Dyno runs...

[alex h]

All text is copied from another thread where we got off topic...

Originally Posted by [b

Quote[/b] ]UK Supra TT
It's good to see a car the same as mine making nice horsepower, even though alot of people on another forum say the figure is untrue.... I saw a UK Spec 6 speed get over 500bhp on stock turbo's at the flywheel 3 times! And he has the dyno sheet. I'm running around 1.3 bar so it's nice to know the horsepower your getting from 1.1 bar.

Cheers

Paul

Originally Posted by [b

Quote[/b] ]GavinL
on who's dyno?

Originally Posted by [b

Quote[/b] ]CeeJay
It's interesting to see how emotive people become when the question of BHP is raised. I have just had my car on a RR and it made 460BHP at the wheels with the following spec:

BL P67 P trim single turbo conversion
720 Siemen injectors
PHR fuel rail
256 inlet and 264 exhaust cams
HKS cam gears
Aeromotive fuel pressure regulator
Blitz LM FMIC

This at 1.4 bar on Optimax

When I took it out afterwards, the performance was absolutely amazing. Now, my point is, I didnt care if it had shown 460 or 960 bhp. I was interested in the performance of the car and not bragging rights over beer.

I am sure that if I took my car to 3 or 4 different dyno guys, I would come back with 3 or 4 different sets of figures but at the end of the day, the performce would probably have remained the same.

Originally Posted by [b

Quote[/b] ]Alex H
Yes different dyno's produce different results.
It's all subjective and only an indicator of what's going on.
But let's not turn this thread into that sort of discussion.

Originally Posted by [b

Quote[/b] ]Martin F
That's what people sometimes fail to grasp.

It's just so hard to compare dyno to dyno figures as you don't know what factors are involved.

Off the top of my head, factors that are going to change from Dyno to Dyno :

Calibration (I have some serious doubts that all Dyno's out there are regularly calibrated)
Airflow
Ambient Temps
Fuel (possibly)
Type of dyno (ie, does it load the car at all or is it purely an inertia type)
Available Traction
Correction factors
Measurement technique
Gear selection

and i'm sure you guys can think of more.

Whats more comparable is the actual shapes of the curves, and looking for any falling off in performance.

Originally Posted by [b

Quote[/b] ]Nathan
In my humble opinion, this sounds much nearer the mark.

Around 550bhp from a big single @ 1.4bar, big FMIC, 720 injectors and cams sounds a lot more likely than 500bhp from stock turbos.

With regard to dynos (not aimed at CeeJay or anyone else- I have no idea how the cars in this thread were measured) I also feel that dynos can be all over the place. Although the Dynapack is able to be quite useful as a loading dyno in the right hands, even they are fairly limited in accuracy, as you would expect with any dyno that uses a calculation for torque based on a flow of liquid rather than a direct torque measurement via strain gauges (like any common-or-garden electric rolling road).

It seems to me that Dynapack have managed to get their superior reputation simply from the elimination of tyre slip, which is a step in the right direction but their method of actual torque calculation is far from ideal, and trying to calibrate the system accurately is always going to be a problem when you're not actually measuring torque in any way.

In fact, if someone could tell me how you calibrate (as in a proper calibration, with a reference point) a Dynapack I would be most interested....

All IMO.

Originally Posted by [b

Quote[/b] ]Roy
i have recently been asked this question but having not been to a dyno as yet - i wasn't sure how to answer (i basically said enough for me). based on my mods - what would be the bare bottom hp/tq it 'should' make ?

i realise this is a very subjective question but was interested in people's thoughts. i have an un-tuned safc2 (how much would tuning it on a dyno give if at all ?), 264/264 cams + gears, fully decatted hyper, airfilter, blitz BC (1.1bar), fuel pump n regulator + sparkies, i/c and erl system.

thanks for your thoughts. i am not interested in the max figure but the basic that it should make with these if at all ?

Originally Posted by [b

Quote[/b] ]CeeJay
The reason I posted it was two-fold:

1. To show that there can be a huge disparity between different dyno machoines and operations.

2. To underline the fact that the paper figures mean nothing and that the "true" figure is the real performance of the car.

Originally Posted by [b

Quote[/b] ]UK Supra TT
I gave my input because I witnessed a UK Spec Supra TT get 517bhp at the flywheel at Well Lane RR, the owner took it to 2 other RR?s in the area (not sure which ones) and the car got around 500bhp again, this is not a fluke?.

If you look on Suprafoums a bpu Supra often gets 500bhp at the flywheel, around 420 at the wheels. Everyone looks to America for influence in tuning these cars but they seem to not take there bhp seriously, why is this?

The stock car makes 330ish horsepower running 0.8 bar, so surely a car running steel turbo?s giving more power than the ceramic ones, bigger 550 injectors, full de-cat exhaust and FMIC running 1.3 bar should achieve 450-500bhp at the flywheel?.

If Nathan disagrees then fair enough, I will take his opinion seriously as he is a tuner, works on these cars daily and obviously knows what he?s talking about.

