whats best option is sky rc same as the competion heaters i have seen thanks for the advice

What are you trying to say?
I don't like SkyRC stuff.
Try getting main brand names. I'm sure you can find people talking abt engine heaters by doing a search in here.
I use IB Prostart.

All heaters do work and all do burn up if they aren't attached to an engine. The Sky (and the cheaper Hobbyking version) have a timer which can be usefull.

thanks for the help and understand what i was asking

I use a HK one which is exactly like the sky rc I think and they do have a timer but I personally don't like the timer it's a nuisance to me but some people prefer it, they will all do the job they are made to do and they are invaluable to have in my opinion. When it's time to buy a new one I prob won't be buying the same one again and will get the pro start one instead. With the one I have I run it with a 3s and I only get three 10min timed sessions before the battery is done cause they have an automatics cutoff with the timer system also that's what I dnx like about the Sky rc ones, so if you are going to go with the sky rc model run it with a 4s rather than a 3s I what I would advise
Edit: I should make it clear that the reason I don't like the timer is because of the automatic voltage cutoff if the battery gets below a certain level but apart from that the timer is a good function, in any case if you do run it with a 4s like I said earlier it should be ok.

i have a nice power supply so was thinking of using that to run them

I have the competition one that plugs into a 12v booster pack, and I control it with my handheld temp gun: 230F is my cutoff point to let the heat sink into the motor until the whole engine is totally heated up past 200F... It works like a charm, and I never need touch the needles to get in the motor's powerband right at startup...

You can not expect that an heater connected to a motor by some head fins will transfer all the heat to the motor. A tight contact will help to make it better as I do see a lot of guys shift the heater over th head as if it is not tight.

You want something better, take a simple hair dryer, put a piece of pipe on it so you can place it over the head. The hot airflow will heat up the engine.

I have used them all and they are all the same stuff. DC is the most popular at the moment. I power mine using a power supply and switch to a battery when in pit lane. Works awesome for me.

yes the dc stuff is popular but I don't like the 10 min timers.. ya I'm old Scholl and like the 110v ones.. but for a while com heaters vanished but since resurfaced. so what I have done is just make my own for racers. 110 elements and all local fabric. think I have sold 25 heaters now and everyone has liked them. recently I made 5 of the heaters for the low pro heads so guys don't have to cut the standard head heaters to get them to work.