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Plugs of Choice for Speed Engines

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Plugs of Choice for Speed Engines

Old 03-14-2010, 11:24 AM
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smoknrv4
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Default Plugs of Choice for Speed Engines

Just curious to know what plugs you experienced[sm=49_49.gif] guys are using on high timed speed engines, I've been using OS#8,3, and F types.
Old 03-14-2010, 01:42 PM
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Ed Smith
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Default RE: Plugs of Choice for Speed Engines

The type of plug (Hot or Cold) is determined by the alcohol content in the fuel. High alcohol content=Hot plug. Low alcohol content = cold plug.

O.S. plugs offer a good range.

Ed S
Old 03-14-2010, 02:13 PM
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Default RE: Plugs of Choice for Speed Engines


ORIGINAL: Ed Smith

The type of plug (Hot or Cold) is determined by the alcohol content in the fuel. High alcohol content=Hot plug. Low alcohol content = cold plug.

O.S. plugs offer a good range.

Ed S

Don't you mean the Nitro content determines the Temp of the plug?
Old 03-14-2010, 02:39 PM
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Ed Smith
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Default RE: Plugs of Choice for Speed Engines

Don't you mean the Nitro content determines the Temp of the plug?
No I do not. Nitro does not light the plug. The catalytic reaction between the alcohol and the platinum in the plug element is what makes the plug glow. There is a relationship between the % of alcohol in the fuel and the diameter of the plug element that has to be maintained for the engine to run and idle properly.

Very Basicaly, More alcohol, smaller dia. element, hotter plug.
Less alcohol, larger dia. element. colder plug.

If the relationship is not correct the result is rough running, pre-ignition, no ignition, poor idle.

Ed S
Old 03-14-2010, 02:46 PM
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lfinney
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Default RE: Plugs of Choice for Speed Engines

i have used KB1-L for smaller engines and my pattern planes, but i like the Merlin plugs alot, and i prefer the flat wound element plugs for high nitro and high rpm, they are called globee style, i used globee flat wound types for my 50 plus nitro engines. the plugs took at least twice the amps to light up. enya four stroke plugs work very well as well, but are very expensive. K&B HP plugs have been the favorites of the ducted fan guys for years, unless they were running a nelson engine.
Old 03-14-2010, 03:06 PM
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MJD
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Default RE: Plugs of Choice for Speed Engines


ORIGINAL: MOTORMAN37
Don't you mean the Nitro content determines the Temp of the plug?
Axiom versus cause; Ed has it right. Methanol is replaced by nitromethane, and oil content essentially stays constant, so there is an inverse relationship that agrees with the phrase "more nitro, cooler plug". If the temp of the element is too high, then pre-ignition of whatever nitromethane is there begins and things go to Hades in a handbasket.

MJD
Old 03-14-2010, 04:36 PM
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Default RE: Plugs of Choice for Speed Engines

ORIGINAL: MJD


ORIGINAL: MOTORMAN37
Don't you mean the Nitro content determines the Temp of the plug?
Axiom versus cause; Ed has it right. Methanol is replaced by nitromethane, and oil content essentially stays constant, so there is an inverse relationship that agrees with the phrase ''more nitro, cooler plug''. If the temp of the element is too high, then pre-ignition of whatever nitromethane is there begins and things go to Hades in a handbasket.

MJD

Also more nitro the thicker the platinum element wire has to be to catalytically react with less methonol because of more nitro content.
Old 03-14-2010, 04:43 PM
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smoknrv4
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Default RE: Plugs of Choice for Speed Engines

I think Dub Jett sells his engines with merlin plugs, doesn't he?
Old 03-14-2010, 05:10 PM
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Default RE: Plugs of Choice for Speed Engines


ORIGINAL: mk1spitfire
Also more nitro the thicker the platinum element wire has to be to catalytically react with less methonol because of more nitro content.
That's exactly what Ed said above..

MJD
Old 03-14-2010, 06:54 PM
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Default RE: Plugs of Choice for Speed Engines


ORIGINAL: MJD


ORIGINAL: mk1spitfire
Also more nitro the thicker the platinum element wire has to be to catalytically react with less methonol because of more nitro content.
That's exactly what Ed said above..

MJD
I find 2v into my colder plugs provides a better glow than 1.5v because the element is bigger and easier first time starts

Old 03-14-2010, 07:17 PM
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Default RE: Plugs of Choice for Speed Engines

The heavy gauge plugs idle just fine at 18,000. The heavy gauge wire might also decrease the odds of finding a hunk of it wedged between the piston and liner someday.
Old 03-14-2010, 08:04 PM
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Default RE: Plugs of Choice for Speed Engines

What plugs would you guys recommend for the Small Block Evolution .60NX with Jett Muffler. I am running about 15,200 with a 10-8 on 20%, but will be runnin 10-15% when I fly the sundowner. I only ran the 20% because that was the only jug that was opened allready. I would like to try some Merlins though. The plug recommended for pipe use according to Horizon is the HAN3015 # 9 Performance Glow Plug. I asume this is a MCcoy plug, but which one is it. I have been running a OS#8, but they are kinda pricey.
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Old 03-14-2010, 08:12 PM
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Default RE: Plugs of Choice for Speed Engines


ORIGINAL: combatpigg

The heavy gauge plugs idle just fine at 18,000. The heavy gauge wire might also decrease the odds of finding a hunk of it wedged between the piston and liner someday.
Been there done that!!!
Old 03-14-2010, 09:12 PM
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smoknrv4
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Default RE: Plugs of Choice for Speed Engines