I?m just going off what I have read on the forums, and also seen at the rolling roads. I have also spoke to major tuners in America who also agree with this.

I?m not sure what cams would do, cams and cam gears would be nice, aswell as a lightweight flywheel which would make the car rev quicker, and maybe a lightweight crank pulley, under pulley set?

Paul

Originally Posted by [b

Quote[/b] ]CeeJay
IMHO, the problem we have here is the reason peoiple take their car to a RR / dyno. I took mine along so that the new Greddy E-manage system could be mapped properly. I wanted the car to run as well and as safely as possible and considered the RR to be the best medium to allow this to happen. It did not matter a jot to me what the final power figure was. In fact, the only graph I took away was that which showed the starting BHP and torque and the final BHP and torque. So, I then went away feeling a very happy chappy because the cars performance felt superb.

Now consider the other scenario. Some people go along to see what the car is producing (BHP) and the only have a power run. If the figures given are over and above what they expect, then everyone is happy. If they are less, then, in their opinion, the dyno must be crap. But the car will still run the same. The car wont be any quicker because it has bigger figures on paper.

OK, so lets take this scenario a tad further. Imagine I run a dyno place and there were two other competitors within the locale. If the figures I gave were consistantly higher than the competition, who do you think would get the most work from the "bragging rights" brigade? Who do you think the punters would reccomend? My point was and still is, the figures mean absolutely nothing. The performance is what counts.

Originally Posted by [b

Quote[/b] ]CeeJay
***Quoting UK Supra TT's previous response***
On that basis, what would you consider to be a reasonable figure for my car considering the difference in spec? Once you have come to a guess, compare it to what was given to me on the RR I attended this week.

So, which would be right? And more importantly, would my car be any quicker?

Originally Posted by [b

Quote[/b] ]GavinL
There are two types of dyno used in the US one of which gives a higher BHP reading than the other type.

Owners in the US complaining of low outputs are very often advised to seek out the "correct" type of dyno in order to get there "proper" power figures.

If you spend a bit of time trawling around car forums in the UK it soon becomes clear which rolling roads have a reputation for being helpful to the owners ego.

IMO the following should also be stated:

Never quote crank horsepower figures, speculative nonsense IMO

Many dynos are not rated at the levels of horsepower a modified Supra is capable of making.

Originally Posted by [b

Quote[/b] ]UK Supra TT
CJ - i havn't got a clue what yours should be making, but you oviously know as you have just been on so why ask?

I was just stating a fact, from 3 different RR venues. One that i witnessed at Well Lane. He had 3 go's on the dyno and produced 505, 517 and i can't remember the other one. you may also want to speak with Thorin as he went on this rolling road at Well Lane, same day and got 400bhp in his J-Spec. And other people went on the same day and seemed happy with the results, some being the same as other places.....

Everyone loves to see what there car is running, the higher the figure the better but i'm sure it's not fixed!

Paul

Originally Posted by [b

Quote[/b] ]CeeJay
I wasn't having a go just pointing out that in all probablilty, if I took my car along to the place that the BPU'd Supra made 500bhp, it should have to be making around 650 - 700.

My point then being which was correct? The lower earlier figure or the higher one? And, once again, I am saying it would not make any difference to the performance.

Originally Posted by [b

Quote[/b] ]UK Supra TT
CJ - I know what you mean, i'd rather have my car setup properly, running good and not know what my car was making than have a high figure which was wrong. I hope rolling roads don't do this......

It is just a nice thing to know, i guess the only way to find out is Thor, there system seems the best. Just a long way from mine lol

I wasn't having a go either mate, just after seeing a Bpu Supra get 500bhp 3 times on the day, and at 2 other locations i can't see why people doubt it. But as you say who cares, as long as your car runs well and feels good thats all that matters right?

*****************************************

Please feel free to comment further on Dyno's in this new thread - focussing on the pro's and con's.

[UK Supra TT]

I think this threads gone Alex, keeping it alive is pointless, will just make more arguements IMO

[alex h]

There was some useful stuff in there...hence why I've split it from the orginal thread - it was either this or lose it forever...

[Martin F]

Well actually i'm interested in some of the pro's and cons of the various types of Dyno's. I know that the eddy current ones are more suited for tuning on, but which of the Dyno's out there are eddy current ones.

I know that the one at MIRA is a water loading one, not sure about any of the others.

Also does anybody know anything about the calibration procedures that are used ?

Alex - wonder if this may be better in tech corner (as you seemed to be getting the hang of the musical threads today ) ?

[alex h]

By your command (needs a cylon smilie)

[Chris Wilson]

I'd love to get into this thread but I don't "do" rolling roads, nortern Ireland, politics or fox hunting, unless *issed

Somene buy me a drink.... ?

[Martin F]

Bit early in the morning for a snifter Mr Wilson,

Unless of course it was a long night !

[UK Supra TT]

Theres no rolling roads at all up in Newcastle, well not ones that can handle a Supra anyway

[Nathan]

Crikey- Alex has obviously got his Masters in Thread Pruning.

