94 replies to this topic

[pauln]

Having been down the "let's compare mods on a rolling road" track with my previous modified car I know what problems it can bring. Many people want a headline figure to justify their spend. Understandable really.
But, the key thing to take from a rolling road session like this is the relative figures. i.e. The figure before and after your modification or a direct comparison (preferably on the same day) of two cars on the same RR.

(The only other thing is to use the RR to set up your fuel pressure regulator so that you are achieving the bost O2 curve - if you have a variable FPR and I don't know how much difference that would make with the Vauxhall engines)

I agree 100% with John's posting and full credit to him for the honesty and telling people the facts as opposed to telling them what they want to hear. That's not to say that other tuners are being econimical with the truth... they're just reporting what their RR tells them - and most will only have access to a RR with non-VX specific transmission loss figures put in.

At the end of the day a RR session will give you hard relative "facts" about an engine mod. As important are the drivability and personal preference aspects of each and every mod.

Having said all that... I can wait to get up there and see my graph to analyse it to death!!!

P.

ps. John, when you going to sort your avatat out?!?

[nakajima]

quoted from John: 3. We did 3 standard NA's to stage 1 tunes and all three owners came back confirming the car felt stronger in every gear, acceprated faster, was smoother and had more torque. However on the rollers the gains on the chart were negligable. This I am looking into as it does seem odd. Certainly the claims of 20bhp from a stage 1 map look excessive but the gains in drive are very evident and very noticeable so there is more to tuning than charts anyone from oop North who is considering the long drive to TMS for a stage one map to the NA and wants to see what it can do, get in touch with me. as i have said in another thread im not expecting any more power on paper but god it really is a different car to drive, VERY smooth and VERY drivable. it pulls far stronger and just makes the car a hell of a lot more balanced. i think its really complimented the suspension and 888's and all seems to be working together now if that makes any sense. i'm one to vouch for the re-map i had

[walkes]

I for one am not having a dig at you John, nor do I think that anyone is, people are using it as a comparision to the same sort of tune level. As to how useful the information is I have no Idea. However I would just like to say that even driving the car back to bristol and taking it for a spin today, I could not get the power dip that is on the graph. It would be intresting to see if those big fans of yours where actually managing to get air into the car or if they where just too powerful for the job in hand and not positioned quite correctly on the day The fact that your graphs on your website are so smooth and mine are kind of lumpy and lower on power overall makes you wounder as too what other factors would be causing the problem, as up to approx 3000 rpm mine are actaully better than yours It just goes wrong there after PS can I have a free hybrid turbo replacement

[Joe-Turbo]

and me please

[Richy]

The fact that your graphs on your website are so smooth and mine are kind of lumpy and lower on power overall makes you wounder as too what other factors would be causing the problem, as up to approx 3000 rpm mine are actaully better than yours  It just goes wrong there after 

PS can I have a free hybrid turbo replacement 

I, just like others mentioned have seen this problem before with different cars/bikes

You could line up five identical cars fit all the same mods and three out of the five will be pushing out different figures.

Its expect 'coz every car has slightly different tolerances, even the way it was first 'run in' can make a difference.

Its not your fault Steve or anyone elses that you got a dog

[sits back smugly knowing your the other side of the bridge ]

Edited by R1CHY, 14 May 2006 - 10:16 PM.

[Thorney]

The issue of dips on the graph is a valid one, 99% of the time a little dip on the chart does not manifest itself on the road whatsoever, does this mean that the graph is too detailed when the drive is not affected? Personally I'd rather have the drive I want rather than the chart so please take the graphs into account with that it mind. There was only one car there (Stewarts VXT) that he complained of a power dip on the road and on the chart it also refected this. The dyno measured the boost pressure and it peaked nicely enough but then collapsed losing 5psi which it never got back -does suggest a turbo problem (although until we've inspected it we can't be sure) - same applied to Joe. In these sort of circumstances the dyno does work very well idnetifying a problem via its measurement of all the engines outputs but at the end of the day its the drive on the road which is important nothing else. The things I'm looking into now: 1. NA maps. They all drive really well (better than some of the VXT mopas if I'm honest) but they show minimal gains on the cahrt that simply do not reflect the performance on the road - why. I intend to find out and re-write the maps if necessary. 2. VXT maps. We peak boost nicely but are too conservative on held boost so I'm going to re-write that aspect a little. The VXT boost controller isn't the best so we'll look into upgrades here to see how much the drive can be improved. 3. VXR Astra turbo hybrid maps. We've already got custom maps for these but the turbo unit is so strong we're going to be more agresive with the maps here. Remember the power from the engine is simply only a part of the tuning, we have clutch issues to consider as well as the ever present heat problems and the maps are designed to relate to those issuse too, happily the spec of our dyno cell (with the highest airflow in the UK) demonstrated that we can run these cars to full power without fear of the ECU backing off so its pleasing.

[VXT Tim]

to the map updates. Can't think of any tuner i've ever seen or heard of for that matter willing to update their product for free especially when the one he currently sells "feels" like such an improvement anyway!

[siztenboots]

how do you know what the temps where?

what are the readings at the bottom of the graph? BP/RH/AT/IT/RR/TN?

