Am I correct in saying that the engine would run a little hotter when running the vehicle in grass than on a hard surface?

I noticed today almost a 50 degree difference in engine temp from grass to concrete with the same needle settings.

I would imagine this is due to extra loading of the engine when running on grass.

Also, what is a danger zone engine? I have heard people running the engine temps from 160 to 280.

Yes I would agree that what you are seeing is based on an increased load on the engine. I kind of wonder if it should actually be that much but as long as you are in the 230 to 240 range then I think it to be o.k
There could also be a factor of speed here, as in on concrete the model is moving faster and getting more airflow through the head.
Maybe moving much slower on the grass.

Lots of people have opinions that go to 280 and I have even seen some that say over 300 is o.k.
Well all I have to say is that opinions are like you know what, everyone has one.
And mine is that if you run your engine up into 280 + it wont last long. 250 maybe is the top that I would let an engine go to.

I have raced for a couple of years and run my engines very hard, they never go over 250, I see no reason why any other engine should either


Dbow

i would say 250 is max performance. I wouldnt run that temp in dirt. but onroad ... ya no need to go over 250. But either way stay about 220 or above or you will lose fuel milage.

Hope this helps.

so ~220 +- is the magic number eh?

I agree, I've seen many expert opinions in magazines raise eyebrows when it comes to temperatures over 230F.

The experts are the ones raisin eyebrows.. not the opinions!
-ram