which heat range plug
 

Last year I bought my first nitro onroad car, hpi rs4 3 .18ss.

Being a noob and a cheap S.O.B. I bought 10% nitro fuel, and not knowing there were different heat ranges for plugs, I got a bunch of tower hobbies generic glow plugs (medium heat).

I always had a problem with my engine over heating. I have the venom smart temp that is set for 290, and it kicks in, in a mater of minutes on a warm day.

I still have 2 quarts of fuel that I want to use up, and need to know if a cold or a hot plug will bring down my temps

Also, when my 10% is gone and its time for more fuel, I need to know what percentage fuel to use with my medium plugs (I'm cheep so I'll use up the 10 tower plugs I have)

thanks for the help!

RE: which heat range plug
 

well the first thing to worry about is tuning, a medium heat range plug shouldnt overheat on 10%, sounds like you're already running a bad tune and/or low air flow, 20-25% fuel is best for medium plugs

RE: which heat range plug
 

Tuning seems to be ok, it doesn't hesitate off the line or bog at full throttle. Has good smoke at full throttle
did the fuel line pinch test, the engine doesn't die instanty or rev up before it dies.
I tried to run it richer to see if the extra fuel in the combution chamber would cool the engine
nothing worked, car runs great but heats up fast. Oh ya, both the front and rear windows are cut out


definetly not lack of air

RE: which heat range plug
 

20% nitro with no more than 11-12% oil and a medium temp plug will give you a reliable tune...

and a reliable tune will mean you are less likely to chase your tail and cause over heating problems.

RE: which heat range plug
 

ok I'll go with 20% with my medium plugs, but what plug do I use now with my 10% fuel?

RE: which heat range plug
 

I would check for air leaks, it kind of sounds like you might have one. If you richened your HSN up and it still has high temps I would check that.

RE: which heat range plug
 

also the smart temp "loop" could be in the wrong spot giving false readings, with my spektrum telemtry just one notch on the engine head changes the temp drasticly! use use a quality temp gun to set the loop in the right place on the head...also them rb filters are about junk as well I have one sitting on the shelf u want it?

RE: which heat range plug
 

Did that, I have a hpi hand held that I tested against a $200 laser thermo. I place the temp loop so it read the same temp as the hand held was saying

RE: which heat range plug
 

Anyone notice that HPI manual recommends using the R5 cold plugs on the rs4 engines?.. I tried an OS8 on the t-15 before and it overheated after a while and acted really funny. The OS plugs have a shorter thread which i find weird. I had to retune it because of its performance as soon as it started