gac1077

I cant wait for the second badge to be build, i need my headers, if anyone its not happy ill take them off your hands. Thank you Jamie, patiently waiting.

Happy Holidays.
Garrick

mqandil

Hi guys, it was my car who Jaime posted the Dyno runs. On stock run the car produced 330 to 333 whp maximum at maximum rpm. We did 5 runs and all within 1 to 3 hp. I just wanted to clarify the 349 numbers. May be other cars are producing 349 stock on some other dyno, but on this dyno and using my car we could not see whp higher than 333 and that was the best run.
I am going to make another post sharing my experience. I actually had a lot of trouble after all said and done and during my trip back home as the car computer would not adapt no matter what. It is al resolved now and I will share with you what happened. But I only have one word to say despite all the trouble I had with the car, is WOW. So worth it. Be back for more detailed update later tonight. Mark

jmartpr

That's why comparing any other data from different car, dyno, location etc, etc...is not the best option. My car was tested and tuned on a Mustang Dyno and the overall number are lower than the other types of dynos...but what I was really looking for was the actual difference between mods not the overall number.

Alan C.

Thanks for sharing and looking forward your update.

belfo

I'm confused by this. I understood that Dundon was implying that the K&N's were more of a kind afterthought for group buy customers than anything else. In reality, the K&N's appear to have been either (1) not fully appreciated as a benefit during dyno runs or (2) part of the secret sauce that wasn't being 100% disclosed. Dundon seems to be pointing to the latter by saying "...there's a point where the filters won't flow any more and are a restriction. We found this quickly in our testing on the headers this is why we included them for free with all of our headers."
I wouldn't necessarily hold #2 (if true) against Dundon, but I would then be interested to see if K&N's would also be a secret sauce with other headers.

This. Dundon did a comparison against a "competitor" set of race headers in Post #284 of this thread. Jamie can confirm if both were equipped with K&Ns. If so, great.

Rick,
If you can include HP gain/losses by RPM bin like Dundon has (3600, 5000, 5800, 6500, 7000, 7500, etc.) it would make this thread much easier for readers to use. Otherwise we are squinting and trying to decipher warped squiggles with inconsistent axes.

Mark,
I believe that Spyerx is citing peak HP numbers that occur around 6400 RPM on Dundon's dyno plot for your car. It appears that you are looking at the HP around 7300 RPM where the gain with Dundon headers is much greater. Correct?
I see Spyerx's point but also feel the gains outside the peaks must be noted.

AfricanHunter

Anxiously waiting for resolution through posted data. I have a full set/tune on order. Based on the independent proven gt3 results and the open kimono approach DMS has shown for their products; I will tend to believe DMS claims until proven otherwise. Dyno results easy to game both ways and DMS build quality looks to be near or at the top of the heap for headers. They are spendy though compared to competitors. If they make within 15% of original claimed gains I would call that close enough ((especially with the terrible California gas)

When my setup comes in will run stock, header, Filter, tune dyno runs separately and provide the datalogs/etc.

If anyone has valid suggestions on sequencing of the runs or methodology I am open to it if provides valuable data to community.

But whats with a 30whp difference in stock form on dyno... that isnt a little bit. Maybe Cobb stage 0 tune is non-optimal and gt4's shipped with more aggressive tune as oem?

not interested in paying equivalent $5k for 16hp gain personally and endanger warranty due to tune at the same time. We'l see how this shakes out but still on board pending further independent tests. If I am going to screw my warranty needs to be 30-50+hp/tq which is what was advertised. Otherwise going to go stroker/FI.

ps- Jamie has been excellent to deal with overall as are many of the proven aftermarket providers.

legin

Ehresman in Germany who are generally credited with cracking the ECU and a top rated tuner claim the following on a spyder

Stock 375 420
Tune + Filter 405 crank bhp Torque 435nm
As above plus IPD/TB 415 crank bhp Torque 440nm
As above plus cat header 425 crank bhp Torque 450nm
As above less cats 435 crank bhp Torque 460nm

Based on this, tune wins my some margin on vfm. Interesting no figures without filters which are BMC, when i spoke to Jens he was adamant that tune needs to be run with filters but didnt elaborate. Some of the numbers look a but convenient but i guess they have been rounded.

Jamie@dundonmotorsports

We've used high flow airfilters since the 2nd time we ran our prototype headers on the dyno as the stockers were a restriction. All data shown is with K&N Airfilters including the comparison "competitor" set.

