Can someone with a Hobao Hyper 28 please measure the bore and stroke and let me know the result? Is there any published spec for this engine?

Thanks
Ron

I presume you mean the Mach 28, if so the bore is 17.4mm (.685" ) and stroke is 17mm (.670" ). Compression is 9.4:1 with the .08mm shim.

That's what I thought! So its actually a "24" (4.0cc) rather than a "28" (4.6cc). Sounds like someone is telling a few fibs? I'll have to buy something else now.

Any suggestions on the most powerful RC car engine up to 5cc? Horsepower is what I'm after - nothing else matters. I'm planning to use it, after suitable mods, in a control line speed aircraft.

The Hyper 28 is acually called a "MacStar" but have heard it referred to as "mach". The Dynamite 28 is labelled as a "Mach 28" right on the head.

You could get a modded Picco .28 or a modded Novarossi 528XR, those are both crazy engines when, and when not, modded.

Banned, whats the price differience between a new Nova 528XR and a Picco .28 .......

Thanks for your help. I like Picco engines, already have a 21 in a plane that goes very fast, so I have ordered a 28. The spec suggests it was DESIGNED to be a 28, not just a 21 with a bigger bore. And the price at Tower Hobbies is hard to argue with - $199.99 less $25.00 rebate.