ORIGINAL: LANNYBOB
id go with a 13-5 or a 13-6 and to hang on the prop id go a 13-4w if they make it. i would recommend a premium sport (synthetic- castor) blend type fuel with 15 percent nitro and 18 percent oil content. all of the major brands have it. for example byron coolpower wildcat etc.
Are you kidding?
A 13x5 or 13x4W is *WAY* too small for a Saito 82 and barely adequate for a Saito 72.
I get just over 10,000 RPMs on the ground with either a 13x6 or 14x4W on my 82 -- and I'm only running 10% nitro. Some folks (who use 20%-30% nitro) run their 82s with 14x6 or 15x4 props.
You really need to prop these engines for 9,700-10,000 RPMs on the ground to get maximum performance in the air. If you run a 13x5 or 13x4W you *will* over-rev the engine and miss out on much of the stump-pulling power the 82 has to offer.