Of course those items are variables that must be taken into account. How do I suggest they are accounted for? Do the best you can to identify each variable, measure it, and list it with the acceleration data as part of the overall package. It's what everyone should be doing, to the best of their ability.

 

What you're not a fan of is testing where variables come into play.

If you really are "not a fan of the use of GPS data", I suggest you not fly on commercial airliners, because many of them use GPS as their sole source of navigation.

 

Did you seriously think I was suggesting that GPS devices aren't useful?

 

Tony

Maybe you have not been following some of the action related to GPS dataloggers on the Porsche forums and that's why some of us could be surprised .

You are absolutely right that many variables impact it and not only that, but there is some due diligence as well to be done on any run by looking carefully at certain "indicators" that can show a miscalibrated GPS or similar issues.

As to the variables you mention, you are 100% spot on, but these can be "ballparked" somewhat. Everyone will try to do some runs in colder weather (except if you live where I do ), however factors like tire pressure, rolling resistence and wind are (usually) not very important since the tester usually would try to use good conditions and a decent setup. Camber and toe will impact just as much as you know, etc..

Slope can be measured with a calculation outside the logger,and also the devices give you the height readings, not very accurate on a 2 dimensional GPS like these "El Cheapo" units that we use, but again, this can also be calculated and checked.

At the end of the day the same factors or more influence a quartermile run (tire pressures, wind, alignment settings, weight etc..) but one has to use some approximation.

All in all, I believe there are less parameters that can impact the truth than a chassis dyno, but this is just an opinion.

FYI, a few tuners I know of ( and some among the most expensive and famous in the world) started using these devices to optimize the performance of their cars and understand better if something is amiss while the car is under real life situations, it is just another "dyno" in a sense.

 

I agree, we do the very same thing using data logging software. This can be done using the same road, on the same day, just by logging time and speed.

My point is, based on TXgold's post telling me to "cut the bull****"...I felt that some may hold alittle to much weight in gps data.

 

Tony,

In the picture on page 1 you show all the parts for the turbo install kit (o-rings, gaskets etc).

For DIY, do you supply some instructions for what all the install parts are for? For example, you have a set of header manifold gaskets, but I don't see a gasket for the header to turbo. Does this mean the header has to be taken off to install the turbos? Thanks.

 

I can only go on what you post here. You said you were not a fan of using GPS data.

The use of GPS to measure a car's performance is as accurate as using GPS for performance and navigation measurement in an aircraft...the GPS is accurate in both cases.

You couch your statements in terms of the GPS being the problem...it's not.

 

Dean, are you planning to port your headers ?

 

Yep. I'm preparing for a DIY exhaust (DGI) & turbo swap (K16/16G) with this kit, looks relatively easy. Waiting on the tiptronic tune and handheld programmer to be released, won't be too long now.

I figure porting the headers will help a little, specifically spool up time, as there is a thread here about DIY porting which looks easy and the science looks good (12% increase in opening size). Not sure about the ceramic coating though, it seems this mod does work by keeping the exhaust gases hot when they hit the turbine, and keeps the heat out of the engine bay (important as I live in Queensland), but as you can't coat the insides of the header due to potential turbo damage if chips come off, I don't know how effective just coating the outside of the headers will be.

Another problem with ceramic coating is that the headers will need to be off the car for about a week, but I may invest in a second hand factory header to do the DIY & coating beforehand.

I also want to improve the airflow on the intake, so plan to use a BMC filter and add a second air intake to the stock air box, or purchase the new vivid airbox when it gets the second air intake added (although I can't see how the conical filters in a few of the aftermarket airboxes can beat a good filter in the stock airbox, as the stock design has such a large surface area).

 

Tony,
the point of the 60-130 times is that it can back up the dyno numbers that are claimed -it removes the 'dyno" debate . Taking real times in a directly comparative way can only help you IMO . It is also reasonable to assume that a fair number of you customers for this "kit" will do 60-130's for themselves so one way or another it will be tested.
There is no doubt that this is a very interesting comparative number that was unheard of not very long ago while 1/4 times were"the" test and how unsatisfactory are they.It was here on Rennlist that the widespread plea for the 60-130 times has gained wide acceptance. Even if you have misgivings - and there is always the potential for innaccuracy- there is plenty to be gained from getting the numbers .
As a last point-- there has been exposure of a number of questionable commercial practices and products on the forums by the closer examination of a wider audience and the "new" world will only see this information examined more widely .A positive result can only help you.

 

Bingo. Best sentence I've read in a while. And it's a Saturday one too!

 

Let's look at a different performance comparison. Tony has worked a little tuning magic on my 944T and my measly 2.5 liter 100,000 mile 0.9 bar boosted track rat makes a whopping 245 Rear Wheel Horsepower on the EPL dyno.

In 2006 during a DE at VIR after I got a good run out of Oak Tree I drag raced another 944T with similar weight, tires, and aero but with a claimed 380 RWHP down the back straight and we were neck and neck until the brake zone when he had to yield to me because I had the inside line. (the other guy was an excellent driver BTW. We had a very good back and forth session)

I don't think Tony's dyno reads high. More importantly it is repeatable on the same day with the same weather conditions. The EPL dyno is very consistent which is what makes it such a useful tool.

In any case the 60-130 data is only comparable between two otherwise identical cars, driven by the same driver, on the same day, with the same weather conditions, the same tires, tire pressure, vehicle weight etc, but with different turbo kits. The variables can be limited down but it is a lot of effort to go through and most folks aren't willing to go through all that trouble just for 60-130 times.

Now lets get back to talking about these sweet hybrid turbos...

 

And this tells us what about the claimed power of the two cars?

Does it mean your car is really producing more than 245 RWHP, or does it mean the other car was not really producing 380 RWHP? If the other car wasn't really producing 380 RWHP, how much less was it producing? Could it be making less than 245?

 

Tony,
Lets get back to hybrid turbos. What's the deal with the 16G hybrids anyway? Why does it make such a nice power curve? Compared to K24 charts I've seen these things spool up nicely. Better even than the old K16/K24 hybrids from a few years back.

Dock,

Its tells us nothing about the power of the two cars except that their performance at VIR on that same day with different driver's was relatively similar.

Fact: A calibrated GPS unit is accurate whether it is in a car or a plane.

Fact: A calibrated chassis Dyno is accurate at least to itself.

Fact: The car, driver, weather, altitude, road surface, tire pressure, tire size, wheels size, numebr of drive wheels, weight of the wheels etc. are variables variables that have an effect on performance.

 

Then listing the claimed power for each car was of no benefit?