flat head screw drivers in the holes and gave it a little tweek outward. Fit just perfect after that.

Quick question though. Have you tried adjusting the pipe hanger to where the pipe sits naturally? Some times you need to cut some off it so it wont hit anything on the opposite side. Not uncommon when building new kits, using new pipes or having to replace the hanger...

Jerm13

iTrader: (36)

And now that I look at the pics again, I see you cant adjust the hanger. So its either bend it out a touch or get a pipe mount that slides the hanger thru a hole so you can slid it in and out for adjustment

And BTW, the JP=1 is a torque pipe which is pretty long by its self. Have you ever though of getting a shorter mid-range or top end pipe? Just a thought.

mercfocus

iTrader: (3)

Now that you mention it, I'm thinking I should have provided a pic of the tank sitting on top there for better clarity. That would show how there's no space for it. Where the pipe hanger sits in the pic now is where the pipe has to go out to just to even fit the tank and even then, there's barely any space between the tank and the pipe.

On this choice of pipe, I had a JP4 hooked up to this engine for almost 4 gallons in a different car, another OFNA. This combo always felt like it was missing something. The JP1 woke this engine up on the bottom end. So far, I've liked the JP1 better than the JP4, on this engine anyway.

But after recently seeing what the 9901 did for my Rex, I think I want one of those maybe for this engine too.

-R2-

iTrader: (4)

I would try this you say as the tank is almost done then the engine starts to lean out, well when it starts doing that fill right away with more fuel and see if it goes back to rich or normal operation, if thats the case then your tank is over expanding and airing out for your lean condition then it the tank that's giving you problems. From the pic you have a straight pipe hanger and that's not good for the JP pipes, when you got the pipe it came a spring loaded hanger and you are to use that because if you don't you might snap off the tip of the pipe. Not saying that it has done this yet but look at the pipe just in case.

-R2-

iTrader: (4)

Can't test a tank when it's cold it will contract and seal up good.

mercfocus

iTrader: (3)

That would make for an interesting observation- if I can get to it quick enough.

When it starts to lean out, it dies like it ran out of fuel. What I have found is if I let off on the throttle and just lightly tap the gas, that keeps it going and it drives perfectly normal after that.

I also once saw it die like this when there was over 3/4 tank but that was after refueling right away, not letting it cool down at all.

So engine heat has to be part of it here. It's never died cold or warming up.

I just removed one of those spring coil hangers from my LX2 and put one on like this one here because I don't like how it bounces on the chassis and dent's the bottom of the pipe. My LX2 has a JP2 on it with a really mean dent under it.

mercfocus

iTrader: (3)

I never thought of that. I always tested in cold conditions looking for basic leaks and weaknesses and whatnot.

Now I need to find a way to do really good tests on these tanks when they're warm, at car running temps. That certainly would give me the most accurate test for sure.

Do you, or anybody, know of a test set up that does this?