I’m with WEXY on this one I always thought the flywheel figs were calculated from the wheel figs. Now if the wheel figs change but the flywheels stay the same. Why do other country’s use PAW?
Mervyn are you saying that if I blast around a track at full speed. Then put the car on the RR I will get better figs with PAW, than a car that has not?

 

Adam.
It appears your time at PTS was not well spent.
Most rollers I've been to allow the car to idle for some time on the rollers, whether or not this affects figures I don't know.
Didn't PTS use any cooling on your i/c at all?? Yipes! I had a cooling pipe attached to mine.
I agree completely that the operator makes all difference. Merv at PE is definitely one of the most knowledgeable RR chaps I know.
I've always maintained that the rollers at PE are certainly consistent, if at times open to some healthy debate.
My car has always performed well at PE (267bhp & 235lb/ft with exhaust and filter) and even showed a great increase in torque after the fitting of my PPP ecu. Shock horror.
It was the figures after the fitting of my fmic that confused me the most though. PAW went up considerably (18bhp) but other figures only increased slightly. What I find interesting is that Merv has said that a 1psi increase in boost can increase power by 7-8bhp and 10-12lb/ft. On the way down to PE the other week, and on the way home my car was boosting to 18psi as it normally does. On the rollers however we couldn't get above 16psi. Does this mean my figures were actually being underestimated by 15bhp and 20lb/ft, and if so, was it because the rollers simply can't offer the cooling required to get the best from a fmic?
Merv?
Sure, a top mount will also not get enough air to operate at it's best, but surely a fmic will be affected more?
As it stands, both PTS and PE have given my car pretty much identical figures in every respect. Merv's the guy at PE, and Paul must do the runs at PTS.
Divert from these guys and on your head be it!

Mark.
I know lots of guys got silly high figures from PTS, but don't forget they had only recently taken the premises over from another company and inherited the equipment and software. They should have adjusted figures for your car now, I'd be interested to hear what they are?
At least they've addressed the high figures issue, it would appear all they need to do now is sort out some consistency .

Stef.

 

<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:<HR>Originally posted by g man:
<B>MR.TANG what is it NOW 220 BHP ho ho..[/quote]

Gary,

Given that it will be warmer than 12 celius on the 14th August, I'd expect a drop in figures.

The PPP ECU is out now, and the standard ECU is there instead.

I think it will still show up a few cars on the day (if you have room for me to run!)

I'm guessing about 270bhp! (You're reading this Mervyn aren't you???)

Cheers
Andy

PS - Arrange a rolling road day for November/December, we'll see what the figures are like then!!!

 

Thanks for taking the time to post Mervyn,

It makes interesting reading. As far as I'm concerned PE rollers are spot on and consistent, I have always used them and will continue to do so. Not only to they take excellent care of the car and settle it in gently onto the rollers but the whole run from start to finish is nothing but professional, I wouldn't go anywhere else.

With regards to the fmic cooling at PE Stef, I'd say it was pretty good

Big thanks to Mervyn and PE for all the RR runs and results they've done on my car, I'll be popping back shortly for another one to measure what performance decrease I've had from fitting a lightened and balanced flywheel!! but i'll try not to look too glum

Thanks
Nito

 

Andy, there will be room for you as I have to cancel due to the fitting of a new toy to my car.

I will hopefully be there, but the car will not.

Think I emailed gary, but havent had confirmation of its delivery so may have to re write. If you are reading this, then sorry gary, something unavoidable has come up, hope you can forgive me, and really appreciate your effort in sorting it all out. Will be a great day.


Stef,

The guy who operated the car was a kid of about 20. I assume Paul is not him as I spoke to a more experienced guy when I asked him to dig up your graphs to compare the drivetrain losses.

I have no problem accepting 186 or whatever at the wheels, but the torque makes me think hmmmmmm . The 22B is without doubt the most torquey of all road going imprezas, and there is no way mine feels deprived in this department.

i can only assume they are using the flywheel power to calculate the torque which explains why it is low!

Your car was losing about 30bhp more than mine in the drivetrain, which doesnt make sense.

