mechanic28

iTrader: (5)

Being thinking about this for a while i know there is a simply answer to this but...

On some rr the operators do the power runs in 3rd gear others do it in 4th gear!But surely the car would be making less power in 3rd gear as the boost will not be as high due to the gearing/load on the engine!

Whats the answer Am i being thick?

TiB

iTrader: (1)

The way i remember is that 3rd will make it read higher because of the gearing.

pani_k

iTrader: (1)

Renders RR figures a bit pointless then if it can vary from gear to gear. As long as the car has decent torque and bhp curves and feels good then that would be good enough for me even if an RR figure wasn't what I was expecting.

simon170

The gear that is nearest to 1:1 is used, on some cars thats 3rd and some 4th. On 6 speed cars is more commonly 4th and 5 speed most of the time its 3rd. But thats not a hard and fast rule.

Most modern dynos can have the gear used for the pull in put in to the software to compensate.

Whatever gear is used I would think that almost any RR will provide enough load for the engine to reach its preset boost limit.

pete mcrash

iTrader: (1)

........on a cossie (5spd) it's 4th thats 1.1..........and a r/r is only as good as it's operator as i've never hit or held full boost on 3 sets of rollers.......

tabetha

And some rolling roads only use the figures for transmission loss that is held on file supplied by the makers, they can't actually measure trans losses.
4th is nearly always the closest on 5 speed.
tabetha

foreigneRS

nobody can really unless they have some strain gauges on the crankshaft. on a rolling road you can only measure the losses during coast down, not when under power and they will be different

Ian M500COS

So Engine Advantages do theirs in 2nd gear then. Or reverse??

costina

iTrader: (1)

My Trans losses were over 200bhp on a 2wd

And the op ran mine in 5th this could be down to keeping wheelspin down

But in most cases don't they run the car to 60 mph in the gear there going to use as a calibration???

C'mon Martin give us some explaination PLEASE

pAUL

CombatSapph

That's why I always tell them never to bother calculating the flywheel figure(s) and to just give me the @ wheels figure(s) and show me the graph(s).