LIL has full boost and full revs

[eastendr]

Brett, I'd heard about your reading discrepancies between the two cells. However, I've also seen the charts you posted LOL - look like they belong in the Tate gallery.

Have you considered removing the rear wheels and getting a Pirelli steam roller wheel as traction ? []

Perhaps later this year we'll get a car run both at Weltmeister and Surrey on the same day to have a look.

As regards the G-Tech, obviously all data measured has to be taken with a certain amount of salt. They are excellent for comparative readings if used correctly but cannot be redarded as entirely accurate as obviously any accelerometer device will be subject to variances because of squat & dive under acceleration & braking etc.

I have to say that the G-Tech RR is a very useful big of equipment as long as you have an accurate weight and a known flat bit of road. It also allows easy comparisons of runs in the software. Recommended.

Rick.

 

[Neil Haughey]

I like the Gtech because it allows for somekind of real world testing, without spending a fortune on pro data logging kit. I still have the one Tref loaned to me last year, perhaps I should buy it of him! The brake testing I did was a real shocker, and it is proper testing that seperates myth from reality. Bring on more testing I say.

 

[Fen]

ORIGINAL: Neil Haughey

Engines power output is accurately measured on engine dyno's not chassis dyno's. It surprises me how for some reason a particular chassis dyno at a particular outfit not a million miles from bridge corner Silverstone has gained this halo. Maybe for some the fact that they have got lower readings then on another outfits dyno makes them believe that this is a true indication of power output.

Sorry Rick this is an engineering statement of fact not a pop at those guys. I am sure if you ask them is an engine dyno in a properly set up engine test cell more accurate then their chassis dyno they will tell you, well of course it is. I am not going to disagree that based on what can be found on the internet they probably have about the best reputation available to those of us who require the use of a chassis dyno.

That second paragraph being the case, the point of the previous paragraph was what? Apparently you now agree the Weltmeister dyno IS the best of breed. Nobody is disagreeing the engine dyno is better, but who is going to take their engine out regularly to test their mods?

A repeatable (due to having atmospheric controls) dyno in the middle-ish of the country seems like a good base to me. Also when you consider it gets close to manufacturer figures when Evo magazine test standard and new cars on it then that would suggest it's pretty accurate compared with some I have used and seen others quote from.

 

[eastendr]

So we all agree - G-tech is pretty good, Weltmeister is much better, engine cell is king.

However, the first two also give real figures of the engine as it's installed in the car with all the local plumbing, exhaust and intake in place.

I do like this interweb [] [] []

 

[pauljmcnulty]

As a complete technical idiot, surely the point is that if everyone uses the same dyno, the results are comparable?

Thus, if a company or individual changes a part, then a before and after run on that same dyno will be definitive?

Please explain if I'm missing something....[8|]

 

[Fen]

You are missing atmospheric conditions which have a massive effect - temperature, barometric pressure and humidity. Weltmeister (and maybe others) have a big cell with climate management to minimise that. Most others I have seen have an open door to outside, so only repeatable with any validity back to back (and not even then necessarily).

 

[pauljmcnulty]

Thank you.

That reinforced my credentials.....[][][]

 

[sawood12]

The only accurate reading you can get from a rolling road is wheel HP. Engine HP is derrived from the HP measured at the driven wheels by a set of assumptions about the internal inertia and drag characteristics of the transmission of the particular car you have - which of course in reality will vary from car to car depending upon the oil you have, condition of your bearings and any mods you have that affect the inertia of the engine e.g. lightened flywheels. The reason the Weltmiester kit is supposed to be pretty good is that it has been specifically calibrated against Porsche models (or so the ownder claims) and so should be more accurate than a rolling road that is using standard off-the-shelf assumptions. I've had two runs on the Weltmiester road roughly a year apart. The first measured 237.5bhp and the second 240bhp with the only difference between the two being a switch from 95RON fuel to 98RON (Optimax). From memory I think Paul Hilux got near as damn it the same reading as his last one. So i'm confindent that the runs are as repeatable as possible - as to what the true figures are, we'll never know but ultimately as long as the rolling road is repeatable then you can accurately establish the effect of mods. It is for this reason the Weltmiester road has been crowned "The Rollers of Truth".

By the way, according to their website Weltmiester also have an engine dyno which is the only way I can think they have calibrated readings between engine rig runs and runs with the engine in the car.

 

[Brett928S2]

ORIGINAL: Fen

You are missing atmospheric conditions which have a massive effect - temperature, barometric pressure and humidity. Weltmeister (and maybe others) have a big cell with climate management to minimise that. Most others I have seen have an open door to outside, so only repeatable with any validity back to back (and not even then necessarily).

Hi

Climate management lol...is that the big fan or the open roller shutters ???

Unless its changed since I was there ??

All the best Brett

 

[Brett928S2]

ORIGINAL: sawood12

It is for this reason the Weltmiester road has been crowned "The Rollers of Truth".

Hi

Ummm in my personal opinion you missed out the letters UN before the word truth..

All the best Brett

 

[Fen]

Brett you're in minority of one thinking Weltmeister's dyno flattered your car as far as I have heard.