Personally I love 'doing' rolling roads. Theres a lot to learn about them and I still know only a fraction. They are as important a tool, if not more so than an engine dyno and if anyone has driven a so-called 'mapped' engine that has come straight off an engine dyno you will know that they are FAR from perfect and further work is required on the rolling road, highway or track.

With regards to different types there are water-loaded rolling roads and engine dynos (we have had both-cue Clayton and Schenk), electric ones (which we currently have on our rolling road-cue Sun) and then dynos that use other types of fluid such as oil (like the Dynopack and and Rototest).

I'm not going to mention inertia type dynos such as the Dynojet as they can't hold a load and so are useless for anything other than flash power readings (and they seem to be inaccurate at even doing that IMO).

All the loading mediums need to be cooled, as you can imagine huge amounts of heat are generated when being held under load. For the electric dynos this is quite simple as they have dirty great cast iron fans bolted directly to the retarder to disperse the heat. No other cooling medium is required. The downside is that due to the physical size of the retarders and the fans they store quite a lot of inertia and this can sometimes be a problem in some instances. That said, electric dynos are self contained, have no external fans, do not require any cooling fluid and are generally very reliable. The only downside is that most of them use rollers rather than being hub mounted and in the last 10 years, with power levels of road cars going up like crazy the single or double roller system has pretty much had it?s day in terms of not getting traction. Still, they are very handy for diagnostics and other ?general? tuning work.

Early water dynos used water as the loading medium. As the loading went up the water would heat so this would then either be piped out and into a drain as a ?total loss? system or circulated through radiators cooled via fans before being fed back into the system.

The lastest dynos use a combination of several mediums and cooling methods. The Dynapack uses water as a means of cooling down the hydraulic pumps that apply the load. It is also known as a total loss system as anyone can confirm after walking around muddy puddles where a Dynapack is being used on location in a field. However, it does mean that no additional radiators are required or their associated hardware. Dynos like the Rototest again use water to cool hydraulic pumps but they instead cool it via rads and fans before pumping it round again. This is a better long term solution for most businesses as water usage can be horrendous for well-used total-loss systems.

Hub mounted systems are where it?s at and they are pretty much accepted as the industry standard now. So while we have cracked one aspect we still have the other ie accuracy and repeatability.

Accuracy is obviously very important, and it?s no real surprise that the best way of measuring torque (which is what all dynos try and do) is to actually measure??the torque. This is normally done by bringing a torque arm off the axis of the dyno (which is itself restricted in movement by the ?load?, the other end of which is laid on a strain gauge. It sounds very basic, and it is, but it?s also very easy to calibrate and to check. When calibrating such a system, a known weight, at a known leverage is hung off the end of the torque arm and a reading is obtained. If that reading is above or below what it should be then it?s simply a matter of sliding the strain gauge up or down the torque arm. The calculations are actually very basic maths, but it?s accurate and unless the laws of physics change between you calibrating such a system and the car going on the dyno then all things being well you should get a perfectly accurate power figure.

The other way of measuring torque is to base it on a mathematical calculation rather than measuring it directly. This can be via measuring the flow of a liquid through an orifice whilst using the pressure and viscosity of the medium as your constant. This is similar I believe to a Dynapack. If I am wrong on this then feel free to correct me, and again if anyone knows how you accurately calibrate a Dynapack I would be very interested as it seems you don?t have a torque arm or strain gauge to do so.

Repeatabilty is pretty much sorted for most dynos nowadays. As long as heat management is made constant in liquid load systems (heat does not really affect accuracy in electric systems) then you should be OK but obviously it all rests on the quality of the components used.

As regards to the ?best? dyno well then it really depends how accurate and repeatable you want it to be. An electric rolling road is still very handy as mentioned above but wheel slippage is the limiting factor. A Dynapack hub-mounted system is a serious tool make no mistake, but it does have one major limitation and that is it doesn?t measure torque directly. It also uses a total-loss system for cooling which can be expensive and/or messy depending on where you put it. So, for our money the finger has to be pointing at the Rototest as the system uses a circulating water system for cooling it?s hydraulic pumps which are then housed in an axially-mounted unit which is free to act on?.yep?..a torque arm and strain gauge. Old school maths meets new-school technology.

Theres some pretty good info on the faq page at www.rototest.com

These are just some thoughts off the top of my head and I think I?m done for a Friday morning tbh but I find it an interesting subject and one which has more than it?s fair share of inaccurate information floating around. Indeed, there may well be some inaccuracies in the above so I?m open to anyone making corrections.

Better get back to work!

Cheers

[Martin F]

Originally Posted by [b

Quote[/b] (Nathan @ Sep. 24 2004,11:11)]This is normally done by bringing a torque arm off the axis of the dyno (which is itself restricted in movement by the ?load?, the other end of which is laid on a strain gauge. It sounds very basic, and it is, but it?s also very easy to calibrate and to check.

Damn, that is a very simple system and as you say i can see calibration being a fairly simple issue. Reminds me of them torque gauges with the spring bar.

Off to do some googling !