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MG ZR ZS ZT Technical - Rolling Road Dissapointment :-(

well went to the rolling road this morning to see what power the zr160 was putting out.
its a 160bhp model and the book rates it as having 157bhp.
its been set up to police mode spec which seems to have given it more low down pulling power, and the result was.........

max power 151bhp @ 6768rpm -1291bft

now the cars done 2.5k so should be run in but it shouldn't be down by so much, mg quote torque to be 132nm (is this the same as 1bft), and power as 157bhp so this means im down 6bhp and 31bft.
now to get 6bhp would cost a couple of hundred quid - filter and exhaust so yes it does make a difference.

has anyone else been to a rolling road to get a true output?

rob



rob

Rob
Looking through the car books it is not clear that the 157 bhp is quoted from the engine or from the wheels.
You may have confirmed what I suspected that the 157 figure is from an engine dyno and not a rolling road.

Nigel
Nigel

1 Newton/metre =.73756 ft/ibs

thus 132 Nm =97.34 ft/ibs

129 ft/ibs =176 Nm

ZR160 @4500rpm listed as 174 Nm, therfore it nearly spot on, for max torque.
Joe

Rolling roads vary an awful lot, so the odd BHP here and there "missing" or "extra" is nothing... The only way to compare an engine with the manufacturuers base line figure is to use the manufacturers RR! Temperature, air pressure, the RR operator, etc. all make a difference.

Take the car to another RR and tell the guy what you want to see and I'm sure he'll manage to get the results your after!

DC
David Coulthard

Thanks for the information away Rob, how is the ZR going? I seem to remember that a Honda was giving you a good chase, would the ZR be better he showed up in your mirrors again?
Cheers
Mega.
Mega

Is there any chance that we might actually get to buy one of the new Z sedans here in the USA in the next few years??? I was out yesterdat testing the small hot sedan market and there are already several good ones out there from Mazda (Protege 5) and Nissan Sentra SER with 165 HP; not to mention the soon to be available new "MINI" from BMW. What's the matter with MG? How long are we to wait before we see some of the new stuff for offer???
G. Wayne Hardy

>>>> . What's the matter with MG?

I say nothing is the matter with M.G.... we can export the cars to all over the world…. it just seems that the States have laws that don’t fit in with the ‘normal’ world… perhaps you should change the laws then we can export our great products over to you!!
cecil kimber

Rob said >>>now the cars done 2.5k so should be run in
I disagree - many modern engines continue to loosen up for up to 20k miles (eg K series) especially if they have fully synthetic in from day 1. Go back to the same r/r in 12 months' time and you should find a few missing ponies....
David

I used to own a 2000 MGF 1.8i and felt the engine "loosen up" at 12,000, 15,000 and 18,000. Each time I noticed a considerable differance to the way it drove. So give it some time and the power will come.

I am thinking of buying a ZS120+ as my next company car, anyone got one? What do you think of the handling/engine? I've driven a ZS180 and wow.....Its like an Impreza Turbo. If only it wasn't so thirsty.
Tim Pottle

Agree with Tim, the engine definitely improves with the miles. And don't feel too disheartened, a friend took his Elise to 3 different RRs and got 192, 160 and 180!
Dot

ok guys i feel a bit better now.
the rolling road was set up through "scoobynet" which is a website for impreza owners. i joined the clubs etc when i had a turbo last year and still follow closely.
The RR day was for all members - the majority whom have Impreza turbos and were they out in force.
Must have been 40+ who turned up including one guy in a fiesta si and a couple in evos.
It amazed me how the outputs varied on cars with the same mods - one car had a full straight through exhaust, induction kit + a couple of minor mods and he only put out 213bhp, a standard one gives out 211bhp?

Why don't we MG followers organise something similar to this sort of meet, rolling road and a run out maybe? then we can compare notes / mods, etc

Rob
rob

good idea Rob, why don't you ?
David

yeh would be a good idea to meet and sort out all our rattles / niggles.
Fancy coming along mega and i'll give you a go in my ZR so you can see what it's like :-)

rob
rob

No rolling road, but Stoneleigh is the first major MG event of the 2002 calendar.
How about a big meet up? Stoneleigh Spares day is on the 17th of Feb!

Kelvin
Kelvin

Thanks Rob
Your one of the few guys on this BB that i would love to have a pint and chat with. I am very bussy right now, i am setting up and new bussness and i have much to do. Besides the Taliban might turn up with there hand bags!
Mega

eez what a whinger

torque just about spot on and only 6 bhp down on a nearly new car
give the thing a chance retest at 30,000miles and then see!!
My F just keeps getting better
recommend a few subtle mods if 151bhp isnt enough
also you would hardly notice the difference a few bhp makes so chill, enjoy and let it run in gently
then if you must go mad get a different airfilter that'll probably get you up to 157

N
Neil

Neil - test again at 30000miles!!!!!it'll be long gone before that, probably before 3000miles at this rate, thats what happened to my old r25 - 2100miles!
If the engine doesn't loosen up until 10k+ does this mean mgr run an engine this long before they print a brochure with the results in - i don't think so
why dont mgr call it the ZR150 instead and if anyone gets an extra bhp or so it'll be a bonus.
if i buy a car which is supposed to be 157bhp from new i shouldn't have to spend a hundred quid or so trying to get that figure :-(
rob

Hi Rob
Just for the record, do you have a print out graph showing bhp/torque/engine speed?

Did "Police mode" give a load extra at lower RPM?
Mega.

By the way, are you thinking of fitting strut braces?
Mega.
Mega

Mega, yes i did get a print out, the power comes in now at 2000rpm keeping constant up untill 5900rpm.
shame i didn't get a print out before the "mod" so i could be positive but it seemed to be around the 4000rpm mark before.
go on then tell me you can get hold of strut braces (polished!)- how much?

rob
rob

Just to add to David Coultard's pertinet comments on rolling roads...

was the max power run done with the engine stinking hot from a period of running up, or done soon after a previous run? Were the tyres hot or cold and were the pressures increased to reduce the significant power absorbing capacity they have? Was the flywheel estimate done by a measure of the costing resistances after the power run? And finally, were at least three power runs done, spaced with cool down time (you never get a rolling road session to run anywhere near as cool as on road running) to provide a representative average.

The base line being that there are so many ways I can legitimately destroy the readings that you have achieved that the actual comparitive value against the standard quoted figures means next to nothing. The value is of course before and after changes with correction to STP. Only when a significant number of standard cars have been on the same rollers doeas a pattern of power start to emerge and then this really only provides a good indicator how different cars vary, but also how they change at different mileages.

No wonder than many rolling roads have read outs that are intended to provide figures that owners wish to see. This then simply creates more hassle as the same car between rolling roads shows vastly different readings. I have had this with my MGF which whlist standard on a Friday showed 103bhp at the wheels and the following day with the same temps and pressures it was 96 on another RR. It wasn't driving any differently and a later rerun on the first RR showed 104!!

Rob the best point to interpret from the RR session was that you car is in the right ball park and it is reasonable to expect it to improve with miles.

Rog
Roger Parker

point taken Roger

car was left for 15mins before it went on the rollers,had 3 runs, tyres remained at standard pressures and the power figure was taken off a dyno machine (with a big dial) showing the power output?

rob

if anyone knows how to post pics then i have 2 of the car on the rollers and a printout of the results
rob

Ask a MR Flint (Jerry)
He sort that one for you Rob, i will try to have a look at a ZR ref Strut braces Rob. There is one on the estate i work.
Mega.
Mega

cheers Mega - polished please

rob
rob

This thread was discussed between 03/02/2002 and 10/02/2002

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