Rolling Road info - what does it all mean?

[DickBarton]

Got my car on a rolling road - Dastek near Inverkeithing, Fife and I got a pretty double sided print out for my troubles...not sure if I should be happy or not, but I'm getting 216bhp at the wheels with apparently 256bhp at the Fly - I don't know a huge amount about the car but seemed to know a hold load more than Dastek guys, however they knew a shed load and then some more about performance than I did so I didn't argue much but I did mention that the manual engine was stock 280bhp - the guy laughed and said no chance...but we agreed to differ on that point.

Anyway, I took it there to see if it was running rich and whilst idling it is, but once running it's fine until about 6,500rpm when it starts to run a bit lean...my main boost is around 3000-3,500rpm and my max brake is just below 7000rpm - this was with it running with the boost controller switched on at 0.7.

Since running with the boost controller on I'm also working out at 23.5mpg...so I'm quite happy with that.

I've yet to scan the graphs in but if anyone is interested or can explain them to me luddite terms then that would be great!

Thing is - is 216bhp at the wheels ok? I'm thinking it is pretty lame but have no real idea - it just feels poor to me when the engine is chucking out about 280bhp.

I've managed to get an airbox so I'm planning on replacing the mushroom filter with the airbox which should reduce the amount of hot air getting sucked in as it will grab air from the front of the car, but will that have any performance improvement? I'd hope it would give it a wee bit extra kick and perhaps make the fuyel efficiency increase slightly as well (but I'm only guessing on 1 or 2mpg).

Cheers,

Richard.

[Nutter_John]

the Vr4 is losing around 24% through the drive and for and auto there is around another 7% lost

216 @ wheels = 267 * auto = 285 bhp at the fly

Basically any rolling road can only work out the values at the wheels and then do some basic maths to work out the loses - from previous RR's the above figures have been used

Thats not too bad for 0.7 bar - should be around 300-310 for 0.9

As for the MPG and the boost , you only use more fuel if you use more boost

[Kenneth]

There have been a few who have gone back to standard air box and been very happy with it.

As Nutter_John has said, the figures don't look too bad if you use 24% drive train losses, in fact I would say its pretty good.

Do you have a picture of the dyno graph you can post up?

[DickBarton]

Will get it scanned in tomorrow and post up both sides of the print out...thanks.

[Nick VR4]

Also some RR are not that accurate there was a big flaming a while ago on the MRL about this
Some guy went to one RR got certain figs went to another later on and no where near the same figs

[DickBarton]

Scanned images of the graphs - not ideal but best I can do for the moment!

[Nutter_John]

Do you have any fuel control as I suspect not given you flat line at 10 afr

[Kieran]

Think your boost controller needs a little more tweaking to prevent drop-off at higher rpm, but 216bhp ATW for a largely standard car (0.7bar isn't a huge increase over stock) is not bad.

Your fuel curve is typical of the standard ECU too - yes, they really DO run that rich!

[bradc]

That is 161kw at the wheels which fits in well with what we've seen over here, with standard cars making 150-160kw.

If you take out a bit of fuel and keep the boost high at high rpm's you will be able to make quite a bit more power :)

[DickBarton]

The boost is running at 0.7...since having it switched on my fuel economy has gone up and I'm driving it a bit harder than before...I may bump it up to 0.8 and see what difference that makes...I'm getting 23.5mpg out the beast now which I'm happier with, would hopefully not drop that much if the bar goes up 0.1...or it might, will soon find out I guess!

Thanks.

[Axeboy]

Richard

have you setup the boost controller?

ie do the self test run to ensure settings are correct?

[DickBarton]

You mean I should read the manual, scare myself silly then hope it is setup properly??? I was going to do it tomorrow - I've got an airbox and picking up an air filter tomorrow so hopefully have that fitted without too much hassle! Then will do the self test scare thing and see if it improves!

I had it set at 0.8 last night and the fuel cut out thing kicked in once...wasn't expecting it so put it down to 0.75...not had it again...will see what the self test thing brings up.

Thanks.