Air was aimed at the intercooler, but only after I shut the bonnet and insisted on pointing the fan at the cooler.

Power engineering is booked for 1:30 on sunday. Hopefully I can trust my car to merve and know it is being done properly.

and there is an sti4 on before me, so ight be a mini meet.

 

I'm confused even more now. If the wheel figure can climb due to thick cold transmissions or other factors and the flywheel engine power stays the same, that means the paw figure only is out, which means the dyno's in OZ are all wrong because their RR's do not measure flywheel hp at all. For eg a car gets 250hp at the wheels in OZ and another gets 270hp at the wheels, we assume that the 270hp at the wheels car, has more power. But in the UK the car with the 250hp may have more power at the flywheel than the car with 270 hp at the wheels. So how can we go by paw?

WREXY.

 

I have to agree that PE's dyno figures are consistent, that is their flywheel power and because they are consistent I too would be using their RR, or PS's without a doubt, if I was there. And with all due respect to Merv who took the time to post I'm sure he does a top job with the cars, as posted by Stef and others, who I've learned to trust from their judgement from reading their posts on the bbs. I'm just confused with the way it all works as I have posted above.

WREXY.



[This message has been edited by WREXY (edited 03 July 2001).]

 

Adam,

We have to agree that the figures from PTS are completely innacurate. There is absolutely no difference whatsoever between you and I on the road, in some instances, eveen, you would appear to have better torque, yet I seem to have nearly 80BHP and 60ft/lb advantage!!

Cem

 

Wrexy,

Never accept the judgement of others as gospel, especially Stefs.

Cem

 

Could be serious I don't see any smilies or winks

WREXY.

 

Cem referring to your posts in order.

1. 80bhp is one heck of a difference, but assuming I believe the power at the wheels it was still around 40bhp down on your car from the day I remember, another reason why it would be nice if you can make it on Saturday.

2. Absolutely agree with Cem here. Never trust anyones word on here. Especially stef . unless you are asking him about how to impress a crowd, which he is very capable at, oh and also how to make tires squeak round long bends (again, if there is a crowd present, he is particularly good)

I am being unfair, but I am also kidding.

The only people I trust are those I have spoken to in person and have come to know their strengths and weaknesses in certain areas. For example, you may respect Simon De Bankes opinion because of who he is, but he is the first to admit he doesn't know much about engines. talk to him about vehicle set up and dynamics, and it is an entirely different ball game.

To gauge you have to know someone, that's why I trust Mark (R19KET) on nearly all practical subjects, particularly mapping, and the same goes for Bob Rawle.

if you are talking engine internals, it has to be Firefox, as he has seen more "hands on" performance tuning than anyone else on here (Steve Lawson excluded).

If you are talking, electrically, and highly theoretically then Pat is the man.

Have to include Cem for web designing and style appreciation I don't agree with the stickers, but he has good taste (red stickered up makinen excluded )

Make your own judgements, but there is NO ONE else I really trust where my car is concerned.

God help me when I need to find someone to put my engine together.

[This message has been edited by Adam M (edited 03 July 2001).]

 

Back to Rolling Roads instead of slagging Stef.

I tend to trust PE RR more than any other. Some people have different views I know, but just looking at the loads of Impreza’s on the dyno site that have run at PE and they just look about right for the mods people have done.

 

Bit difficult to get to speak to these people face to face from where I am. However I have to say I think Stef can judge if his car is being well looked after on the dyno. The other thing is that the people you mentioned are the "others" I seem to take more serious. I am new here so I'm still trying to work out who I should take more serious, but I am getting there. I've gone into the 22B bbs and read everything posted technical and found that the quality of posts is more serious and I feel that quite a few of those people know what they're on about. It is also these people that produce the best TECHNICAL threads on this bbs, including, yourself (Adam), Bob Rawle, Pete Croney, Robski, R19KET (Mark), Firefox, Sam Elassar, Jan Shim, Evil Bevel (Theo,) Greg115, Nito, Cem, Bob, Andy Tang, Stef, Harj, Richard Squire, Dave TS, to name a few, I,know Dave mucks around a fair bit and good on him as the bbs needs some humour, however when he's serious I've seen some good points posted by him. Forgive me if I've missed anyone as I can't recall them all in my head and there are others. I'm not saying they are always right however they seem to know whats going on.

