hallsy67

hi everyone just looking for some info on the above. i had a power figure given me when bob rawle mapped my car and im putting it on the rollers at the end of the month so was just wondering what results other people have had? was there a difference from the road map printout to the rollers and what sort of difference. cheers mike

jd5217

prepare to have a lot of contradicting replies.

ZEN Performance

why not just wait and see?

hallsy67

i could, but im impatient

53

iTrader: (41)

16% above the Road Dyno has always been reliable round here, but depends I guess on the rollers. What did you get on the road ?

Fat Boy

There'll almost certainly be a difference, but so what? Where do you drive the car - on the road or on the rollers? What matters more to you- how it drives or what is the biggest set of figures you can get for pub bragging?

Answer all those to the best of your own satisfaction and you'll be happy which is all that matters, surely?

ScoobyDoo69

iTrader: (17)

I've always considered that the reading would be lower due to the car maybe not hitting full boost, or a lack of air compared to on the road. However, I've seen a few Andy F remaps that have been pretty much smack on the delta dash output, when put on a Dastek RR. Suppose it all depends on the dyno at the end of the day.

GazTheHat

True, the delta dash has been a fair calculation.

New_scooby_04

iTrader: (4)

The software that Bob uses to estimate bhp and torque should be around what a "conservative" RR, operated properly, will give you ( I don't think it's prone to being optimistic) BUT there are sooo many variables that can confound comparisons between road and RR as to render the exercise a bit pointless.

Fundamentally, you don't drive your car on a RR. how it performs on the road is paramount and you have that info from Bob already.

Putting it on the RR would just seem to be confusing the issue unnecessarily!

Ns04

Tidgy

lol, bob's are guessed figures, so may be newar the mark or may not be, just wait till you get it on a dyno to find out

hallsy67

dont get me wrong im very happy with car and the way it drives but just wondered if the figures would be different. the road map showed 369 bhp and 417lbs ft but didnt know if the figures would show differently

lunar tick

iTrader: (2)

To the OP - go and make yourself a big pot of tea and then sit down and read this excellent discussion about the merits of rolling road/open road mapping and power outputs:

https://www.scoobynet.com/general-te...ling-road.html

Fat Boy

LOL

hallsy67

tea made reading now cheers

rcwhite

your figures are near about give or take here an there the same as my 06 spec C would love to see how they compare on the road...bob mapped mine as well.

Tidgy

ist a long long read, and tbh no agreement is made, from what i can gatehr any way lol

i think all in all, the answer you get depends who you ask, and each has its own advantages and disavantages.

the method isn't important, who does the mapping is

andy97

iTrader: (1)

This is what will happen, you wil get asked, what bhp you thinks its got. now either you will get a really high bhp reading, satisfying your ego, a very low bhp reading, followed by " we can sort that" from the rolling road guy, or approx the bhp it came up with on the road mapping.

I think that covers most scenarios

Andy

Tidgy

think thats rather harsh, not many companies out there with a rolling road make up problems to solve.

and if your unhappy with how much power you have then it dont mater if its on the road or a RR

New_scooby_04

iTrader: (4)

The whole RR vs Road thing is something of a false dichotomy anyway. Most road mappers will happily admit to having used a RR at some point to develop base maps etc.. and those who use the RR to map, will advocate on-rad testing to finalise the map!

Personally, I don't give a damn about RR outputs. When I get my car mapped I'll ask bob to do a delta dash run and the sector times will be logged. This is a representative "rubber meets road test" of how fast the car is in the environment in which it is driven and much more meaningful than peak bhp and torque figures, no matter how they are derived.

Ns04

PS I'm still going to ask for the power and torque calculations though

andythejock01wrx

I found there to be a big difference between Andy F's DeltaDash figures and Dastek's rolling Road...............well if you consider 2bhp to be a big difference !!

Or in other words, pretty much spot on. You'll get every bit as much of a difference simply by going to another type of rolling road.

AndytJ

Barnesy

Here's when I had it mapped by Andy F a few months back.

http://i2.photobucket.com/albums/y11...uartbarnes.jpg

Here's the graph from the rolling road, they said it was running on the lean side and should be nearer 400bhp.



Car feels no different from the day I had it mapped??
I'll try and different set of rollers and see what they say.

New_scooby_04

iTrader: (4)

Not uncommon for cars that have been mapped on the road to appear lean on the rollers, IIRC they often make boost later on the RR too! I'm sure you could have it adjusted to it runs right on the RR, but how much time do you spend on that??

Would suggest that you speak to Andy F if you're worried about it on the road, if not leave well alone!

Ns04

WRX_Rich

iTrader: (5)

haha best i had was the first run was over 400 bhp after I guessed about 380

was then told ahh thats wrong did it again and got 350 and told they could do so much job of the map

BUT i now only ever take my car to scoobyclinic for rolling roads use and I always get given an honest figure and no bullSh1t "your mappers useless we could do a much better job"

New_scooby_04

iTrader: (4)

I think Bob Rawle best summed up the situation as relates to RRs manipulating figures either unintentionally or otherswise, and in a way that anyone who deals with data will relate to:

Garbage in, Garbage out!