BP = Barometric Pressure ( e.g. 1018 mbar )
RH = Relative Humidity ( % )
AT = Air temp ( 'C )
IT = Intake temp ( 'C )
RR = ?
TN = ?

These are my guesses.

[The Knobs]

Perhaps you should try a placibo stage 1 NA. I bet the driver will think the car drives better than before the remap. Just like they seem to drive better after a servic

[mcbunny]

rolling roads are about as accurate as flinging sh*t at a wall while wearing a blind fold the best way to get a power figure is by a engine dyno but as that involves removing an engine no one ever really wants to do it. couldn’t john find an engine somewhere both turbo and na and run all the different mods on a dyno ? that way you have a test bed that wont change ? i have never trusted rr's and i doubt i ever will

[Stav]

3. We did 3 standard NA's to stage 1 tunes and all three owners came back confirming the car felt stronger in every gear, acceprated faster, was smoother and had more torque. However on the rollers the gains on the chart were negligable. This I am looking into as it does seem odd.

Good to see you all there, what a day!

Mine was one of the NA's remapped, although not expecting a great deal of an uplift, there was virtually none. At this point in the day I was questioning the departure of my hard earned!

I then drove it and although there wasn't an uplift in performance as such, the car did feel massively smoother (particularly sat in traffic this morning, it's normally really lumpy at low revs in the daily commute), everything felt torquier and moving the rev limiter up definitely has a excellent effect on the fun factor!

If John does however manage to eek out a few more ponies through reworking the maps though I'll certainly be interested to see what happens.

Dubious as to how much of this is due to the placebo effect as I was expecting uplifts and looking for them, however the car now feels how I would imagine that it should have done coming out of the factory and money well spent!

For the record (from memory):
Standard - 121.1 bhp (at wheels)
Stage 1 remap - 121.7 bhp

[mcbunny]

people do seem to focus on peak bhp too much its about the general shape to the curve and how much power there is all the way through the range and ofcourse the most iportant factor torque !!!!!

[Richiemouse]

I might have missed this but is the TMS Dyno showing the same standard power values as Courtenay and Regal, or is it also lower? If it's also lower then surely the only thing that matters is the comparative gains from standard to tuned. I suspect that I did miss something and the TMS standard figures are the same as others. My one observation on this is that when my car was done at Courtenays, for the standard run they loaded the boot with a barrel of water and John also leaned on the back of the car. They explained that they had found problems with wheelspin giving false high readings. I noticed that post Miltek and remap the water barrel was put in the boot but there was no leaning on the back end. I wondered at the time (although I didn't say anything) whether this might give a slightly higer tuned figure. Please don't think this is an accusation of foul play, I don't think that at all and was/am VERY happy with the work they did and at the end of the day I've never trusted the numbers from Dyno's but they are useful for comparing before and after. I've seem this on bikes in the past, I've got two graphs of my tuned GSXR1100 taken on two different Dyno's a few days apart and they are completely different, I'll see if I can find them and get them scanned.

[walkes]

Its not your fault Steve or anyone elses that you got a dog

[sits back smugly knowing your the other side of the bridge ]

Oi R1CHY get back too being a power ranger

Just for the record when John re-mapped it and drove it he actually said that I had a good one.
I have got to agree with him.

Even though I have noticed this power dip (see pictures) it only seems to appear when you drive a certain way or is it due to lower amounts of petrol onboard . I had less than a quater of a tank when the test was done, and filled up and drove home and no problem.

[Wellus]

Its not your fault Steve or anyone elses that you got a dog    

[sits back smugly knowing your the other side of the bridge ]

Oi R1CHY get back too being a power ranger

Just for the record when John re-mapped it and drove it he actually said that I had a good one.
I have got to agree with him.

Even though I have noticed this power dip (see pictures) it only seems to appear when you drive a certain way or is it due to lower amounts of petrol onboard . I had less than a quater of a tank when the test was done, and filled up and drove home and no problem.

is that 2 pics from before and after a remap?

[Richiemouse]

Looks more like power at wheels and power at fly to me

[Thorney]

Its the issue over wheelspin whichis why we went for the Dyno dynamics rolling road, adding weight to the car to get it to grip will erode any possible accuracey from the run; it will change the tyre performance on the roller, change the % losses to flyhweel etc etc. We strap em down and they stay strapped down. We've just done another VXR Astra - 199bhp at the wheels, 235bhp at the flywheel - ie bog stock. This road is not wrong. However, I really really want to get accross that the only number we or anyone else with a dyno can measure is power at the wheels - nothing more.

[SuperCooper]

Never heard of tyre slip on a dyno producing MORE power! I lot of our customers go for abrasive surfaces on the rolls to increase the friction between tyre and roll. Thorney I can't remember when we spoke @ Mallory if you have anything like this fitted. Strapping the car down tight to the dyno will reduce tyre slip, but also increase the amount of tyre deformation around the curvature in the roll leading to increased vehicle losses. You would have to run a calibration test on a per vehicle basis to be able to negate this from your results

[cheeky_chops]

so was mine the best result of the day??? 215bhp @ wheels!