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Old 06-23-2003, 12:06 PM   #1
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Default HPI 12R SC Motor Questions???

Hey all...

I have an HPI RS4 RTR 3, to which I have the following upgrades: OFNA Failsafe [in the receiver box!], Dynamite fuel filter, 2 speed transmission, RD Logics RS4 Exhaust Pipe, and HPI 12R SC bump start, slide carb engine.

I am wondering what the "proper" range of temperatures is for this engine? I have been running it at 220 - 245 and it wants to bog down off the line, but when I lean out the low end to where it has a crisp take off, the engine temps get up to 260+.

Does this engine run hot normally? I am making sure there is plenty of smoke at all RPMs, but I don't want to burn out my new engine.

Has anyone put this engine into their RS4 3?
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Old 06-23-2003, 09:51 PM   #2
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It's perfectly normal for an engine to run at 250+, but 280-300 is when you enter the gray area/danger zone. That sounds about right that when you lean the low end for good response, the running temp gets a little hotter. The low end does affect this, and after you get it set, check your high needle again. Tune that high needle so you can hear the engine reach peak RPM, but you can also see a healthy trail of blue smoke and the engine is running at a safe temp and not cutting out/starving.
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Old 06-23-2003, 10:55 PM   #3
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Thanks allot!

I will make sure I see a "healthy" trail of blue smoke! I have a tendancy in my tunings to keep the engines running rich on the low end. This wasn't a problem with my T-Maxx, but it is a problem on-road, ya know?

Anywho, I am going to [hopefully] run tomorrow nite, and I'll try leaning out the bottom end and making sure the high end needle is rich enough to keep the engine cool.

Oh, and I just wanted to let you guys know that this combo, even tuned rich and getting about 75-80% throttle [due to linkage bindings in my cobbled-together linkage], is pretty quick. I can't wait to get her dialed in and see what she'll do!
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Old 06-24-2003, 12:45 AM   #4
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i would say 260+ is ok.i use the same engine too.
also,if u are too worried about running lean,try higher blends of castor/lubricant.
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Old 06-24-2003, 07:41 AM   #5
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Default Re: HPI 12R SC Motor Questions???

Quote:
Originally posted by DraKhen99
Hey all...

I have an HPI RS4 RTR 3, to which I have the following upgrades: OFNA Failsafe [in the receiver box!], Dynamite fuel filter, 2 speed transmission, RD Logics RS4 Exhaust Pipe, and HPI 12R SC bump start, slide carb engine.

I am wondering what the "proper" range of temperatures is for this engine? I have been running it at 220 - 245 and it wants to bog down off the line, but when I lean out the low end to where it has a crisp take off, the engine temps get up to 260+.

Does this engine run hot normally? I am making sure there is plenty of smoke at all RPMs, but I don't want to burn out my new engine.

Has anyone put this engine into their RS4 3?
I agree, 260+ is just fine. On Hot days in long mains my motors will sometimes hit 280 degrees. Thats when I start to think of ways to get it to have better cooling...

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Old 06-24-2003, 08:33 AM   #6
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Ok, I'll try all of this tonight when I run.

By the way, I have the Raytek MT4 temp gun... where should I be checking the temperature from? The glow plug seems to be the coolest part of the engine, and the front of the head is usually 25-50 degrees cooler than the rear of the engine, and the glow plug is usually another 25-50 degrees cooler than the front of the head!?!?!?

When I run, I have been kinda doing circles with the temp gun around the head and glow plug and taking a mix of the temperatures, some of which are 75+ degrees different from each other! I'm kinda confused.

Also, do different engines run at different temperatures? Allot of people specify 220-250 degrees as proper running temperature for all engines, but then like in this thread, someone specified a hotter temperature for a specific engine model.

Maybe I should get a better head?
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Old 06-24-2003, 09:18 AM   #7
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u are supposed to point the gun at the glow plug to take the core temperature of the combustion chamber.
using a temp gun,it's actually more accurate than what i use(on board).
when u check,u would have already stopped from full power for some time,which results in immediately low temp from the plug,but in high temps from the head,which has mass to store heat that was already previously generated from full power.

another point:the avg atmosperic temp in my place is 30+ C's or 90+F(sunny Malaysia) so my engines are bound to be a little hotter than urs.
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Old 06-24-2003, 09:20 AM   #8
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SO, from what you guys are telling me, the glow plug, which is usually running at 170-190 degrees [fahrenheit] when the head is up into the 230-250 range, means that I'm actually running rather COOL???
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Old 06-24-2003, 07:10 PM   #9
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[scratches head]
i suggest u get an onboard temp gauge,and then u can compare more accurately with everyone else who does the same(usually)
bcos as u take the temp of the combustion chamber,it is fluctuative , depending on the current level of throttle.
maybe u should measure the temp when u full throttle it on a bench or something like that.
as for me,i get the max temp of any run as per recorded.u r measuring the current temp.
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Old 06-24-2003, 11:44 PM   #10
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Well, I ran the car tonight.

I ended up needing to lean her out ALLOT!

She only needs minor tuning now, because when she sits at idle for more than 5 - 8 seconds, when I nail the throttle, she tries bogging down and sometimes dies.

The temperature seems to be running in the acceptable range, with plenty of smoke during the whole RPM range.
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Old 06-24-2003, 11:46 PM   #11
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lean the low speed/idle needle.
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