If I had my car mapped by someone as reputable as Andy, it ran fine on the road, but I was subsequently told that it wasn't running right in an environment where it spends about .05% of its time and that is subject to confounding variables that I had no control over, I'd disregard it as a mapping problem and put it down to a) a faulty part, b) an a RR artefact.

If you're worried, it should be checked on the road, not on another RR.

Ns04

Andy.F

I just typed up a quick reply

We have found that there is a wide variation in power output reported by different rolling roads

There are many reasons for this – here are just a few:
1. Variable loading and acceleration rates.
2. Varying effectiveness of cooling systems
3. Different diameter rollers
4. Different surface on rollers
5. Compensation factor applied
6. Operation of rollers


1. Most rolling roads control the acceleration of the rollers to a fixed rate. The slower the acceleration then the higher the effect on heat soak of intercoolers. This can reduce power. With a high acceleration rate then turbo spool can be affected resulting in a lower boost level than would normally be achieved on the road. Different gearing throughout model years will affect run up speed on some rollers. Consider that on the road the acceleration rate of the car will change relative to torque output. On the rollers it is held at a constant rate regardless of output.


2. There are no rolling roads that can properly simulate the airflow normally achieved on the open road through the intercooler, radiator and induction system. Proper cooling simulation would require a moving floor and variable speed fans (as found in professional wind tunnels). Some rolling roads do a better job than others, using high-powered centrifugal fans. Others just have a single axial flow low-pressure unit. On occasion this is just aiming at the intercooler and not actually producing any significant flow through it. Very few rolling roads cater for top-mounted intercoolers. Proper flow through the intercooler is critical in order to simulate normal running conditions a 10 degree increase in charge temperature can cause a considerable loss in power The airflow can also affect the MAF signal on cars fitted with an induction kit, this can lead to totally wrong air fuel ratios existing during the test and knock/detonation may be experienced.


3. The diameter of the rollers and their distance apart will have an effect on the heat generated at the tyre interface. This requires power. Some rolling roads will calculate the rolling losses during the run down phase of the power run. This however only measures the drag on the tyres and transmission under zero engine load conditions. No rolling road software can calculate the increased loss occurring when the tyres are fully loaded. This is dependant on the individual tyre size, profile, construction and compound. Some rolling roads don't even try to measure the rundown losses ! The DynoDynamics for example, when running in 'shoot' mode just uses a lookup figure from a table to estimate the losses ! Simply pump your tyres up to 50 psi and find yourself some bhp. It has been known for some rollers to produce 25bhp gains just from warming up the transmission and tyres over a few runs. Mike Wood from Prodrive experienced this recently when testing a WR1, the bhp increased by 20bhp from the first run to the final run, nothing was changed !


4. Surface finish of the rollers can also affect the power loss due to friction losses and tyre deformation. Smooth rollers are prone to allowing tyre slip on high output cars. This can either cause the bhp figure to rise or fall depending on the how the engine rpm is calculated. If rpm is calculated via the roller speed monitor then slip will generally cause measured bhp to fall, however as the engine torque reduces at higher rpm the rollers eventually “catch up” with the tyres and get an inertia “kick” as they synchronise speed. This normally shows as a blip of 20-50bhp in the power graph close to maximum rpm. If the engine rpm is read directly from the engine then slip will show as a considerable increase in displayed bhp.
This is due to rolling roads measuring torque x engine rpm. If the software thinks the same torque is produced at the higher (slip) rpm then the power figure is multiplied in direct proportion to the percentage of tyre slip occurring.

5. Most rolling roads “correct” the measured bhp to a din standard for atmospheric pressure and temperature (and some don’t bother!). The purpose of this correction factor is to allow for example a comparison between a five deg C winter day power run and a 25deg C summer day power run. The cooler air in winter being denser will (all else equal) produce more power than the 25 degree summer air. The din calculation compensates for the different air density and corrects all results to reflect what would have been achieved on a standard temperature and pressure day. This correction works well on normally aspirated cars but is inappropriate to turbo charged cars.The rollers which do not compensate are likely to read high results in winter and low results in summer. The din calculation looks at only air inlet temperature. There are however, two temperatures that affect a turbo cars output – air inlet temperature at the filter intake and air temperature after intercooler (charge temp) The air temperature at the filter does not affect the turbo car in the same way as it does in a non-turbo car. This is due to the turbochargers ability to partially compensate by spinning faster and still compressing the same amount of air regardless of temperature. There is however, a price to pay for this in increased exhaust gas back pressure and higher turbo discharge temperature which is dependant on density recovery in the intercooler.
The air temperature after the intercooler will normally be higher on a rolling road due to the reduced cooling airflow. Depending on the ECU this may or may not be compensated for in the fuel and ignition maps. Power output will be reduced as a result. It is not uncommon to see a 40 degree C rise in charge temperature on a rolling road run. This is not compensated for within the rolling road software.
Some ECU’s have there own internal compensations to adjust boost pressure in relation to atmospheric pressure and temperature. This also is not considered in the rolling road din correction factor and the two can either work together or against each other.

