8 replies to this topic

[Jamie K]

Hi all, Had my VX rolling roaded yesterday (standard minus pre cat) Quoted 145 Bhp @ 5800 rpm 149.7 LbFt @ 4000 rpm Actual 142.5 Bhp @ 5970 rpm 146.3 LbFt @ 4313 rpm Not too shabby I suppose. The figures also showed the air to fuel ratio, my car suffers above 3750 rpm and on full throttle as it funs far too richly I am glad I have got a "benchmark" before I have anything done to the car. Current thinking is around Exhaust system, fully mappable management and throttle bodies, if the price is palatable. I'll let you know what I do next Jamie

[TheRockstar]

What was the BHP measure at the wheels? (I assume those figures you've quoted are estimated flywheel figures.... and therefore open to a large amount of debate over accuracy).... I assume he did a coastdown test to calculate the losses in the gearbox? If so did he give you these figures aswell?..... Don't mean to open up a large can of worms here......

[paulb]

Looks pretty good to me Jamie. Remember that power at the flywheel is always a bit subjective on a RR (only true way to measure power is to whip the engine out and run it on a bench dyno). You're within 2% which is well inside experimental error. From the digging I've done, head flowing and cams could well be a useful addition too. Paul

[Jamie K]

What was the BHP measure at the wheels? (I assume those figures you've quoted are estimated flywheel figures.... and therefore open to a large amount of debate over accuracy)....

I assume he did a coastdown test to calculate the losses in the gearbox? If so did he give you these figures aswell?.....

Don't mean to open up a large can of worms here......

Can on the floor. Worms everywhere.

It is a "coastdown figures" calculation. I have not got any seperate coastdown figures although from looking at the screens it did seem to be around 22 - 25 bhp on the "drag" side. (i.e. around 120 @ wheels)

I know that no RR gives a true "dyno" representation, however I wanted some consistency and rather than go from one RR to the next I thought it best to get a benchmark before and then after. I may even get another done for a second opinion !

How is that exhaust sounding Paul ?

Jamie

[paulb]

How is that exhaust sounding Paul ?

Jamie

Dunno yet. About to leave Cambridge and head to Nottingham. Will post more when I get back this afternoon.

Paul

[garyk220]

The figures also showed the air to fuel ratio, my car suffers above 3750 rpm and on full throttle as it funs far too richly

I wonder if removing the pre-cat has anything to do with it running a little rich?? Perhaps an induction kit, or removing the restriction in the standard airbox would improve the airflow at higher revs and lean the engine out a little.

I'd be interested to see how the standard ECU copes with induction and exhaust changes though. I'm also sceptical about the benefits of 'chipping' the ECU. Throttle bodies and a programmable management sounds good though The QED system for the 2.0 Ecotec looks good for 200PS with this set-up and reprofiled cams. Just a pity they are not doing a kit for the 2.2

[Jamie K]

I wonder if removing the pre-cat has anything to do with it running a little rich?? Perhaps an induction kit, or removing the restriction in the standard airbox would improve the airflow at higher revs and lean the engine out a little.

I reckon you could be right on this one Gary

Jamie

[cheeky_chops]

Would disconnecting the battery which apparently resets the ECU do anything to the mixture??

[TheRockstar]

Interesting article here : http://www.pumaracin....uk/setup01.htm about the pros and cons of rolling road flywheel figures.....