Sean Bowf

This is not quite the test I wanted to run...was not done in my boat, or with my fuel...and is nothing scientific or anything. But when we were tuning a friends Mod RTR we tried 3 different plugs in it, and thought I would pass along the numbers.

The engine was an OS 18. The fuel was 50% nitro (did not catch the brand). Swapped the plugs out without making any other changes.

MC9 = 37.9
OS A5 = 37.7
Odonnell's #99OS = 37.4

I got these plugs because I wanted to do this test with the 40% I normally run in my boat, but I never got around to it today (too busy trying to get my kids' boats running right for the Chanute race in a month).

Top speed today on the boat above was 40.0MPH with the MC9 (obviously, after a bit of tuning...to get it from 37.9 to 40).

I say it is not the test I wanted to run, because I wanted to compare these plugs to the OS8 I run in my boat...and since I have been kind of bad mouthing the MC9, I figured I would post this now, and eat a little crow, then finish up the testing later and see how it all turns out.

Sean

007clint

Very interesting! I am guessing that the different heat ranges must change the exact firing time. Sort of like firing at 1 degree after DTC or 5 degrees after DTC? I hope someone that knows more about these little 2-cycle engines will chime in!

Dan S

Nice results Sean,

Nah! you weren't bad mouthing the MC9, you were only stating that you weren't getting the performance you were looking for with that plug.

The thing is we all have our favorite plug, we all know the rule about higher the nitro colder the plug and lower the nitro hotter the plug, we know that a lot of racers will prefer to use a hot plug on high nitro, but lets keep in mind that the rule was written when talking about a stock engine.

Stock engine = no porting done, no head shims removed or added etc.

In a stock engine when using higher nitro with a hot plug it will cause pre-detonation, ergo changing to a colder plug. if head shims are removed or added this will change or affect the type of plug (and other things) because we have now changed the size of the combustion chamber.

I'm not trying to tell anyone how to suck eggs as most of us know this, but there are a lot of new people that don't.

Keep us posted Sean and if you can, try an MC59 for fun.

Dan

Sean Bowf

Clint, along with timing, I also think part of the difference in speed is from how far the plug screws into the cylinder. The more it screws in, the smaller the combustion chamber is, and the higher the compression is. With thinking along these lines, the Odonnell's plug had the thickest crush washer on it...but who knows how much of a difference it makes. I could probably spend a day or more testing them with different washers on them too...heh. If I only had time...

I too would like to hear from someone that is a lot more in the know than me.

Dan, I will see if I can pick up an MC59 this week. We are taking a little road trip tomorrow (remember, no hobby shop in my town), and hopefully we can come across a hobby shop while out and about.

Sean

cmiller73

Hint Hint, MC59 and High nitro do go together. I learned that the hard way. Just so you don't waste mony Sean, the coil in the MC59 will contract and break runs great for one run. I found this out at VooDoo one Sunday. Bought 2 plugs on Saturday, burnt them both up in 20mins. But I may have been a tad bit lean, but I ran the MC9 on the same setting as the MC59. 59's burnt, 9's didn't

Just my $.02, which ain't worth much.[]

Sean Bowf

I dont know that I would agree that your 2 cents aint worth much...

Something I have learned about this hobby, is you can learn from anyone from an expert down to a beginner. Sometimes it pays off to just sit and listen to folks... When a person thinks they know it all...they quit learning.

Anyhow, I did the same thing when I went to try the A5 in my boat during the test and tune prior to Splash. I picked up a couple to try out, and burned the first one in the very first run I did with it due to being too lean.

We go through A LOT of OS #8s...but have not found anything as fast for my setup. That is why I wanted to do some glow plug testing. I want to find a plug that is as fast as the OS8, but will last longer. I bought 9 plugs prior to splash, I have 1 left right now. Gets expensive. I would be better off to pay a little more money, and get a little more longevity out of a plug...if it maintains the same speeds. So the quest to find another plug goes on. I will give the MC9 another try with my setup just to make sure it was not a fluke when I ran it last time (bad plug or something).

What percent nitro are you running Chad?? If you don't want to say...I understand...speed secrets...

Sean

Dan S

Sean,
the only reason I ask you for the MC59 is since your on a quest for a better plug why not give this one a try, I have a buddy here thats all he runs on his Vegas and sport 21 with all good results (on 35% Nitro).

Dan (I use MC9).

Sean Bowf

OK...I did a little more testing yesterday, in my boat, with the 40% nitro. Again, nothing scientific. While doing this, the wind was trying to come up...so if I got a bad run, I tried to do it again. Later in the day, the wind calmed down, so I ran a couple of the plugs again. Anyhow, here are the numbers I got:

42.6 Mine
40.2 MC59
39.1 OS A5
40.5 O'donnells OS99
39.1 MC9

This is when the water calmed back down and I tried a couple of the plugs again:

42 Mine
39 MC9
41.9 Mine again, just to make sure
39.1 MC59

Leaves me wondering what an O'donnells OS77 would have done... This testing was done on a a Miss Vegas boat with a CVRM in it (Mod RTR). I did not get around to testing in a stock Miss Vegas. Your mileage may vary.

Sean

RaysonCraft

Interesting. Thanks for posting it's good to see what others are trying. Are you adjusting the engine with the different plugs? I just ask because I've had to adjust after trying a different plug to get the AQU. engine to be happy again. (stock plug and duratrax LR3 plug about the same HSN setting but with an O'donnell purple plug I was able to lean it out about 1/4 turn. It liked the purple plug alot more from the sound. I didn't have access to a radar gun to test the speed at that time.)

Sean Bowf

No, no readjustment...that would take me a week...and would be scientific..

Just pulling a plug, and putting the next one in...then putting the boat back in the water until I felt I had a good straight line run (hit max speed), lather, rinse, repeat...

EDIT: also, I get my speed readings from a GPS.

Sean

RcBoatman59

you forgot to mention that it was a touch over 100 degrees out ! ( 103 to be more exact !!! )

Sean Bowf

That's like a cold front aint it??

Just getting into the hot season...and I am tired of it already. 100sh+ every day here...wind up stuck inside.

The test and turn was a good day though Norm. As I mentioned when we left, nothing big broken and a long day of running. Got Ashley's boat figured out, got some testing in. Even looked like Tom had a good day... It was a good test and tune day, even if it was over 100 degrees...

Sean