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Old 09-22-2004, 08:49 AM   #1
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Selecting the right Glow Plug

Hey,

i'm looking for advice on glowplugs, i usually drive my car on a BMX track, with a LOT of on, off,on, off throttle, and run 16% nitro and 18% synthetic oil.

I don't really know what one to use, and i'm not sure how a plug changes the timing...I usually Use #8 but am sick to death of paying $13 each for them at my LHS.

I've noticed a fair few different brands, OS, DuraTrax, Tower Hobbies, Associated, Megatech, HPI, OFNA....

What would be the best performing plug for my application? best transition, idle etc for a .12-.15 offroad truck/buggy?

Thanks
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Old 09-22-2004, 12:22 PM   #2
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18% oil is going to foul plugs like crazy. Racing fuels are down to as low as 8% oil. Any more than that will cause your engine to run hotter than it should, with less power and increased stress (oil doesn't compress in the combustion chamber).

As a rule of thumb, .12's run best with hot glow plugs (the ODO77, O.S. 8, MC59) and .21's run best with cold plugs (ODO99, MC9, Nova Rossi 7 or 8).
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Old 09-22-2004, 09:44 PM   #3
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will most engines fair well on only 8% oil though? and how much cooler will an engine run on it?

my .12 CVR runs hot as hell and im using blue thunder racing fuel 20% nitro.

whats a good fuel to use in most situations?
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Old 09-22-2004, 09:58 PM   #4
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Hmmm I thought than no liquid or solid was compressable...only gases, so that would mean the oil, nitro and methanol wouldnt compress

The fuel i use is pre mixed sport fuel 16% nitro, 18% oil and 66% methanol.

Its' recommended that the kyosho motor runs AT LEAST 18% oil...and 10-20% nitro.

Are you sure that its ok to run down to 8% with my engine???
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Old 09-22-2004, 11:06 PM   #5
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its my understanding that most nitro fuels used super ultra mega high tech synthetic or synthetic blend oils that do the same job in much lower concentrations. i think its the trinity race fuels have rediculous low oil levels in them and they run fine.
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Old 09-23-2004, 12:32 AM   #6
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Both Trinity's Platinum and Horizon's new White Lightning have only 8% oil. Your engine will come up to running temperature faster, the engine runs cooler, and there is no loss in engine life. The fuel can be slightly more expensive just because the oil used in the fuel is higher quality.

Most fuels with high oil content contain a lot of castor oil. Castor provides a cushion when making an error in tuning. An engine running very lean while using a fuel with a high castor oil content won't be affected as badly as when running a fuel without castor. That's not to say it's good for it, but castor helps protect when the engine is tuned incorrectly. Racing fuels tend to leave out most of the castor because racers understand how to tune.

I have run a lot of the fuels on the market and Platinum is my favorite. It makes power, runs very cool, and protects my engines.

jamie - You're right..liquid doesn't compress. During compression and ignition in the engine, the methanol and nitro are in the gaseous state; oil doesn't become gaseous, which is why it doesn't compress.

Excessive oil causes the running temperature of the engine to rise because of the higher burning temperature of oil as compared to methanol. A fuel with 8% oil will have more methanol than a fuel with 16% oil.
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Old 09-23-2004, 02:17 AM   #7
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great, so i may have been running fine this whole time with my engine tuned like an evil monkey wrench experiment?


well mr. waldron sir, perhaps now would be a good time for the sake of everyone following this thread (besides myself) to go over the finer points of perfecting your tuning, learning when tuning errors can cause disasters, and how to pick out bad tuning. i know i would most definitely benefit from such a learning experience. the rest are just too chicken to admit it

im definitely going to swap my fuel out when my bottle is dry, which should only be another 5 tanks or so worth. i dont know where to find trinity locally, i have a hobby town and an LHS and i dont think either carry it. my LHS carries odonnel in small quantities and hobby town only carries blue thunder
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Old 09-23-2004, 12:05 PM   #8
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Horizon's new White Lightning Fuel is great stuff as well.

Tuning:

The days of tuning by smoke are gone. Most fuels (especially those used for racing) produce very little smoke. We now only have our perception of speed and the sound of the engine by which to gauge our tuning.

The HSN must always be tuned first. The HSN affects the air/fuel mixture across the entire range of throttle. Once the engine is running decently and is thoroughly broken in, the HSN should be tuned for strong acceleration and should allow the engine to clean out and rev freely at top speed. An engine that surges is usually a sign of being too lean, as the engine will be starving for fuel; blubbering and an excessive amount of smoke at full throttle means the engine is simply too rich.

Once the HSN is dialed in, you can begin working on the LSN. The influence of the LSN is small in comparison to the HSN, but still important. Tune the LSN to allow crisp acceleration from idle and to control the consistency of idle. An idle that surges suggests that the LSN is set too lean, while an engine that loads up and dies immediately means that you're too rich. Your engine should load up and die on its own after about 30-45 seconds if the LSN is tuned right.

The idle is the last thing you should mess with. Your idle speed will always drop once the engine reaches running temperature, so don't be alarmed if it sounds too high when you start your engine. The ideal idle speed is anywhere between the low point of having your engine die when coming to a stop, and the high point of having your car creep forward.

Most common mistakes:
- Tuning the LSN too lean and tuning the HSN too rich to compensate. This is probably the most common mistake among new tuners.
- Re-tuning after replacing the head with an aftermarket one. Just because your engine temperature dropped 60 degrees does not mean you can lean out your needles. Running too lean robs the engine of vital lubrication.
- Trying to tune the engine while there is an air leak somewhere. If you simply cannot get the engine tuned correctly, replace your fuel line and check for other air leaks (such as the tank, engine, and pipe fitting).

Hope that helps!
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Old 09-23-2004, 02:02 PM   #9
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well that certainly makes a hell of alot more sense than the OS manual. i always hated that thing. i think my goals this week will be A, replacing my glow plug AGAIN, B, trying out odonnel or trinity plat if i can find it, at 20%, and moving to CVDs, new rims and hole shots.

w00t! im going to make the last race of the season yet
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Old 11-30-2008, 10:34 PM   #10
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Hey there, im the new guy, trying to tune his cars, two of which are fine, i brought a cheap hsp off the net which has not missed a beat in nearly 6 months its been great, i recently got a hpi savage 4.6 which also has not missed a beat following tunning instructions i thought was easy until i brought the team associated RC8 ive set and run in car and have put about 8 tanks through it i have now tunned and started to fine tune everything semms to go fine car runs at about 105 C, problem being now to start i have to turn up control so carb is fully open i need to run the car for a little while before closing carb, car will run exellent for a while maybe half a tank then it seems to bog down, it sits at idle fine no surging, i done a 15 sec test(idled then full accelleration) it has heaps of punch off the mark and seems to clean out has anybody any info that could help, i like the way this car moves, but the lack run time is a bit anoying
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