Alan C.

Easy to follow and makes sense.

COBB Tuning

Hey guys,

I don't get on here much but I just want to feel free to reach out to see if there is anything I can help to clear up.


I keep seeing this as a theme but the adaption time after you reset the ECU is not very long. This can be verified by taking a log before you reset the ecu under wide open throttle and then compared against a log after the reset. We do see on cars with headers that they need to be up to temp in order to have consistent numbers, so you would want to do 5 or 6 pulls back to back to verify that they are up to temp. Food for thought.

If anyone has questions on the ECU stuff please feel free to ask us. We are more than happy to help answer anything you guys are unsure of.

On a side note Jamie the headers look bad ***!

Also- New Year and big things coming for 981 owners. Keep an eye out

Thanks guys!

-Mitch

mitch.mckee@cobbtuning.com

Rick DeMan

It has been my experience with the 9A1 based engines and ECU's that the adaption time is almost instant, the data logs before and after have the same values showing no adaption is needed. And if I remember correctly the ECU is not an Adaptive type.
Is that what you have seen?

Jamie@dundonmotorsports

Thanks Mitch for the check in. We've had some differences, Stage 0 flashed cars adapt very quickly, stock cars with no Cobb flash don't seem to adapt as fast.

What we're suggesting is to ensure the car is fully adapted drive the car for a tank of gas before a dyno. You're welcome to run it whenever you like.

We had a customer in recently that we did a before and after dyno on with no drive time, we did a PIWIS adaptation reset on the dyno and the car adapted on the dyno. Car wasn't adapting well and was running a bit odd on the street... Customer then had to do a negative battery cable adaptation reset and car runs great now. Most have adapted fine, all of our 991 GT3 systems adapt fine.

Annecdotal yes, but out of an abundance of caution and to ensure other customers have a good experience.

We do have a bunch of questions for you when you get time, give me a ring when you get a chance...

And thanks, we worked hard on the headers!

Jamie

Rick DeMan

Today we installed Andy Kims Dundon headers WITH K&N filters and repeated our original tests as seen from few posts ago.

Results and Dyno graphs are listed below.

Peak HP Stock was 359.6 HP
Peak HP Dundon headers AND K&N filters installed 371.4 HP

These results are pretty much identical to the first test, totally different car same results.

As all of you on this thread can see, I do not endorse any brand of headers, manufacture, or try to sell anybody else's products. I have not expressed an opinion on the results nor do I have any bias or reason to discredit anybody's work or product.

It is my conclusion that these headers have the same gains as EVERY other header we have tested, between 10-18 HP peak gains at the wheels. We have not seen the gains presented by the OP who is the manufacturer. The Header is of EXCELLENT quality and beautifully made.




Totally Stock GT4
2016 GT4 Stock Andy Kim




Andy Kim Headers and K&N filters
Dundon Headers with K&N filters




Andy Kim with Dundon headers K&N filters compare
Stock verses Dundon header with K&N filter comparison chart

RealityGT

^This is why independent testing is always necessary.

belfo

Rick,

Awesome. Thanks very much for taking the time to share these results. I remain interested in any further clarifications from Dundon before concluding that the best price : performance ratio for me is found elsewhere.

CAlexio

So looks like short tube, long tube, and magic 4th voodoo tube header types are all the same from a performance perspective..

that's cool.

Thanks for taking the time to demistify and clarify the claims Rick.. it's so rare to get irrefutable info on this forum.. we are 99% perception & supposition, and 1% facts.. hats off to you and your team for adding to the facts side. .

Bardman

Its hard to argue with the data, but I find it really puzzling. Dundon have apparently had proven results with the GT3 and they have obviously spent quite a bit of time developing something quite different for the GT4. I find it strange that they would spend so much time and energy for no apparent benefit. I am also confused by the fact that these results do not align with their results. What are we missing here?

