FWD = 80% efficient
RWD = 76% efficient
4WD = 74% efficient

Didn't really try out the head guesstimate page much, but it seems within the realms of possibility. Probably about 25% accuracy on it, if that. Which is why no one would use it, as it's either far too simple or far too inaccurate. You're either doing something 'new' (i.e. you're in an F1 team) or someone somewhere has done it before - why not just ask them like anyone else?

Your transmission efficiencies are wrong, although not by as much as alot of "tuning" companies claim.
Click the Puma racing link at the bottom of the module and read the 3 power/torque articles followed by transmission loss article to see why. Also read the top speed article for further verification of it.

As for cylinder head estimation, it's again taken from a Puma Racing article, which tried to pin point the main variable which decides engine output. Alot of people just think displacement when it isn't, although it indirectly is through inlet valve area.
It's just a bit of fun but does give you a ball park figure of what really to expect if you don't trust the wild claims given by the people trying to sell their products.
The forced induction area isn't from Puma Racing, but is taking some math from Forced Induction Performance Tuning by A.G.Bell.
I've tried to mash the two together so people can see what to expect if changing between different charger technologies, or upping their boost etc.

But like I said, the boost stuff was never a part of the original forumla so it's probably miles out, although doesn't seem too far off what I've seen with my own car.

MY Transmission efficiencies are wrong? All I did was put in some number to see what generated 100 at the flywheel. If you type in 80 in the box with FWD selected you get 100hp at the flywheel, thus 80% efficient. Not my numbers, but yours, which is why I flagged them mate.

So please, don't tell me I'm wrong when you are, otherwise I'll lose what little credibility I have.

It is somewhat accurate; my wheel HP for my vehicles is 12, it showed 143 at the crank. Factory rating is 140.

Quote from tristancliffe :

MY Transmission efficiencies are wrong? All I did was put in some number to see what generated 100 at the flywheel. If you type in 80 in the box with FWD selected you get 100hp at the flywheel, thus 80% efficient. Not my numbers, but yours, which is why I flagged them mate.

So please, don't tell me I'm wrong when you are, otherwise I'll lose what little credibility I have.

Try putting in something other than 80, it's not just worked out via a percent, as not all transmission loss climbs with engine power. The workings are not mine, they are explained on the website I mentioned, but no, they're not strictly the % values you listed, they are wrong or I've programmed it wrong. I'll check it now.

These tools do seem to be extremely vague with too many variables to be accurate.

Quote from tristancliffe :

So please, don't tell me I'm wrong when you are, otherwise I'll lose what little credibility I have.

You lost that ages ago

Quote from ajp71 :

These tools do seem to be extremely vague with too many variables to be accurate.

The more variables you factor in the more accurate it will be assuming what you're doing with them is right. Check the article on computer simulation and drag time estimation. I'd love to know the formulas for that.

THat is excellent tool for car tuner.