SimonExtreme

Jean

I am sorry but the dyno debate is at the heart of all the comments and matters you have raised and if we as a community are going to be able to have meaningful discussions, we need to get over this. This is the whole basis of discussing tuning, beinga ble to accurately compare modifications. I have been through this debate in other car clubs so much and in every case, it is not until concensus is reached on thsi subject that all the negative cynisisms stops and constructive discussion goes on.

First thing that we need to agree is that there is only one way of testing the power of an engine that is guaranteed to be right and that is with the engine out, on a dyno that is being correctly operated and is calibrated to a recognised standard. Everything else is an estimation.

From there on in, any chassis dyno is only any use as a comparison tool. Even then, it relies on the operator to gain consistancy. You cannot say that there is one make of chassis dyno that is better than another. You can say that there are some that are easier to get consistant results on and there are some that are easier for the operator to get "false" readings from. However, ultimately, its all about competence and integrity.

I have seen the same make of rolling road produce very different figures in different locations and have seen that even when being operated by the same person. Therefore, any power claims should, IMO, be quanlified by a statement of where the power run was done and on what equipment. Even then, a power run in issolation is worthless. You need to have proven base figures, such as a standard car. What matters is the comparison between a known quantity and whatever is being tested. As I have said before, I care about % improvements to either standard or what I already have, rather than headline numbers.

Having said all of the above, there is one maker of chassis dynos that is trying to tackle the problem. Dyno Dynamics are trying to set an international "standard" for the operation of their chassis dynos and this is refered to as "Shoutout Mode". The idea is that in shoutout mode, everybody is using the same methodologies, corrections etc. An operator who has shoutout accreditation should produce the same results on the same car, anywhere in the world irrespective of conditions.

This is very ambitious but in another car club, we have found that dyno dynamics chassis dynos to be the most consistant over time and that the condition correction factors seem to work better than on others. having said that, I do know of one DD set up that is inconsistant, but that is due to different a different booth set up.

And while on the subject of fans, the booth and fans make a huge difference. Colin, for instance, has one of the best fan systems for Porsches I have seen while there are some companies on whose equipment I would not put my car! This is not a plug for Colin, just a statement of fact. I suspect this could lead to him getting different figures to somebody else, but that really doesn't matter so long as you are comparing a particular claim against a known base.

In the other car club I have mentioned, everybody uses one particular Dyno Dynamics dyno for bragging rights! Because we have a data base of cars on it, and it's consistant, it is possible to understand exactly the power differences between cars.

Another thing that we also tend to do is to cut the BS about extrapolated flywheel figures and talk only about power at the driven wheels. After all, this is what the car really experiences! now, I accept this is a big step but it does remove a variable. Again, this is fine so long as it is being used for comparisons.

So, IMO, to understand any paricular moification, you should be looking at a graph with a known base graph overlaid. Then you know exactly how much better (or worse) the modifications are. This only leaves 2 posibilities for a power gain. 1- the mods work or 2- the operator is cheating. I have seen the second one with a well known UK tuner. He was caught cheating, although threats of law suits means it is not generally known. Suprisingly, the car he was trying to sell made more power than everybody else when he hosted a dyno day and when customers asked for the same on their car, BS was used as to why he wouldn't do it. In another case, he gave a customer a graph which he was later unable to reproduce when he needed to do so with independent witnesses there.

And I guess the above is why Colin and others get a bit hot under the collar when people doubt their dyno claims. While I am sure most don't intend to do so, in doing that they are calling into question the integrity and honesty of the person. I personally find that unacceptable, which is why I always seem to want to defend tuners, until it is proven otherwise.

I guess i should climb off my hobby horse now..................

mr_bock

You want more power and low end torque??? Stop playing around and just put on the TPC Supercharger!!!!!!!!!!!!! That thing rocks!!!!!!!! Over 400 crank hp/322 rwhp dyno'd. I have had mine on for over a year with no real problems. I will be doing the new computer upgrade once I get my car back from the body shop in a couple of months. Forget all the add-on mods etc... just do it and enjoy!!!!!!!!!!

94twin

Not quite 400+. 322rwhp equates to about 370 crank. But still the best bang for the buck!

TB993tt

I am unsure about naturally aspireated cars, but with turbo cars, chassis dynos can do weird things. Yes they can measure a stock turbo car accurately for stock numbers, but when a "tuner" tunes using shootout runs to verify his extra power the voodoo starts happening - gains can be got which we know from experience are ludicrous - check out the mega torque claims and subsequent discussion:
https://rennlist.com/forums/showthre...ht=weltmiester

It is to do with the extra heat generated by turbo cars IMO which doesn't happen on a 10 second shootout run, giving spurious numbers which the "tuner" can claim as gains, but which do not translate to real numbers when loaded up and hot in a higher gear. That is why for me, turbo engine numbers are only meaningful if they are done under load on an engine dyno or a chassis dyno which has the capability (both dyno and importantly operator) to do this. Kevin M and Stephen Kaspar on here both have experience in doing this and it wouldn't suit most owners of chassis dynos since having to remove one's rear bumper (so it doesn't melt) is not what your average punter wants to do, he just wants some nice numbers

A 60-150 run will also usually filter the real from chassis dyno gained hp.

901aero

Let's get real. If a simple chip could add 50 plus HP do you really think Porsche would have left that much power on the table untapped? And really, 10 to 15 HP? is that a real advantage that can even be felt in the seat? Try running on only a 1/4 tank full of fuel and put yourself as a driver on a diet and I'd be willing to bet your gains would be very similar (and equally as noticeable!) I'm with mr_bock. Bang for the buck, he's got it.