Rick DeMan

I believe the results are well aligned on the Peak numbers.
Both the Dundon results and our results show 374 or so round about numbers on the peak power. Dundon's results show a significantly lower baseline creating significant gains.

I can not explain the delta between our baseline and Dundons. We both are using the same equipment and testing methods.

We have had 11 Stock GT4 cars on our dyno and all have had baselines within 3% of each other landing in the 348-360 mark.

Honestly, the starting point is irrelevant and what we are looking for is the claimed gains using the product as advertised.

We did not find the gains as advertised after doing the tests on 2 separate cars at 2 different times. Another car was tested in Ohio also not seeing the results as advertised.

So that's 3 tests without the results from dynos outside of the manufacturer.
I'm open to see more results from more GT4 owners who Dyno the results as we have presented.

There are a few "I drove it and it feels really fast" testimonies here, but any header/flash combo on a GT4 for a new owner feels awesome and I can relate, but let's get real data out for a fair evaluation please.

Jamie@dundonmotorsports

I've spent my career as an engineer, so data is something you start with, not finish with. Data is always arguable, currently we have our dyno data that we know how it was produced. And other shops have their dyno data that they know how it was produced.

The devil is always in the details (intake air temps, gear ratios programmed, redline used) and when there's a discrepancy there needs to be investigation. We've done this when there was a question about air filters and will do it this time as well. Will it push back the next batch of GT4 headers, catted GT4 headers etc... Yup, but it obviously needs to get done...

We're putting together a test to put this to bed and everyone can make up their minds from there.

One part of the test we're looking at is IAT (Intake Air Temperature) control. This isn't the ambient temp, but the temperature of the air entering the engine as measured by the engine. We have logs from the first Dundon GT4 that was dyno'd at DeMan, and a few things show up immediately, Intake air temps on those runs were not stable:

Pull 1: 113.0*F dropping to 79.2*F,
Pull 2: 95.4*F to 78*F,
Pull 3: 90*F-76.6*F

Three runs that we did recently on the GT4 on our dyno:
Pull 1: 64*F-56*F
Pull 2: 61.7*F - 59*F
Pull 3: 61.7*F - 60.4*F
This is typical of all of our runs.

I'd say our method yields a more stable IAT and stable through the run. Would this have an impact, we think so, we will have to see when we test it and duplicate the methods employed at other shops (which means no blocking hot air from the front and no fans for the side intakes). Is one way better than the other, don't know, but typical basic engineering test design is to control as many of the variables as possible to truly understand what the variable your testing (an exhaust in this instance) is telling you. Modern Porsche's are very finicky and constantly trying to keep the air clean so care must be taken with how they are tested, for example, a USA 991 GT3RS loses 30whp stock if the intake temps are not controlled well (like less than 85-90*F well) and just putting a fan at the front of the car doesn't cut it as the hot air from the radiators blows into the side intakes...

The way we design exhausts and how they work hasn't changed. Our 996, 997 and 991 GT3 systems are well proven. And our GT4 will be soon enough.

We're putting the experiment together so it's repeatable and reproducible if all of the steps are followed. So far our contention is that if a shop was trying to verify our results and they didn't get the results we achieved doing it their way, then doing it their same way over and over likely isn't going to show a different result.

Sometimes you have to have a curious child like mind instead of one already full of "how it's done" since "it's not their first rodeo".

We're new here, but not intending to go anywhere, and like we've seen from some of our competitors recent offerings in the 991 GT3 header market, we seem to be making an impact, if we can make a market place where everyone's products get the amount of scrutiny and vetting as ours are, then I feel like we've done a great thing.

Please give us a little time to get the data taken and presented, should have it in a week or so.

O5C4R

dyno wars can get depressing, here is something to liven things up a bit

Leuz

that pop at the end tho...

O5C4R

yeah the scream and pops are insane, if you are in a quiet forest you feel like you're in a group b rally car lol

d00d

Al Cantara, funny.
:)