looks like it made some great gains if you just keep it under 3k RPM?

 

Exactly my thoughts when I first received the graph.

 

Well I put the two sets of dyno's together and made some notations. I don't understand why the results with the FVD headers seem to be the same as when the car doesn't have the intercoolers or the new GIAC tune. Seems to me something isn't right here because Tom has commented

So is this graph on the left with the changes Champion attempted to make to the software? On the other hand, Tom seems to be suggesting that I am correct and that GIAC could write an appropriate tune that included these headers. Of course if that is the case, then the problem is simply that GIAC doesn't support the headers and in fact, the problem lies with the tune not the headers. The GIAC tune was developed with the factory headers. The FVD tune for their headers and exhaust produces the same "better" results posted here but they do it with the standard intercoolers.

 

That's where you are when you drive around town most of the time.

 

That graph IS with the attempted corrections to the software. However, no matter what type of magician you have writing software, it's impossible to overcome hardware limitations. You asked in your graphic "how do we know the headers caused the power loss?" We know because they are the only variable that changed.

GIAC are not novices at tuning. Let's not forget who pioneered performance tuning on the 991 Turbo platform and still leads to this day. They have the capability to tune for any scenario, except the ones where hardware provides a limitation, as was the case here. You and I have had this conversation MANY times and I'm not going to get into it with you again, re: software. You seem to love to suggest that GIAC and we (Champion) don't know what we're doing or that we're somehow lying to skew the truth, and it's quite frankly a bit insulting at this point. I'm not sure how much more neutral our approach could have been to this scenario. Same car, same day, same fuel, same dyno, same temperatures, and a custom tune. What more could you possibly want???

Bottom line is that SDG asked me to validate whether or not the headers made power. They simply do not. I WISH THEY DID, because I'd love to have good headers to sell along with our package and would gladly sell the FVD product if the results were different.

 

You also tried changing the software, what does the graph look like before you changed the table data? Clearly there is some area of the tune data that adjusts for exhaust flow which is different for different headers and exhaust combinations.

I am not quite sure what the limitation is to which you are referring? When FVD replaces the stock headers and leaves the standard Porsche ECU tables in place, they measure hp and tq gains, ergo, the limitation is the tune, not the headers.


Now you are accusing me of writing/saying something I never said, that is insulting. Don't put words on the screen and ascribe them to me without a quote.


Bottom line is that the headers actually do make more power on the lower end in this configuration. However, now I want to ask you some more technical questions that are not apparent from the graph.

What gear is this done in?
How many runs did you make in both configurations?
How long were the runs?
How does any of this address his issue of heat soak? My understanding is that is where SDG has concerns.
How will the "loss" in hp affect ET or trap speed or performance at the track where RPMs generally are above 5000 rpm?

 

The graph looked worse. I'm not going to post every dyno run in which we attempted to adjust the software for the headers. The one SDG posted was the best of them, in which the losses were the smallest.

The hardware limitation is the headers.

You're free to interpret the graphs in any way you like, but above 3000 rpms, the losses were consistent for the rest of the rpm range. They varied from less to more, but were consistently lower then when the headers were not installed. To answer your questions:

-All dyno runs are done in 4th gear, as this represents the closest 1:1 ratio from engine to wheels.
-Any time we conduct dyno testing, we perform 5 back to back runs with a 1 minute cool down time in between. Then an hour break with cooling fans still going, followed by the same 5 back to back runs. We repeat this until we're comfortable with the results we're seeing.
-The runs are all made in 4th gear all the way to redline.
-By repeating the runs back to back, we're able to attempt to heat soak not only the intercoolers, but the turbos and exhaust as well. In a 95 degree ambient temperature (our dyno room), this is quite a grueling test for the car. In this case, IAT's never deviated during all 5 runs. That is data I'll be posting in a separate thread.
-How this loss will effect trap speed is anyone's guess. I can only guess that the large chunk between 3000 and 5000 rpm's would definitely effect the 1/8 mile and the overall trap speed too. On a road course scenario where the car is consistently over 5000 rpm's I suspect the loss may not be as apparent, since it's not as great in the range. Although the loss with the headers was not as great at those rpm's, it still showed losses anywhere from 15-20hp/tq above 5000.

 

That's fine, it doesn't matter because FVD gets gains when they put only the headers on with the OEM ECU.


Only with the GIAC ECU mods. FVD does not get lowered hp and tq when they replace the stock headers and leave the ECU alone.


Of course the car never runs at low rpms in 4th gear on the track or at the dragstrip. I never even get to fourth gear in a drag race until I am over 135 mph. In other words, I don't notice the shift to fourth gear until after the quarter is over. At the track, I am often in 3rd gear and only in 4th once I hit about 103 when it shifts at the top of the power band to fourth gear and finds itself at about 5500rpm again. Keep in mind that in sport plus, the ECU keeps the car over 5500 rpm. Basically, I think your dyno data could be misleading. We probably need to see if those gaps are there in lower gears to really evaluate the negative impact you are seeing and if it exists in the lower gears. But of course I am an engineer that is interested in these things and people buying peak tq and hp gains don't really care, they just notice this kind of thing and think it's bad when it may not be

That sounds pretty good. The heat soak is more of an issue at the drag strip than at the track because the air flow is high when running at track speeds continuously. There is usually about an hour between runs at the track and the car is turned off. At the dragstrip you tend to idle between runs waiting in line, that causes the heatsoak.

 

wrs, I know you have the FVD package and love the FVD package. and that's great. I'm glad for you.

but the way you're trying to pick apart and discredit some pretty conclusive data here just makes you seem like an FVD homer that has no interest in listening to anything rational.

we also have stef@europipe commenting in my other thread that he has done real world testing on the drag strip with and without the headers and that they provided no gains in time or higher trap speed.

so 2 independent tests show no gains or, even worse, slight losses and you're still stuck on one in-house FVD dyno that shows gains?

if I were you, I'd be pissed at FVD for selling you snake-oil, not defending them to the grave in spite of some pretty hard evidence to the contrary.

 

My questions are completely rational. FVD posts gains in both hp and tq when they add their headers to the OEM equipped 991tts without a piggyback or GIAC ECU mods. Clearly then, it's not the headers that are responsible for the drop in power shown in the dyno charts from Champion.

So then why do real dragsters have headers instead of factory exhausts?

I saw some iphone snap of an opinion texted to you from someone at europipe who sells an exhaust system only. Gosh, what independent test did they run with FVD headers? Do we want to badmouth the GMG or Fabspeed headers too? How would that work. SDG happened to have the FVD headers but my bet is that the results would be the same with the other headers because the GIAC tune is optimized for the flow characteristics of the OEM exhaust manifold.

What evidence to the contrary? I don't see it. I have posted my quarter mile times and traps. I didn't buy any snake oil as far as I can tell. If you bother to read my post you will see that the dyno data is more snake oil than useful information. This is why so many people don't care for dyno data because it really doesn't have much to do with real world performance.

 

glad we cleared that up.

 

Keep in mind when the engine is shut down after running hard there is significant heat soak (sitting) when the cooling system and fans are not operating.

 

Yes but supposedly the fans will keep running if the compartment temperature is over some value I can't recall now. There are a couple of threads about this. I know that in the garage, my fan didn't stay on after shutting the car off but the 2009 C2S next to me did. I need to get some better data at the next COTA event wrt to temperature. I am buying one of those wifi OBD monitors that I can use to collect data while I am running at the track.

 

well, damn.

I thought I finally found some place that had the rears in stock and they just called today and said they can't get them either.

nobody can get them.