ORIGINAL: MOTORMAN37

What plugs would you guys recommend for the Small Block Evolution .60NX with Jett Muffler. I am running about 15,200 with a 10-8 on 20%, but will be runnin 10-15% when I fly the sundowner. I only ran the 20% because that was the only jug that was opened allready. I would like to try some Merlins though. The plug recommended for pipe use according to Horizon is the HAN3015 # 9 Performance Glow Plug. I asume this is a MCcoy plug, but which one is it. I have been running a OS#8, but they are kinda pricey.
The K&B 1L plugs are reasonable thru mecoa, 4.99 us.
http://www.mecoa.com/
Old 03-15-2010, 08:09 PM
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Default RE: Plugs of Choice for Speed Engines


ORIGINAL: smoknrv4


ORIGINAL: MOTORMAN37

What plugs would you guys recommend for the Small Block Evolution .60NX with Jett Muffler. I am running about 15,200 with a 10-8 on 20%, but will be runnin 10-15% when I fly the sundowner. I only ran the 20% because that was the only jug that was opened allready. I would like to try some Merlins though. The plug recommended for pipe use according to Horizon is the HAN3015 # 9 Performance Glow Plug. I asume this is a MCcoy plug, but which one is it. I have been running a OS#8, but they are kinda pricey.
The K&B 1L plugs are reasonable thru mecoa, 4.99 us.
http://www.mecoa.com/

How would that run compared to a OS#8, and what about the life.
Old 03-15-2010, 08:27 PM
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smoknrv4
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Default RE: Plugs of Choice for Speed Engines

All I know is Dub Jett recommends them on his website, so they can't be that bad, I've have used them and they seem to last as good as the OS 8 plugs.
Old 03-15-2010, 08:35 PM
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Default RE: Plugs of Choice for Speed Engines

There's so many variables that effect plug life...I don't think I could list them all in one sitting.

prop not balanced
prop load too high
engine mount weak / loose
worn engine bearings
not enough oil in fuel
needle too lean
flaw in fuel system plumbing
too much compression
too much voltage
cranking through a flood
high rpm in general
tuned pipe too short / small
too much nitro
combustion chamber design
running engine out of fuel.......

Old 03-15-2010, 08:43 PM
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Default RE: Plugs of Choice for Speed Engines


ORIGINAL: combatpigg

There's so many variables that effect plug life...I don't think I could list them all in one sitting.

prop not balanced
prop load too high
engine mount weak / loose
worn engine bearings
not enough oil in fuel
needle too lean
flaw in fuel system plumbing
too much compression
too much voltage
cranking through a flood
high rpm in general
tuned pipe too short / small
too much nitro
combustion chamber design
running engine out of fuel.......


Yeah no kidding CP, you could go on and on about different variables. You can spend big bucks on glow plugs and they still blow.[:@]
Old 03-15-2010, 09:01 PM
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Default RE: Plugs of Choice for Speed Engines

SRV...The worst is to stick in a new plug and realize that either the voltage was too high or it was just bad right out of the package....[:@]
Old 03-15-2010, 10:25 PM
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RVman
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Default RE: Plugs of Choice for Speed Engines

I'm using the merlin plugs in most of my engines now. I think they are the 2002HD or 2003HD and they seem to be working pretty good. I like that they are full length instead of the medium/long OS plugs.
Old 03-16-2010, 12:01 AM
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Default RE: Plugs of Choice for Speed Engines


ORIGINAL: smoknrv4

I think Dub Jett sells his engines with merlin plugs, doesn't he?
that's what both my Jett engines came with.
i just bench ran my BSE 50 this weekend........14 runs so far with the original plug. not sure if it is the 2300 or the 2300HD as i never asked Dub, but i did buy some of the Merlin 2300HD's with my 56LX.

the BSE 50 ran flawlessly and was at one point turned up to over 18K with the breakin prop.

other plugs i will use are the K&B 1L and the McCoy 59.
Old 03-16-2010, 03:51 PM
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Default RE: Plugs of Choice for Speed Engines


ORIGINAL: combatpigg

SRV...The worst is to stick in a new plug and realize that either the voltage was too high or it was just bad right out of the package....[:@]

Yeah I've plugged in my ignitor into the starter port before(12V) on my panel, what a bummer!! Then you look around and hope nobody was watching.[:-]
Old 03-16-2010, 03:54 PM
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Default RE: Plugs of Choice for Speed Engines

I just ordered a bunch of K&B 1L plugs, if you buy 12 you get 20% off, at 3.99 each, I'm happy.
Old 03-16-2010, 05:43 PM
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Default RE: Plugs of Choice for Speed Engines

If we're talking high nitro, high timing and high loads then the K&B HP and McCoy #9 are the way to go.

I run them on my 46AX with 15% nitro and a 9.5x6 prop and they idle just fine at ~3k rpm.
Old 04-11-2010, 06:18 PM
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Default RE: Plugs of Choice for Speed Engines


ORIGINAL: smoknrv4

I just ordered a bunch of K&B 1L plugs, if you buy 12 you get 20% off, at 3.99 each, I'm happy.

What the #%$ is going on.... I went thru 3 plugs today on these K&B 1L plugs on three flights with my Q-500 .46FX plane today[:@], never had that happen before, although this is the first time I used these plugs, what went wrong. This engine prop set-up hasn't changed from last year (jettstream muffler,9X7 apc), so thats what makes me think that maybe I got a card of bad plugs.

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