QuietStorm1122

Sup guys, been racing on road nitro cars for about a year and I still don’t get how to tune an engine for racing..

I currently have a
(Nova .21 Mito 9 port)
(Nova .21 Rex legend 7 port) and a (Picco .12) already broken in.

I understand the high speed needle and I see the low speed but I usually don’t touch it. I understand the difference between lean and rich and what they do. the idle screw i have never touched.

I don’t have the ear for what it should sound like or how to fix the bogging sound for example.

I usually have the guys at the track take my car and they fix it for me but they never explain how they do it or why and I understand that everyone’s busy on race day so i don’t ask for a lesson at the track.

Is there any exercises I can do to practice getting the ear for it without blowing the engine?

Thanks guys

MarkA

iTrader: (21)

You're probably not going to get a better answer in this part of the forum than a re-direct to this thread: "the tuning bible" and you can ask again there.

Evoking1230

iTrader: (8)

bogging on take off is a rich bottom end, in which case you would start leaning out the low speed needle, but only after you have your high speed set.

I would suggest going on Youtube and watching a few of those videos on how to tune a nitro engine. You can then hear what it should sound like and what it would sound like if its too rich/too lean, etc.

Hope that helps.

jonnyc

iTrader: (6)

i haven't tuned a nitro engine for a while but the best way i knew was to make a few full throttle passes and bring it back to you and immediately take a temp gun and check the temp at the head.i liked to see about 240-250.if you are higher temp than that it's too lean you need to rich the high speed needle if it's lower than that you want to lean the high speed.once you get the temp around 240 run again and make sure you have some blue smoke still coming out.if not richen it up until you see a little smoke.
once the high is set make a couple passes bring the car to a stop let it idle for about 10 seconds then nail the gas.if it bogs you are to rich on the low.i like to richen the low until it bogs and then lean it out a quarter turn.
once the high and low is set you can adjust idle to where you want it.

QuietStorm1122

Brother thank you soo much.

I’ll practice that.

QuietStorm1122

Thanks bro
I’ll try it out.

blis

It's hard to differentiate a poorly tuned engine from a LOT of other issues that can happen to make you think it's the engine tune. More often than not the effects are most prominent at lower speeds.

So while you search through the tonnes of posts on how to tune an engine, some questions to ask yourself before grabbing the tuning screwdriver.

• A RC nitro engine rarely richens, if it does it's likely something on the drive train is causing resistance
• Your fuel tank provides the fuel pressure, if the engine leans for no reason, it's definitely the first place to look (gaskets and fuel line too)
• Your glow plug tells you a lot about the mixture, if it's frosty and pitted, then it's likely lean on the TOP needle
• Frosting is caused by excessive unburnt oxygen being torn apart and rebonding at WOT, yes, it's too LEAN!
• If it was working fine yesterday and not today, your clutch is likely to be a major cause of engine tune issues
• Using a rubber band to keep your idle shut is the most important tip, A 2 stroke RC engine will by default want to open to WOT due to the venturi. It also helps tuning at idle.
• When you decrease your idle, you are in effect reducing the low end fuel supply. An older race engine will rarely sit and idle when hot, that's life.
• If you've swapped engines, always check your servo end points.
• Oil burns at temps over 140c, you can smell a hot engine.
• Sometime's the fuel is bad, rarely but it has happened.
• A well tuned nitro engine running the same fuel and plug doesn't need more than 1/2 turn change because or air temp changes.
• If your top needle impacts the flow of fuel to the low needles, you're probably too lean. (When pushing hard in race trim with lean top needle, richening the low needle helps compensate - this is extreme)
• The hotter the air gets, the leaner the air is of oxygen
• Only tune your top needle once the engine is up to full operating temperature
• Methanol is the primary coolant for an engine. Castor/oils are just lubricants.
• NitroMethane is corrosive and engines need to be regularly dismantled (not bearings) and flushed clean and lubed
• If you flood your engines with after-run ensure you don't have a glow plug installed and the next time you want to start, leave the plug out and turn it over before to prevent hydraulock
• If there's someone that is experienced at tuning engines, let them help you and don't retune it until you're sure it's not everything else above.

It's daunting, it takes time to master because it's not really the engine, it's everything around it that needs to be perfect for it to perform.

Enjoy...

Evoking1230

iTrader: (8)

This is pretty much how I tune my engines, hasn't let me down.