Backpressure on Nitro RC Engine

by Paul
(New Zealand)

I have just purchased a new ASP91 AR,I have run two and a half tanks approx 1 litre of fuel and ran it with the OEM muffler and with a 13x6 prop.

I have removed the muffler and fitted a slimline muffler that I have modified to give the plane a scale look by removing and welding up the one tailpipe and have added a single length of pipe 160mm long 1 1/2 diameter bigger than muffler tailpipe to it.

The motor starts well but runs very erratic on idle. I have been able to get top end set at full throttle. However, very fine adjustments,when motor has run at full throttle for a few seconds and then brought back to idle the engine takes ages to fall back to normal ldle pinging at the same time.

After it has settled to normal idle and then full throttle given it splutters for a while and then revs up but very rough.

I have been adjusting the lower end and just cannot get to that happy medium like I had with the OEM muffler.

I feel that there is not enough backpressure on it,if this is the case someone told me that I could put steel wool into the muffler which would help this.

Would this help and do I have a backpressure problem?

Comments for
Backpressure on Nitro RC Engine

Average Rating

Click here to add your own comments

Jun 05, 2009
Rating

Sounds like Backpressure Issue
by: Matt

Hello Paul,

I don't think slimline mufflers have internal baffles like the stock mufflers.

You probably have seen the internal baffle in your stock muffler. This baffle is in place to create back pressure. So if your slimeline doesn't have it then adding steel some steel wool would probably do the trick.

But be careful not to restrict the flow too much as this could damage the engine too.

Setting up the exhaust systems of glow engines can be an art in itself. You may find this article on tuned pipes interesting.

Explanation of Tuned Pipes on O.S. Engines Site