WREXY.

Edited to add Pete Croney, Stef, harj and Richard Squire in.




[This message has been edited by WREXY (edited 07 July 2001).]

 

Wrexy, I will take that as a compliment.

what I said about stef was a joke. He is a good bloke and yes I am sure he knows exactly what he is talkinmg about as far as people operating his car on the rollers is concerned.

Doubt it is worth coming over to meet us all, but needless to say you are welcome.

Gald you pointed out theo in there too, I feel bad for not mentioning him. Plus he is a big mother bitch whom I would rather stay on the right side of .

 

The reason that the figures vary so much, and why 22Bs and Type-Rs seem to get strange figures, is to do with gear ratios rather than diffs. Obviously figures are affected, as Merv said, by tyre pressures, wheel sizes etc. but the major cause of inconsistent (calculated) transmission loss figures come from the difference in gear ratios.

If all cars are run on the rollers in 3rd gear then they wheel speeds are going to be a lot different between the high ratio (shorter geared) type-r/22B than a low ratio UK car. A higher geared car is going to have a faster tyre speed on the rollers than a lower geared type-r or 22B. This increase in wheel speed leads to more power being absorbed as heat and friction, and hence the measured PAW therefore goes down a bit. Therefore cars with a higher ratio (lower geared) gearbox will show higher power @ wheels figures than those with a lower ratio 'box. This is echoed if you look at the dyno site and compare the 22B & Type-r PAW figures with those of a normal a STi which should be developing the same power.

This means that using PAW as a way to compare power figures is of no use if the gear ratios of the cars are different.

What should happen is that the rolling road system would compensate for this; it should reflect the larger losses in the higher geared cars by showing a larger coastdown loss, which when added back to the wheel bhp should give an accurate(ish) flywheel bhp. This means that although a standard Sti 4 type-r may indicate more a, for example, should equal the same bhp as a standard 4 door Sti.

However... I was reading an article recently on which a transmission loss test was carried out on a Fiesta XR2i. The car was run on an engine dyno to get an accurate flywheel power figure. It was then run on a dyno in 3rd, 4th, and 5th gears; as expected higher PAW figures were shown in the lower (higher ratio) gears, this should have been compensated for when coastdown losses were calculated, the results however were incredibly inaccurate. The rolling road showed the coastdown losses rising much more in a higher gear than the actual transmission losses are, and much less in the lower gears. This lead to larger flywheel bhp figures in the higher gears and a smaller flywheel bhp in the lower gears. The test was carried out several times with consistent results.

What this means is that when cars with a lower geared 'box, such as the 22B and Type-R, are run on a rolling road they will generally return high PAW figures, but low flywheel figures - the dyno site confirms this. Higher geared cars will generally go the other way; low PAW and higher flywheel.

This can go someway into explaining why standard UK cars, with higher gears, generally produce more flywheel power on a RR than the factory quoted figure, and why the shorter geared Sti cars tend to produce slightly less and yet PAW shows the opposite. Andy Tang’s car is a perfect example of this, up on flywheel power, but down on PAW.

All the above depends on the rolling road, I don't know where the Fiesta test was carried out, but the results do seem to echo those that we see on the Dyno site.

Adam, maybe it would be an idea to run your 22B in both 3rd gear and 4th gear at Power Engineering and compare the figures, obviously the flywheel figure should be the same.

Simon

 

Cheers Adam,

Well I may come over with the car at some stage, cause I do plan on some type of mapping for the car be it Link, Unichip or Motec. I was always thinking Unichip but as I go on reading here I may change my mind. If and when I come I will post here, so I don't think it would be a bad idea to meet up with you guys. Plus you are also welcome to come to Greece for a holiday and I'd make the effort to meet up with any of you too.

WREXY.

 

thanks wrexy,

and thanks simon too.