SimonExtreme

I cannot agree that the problems you mention only apply to turbo cars. I have seen normally NA figures fiddled as well. However, temperature related correction factors make more of a difference in turbo engines.

I have seen how it is possible to fiddle almost any chassis dyno. The company you mention is one that has caused controversy before, to the point where they were banned along with other tuners, from a forum in the UK. I know. I was caught in the middle of it as a moderator, with one tuner saying the results were fiddled while the other said they were not.

The Dyno Dynamics dynos are great if used correctly. Shootout mode should mean consistancy across geography. However, the key is setting and maintaining a standard and if people want to fiddle that standard, there is little that can be done. Strange thing is, for some reason people don't seem to fiddle engine dyno results and they cannot fiddle on the road speed tests.

ZombiePorsche44

I've beaten lots of really powerful 911's over the years with half the HP!. Lots of HP with novice race drivers = slower than race pace lap times or a wrecked car if they get in over their heads(talent level). Seen it happen many times in the last 20 yrs.

I always suggest you find the exteme outside of your cars current performance envelope and get comfortable hanging out there before you slap a ****load of $ to get a few more HP.

Losing weight off the chassis and upgraded suspension & brakes can be the fastest thing you can ever do to your car besides learning how to really drive it!

Chances are that when you get to the "REAL" outside of your stock motored 993's current performance envelope, you will pucker bad enough to not desire any more HP...........................LOL

ZP44

Carrera GT

"... I'm waiting until I adjust ..."

L O L !

Carrera GT

You've got options, but without going inside the engine, you're not going to get 50hp -- you could, however, achieve the same net effect. I agree with recommendations for conventional "add lightness" along with a lightweight flywheel both of which will make a lot of difference.

Shorter gears would be great, but a bit spendy.

If you really want to keep the particular 993 -- budget willing -- consider the stuff coming out of 9m.
http://www.ninemeister.com/

tonytaylor

I'm not really sure of your point of view here. On the one hand you are saying chassis dynos will measure a stock turbo car accurately which would infer that said dyno is capable of delivering accurate results. However when tuning on such a dyno the short duration of the run does not replicate what happens to the engine in use on the road and allows for higher torque and hp numbers than would be seen at the wheels during extended road or track use. All of which is fair enough and my experience on track running with various turbo cars is that they are not making the numbers the owners quote for them. However if the dynos are accurate ,as you say they are, then those hp and torque numbers acheived in the short dyno runs after tuning may well be accurate as well, albeit not sustainable.

On the other hand you seem to be suggesting that certain hp and torque outputs are simply not acheivable with certain modifications. Which means that either the chassis dyno isn't accurate after all or the operators integrity is questionable In some cases the latter may well be true but I suspect that in other cases the gains are recorded accurately and are acheivable albeit in an unsustainable way as above.

The best way of comparing car performance is in competition; To me a single pull from 60-160mph or whatever is as near pointless as the bragging rights of a shootout dyno run.

TB993tt

The engine as set up by Porsche/Bosch developed using their engine dynos gives a set of numbers which will hold up well under road conditions and not start pulling timing in arduous conditions, the same engine run on a chassis dyno will not give MORE power (than it was set up to produce) on a chassis dyno, it will not dramatically increase its timing and fuelling to show bigger numbers for THAT chassis dyno run .
Step in the tuner who will adjust the ECU and allow the Porsche set up to run more timing and more power confirmed by the chassis dyno run, but soon lost when the conditions are more severe.
Same happens with turbo cars but with more variables and more heat - as you've pointed out the hp which was "found" on the 10 sec chassis dyno run dissapears when things get hot.
So yes you are right the numbers are probably accurate for the chassis dyno run, but they are not the same as Porsche's numbers, so difficult for punters to make informed choices ?
This issue follows on from the last, a pefect example is the tuners who manage to get bog standard Porsche 450hp K24s to run up to a whopping 550hp and mega torque ~800NM on their rollers - this ain't possible, the stock K24s cannot sustain those levels other than for that chassis dyno run - 9M are/were (don't know if any tts are running 9M stuff anymore) amongst those who think they can and I invite any of his tts along to the forthcoming Vmax where they can make their minds up

A 60-160 can be fudged a bit if intercooler water sprayers and the like are used, but it generally shows whose engine is making the power due to the ~15+ seconds and decent 6th gear loading needed - witness MOD500s 533hp/1600kg car out accelerating other supposed more powerful tts at the last VMax

tonytaylor

Well we share the same opinions over all that

Saying it isn't possible to acheive the numbers and saying that the numbers aren't sustainable are not the same things though.

I accept that hp numbers only acheivable on a dyno are pointless but unless it can be shown that those figures can't be replicated on the road, (or more likely a proportion of them can) then it's unreasonable to dismiss them totaly. Have any of these cars been tested side by side?
Comparing cars side by side ( even if it's in a virtual fashion using AX22 or whatever) is a better method of determining the relative power units merits. It's just I'm not entirely sure of the point of the exercise of a solitary 60-160mph run.

TB993tt

I guess after wasting money over the years on some of this chassis dyno tuned stuff I class it as pretty pointless although I do accept that if the power lasts long enough for a quick, single blast up to XXXmph then it may well be perfectly suitable for some people's needs.I think MOD500s engine dyno derived 533hp car opened a few people's eyes on this subject at the last Vmax, but there was no data taken.
agreedObviously more than one run back to back are of more use to determine durable power.