Glow Plug question

[millerracer]

When I got my RS4 - I picked up some new glow plugs just to have in the tool box from the LHS.

He suggestion A3 and A5 plugs (OS). I got several spare plugs when I bought my car used - and I noticed it had an A8 in it....

I am assuming the higher the number, the hotter the plug?

Well - my question is - this guy recommended these 3's and 5s and I have noticed the 8 ran the best out of all of them... crisper and it would scream on top end. Put the 3 back in and ran rich. So I am assuming that the higher the # the hotter, therefore the more fuel it must have?

Anyone care to school me on plug selection? Also - recommend a good plug to use for OS18 and HPI 15fe?

Thanks

 

[jetmechG550]

Check this:
http://www.outlawrc.com/glowplugs.htm
Numbers don't mean anything. An MC-9 is cold while an MC-8 is medium. Depending on weather and fuel (%) you'll most likely want to run a hot plug. I ran MC-59's in my OS .18TM in my Revo.

 

[millerracer]

What OS plug is a reference for those MC plugs?

Also - anyone else care to share what plugs they run and what motor they are using it in?

Like I said - I run only OS plugs.. A3, A5 and I have a couple A8's that seemed to work best in 70 degree weather. I assume the colder it gets outside - the hotter the plug will need to be.

 

[jon2]

I actually run MC59 with 20 % and when I go to 30 % I may or may not go to a medium plug. It depends on the weather. I have run the McCoy plugs forever. Since my first Nitro RS4 3 RTR it has been that brand. I personally don't like the OS plugs.They just don't last but I am sure that is the way I tune my mills. No worries though if you like them and they work..stick with em.

Follow the link as it has some insight to help you out. Makre sure you use plugs that are not for airplane and since you are running a non turbo engine, than use a non turbo plug. Your wallet will love you for that last tip.

Jon

 

[millerracer]

thanks again fellas.

 

[olds97_lss]

OS plug chart: http://www.osengines.com/accys/glowplugs.html

That should help you iron out your hot/cold at least for OS.

I run #8's in my big blocks and I used to run A3's in my small block OS engines (15-cvr and 18-cvr). I run the LC3 in my 18TM and the 8's in my OS 21 RG and SH 28.

The #8's are expensive. Granted, they aren't a turbo plug (really expensive), but I pay about $7 per plug at both my LHS's. Sometimes they last a few gallons. Sometimes they last a few quarts.

Typically with small block engines (.12-.18) you run a hotter plug like the A3 and for the BB (.21-.32) you run a cooler plug. I've tried running A5's but my 21's always ran like crap. Then again, that was 6 years ago when I was new to the hobby... I should give them a try again.

I tried the A3's in my BB's and the engines ran hot and the power wasn't quite what I expected. Running the #8 dropped the running temps and the power increase was significant. The temp of the plug doesn't relate to the "temp" of the engine, but it directly relates to when the fuel/air mixture inside the engine detonates. BB engines like to detonate later than SB engines. That's why my 21's were running hot and with low power with the A3's. I was getting early detonation so the engine was trying to run back-wards. So, I got poor power which made me lean it out thinking it was rich, which drove up my temps and then it detonated sooner. Kind of a vicious circle...

 

[jetmechG550]

Olds, that's an LC3 in the TM right? I ran the MC-59 in my TM, had the best luck with them over everything else.

 

[olds97_lss]

Yeah... typo. I run with the LC3 because it's a little longer and fits flush with the combustion chamber.

Is the MC59 a hot plug? I can't remember. I ran the MC59 3 years ago in a TRX 2.5 (along with 4 other brands) but I didn't have good luck.

 

[jetmechG550]

yeah it's a hot.