Hi

I don't know the ins and outs of rolling roads, but does the individual car have any effect on the speed up of the rollers?

i.e. due to shorter gearing, would some cars not accelerate up the rev range quicker than others with higher gearing? or does the rollers have the ability to regulate the rate of acceleration?

A

[Edited by AlanG - 4/3/2002 2:04:19 AM]

 

With the next rolling road day 'just' over the horizon I was wondering if there is anything we can do to reduce the stress on the cars ?

I believe Sam done some fine work with Jim at Star a few months ago, one of the outcomes was a shorter run duration. This is something I would like to explore further.

The last rolling road day I attended, the power runs lasted about 40 seconds. I don't think this is representative of a real life power run on the road. In most of our cars, only six seconds full throttle has you up at the motorway speed limit (to which we all adhere )

40 seconds on full power is like up to max speed and banging off the rev limiter for the last 20 seconds in my car..... ie It's never going to happen.

So, unless you intend towing a caravan up Pikes Peak this duration of run only serves to unduly stress the engine.

In a recent thread in Drivetrain, one guy stated that his power run at Well lane was over in less time than it would take to go from 30mph to max rpm in 4th gear on the road.

What would that be ? about 15 seconds perhaps ?

This sounds a reasonable duration. If the Rollers can complete the same power calculation in a shorter, more representative time, then the stress on the engine/transmission is reduced. This can only be a good thing in my mind.

In the case of Scooby's , which rely to a degree on the thermal inertia of the intercooler and intake system, it will mean a more accurate reading of BHP.

I believe Sam's latest run duration was reduced to around 30 seconds. He commented that it felt a lot easier on the car, no big puff of smoke from the exhaust after the run as I recall.

As Jim's rollers are 'state of the art' I would suggest they can be configured for any rate of acceleration test ?...Sam? Jim? Dave?
Dave B ran a 0 - 60 on them so I assume they can compensate.

More time could be spent setting up each car properly and less time power running.
Maybe even time for 2 runs each if required, say adjusting boost setting for comparison purposes ?

Assuming that adjusting the run time option is available, what do you guys consider the most appropriate duration ??

My personal preference is for a power run no longer than a typical 4th gear 30 to 120 mph acceleration run on the road.....say 15 seconds ?

What do you think ?

 

I would have thought that to be the case Alan, but a 500bhp skyline was 'held back' by the loading and still had a slow run up to max rpm.
I think Jim could regulate the load from a handset, not sure

Andy

 

Hmmm......hypothetical thought.....if a car is allowed to run up the rev range quickly on the rollers, then surely there would be less load on the car and therefore it would use less power getting to its max rpm, in which case the readings obtained wouldn't be representative of the cars potential output.
Whereas if it were under a heavy load i.e. *stressed* then that would highlight the limits of the cars capability, cause it is struggling to overcome the resistance of the rollers.

Does this make sense?

A

 

Yes, that makes sense.

What I'm trying to say is, what do you want to know about your engine ?
Do you want to know how much power your car produces at a steady speed, on WOT ?

Your car will never produce this on the road, it is always accelerating much faster. Turbo spool up will be different, transient fueling will be different, ignition timing will probably be different too due to the increased charge temperatures involved due to holding the RPM back.

I want a reading of what my car produces, to the wheels, whilst accelerating flat out.
To simulate this, I consider the run up acceleration rate on the rollers needs to be similar.

I don't think the figures are realistic otherwise.

If Well Lane and PE are 'sprinting' for 15 - 20 seconds, why the hell are we 'slogging' them for 30 - 40 seconds ?

 

Hmmm....

Can c this has the makings of a good thread guys
Where did u get the 120 from Andy? or is that just a hypothetical figure?

Someone please correct me if I`m wrong but the loading is an important factor in that unless the engine is being made to work a true representaion of power will not be given. i.e. a more powerfull car will out accelerate a lower powered vehicle on an incline, no ?

Isn`t it also dependant on how the individual car is mapped?
Some are mapped for blistering 0-60, some for mid range, some for top end speed? Doesn`t that determine where the load should be applied ?

Soooooo many questions

Pete

 

Good point Andy and I agree.
Since Jim runs the cars up in 4th gear, I think it would be worthwhile timing on the road, how long it takes to accelerate from say 2000rpm to maximum in the car.
If it takes, say, 15 seconds do that, then it would be representative to have the rollers give a resistance to replicate this as close as possible, if it is possible to do so.

However, in the future, you may not have the same resistance on the rollers to compare readings from previous occasions, so it can be a case of figures for figures sake. (read pub talk)

I know Sam did quite a bit of investigation into rolling roads, so maybe he could throw up some suggestions or point out where i'm going wrong.

A

 

I suppose though.....the rolling road is only good as a comparator on the day, to compare outputs between different cars since they would all have the same resistance loaded on them.

 

Sorry to interrupt your techno speak ladies, but when is the next RR Day?

 

Pete

I just used 120mph as an example. I just consider the rollers run needs to be similar to a road acceleration run.

Not sure how you map differently for a 0 - 60 run or for mid range although I can see why you may be conservative for top end speed.