Raises some interesting points.

Too my knowledge most rolling road power runs are done in fourth gear since it is believed to be direct drive????

I did notice the tendancy you mention on the dyno site but could not jump to the hypothesis you did for lack of practical knowledge of how the things work.

I thought that some consideration must be based on the loading of the engine. Under insufficient load, not enough exhaust gases are generated to provide the boost required.

I was sceptical about a rolling road in the first place, preventing a turbo from doing its job properly, but would like to run that past mervyn.

Bob Rawle and Mark both commented whilst mapping my car originally that the lower gearing of the type r gearbox made it more difficult for the car to generate boost.

With this in mind, would it not be better to try fourth and fifth as a comparison rather than fourth and third?

 

Simon,

Good points there.

I can understand that, In Australia all cars are dyno'd in fourth, The 1:1 gear or close to it for example 0.977 or whatever, but always in fourth as it's the closest to the 1:1 ratio, as the operators have said that in third the figures are exaggerated. They don't measure flywheel hp at all, This seems to be the reason for the differences. Maybe for a correct paw figure and only power at wheel figure, you would need to do the runs in 4th like they do in OZ and to get the flywheel power you would need to do it in 3rd for the UK dyno's. Don't know if this makes sense but in OZ they definately only run the cars in 4th, and the dyno's there do not have the flywheel power facility.

WREXY.

 

Adam,

When you posted I was still typing, so I just read your post. The direct drive theory you mention is correct. And this now goes to show why your figures were so low, done in third, due to the lower boost pressure in third. In third figures are usually exaggerated however this may be for atmospheric engines and not turbo's due to the lower boost. I would like to ring my friend in OZ who has a RR in his shop to ask him, but they are asleep at this time.

WREXY.

 

I thought Mervyn said he used 3rd gear... maybe I was wrong. Even so, using 4th gear, you could still not use PAW to compare accurately the various models of car. As you can see from this chart, the gear ratios of the cars are quite different:


Gear----TypeR----Sti------UK

1st-----3.08-----3.17-----3.45
2nd-----2.06-----1.89-----1.95
3rd-----1.55-----1.30-----1.36
4th-----1.15-----0.97-----0.97
5th-----0.83-----0.74-----0.73
Final---4.44-----4.44-----3.9


Adam, I would suggest running the car in whatever gear is normally used ie. 4th, and then one higher (5th), I am pretty sure you will see a large drop in PAW, and probably an increase in the flywheel figure. The difference between the two flywheel figures should give us an idea how inaccurate (if at all) the coastdown calculations are.

Simon

Edit: Due to crappy proportional fonts

[This message has been edited by Simon (edited 03 July 2001).]

 

Simon,

Merv did not mention 3rd gear runs. From what I remember, in OZ the dyno measures the torque first, then somehow by the way the torque came on and by some mathematical table programmed into the dyno, it gave a hp reading. Apparently compensating for different direct drive ratios. I remember my friend showing me a table list of differnt torque equalling hp and by this list they knew if their dyno was out.

But one thing I dissagree with is that the paw method is wrong, as it can't be, in OZ anyway. Perhaps the dyno's are different in OZ especially in the paw department to the UK ones.

Confused again.

WREXY.

[This message has been edited by WREXY (edited 03 July 2001).]

 

<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:<HR>Originally posted by Simon:
<B>I thought Mervyn said he used 3rd gear... maybe I was wrong.[/quote]

When I went to the rolling road day at Power Engineering a few months ago I am certain they tested it in 4th gear. I seem to remember it was doing around 130MPH before it hit the rev limiter and a big puff of unburnt fuel came out of the exhaust. Poor girl, still don't think she has forgiven me...

I seem to remember the car made 230 BHP and 217 ftlb of torque which for a completely standard MY00 fits in with what Mervyn said above.

 

wrexy,

power = force x velocity,
which when talking rotaionally

= torque x velocity or rpm.

if they measure the torque they simply mutiply by the angular velocity of the rollers at that point to get the power at the wheels.

I am guessing, but i dont see why not.

