I am looking for the fastest engine that is capable of an electric start that will fit a losi xxx-nt without any modifications. It's a gift so any help would be appreciated. Also, do they make a two speed transmission for them? Thanks.

No 2 speed.How much are you looking to spend?

Under 200

Well you could buy a O.S .18CVR. The engine cost $109 on towers and then you could buy a box starter on ebay for cheap. Or you could buy a new box starter for $70 or so. That will keep you under the $200 mark and you will have a little left. Enough to buy a quart of fuel or 2 or 3 glow plugs. But they do not make a 2 speed for the xxx-nt.

You could get a box starter on Ebay for cheap. I have seen some go for $20 or $30 so you can get them pretty cheap if you willing to go that route. Then if you but one of Ebay then you would have a lot of money left over. Thius isnt exactly what you wanted but this is actually better (in my opinion). If I had to choose, this would be the way that I would go but of course this is your decision.

Or it you can go a little more get the OS .18 TZ and a cheap used starter box.