If you're really worried about cost by looking at a cheap and nasty petrol lump then why on earth are you considering putting a 'large nitro engine' in? They're far more fragile, far more expensive to buy and use much more expensive fuel, and an awful lot of it too.
A fair point from the perspective of some. I am not worried about cost I can assure you. The only way to determine that such an engine is cheap and nasty is to ask. I have had maybe thirty or more nitro engines and have only had a few problems, some of my engines are over thirty years old and operate as new, all are sports engines, all left stock, I have no interest in ringing the neck of them by modifying them, believing that if you need more power you need a bigger engine. I don't race, singly because when i have my fun was trashed by some goon that didn't know how to control a model, so have no interest in maxing out power under the confines of a capacity race rule. In my view as an engineer almost all glow engines knock converted industrial petrols into a cocked hat when it comes to manufacturing quality, materials, tolerances and longevity. Frankly I dont understand when folk report problems with glow motors, other than high end and seemingly temperamental competition engines where it's expected to replace parts in normal use.
But, in this instance the boat is for a 13 year old new to RC, and whilst money is not a problem it would be foolhardy to invest in best of everything whilst he's still finding his feet with the hobby, and for it to end up on a shelf should he decide his interests are elsewhere, better to provide exposure to the various models one can have and should he want to pursue better performance an engine can be upgraded. But, the 'best' does not mean the most powerful, the fastest, or the prettiest, it can also mean the most reliable, the most rewarding and the one that lasts the longest. The achievement in a hobby is the fun you get out of it, so to avoid the frustrations of failure I'm more than happy to stick with the established and firmly proven ground for me of using glow engines. Fragile? Nah, no way, damaged yes, abused yes, instrinsicly fragile I don't agree with.
Fuel costs? Certainly more with nitros of course, but were talking pence per run difference here. Some costs are more direct and visible than others. Whining about model engine fuel costs after a twenty mile round trip to the lake is not a place I'm going to.
So back to square one, if there is no faith in this engine then I have my answer. Thanks.