My understanding was that the rollers can calculate the power required to accelerate as well as the continuous load applied to them. I can't see how it can do a 0 - 60 time otherwise ?

Anyone else prefer to run a shorter run ?

I don't know when the next Scooby day RR is. The MLR are running toward the end of April, be interesting to have their views.

Andy

 

Shorter run definitely. In these temperatures in road use my charge temperatures are only about 30 deg C at 18 PSI, so a rolling road run more reflective of this would be nice. It would also be nice to get the load turned on in a more realistic way - peak boost did not arrive until 1000 RPM after it arrives on the road on my last run!

 

Andy,

Not 2 sure on the shorter run thing, yeah it would be great if we could produce realistic results in a fraction of the time, but can we? I know my loco doesn`t start really pulling until i`ve hit round about the 100 mark which takes around 11 seconds alone
And (Jim correct me if I`m wrong) the fan at the rollers is only a simulated 80mph so when we go much above that there is insufficient cooling available so the full potential can`t be reached in such a short time ?

Like every1 else here I`m still trying 2 get my head around the in`s & outs of the rollers, so all input welcome.

Me n Dave r gonna b there on the 28th flying the flag 4 the lads
it should b interesting

Pete

 

I hope the MLR are not looking to take some Scooby scalps on the 28th If they are, perhaps they have invited the wrong 3 scoobys Yes I did say 3

 

Good stuff Andy,

I believe we may even have 4 "upr8ed" scoobs in attendance

Pete

 

Mmmmm shorter run won't make as much difference to a FMIC car due to the more appropriate cooling fan. TMIC's are struggling with the longer run time.

Perhaps we can do a back to back test on a 'volunteers' car to compare power recorded from a 15 second sprint run Vs 30+ second slog run ?

The general concensus seems to be that a shorter run will record less horsepower due to less load being applied. On that basis then, I don't suppose anyone could grumble if I opt for a short run for my car ? Assuming this is an available option with Jim ?

[Edited by Cosie Convert - 4/4/2002 12:36:20 AM]

 

I`m still unsure about this Andy, as for any results to be used
for comparison the parameters would have to be identical, i.e.
all motors would have 2 b run under similar conditions, no ?

Hmmmm.... wonder if we could get a top speed figure, w/o overheating the car ???

Pete

 

hi andy

the 30 sec runs are as good as you well get, anywhere really. i am sure most cars are ok until you get to the 4500+.

you really can't set the roller for each car individually like that, because you will need the exact weight of the car and then will need to expreiment with the load. the load is not something you can set on the fly or with the controller, it takes a lot longer than that.

if the run is any shorter than 30secs you can''t measure the trans losses!. so you can have 240bhp at the wheel and 20bhp loss and you end up with 260.

the problem with you andy is you are running your car on the limit, so if you want you need to play by the rules. all the cars are going to be put through the same engine stress. my subaru and evo have on the rollers loads of times. as in over 20 runs each car!!

and the shorter gearing makes a big difference. as the cars with shorter gearing should need more load to get comparable paw figures that is why paf is very improtant.

i feel the setup me and jim came up with last time, is as close as you would get with out putting too much strain on your car.

try tunning for reliability
sam

 

GULP - As Andy swallows the bait, hook, line and sinker

""if the run is any shorter than 30secs you can''t measure the trans losses!. so you can have 240bhp at the wheel and 20bhp loss and you end up with 260.""

Sam, Ur talking CR4P

Suppose you can explain why the 'experts' at Power Engineering and Well lane run for 15 - 20 seconds ? Guess they must all be wrong then

I tune my car to the limit Yes absolutely. If you don't then someone who does, is going to pass you and pull away but I guess you're getting used to that now :

I tune my car to be at it's best during acceleration 'on the road' cos that's where I use it and have most fun Living in the UK as we all do, I'm not interested in 170/180mph top speeds, which is all you need a constant power output for.

See you and your 'reliable' car at Crail then That's if nothing goes wrong with it this time, unlike last time at Crail and Knockhill

Andy (trying to pull sam and his rod into the sea before munching on his leg )

Edited to take another bite

[Edited by Cosie Convert - 4/4/2002 10:59:09 AM]

 

MEEEEEEOOOOWWWWW !!!

Pete steps back so the cats have a clear path

 

that is very original andy.

right buddy, so lets see,

hmm, i have never done crail ever before but i went because you guys were going so i went for a laugh. so what if you have beaten me on a 1/4 mile? i would have got something else if that was my thing.

you on the other hand will not even attempt anything, unless you are sure you have an edge. perfect example you did not take it on knockhill because your breaks are not up for the job? as if......

ran your car at 26psi at crail... fair enough it is your car.

i was at knockhill with warped discs, loose camber nuts, new car and still overtook every car on the track so don't kid your self mate. if you were really as good as you are you would have taken your car on track to show your stuff. but you did not.

if you going to compare soemthing very basic and 10 years of age as pe to star then why don't you just go there!!

i think you are just chickening out of getting your car on the rollers just in case you get beaten. there is a trend starting to develop here about you. you just don't want to loose. this is not a competition never has been never will be.

so bring your car to knockhill next time and lets see no excuses this time. the ball is in your own court or do you just like to talk the talk?


sam
i sometime wonder do i even bother.