A roller shutter to isolate the cell from outside and a system of fans to manage the quality and pressure of air inside may not be perfect (hence I didn't term it climate control), but it's a lot better than every other dyno I personally have seen where the cell is open to outside, or even the back of a truck and open to the elements. Ultimately though who cares if the figures are accurate in absolute terms or not? As Scott has posted and as experience shows from 2 dyno days 12 months apart the results are repeatable within a few percent on cars that ran the same spec both times. I care more about being able to measure my car with the same yardstick as I used last time and not have to worry if it has stretched. Similarly if everyone else uses the same one also then we get to build a picture of which mods work best. If people choose the dyno that best suits their purposes we have worthless pub chat and nothing more.

 

[eastendr]

... hence the UK944 league data on my website ....

 

[Indi9xx]

IMHO

An engine dyno in the right hands will give more accurate flywheel figures than a chassis dyno in the right hands.

A chassis dyno in the right hands, will give more accurate flywheel or rear wheel figures than a g-force meter in the right hands.

Any of the above equipment is only as good as its opperator.

Dynodynamics have a reputation for spending a lot of money making sure that their dyno's produce the same figures anywhere in the world, in all kinds of atmospheric conditions and temps. Which makes their rolling roads very good at producing results that are comparible from one of their rolling roads to another. Not only this but repeatable from one day to the next.... But it still boils down to the right set of hands.

A dyno or a g-force meter also needs to be used for the right reasons.. using them and then comparing the readings of one against another is a bit pointless... as is comparing one rolling road figure made by Sun against another one made by dastek.

I don't know about g-force meters, but I do know about rolling roads... I would only trust a dyno to tell me if car A is more powerfull than car B, or to see if mod-A performs better than mod-B on the same car.

 

[eastendr]

Jon,

do they make left-handed ones as well ?

[] [] [] [] [] []

 

[Indi9xx]

Oh ha, blooming ha! lol

If the Americans can mess up the language and get away with calling it english, I am sure I can too!

 

[Neil Haughey]

When comparing mods it is assumed as well that the mod isn't relying on something like 100 mph of air speed at the front of the car i.e. some form of ram charging. I don't know what the characteristics of the fans are like at these places but I assume they are there principally to stop the car from overheating. This then brings up the problem of heat soak. The air box in the S2 is on top of the radiator area so I would be concerned about the airbox getting hot (does this happen?). Lastly what about the effect of the tyres on the rollers. I would imagine that the tyres could get very hot on the rollers, is this a problem I don't know.

Some guy in the dim distant past told me that engine test cells are accurate to within fractions of 1 Hp. I don't know how true this is but if for example somebody is tuning race engines where one may be looking for a 2 Hp gain then this sort of accuracy is a requirement.

Jon when are you getting your dyno, it would be nice for all us southerners not to have to travel all the way up north!

 

[sawood12]

Ram effect wont have any bearing on engine performance. It has very little effect on aero engines until you get up above Mach 3 and i'm not even sure Lil can manage those speeds... yet! In fact the intake and nacelle design on aeroengines is designed to slow down the ariflow entering the engine to increase the propulsive efficiency of the engine i.e. the difference in the intake velocity and the exhaust velocity. It's only a consideration on F1 cars as they are trying to squeeze every fraction of a percent out of the engine.

At Weltmiester they have huge fans that draw air through the entire building and to make sure the engine is getting enough air there is a huge fan postitioned right in front fo the car. You can see this in the photo, its the big red cabinet in front of the car. Trust me it's very loud in there even before the cars start running. It is an impressive set up.

 

[John Sims]

ORIGINAL: Neil Haughey

....Jon when are you getting your dyno, it would be nice for all us southerners not to have to travel all the way up north!

There is a Dyno Dynamics Rolling Road at Sussex Performance Centre on the outskirts of Horsham (apparently!)

Heat soak can be an issue but also is achieving the optimum cylinder temperature to ensure efficient (and thus powerful) combustion. According to Chris at Weltmeister Turbos are particularly sensitive to this.

The last time he ran Beaky I asked him what he did to increase the power on each run. Apparently he did nothing; each increase was due to the rise in cylinder temperature. He generally does three of four runs before the hp stabilises.

Tyre heating isn't an issue as the tyres shouldn't be spinning. Beaky spent an entire day on a dyno a couple of years back - not an experience I would necessarily like to repeat.

Herewith a picture of his exhaust manifold glowing red hot:-

 

[John Sims]

When we were racing we did discuss the advantages of ram induction. While a designed inlet would pressurise the air into a carburetor the difficulty was in ensuring the car didn't run lean at speed due to the additional air being forced into the carburetor.

There was further difficulty as forward velocity and wind speed was always varying and so you couldn't accommodate the changing air pressures by assuming it would run lean and adjust accordingly.

This could be twaddle as we did no more than debate the possibilities - but it did seem to make sense at the time.

 

[Neil Haughey]

ORIGINAL: John Sims

ORIGINAL: Neil Haughey


Heat soak can be an issue but also is achieving the optimum cylinder temperature to ensure efficient (and thus powerful) combustion. According to Chris at Weltmeister Turbos are particularly sensitive to this.
Tyre heating isn't an issue as the tyres shouldn't be spinning. Beaky spent an entire day on a dyno a couple of years back - not an experience I would necessarily like to repeat.

Yes, thermodynamics. If someone invents low cost ceramics for engines one could more or less stop any heat energy being lost into the combustion chamber components.