6. The rolling road operator is able to affect the power result either up or down. If the car is not fully up to temperature, particularly the exhaust system and turbo then power will be down. Also if the car is run a number of times in short duration then heat soak can also adversely affect results. If the clutch is only partially depressed or is binding slightly during overrun then the drag figure will be increased, this will increase the measured power output.

The above just skims some of the issues with rolling roads but hopefully gives an insight into why figures can vary so much from roller to roller, from car to car and from day to day.
It is our experience that a 15% variation exists across the UK’s rolling road facilities.
Now add to this the fact that you can gain up to 10% extra power depending upon the fuel/additives used (even a 3ml per litre dose of NF can add 5%) and it starts to become pointless to compare results on different rollers with different cars and even different operators.

The table below shows the variation that may be claimed/achieved for similar specs depending upon which rollers/temperature/pressure/fuel/tyres etc etc.
98 Octane average result UK Rollers Variation Increased octane

Span of 15% across Rolling Roads (+/- 7.5% from average)
+ up to 10% additional power using NF/Methanol/Race Fuel

V-Power Average result --- UK Rollers Variation --- +Increased octane
--------- 300 bhp -------------278-322bhp-------------352bhp
--------- 320 bhp -------------296-344bhp------------ 378bhp
--------- 340 bhp -------------314-346bhp-------------399bhp
--------- 360 bhp -------------333-378bhp-------------423bhp
----------380 bhp -------------351-409bhp-------------446bhp
--------- 400 bhp -------------370-430bhp-------------470bhp
--------- 450 bhp -------------417-483bhp-------------528bhp
----------520 bhp -------------481-560bhp-------------611bhp



Tuning, Road and Rollers

Engines tuned on bench dynos or rolling roads are generally mapped at fixed rpm intervals. Whilst this allows an approximate setting to be achieved, real life conditions are always occurring not at static rpm but at a rate of acceleration. A fixed speed derived map will be slower on the road than a map optimised to the cars actual acceleration rate (although the rolling road derived map may well produce bigger numbers on the rollers).
This is one reason why we tune our turbo cars on the road under real life temperature and conditions.


Prior to Rolling Roading your car


Due to the vast differences in dyno power run duration and Subaru specific TMIC cooling set ups, I would recommend that anyone with significant upgrades should run some decent octane booster (such as NF)
The reason for this it to retain the ECU safety margin under potentially heavier loading conditions.

If the car is not overloaded, then this addition alone will not net you any more BHP but it will minimise the risk of your ECU retarding the timing which may then take some time to recover to normal running on the road.

Newage cars and AVCR's have gear recognition control of boost, ie they will target higher wastegate settings in a lower gear to achieve the boost target. The rpm/mph rise rate on the rollers will be different to the rate achieved on the road so some cars may overboost whilst others fail to achieve target boost. This is neither a fault with the car or the rolling road, its just a typical condition.

Cars with underbonnet induction kits would be advised to run with the bonnet down, the reason for this is that a direct blast of air from the cooling fan onto the filter can disturb the airflow around the MAF sensor, this can cause the car to over or under fuel.

Finally, ensure your transmission is fully warmed up by giving the car a 10 min run on the road shortly before your run is due, also pump your tyres up to the recommended level (ask the operator) this is particularly important on Dyno Dynamics rolling roads as the transmission drag is not actually measured, just estimated.

Tidgy

please please tell me that was a cut and paste andy??? lol

Andy.F

Yea found it whilst surfing my website ! Had to change Optimax to V power, there's a clue how long ago it was written !

Tidgy

pmsl, was gonna say if it was a quick post you must type as fast as your car goes lol.

was any sort of outcome ever reached about it? or is it def a case of depends who you ask and we agreed to disagree?

andy97

iTrader: (1)

Ive had my car RR power runs twice, the first time, the guy said it was pinking, but a further check by the mapper, disproved that. The second occasion my clutch was supposed to be slipping and they could fit a new one, circa £1000. I tried to induce clutch slip by driving on a dual carriage which has quite a uphill slope to it, in 4th gear from 1500rpm and 5th gear from 1500rpm, no slip was evident at all.

On each occasion I was asked what power I estimated the car had, why ask the question. I didnt know, thats why I was there having it RR.

These are my only experiences with RRs so might not be a common occurrance. I wont be naming anybody.

Andy

MartynJ

We as a company have been rolling road tuning for over 20 years...
I have seen and heard just about every argument for and against rolling roads in that time ....
My take on things has always been the same , to obtain the best result you should tune on the rollers and on the road and use all of the tools at your diposal.....