Exhaust Cone Test

[02R6420]

Hey guys just thought I would pass on some hopefully useful info. I have just over 2 gallons on my F4.6 Savage X, and I decided to try this aluminum inner cone for the stock tuned pipe. I have heard good and bad things so I wanted to see for myself. First I tuned the savage without the cone, not much just minor adjustments due to the change in weather since the last run. HSN and LSN set up perfect, it was running around 240-250 degrees. So then I installed the cone and fired her up, I was lucky if I got the thing up to 200 degrees. I had to lean out the HSN about 1/4 turn to bring the temps up and start making good power again. Once I had it tuned it was pretty obvious that it was making more power all through the rev range. It was wheelieing out of controll (more than it already did) and top end was faster (more revs). Maybe I'm crazy but I wont be taking that cone out any time soon! IMO the stock pipe on the savage does not build enough pressure to feed enough fuel at high rpm, I think this helps this issue alot. Another thing it seemed to help is that pain in the azz HALF TANK LEAN. My temps were not fluctuating (spelling?) as much when I fill up. I'm not saying it is the fix for the HTL just that it seems to help. IMO the cone restricts exhaust flow a little bit, enough to create more back pressure in the exhaust which is why you will have to lean the needle settings. This higher back pressure seems to be feeding more fuel at high rpm allowing this thing to really wind out without having to run rich in lower rpm. I dont know why it seems to help the HTL issue but it does. Hope this info helps some of you and I'm sure some disagree with my findings, I'm just telling you about my experience. Man I am starting to really like this cheap RTR mill!
Peace.

 

[cuz]

what type of inner cone came stock in it?

 

[Rolex]

It's the cone of silence that comes with the car and can be added to the stock pipe.
Interesting information. Thanks for doing the comparison.

 

[Ofna1]

What is the half tank lean ? Is there a way to fix it ?

 

[02R6420]

What is the half tank lean ? Is there a way to fix it ?

When your fuel level gets down to the step in the tank the fuel mixture leans out. As to why this happens there are a few different explanations, most common one is the surface area of the fuel reduces at the step in the tank so there is less area for the air pressure in the tank to push on. This causes less fuel going into carb leaning out the mixture. The only real fix is to ditch the stock tank and install one without a step in it.
Peace.

 

[flm_savage]

mid tank it to get rid of the half tank lean problem

 

[v12revo]

i have a savage x & i took the cone off of it. i thought it was supose to give it more power! i noticed it made it louder! as for the half tank lean? mynes fine i just put one of those back pressure filters that they use on those on roads & its to prevent the engine from leaning out when your running on phumes. it doesn't lean out crazy & then turn off it just turns off now.

 

[boody1981]

Half tank lean? yeah I've heard of this issue so many times on here. I am on my 15th gallon of fuel in the same engine and I have NEVER experienced this so-called lean issue. I call this myth... "busted"

 

[ratchet1974]

Another thought to the HTL issue.

As your fule level goes down, there is more air in the tank. It is a lot easier to compress air (a gas), then it is fuel ( a liquid).

I believe this to be the case, as my temps begin to rise about a 1/2 tank & continue to rise, as the fuel level decreases.

Good info on the cone.

I am not looking at it now, but depending on where the cone goes in relationship to the pressure feed tap for the tank, if you restict the flow, you would create more back pressure on the engine (typically increases torque). That pressure has to go somewhere. If it goes into the fuel tank, because it's the path o least resistance, it would make sense that is's helping the lean out condition ?

I'll have to try this when it gets warmer & monitor the temps throughout a tank before & after the cone install.

Interesting..................

F = P x A

Force = Pressure x Area

If the pressure fed into the tanks from the muffler is the same or consistent, which it should be & the area decreases at the step down in the tank, then then what 02R6420 says makes sense.

If adding the cone increases the pressure to the tank, then the force the fuel is pushed to the carb is increased throughout the entire tank, but it would still vary once you step down in size.

:whhooo: too much thinnkin. Time to go to bed !