Glow Plug head button's

OK all U engine Guru's has anyone done any performance testing to see if there is an advantage to running the Standard Glow Plug head button over the Turbo head button ????

Concensus is a turbo adds about 500 rpm at the top end. If my memory serves me Dick Jones did testing as well as others
Thanks John

I would go with the turbo plug. when I was Reading in the RC car forms they had the same results around 500 more

how is that? Does it effectively "advance" the ignition timing compared to a standard plug?

Have ya ever noticed that small amount of black around the threads and washer.. that is your answer. A washer and thread does not perfectly seal.

Grim

None of my boats have telemetry or a tach, so I’m not sure about any rpm gains, but the boat/engine combinations I’ve run with both standard and turbo plugs by changing head buttons, are more economical to run with turbo plugs. When running K&B 1L plugs in several different Novarossi .21’s they would last about 3 heats worth of running, before the plug wouldn’t light anymore. When racing I would put a new one in every round, and use the ones I pulled on test days. I’ve had O’Donnell T77’s last a whole season.

I was a tool and die maker for almost 20 years. The way the standard glow plug draws itself up using helical threads, only one side of the plugs thread is actually touching the threads of the head as it tightens up. This means that any gap between the two threads is full of air or unusable volume. This unused volume between the threads of the plug and head become part of the compressed Air/Fuel charge because it falls underneath (inside) the seal of the washer and even though its a very small amount of volume it can not contribute to the combustion so it therefore robs each stroke of a tiny amount of what could be usable compressed volume.

I say tiny but actually the helical thread of a plug when unwound is longer than you might think. Just this fact alone and without any sophisticated equipment will prove that the turbo plug is better because it allows ALL of the compressed Air/Fuel to be ignited on every stroke. Other advantages of the turbo plug is its small face provides less interruption in the dome and the "cone" portion faces up with the head and forms a positive bond between the plug and head that provides more of a heat sink than a standard plug can provide plus you never drop the washer in the dirt when changing or checking the plug. I hate that... I love the turbo design plugs.

Okay let the plug fight begin! LOL

Larry, Using a properly selected plug, fuel is the largest contributing factor to plug life that I have found. The wrong oil and all bets are off on plug life..

Grim

Larry, just get 4 or 5 of each and go test them and see if you can actually see a difference in your lap times. Some of us do things because we feel like it just makes sense weather we can actually prove the difference or not.

K&B plug you mentioned are a little lite for the NR21. I use the NRC6 If you want more info just email me I would be glad to help you further.

-Carl

A turbo plug seals at the face of the plug.
A standard plug seals at the washer.
So if you have identical bowl volume the turbo will have more compression. This is why they make a larger difference in smaller engines. The volume around the threads stays the same no matter the displacement but the bowl is larger on a larger displacement. So it makes less difference.
A turbo plug may not need a washer but they sure do strip or cross thread a lot easier.
Very few people can utilize the difference in a .21. And it really won’t matter in a true heat boat.
On a time trial you can see it.
If you have access to a lathe you can adjust a standard button down. Or a simple flat surface and sand paper if it’s a flat squish. If it needs it.
There is more speed in props or pipes or even heat ranges then in plug types.

I hear there is different angles on the taper?

Brad

I know the Nelson plugs only fit the Nelson head, different from most of the Italian taper plugs. I believe the 3.5cc on road car engine manufacturers originated the taper seat plugs

Grimracer said:

Larry, Using a properly selected plug, fuel is the largest contributing factor to plug life that I have found. The wrong oil and all bets are off on plug life..

Grim

Click to expand...

Klotz synthetic/castor blend, mixed 14% with 65% nitro, 21% methanol. Hot 1L plug kept it lit. Medium heat range plug, the boat didn’t start as well or throttle as well on the water.
Novarossi 5 port prepped by Steve Wood. He reduced the chamber volume, but I don’t recall the number..006” squish, OPS 3280 at 8 1/8” spinning pitched up 1450’s. Gen 1 Blackbird. I won a lot of heats with that little orange missile. In our stable upper Midwest air, I seldom had to tweak the needle more than a click or two fat or lean. Very consistent and as fast as any .21 rigger I ever raced against, and a whole lot faster than a bunch of them.