 

and it worked SPLASH

Mmm

It's tempting to take my Subaru out at knockhill just to silence you but maybe I'll just get a Fiesta XR2, after all, thats all you need to do 65 second laps round there

"Don't like to lose" ? Agree, Looks like both of us will never be happy at the same venue

"Not a competition" Agree, but you forget, I was in the car with you at Knockhill when Willie's car just passed you and pulled away from you and you couldn't catch it. You were in a well competitive mode



[Edited by Cosie Convert - 4/4/2002 6:37:51 PM]

 

I've not seen Fast and the Furious yet. Maybe I should rent it tonight to continue the drama.

I think it is fair to say the Star rollers give a FMIC an unfair advantage. The 1/4 mile terminal speed seems a more realistic estimate of who has more power at wheels to weight ratio than the rollers, although it is obviously technique dependent.

What time do you lap Knockhill in Sam? You can pass me if you like I think you would whether I invited you to or not

It is all fun after all, not a who has the biggest dick (substitute) competition.

 

i have two submarines

1/4 mile and race tracks are very different.. obviously
so are gravel rally stages...

ur ALL good ... at different things...

AND

ull all pass me on the track.. and ill be left by about 3 or 5 secs on a 1/4 mile strip...ud also all beat me on the road...

but at the end of it all... ill still be

isnt that what its about?

funny how the line and hook turned into pistols at 20 paces

keep it up

edited to say:
to work out the exact power at the wheels in completly consistant and non-biased enviroments is probably down to lots of measurements and tons of extraplotation and calculations...
**** that! thats boring!
get out and drive

or get two rental cars

[Edited by SCOSaltire - 4/4/2002 4:25:58 PM]

 

Rental cars at Knockhill that sounds like fun

1/4 mile technique ??? like eh, just accelerate fast, we're not even bothering with the lights / reaction times, get in car , go fast how much easier can it get ?

Seem to be well off topic here admittedly my fault

Anyone else have a view on rolling roads and their relationship to reality ? If we all agree that they just produce an innacurate 'pub talk' number, whilst giving your car the hardest time it's ever had, then that's not my idea of fun.

I'm only trying to get some reality back in the equation and minimise the strain on the cars. (and of course say my car's faster than Sam's )

 

You in the same specification car as me would do better at a 1/4 mile - your times are consistent to within 0.1-0.2 seconds, your launches are good and your gear changes are good - I have seen you drive. Don't underestimate how crap one can be at launching in particular. It is so easy to spin all the way in 1st banging off the rev limiter, or with a laggy car to bog down. Although of course I just need practice

 

Maybe ? Not sure though........

A Female friend of mine had her 16v Astra at Crail some time ago. She eventually got the bottle to go on track. I was trying to give her tips on how to launch it, less wheelspin, change up sooner etc etc. She then handed the keys to me so I could 'show her how it's done' My times were slower

So now, when somebody asks me now how they are driving, I don't offer advice but just say "fine" (even to Sam)

 

on topic too...
ive not put my car on a rolling road because of the strain (had to watch the spelling there... think about it )

so a discussion by the people in the know to sort out the least stressful workout for the car sounds good to me...

then when uv sorted it.. let me know and ill go on the rolling road... would be good to find out what ive been driving...

 

I just went out tonight in typical Scottish weather - and ran 1.3 bar with a pretty good attempt to get the charge temperatures up and I just could not get them over 23 deg C. Ambient 6. This is on the supposedly rubbish TD04L-13G and factory MY00 TMIC. Very smooth, no hint of it retarding, positively flying all the way. I don't expect the temps to go much above 40 C even on a hot day from what I have measured so far, and at ambient 15 I just could not get them over 30 C.

Now, compare my car at the last rolling road day, similar ambients and only 1.15 bar and you can see two points on my plot where it looks like it was retarding. It felt $hite on the road for a few miles afterwards.

Go figure. Rolling roads are crap.

 

Cheers guys, I think I'll take a run over and speak to Jim at Star before dismissing my ideas on the basis of second hand information.

The other MAHA rolling road (same as Star), was that at Tuning Japanese ? I could call them and see how they are configured.

 

Geez, I'm glad I'm daft towards cars as I NEVER take bait

Andy, your right about the cars that were invited to the MLR RR Day. As a lot of our members don't do very much club stuff, I thought i would invite cars along that were above standard spec,

The list as it stands is

Modified Evo 4
Slightly Modded Evo 4
Slightly Modded Evo 6 (2 off)
Slightly Modded Evo 7
Slightly Modded 22B
Modified Imprezas (4 off)
Monster Skyline

One Evo vacancy still to be filled by MLR member (possible E6)

We should be looking at each car achieving 300bhp, that's the target. I will be down on my previous of 340bhp, due to Sam/ Jim changing the set-up of the rollers, so we don't get a head start.

...John