Just got back from the rolling road...

[Robatron]

The chap who runs the rolling road is very concious of heatsoak and has possibly the biggest fan I've ever seen in my life. Quite often, people don't have the correct setups which means some figures under-read and some over-read.

It's a very reputable rolling road and had glowing reports from Evo when they testing a Sport Ka all over the country at different rolling roads and Charlie's was the only one that was accurate.

Doug and Mik from MRC are often there for power tests too.

[AndyP]

I know Surrey Rolling Roads reputation is excellent, so I'm not disputing the figure. But, even for two different rolling roads, a difference of 70ft/lb for similar cars is a lot.
I think I might need to make a trip to Surrey

[Robatron]

Yeah it is a big difference.

A friend of mine had an Astra VXR and for some reason unknown to man, alot of the VXR owners get their cars remapped to 300bhp and sticker a badge on the back claiming that the car is a VXR300.

Anyway, this friend of mine stuck his car on Surrey Rolling Road and got 260bhp and a slightly lower torque figure and claimed that he wouldn't stick the badge on his car until it had all of it's 300bhp. Instead of actually finding out what was wrong he took the car to 3 more rolling roads until he found one that gave his car 305bhp on a dyno run.

As it happens, I'm seeing Charlie tonight so I'll ask him why he thinks there is so much difference between rolling roads.

[T2Andy]

like you said i think we need to try another RR just for referance ,has any one else
got any ideas on the varied results .

[T2Andy]

Its a black art i think,

[Rusty]

320 ftlbs is chipped ABY torque, something in the region of 1.4 bar on the 2.2, I got a bout 270bhp/285ftlbs out of the MRC low boost chips with a small boost leak and then 294bhp/310ftlb out of a homefries and 297bhp/330ftlbs with the addition of an RS2 IC, all on the same rollers within 6 months of each other.



Standard car was somewhere in the 250s with 285ftlbs, that was running stock chips so something like 1.0bar dropping to 0.6.

320ftlbs does seem quite high if you're running a 3B at 1.0 bar max but might be a different MAP sensor in there to run more boost or something. Do you know what boost or bboost profile you're running? (was it measured?). I think my Homefries runs 1.5 bar max, 0.8 bar at the red line and somewhere between 1.0 and 1.1 bar at max power.



The ramp rate of the RR makes a difference here, as does whether it's measured or estimated run-down losses and if the brakes are applied towards the end of the slowing down run, on a car where max torque is at 3000-3500 this could be a genuine mistake if the RR operator is in a rush.

No RR figures are gospel, as you correctly identify, they vary from place to place but still worth comparing what you expect the setup should produce in theory and compare to what the RR says, if they're more than 10% out then I'd be a little suspicious.

[Robatron]

Thanks for posting Andy.

I'm not entirely sure what boost the car is running if I'm honest but 1.4 bar rings a bell when I had the boost gauge hooked up.

It's also worth noting that since the vacuum hoses off the back of the IM have been tightened up, it's made a big difference. The biggest difference of all was when I had the RS2 Airbox, RS2 Maf (with rubber gasket) and all the Airguides fitted. The torque jumped from 280 to 320 after that.

The one thing that everybody seems to comment about is the surge of torque at 3000 - 3500rpm when I take them out for a drive. Fun times!

[Rusty]

40 ftlbs off an airbox sounds a bit unlikely, even with the 3B item being a bit more restrictive. Still, as long as it's working well, that's the main point, would have thought that there were a few more ponies left in the car with a more aggressive map up top, no reason on that setup not to have 280bhp or so

[Robatron]

I think you're right, a change in airbox wouldn't have made that bigger difference but there were no airguides for the previous airbox (aby), it was taking hot air in from the engine bay.

If I ever got stuck in traffic, the heatsoak was so bad the car felt asthough it had lost about 100bhp.

[Rusty]

My car has a completely open front to the airbox (check out my bodge thread ) and was like that when it was measured performing with the figures posted above so as long as there is good aier supply on the RR then I don't think you need to worry too much about that, sure it's not the same as being on the open road but not much is really An open cone filter is not a scratch on even a butchered airbox and I can imagine that there would be a small increase in power with an RS2 airbox over my setup but a decrease in noise and wallet weight so I've left it as is

[Rusty]

Excuse me if I've missed it but what fuel was that on Rob?

[Robatron]

I know what you mean! I waited for yonks for a decent (and cheap!) RS2 airbox but eventually bit the bullet and bought a brand new one.

The fuel is/was Tesco 99ron.

[T2Andy]

Andy in comparison to your first graph i get peek 331lb\ft at 4900rpm ,at 3000rpm 161lb\ft but my boost profile is much like yours but i have 1.6bar @3400rpm 1.77bar at3700rpm to 1bar @6300rpm all with full RS2 set up [hybrid turbo] worth 10lb\ft extra .

[Robatron]

[ATTACH]25491[/ATTACH]

As promised, the power graph.

I didn't realise how long ago this run was! I've had a couple of other things sorted on the car since so I'd be interested to see the difference it's made as it feels very spritely indeed at the moment.

Mind you, I'm sure all the cold weather we are experiencing at the moment is helping!

[Jonnybravo]

DD Graph !

Depends how the operator has set things up as those rollers ALWAYS seem to give strange figures, mainly caused by so people owning them but only a few actually knowing how to use them.

I'd have more faith in those than a older set of rollers for example though but again as good as they are it all depends on the operator.

I can't remember what the problems were with running in Shoot44 mode or if it was something else but there was a huge discussion on Scoobynet about the DD setups giving different readings from one setup to another and someone who had a lot of input in the development of the software explained where people go wrong with running cars on them.

I once used TOTD and their results were all low and when asked why they just said the setup was the best and proven around the world so its right and all the car owners were just being optimistic, which for some may of been true but I knew a few cars were running a LOT more than they came away with that day.

Did you check for boost leaks ?