I have seen a lot of claims about "so & so" engine produces "X" amount of thrust. I believe claims of thrust are worthless unless a specific prop at a specific RPM is stated.
And while I'm at it, what RPM was that huge H/P number?
Why can't all engine makers quote RPM & prop numbers. And H/P numbers at usable RPM.
I yield the floor for discussion.

Engine "X" with "Y" brand prop of "AxB" size will produce a comparable, defineable thrust, allowing for tuning variations, exhaust configuration, fuel/glow plug, and climate conditions.

HP ratings for engines are useless; the ones quoted by most companies are at ridiculous RPM figures. The only REAL comparison between engines is RPMs with a specific prop on a test stand with a specified fuel and glow plug combination (plus the aforementioned variations).

Anyone who believes the figures claimed by manufacturers are fooling themselves.

My $.02 worth!

it isn't just glow engine manufacturers that do that, i used to be heavily involved in competition car audio, and ran my entire system on two amps, one rated at 2 channel 20 watts/channel, and the subs on a 2 channel 30 watts/channel amp. In reality the 60 watt amp was pushing out close to 500 watts. in this case they went the opposite of HP numbers here, but it was done for a specific reason. (at the time competition classes were set by wattage, hence I competed in the <150 watt class.

the problem with standard ratings for motors is there are quite a few variables. assuming they rate for the recommended props that they themselves recommend for use, what nitro/fuel to use? what altitude? what brand of props? and assuming the manufacturer uses the average number, what do you do with the 50% of customers angry that their new engine won't get what the manufacturer says? and if you use a low number the manufacturer just shots themselves in the foot for marketing purposes.

Fox MFG is the only MFG that I'm aware of that says their engine will turn a certain prop at a certain rpm, for example they say that the Eagle .74 will turn a 12x8 at 11,200 rpm and it does precisely that. The .60 turns the same prop at 11,000.

An engine without a prop doesn't make much thrust. A static (non turning) prop makes no thrust. A prop turned at xxx rpm will make the same thrust on any engine turning it. Each brand of prop will make a differing amount of thrust at the same rpm.
RC Report magazine publishes test reports using the same set of test props and on the same bench with the same fuel and even a correction factor for the weather. For years I've found their reports to unbiased and accurate. Some times they will even try some different brands of props and different fuel in addition to the standards for extra information. I can refer to a 5 year old report on an engine and compare it to a current one without fear of differing test conditions.
I appreciate the shootouts from MAN and RCM but they are only good for those engines included in that article as the test conditions and author are often different in the next test report.

Well Hobbsy, now you know that Fox is not the only one:

JETT engines are AWESOME. Can't beat their power/weight ratio (OK, a Nelson will, but they're for all out speed and not very user friendly).

You ask why manufacturers publish hp ratings at rpms that their engines will never reach. Why are thrust ratings published with no criteria to get it. SALES, SALES, SALES I've actually seen posts where people actually believe these ratings mean something.
Engines from mainland china are all the buzz in the forums and at the field..because of advertising, news reports, and press releases. What do these advertisers have to say..amazing power, blazing speed, affordable pricing. Reviewers seldom review engines that have remained unchanged for years. Recently MAN relaesed a shootout where the old FOX .60 out powered all competetors. The K&B .61 twist was not included although that company has been established for much longer and has produced more engines than many if not all the others.
Enya, Fox, K&B, and Webra don't spend the advertising dollars that OS, TT, ST, GMS, and Magnum do. The multi color catalogs with glitzy pictures feature and promote the latter group of engines. The engines produced by these manufacturers are not much different in street price (except OS). The latter group in head to head testing seldom out powers or outlasts the modern offerings from any of the Enya, Fox, K&B, Webra.
I have noticed that the Russian companies have built quite a good reputation (except MDS) not on advertising but on sold performance and superior design. They are to be commended.
What does it say for our intellegence level if we are duped by advertisers, pretty colored pictures, slight of hand, and down right lies.
I test them myself on my own bench, with my own test props, and in the air.