 

there is no doubt taht normal rolling road tests are done in fourth gear.

I might ask mervyn on sat if it is worth trying it in fifth gear.

 

Well all this talk about dyno's is again a very interesting topic. No conclusions yet as to whether the consistent way to dyno is just paw or paw and flywheel power together as there seems to be two arguments to this. I'll also try contacting my friend in Oz to see what he thinks. Adam I like the formula, seems to be right for converting torque to paw. At least the PE RR seems to be consistent, which really is all you need for before and after mod runs. Good luck with it Adam

WREXY.

 

WREXY
I can see now that with different gearing the PAW will be different. Is there a way of compensating for the gear ratio’s in Oz or are they just miles out.
See I have now jumped on the flywheel side.

 

I like the way Oz and many other countries do their dyno’s with the PAW. In my mind it gives what power the car is really laying down. Over here we tend to beat around the bush and use lots of equations to get to the final figure. Should we go by PAW, Torque or BHP. I still would like to know why different countries give the dyno readings in different ways, and which ones do you think are best?
Bet WREXY likes the PAW But what about you.

 

Bob,

you are right. I like the PAW. But what confuses me is how the paw changes, yet the flywheel power stays the same for a car on the UK dynos. If PAW changes, that means all countries that only use PAW will be out on measurements. COZ the car with 250 at the wheels may have more power at the flywheel than a car with 270 at the wheels according to the UK dynos, whereas in the country where paw is only used the car with 270 paw is automatically assumed to be more powerful than the car with 250paw. Confusing. However, sinse the RR's are like that in the UK and at least PE seems to be consistent in there flywheel measurements I suppose they are the ones to use. It would be costly for everyone to change their dynos. I don't know if the dynos have to operate like that there, ie the flywheel power being a compulsory part of the equation or if the flywheel part can be disregarded and only the paw be concentrated on. If flywheel power can be disregarded what happens if the paw figure still changes?

How long have 4wd RR's been around in the UK? In OZ they have been around for 4 years. I'm just trying to work out which ones have the newer technology.

Anyway I still vote for PAW. What does everybody else think? as Bob has asked

WREXY.

 

Interesting, the thing to remember is that PAW is totally dependant on gearing. Simple math as Adam says, so a UK car will give different figures than an STi saloon 4 door which will be different to an STi Wagaon which will be different to the STi Type R and RA's or 22b's. Imagine this, same engine put in all the different cars, the PAW would be different for each due to the gearing.

So, in actual fact tha flywheel power is the constant, only real way for that is bench dyno, Scoob transmission loss is pretty variable car to car and certainly type for type, the different set up of the variable centre diff, for example, means that the transmission seems to have lower losses.

PE always use 4th and Merv has evolved the technique to provide as consistant a result as possible, the Rolling Road itsef and its software will always affect the result but the operator makes the biggest difference.

BTW geometry set up also affects as it will contribute to the losses on the rollers.

So best practice is to pick a rolling road and stick to it, thats what I have done, Rolling roads are best for comparative checks. Always nice to get good figures though.

BTW looked at Nitos graphs, lost alot around the 2-3000 mark but thats expected with turbo, Merv's comment on funny graph shapes comes into play here as the flat top to the power curve and the odd bulge at 6-7000 smacks of slippage possibly ?

 

Adam.
I guess that's what the problem was. I should have told you to only let Paul do the run, sorry.
I wouldn't let a 20 year old anywhere near my car on a dyno personally. By your figures, I can only assume that the rollers weren't correctly set which obviously makes a whole heap of difference. And how were my drivetrain losses 30bhp more than yours? My final flywheel figure was 260bhp and paw 182bhp.
I'm not saying that any rollers are better or worse than any others, especially in my case as both PTS and PE give the same for my car. I was just hoping that PTS were going to be more consistent and offer a closer alternative to PE. For me they still will. I'll have a word with Paul and make sure that he does all future runs on Scoobs himself. I'll still use PE as well though, purely for comparitive and social purposes.

Nito.
I guess the bigger turbo making more of the available air helps though.

Stef.