What back pressure?

[Chuck21387]

What kind of back pressure from the exhaust do you need for these little nitro motors to run on? Can you just run a straight pipe? i'm sure it'll be loud as all get out, but will it still run and perform OK? Its a .18 motor in a tmaxx 2.5

 

[HeartBreak]

Nope, you need to have a pipe that has a 'bulge' to it, like the exhausts commonly seen on 8th scale buggies and what-not. It has to do with reversion waves.

You see, the shape of the pipes' divergent and convergent cones 'tune' the reversion wave, so it hits the engines exhaust port (like an echo) at just the right moment to shove the fuel charge right back into the combustion chamber.

Without the cones, the engine will run like a dog. Not to mention, the engine will run fatally lean, and will have a VERY short lifespan.

Stay away from the copper tubing "dual rear exhaust" pipes you see on ebay; those are engine killers.

 

[Jeep]

This past sunday I was running my buggy and it suddenly lost power and would die at anything much over idle. I checked it out and found the exhaust port seal had split and the header to muffler coupling had burnt a large hole in it.
You definitely need the exhaust as it is and sealed well.

Jeep

 

[Chuck21387]

Thanks for the responses....i'll be modifying a stock 2.5 manifold to accomodate my new .18 motor...i'll use an exhaust coupler to connect from my engine exhuast port (round) to my "custom" manifold (round). then use the stock pipe configuration.

thanks again!

 

[Plaidfish]

if you really want to see that mill run well I'd suggest getting a tuned pipe...the stock 2.5 pipes aren't all that great and you will be fighting the tune on the .18......