davross1986

Can anyone please tell me the volumetric efficiency of a ST 225?? Or even one better, a rough estimate with an airtech gen 3 intercooler and an autospecialists CAIS fitted?

Cheers,

Dave

xr2wishy

iTrader: (2)

It doesn't work like that, an engines a dynamic environment, changes constantly dependent on temp, load, revs acceleration enrichments etc.
So no definite figure.

davross1986

yeah I know that mate but there should be a rough average guide figure that ford/volvo use when putting engine together, and also engine tuners use when designing upgrade parts for the engine

Karl

91% average?

Karlos G

iTrader: (4)

Why do you want to know mate, what are you trying to work out?
I'm interested BTW, not being rude! lol

davross1986

I want to know because some told me about this app for my phone called 'torque'. You need a blue tooth OBD connector and it tells you all sorts of stuff from your ECU inc bhp and allows you to clear fault codes. For an accurate reading of bhp it requires volumetric efficiency figure. I don't know how gud the app is yet, it almost seem to good to be true at the moment. Im still waiting for my OBD connector.

He says his Ibiza showed 268 bhp which is pretty close to what it produced on a rolling road so it seem ok.

91% seem pretty low for a turbo car, I was expecting nearer 100%.

As anyone else got experience of this app??

xr2wishy

iTrader: (2)

ve can happily be over 100% in a turbo, depends on pumping losses and valve timing etc though.
the ve figure will change so much with variations of atmospheric pressure it would be completely useless.
ford/volvo use trial and error and engineering theories and lots of cad to determine how a combustion cycle works and then build lots of prototypes and then give up when it's good enough and not worth keep making engines to test.
the obd port will have all sorts of computation going on, perhaps it just learns a torque figure and cross references with the revs.
i know our 206 when hooked up to a code reader gives a torque figure.
sorry if that was less than helpful, just food for thought.
infact leon cupra r's are able to connect a screen which tells you the power figure as you drive, obviously some inputed data/calculation going on.

Karlos G

iTrader: (4)

Ah I see, I wonder what other variables is uses to calculate BHP?
Normally these apps use your cars weight and then the g-force applied to the phone under full acceleration to calculate torque and then BHP...
Interesting that it wants the engine's VE, must be calculating it from injector flow or air flow I guess?

davross1986

yeah I think it uses MAF sensor information. It tells you your bhp in live time while driving. All for £2.99!!!! Seems to good to be true doesn't it?

It also asks for a atmospheric differential pressure from sea level and 15 deg C to rid any errors of altitude, heat etc.

xr2wishy thanks for info pal