Tranny losses

[Dodo Bizar]

Another copy paste action fro myself:

During the dyno meets I organised we've constantly monitored the wheel losses of all cars. At 'our' bench we express them as hp per kmh since losses are usually linear with speed. Now since we're doing this for the 3rd time we're seeing the following trend.

D-series usually have 0.13-0.15 hp losses per kmh (in 3rd gear btw). My car is an exception with just 0.12... (I got a lot of whp!). Now the difference in my gearbox could be that I use Shell 10W40 oil for 250.000 km now instead of Honda MTF like the others. The owner of the dyno even suggested trying 5W40 with a little drop of ATF to reduce internal resistance further. No idea what it does for the reliability of my tranny, but I am very willing to test it out. I'll have the wheel losses monitored as well once I change tranny oil again (which is needed anyhow).

On the other hand, the B-series (though tested in 4th gear usually) have a lot more losses. 0.17-0.20 and we even registered a 0.23 once. Those B-series roll very heavy. My B16B is no exception with 0.19. And it is really noticable, when the starter wont work I can easily push my EJ9 forward and start it by myself, for the EJ1 with B16B I need an extra pair of hands.

So... we're not sure why B-series run so heavy. Since practically each B-serie equipped car that we tested was lowered heavily we are a little bit suspicious of the axles being under pressure and increasing bearing resistance in some places. Plans are to test a B18 equipped EJ9 car with no lowering and see what the wheel losses are.

[Law_]

This topic has major interest for me ! Front WD cars are generally accepted to lose 15% from its max power to max whp. I can agree that the effect of lowering the car can affect this. a friend of mine has an 175hp Audi with exactly 15% loss to the wheels, but i've heard Dseries used to lose less.
in %, how much is your loss Dodo?
The oil change is cool too, but using 10w40 oil isnt suppose to start to burn your gearbox down...? Cheers

[Dodo Bizar]

For some tranny's 10W40 was actually the recommended oil by Honda and NOT use MTF, but forgot which tranny that was. Percentage... well as tested in 3rd gear, max hp around 150 kmh means 150*0.12 is 18 hp losses, which on my current 139 bhp is around 13%...

[Law_]

Low value as expected x) Great ! What is your ground clearance? Cheers

[BETEK]

The honda MTF has as base oil the 10w/40 with some additives.
One reason that the D-series have less tranny losses than B-series is the thiner drive-axles.

[Law_]

nicely pointed

[Dodo Bizar]

Ground clearance, I guess it should be 10.5 cm... but there might be spots on the car which are lower.

[saxophonias]

Nice topic! Bear in mind also, that the final drive plays important role, and the interior of the gearbox.
Still Joris are you sure the cars you have tested have the same toe numbers? These also play great role, let alone the tyre pressure and the wheel weight. Different values on these can make the difference among d-series or b-series alone. B16/18 are known to have many power loses due to extra strong shafts too. This is why they can handle great power increase without problem.

[Dodo Bizar]

You are right about toe and tyre-pressure, they are garanteed not the same between cars. But it averages out between all D and B's I've seen, and there is a definite difference between the 2.