We use them on our 991 GT3 systems and on our 997 systems we developed a dual cone airbox.

If you create suction waves with the exhaust side of things but don't recognize there are pumping losses (or restriction) on the intake (the side you're trying to get to fill the cylinders) you're leaving easy HP on the table.

Seems obvious to us... and it's not really secret sauce when everyone can use them. I don't think there's much difference between K&N and BMC, both should work well...

Jimmy-D

Are new filters hard to install on the GT4?? Do you have to remove bumper??

Also - I just want filters that are plug and play. Do not want to oil them ect. What do you recommend?

legin

Fitted from inside the boot and takes a little effort. If you want plug and play then just fit new each time rather than clean them.

mqandil

Hi everyone & Merry Christmas
As I promised in earlier post I was going to write about my experience with installing the headers on GT4. Last Wednesday I drove up from Vancouver WA, to Dundon Motorsport shop to install the headers. This was not the first time I met these guys, as I attended an open house few weeks earlier and had the pleasure of meeting their entire team. Really great guys, who are diehard Porsche enthusiasts and what you see is what you get.
I dropped off the car in the AM, and shortly after they placed the car on the Dyno to get a baseline. They did a total of 4 runs and all were very consistent and it showed a peak best of 334 HP at 7300 RPM. Coincidently the absolute maximum HP occurs at lower RPM (below 6800 RPM), which sometime causes confusion. They dropped me off at local Starbucks where I spent the next 2.5 hours working from my laptop. They picked me up around 2:30 PM and brought me back to the shop to witness the Dyno runs after finalizing the installation. They hooked up the car to the Dyno and initially left the stock air filters so we can see what the effect of the stock air filters vs high flow filters on performance and ran a total of 3 runs, which are all recorded by video and I will send you at a later post a link where you can watch & download the stock runs and also the runs with both stock filters & high flow filters in place. Then we ran an additional 5 runs with the high flow air filters in place. The car was never driven after the headers install and Dundon guys ran the car under moderate load on Dyno at steady state to get the PCM to adapt. Jaime has posted some of these runs on their website. My observations:
1- the stock air filters reduced the power by as much as 16 HP at high RPM but the effect at Low RPM was not as drastic.
2- the car did not seem too happy around 3000 to 5000 RPM and partly due to adaptation issues.
3- the sound at anything above 3500 rpm is unreal.
4- the biggest gains did not occur at maximum RPM but rather at lower RPM range and the most impressive is the torque & HP gains at mid range between 3000 to 5500 rpm.
5- Dundon guys were very apologetic becaus they were expecting to see 7 to 10 additional HP on the Dyno and offered for me to come back next week to check the installation and do few more runs on the Dyno. They did not even want to collect the money until I come back next week but I insisted to pay them. Really impressive people.

At that point it was getting late (after 5:00 PM) but they were determined to find these few additional HP, but it was decided I go home as I have a long drive ahead of me. On the way back I got to experience the additional power and it was truly amazing. I used mostly 6th gear all the way home, where I was using 4th mostly on my way to Dundon. The mid range power is amazing allowing me to use 6th gear most of the way back. However with all of these great gains, I have noticed the car bogging down or hesitating between 2900 to 3100 RPM. It was a noticeable bog, as if fuel is cut out for a moment. I tried various gears and I could not shake it out for the next 200 miles. I called Jaime and explained the issue and he thought it was probably PCM is adapting, and suggested I continue to drive the car while cycling Through sport & exhaust bottoms. The next day I did that and added 150 more miles and it seems the problem was getting worse, but there were no error codes. So I called Jaime again and he asked me to just bring it back next week and they will try to diagnose the problem. A friend of mine who rode with me mentioned he had a similar issue with his 991 911 when he changed his headers 3 yrs ago and no matter what he did the PCM would not adapt, and suggested I disconnect the battery for 10 minutes. I followed his suggestion and disconnected the negative on my battery then reconnected it and went for 20 minutes drive. Immediately I have noticed the car is much much happier and the power is even greater over entire RPM range and the best part this hesitation is completely gone. I proceeded to add 200 more miles in the past couple of days and the problem never came back and the power is unreal. I am still taking the car next week to Dundon to do more runs on the Dyno and I honestly expect to see more power. The car feels like it. I personally think the PCM never adapted until the battery was disconnected, which explains why the car felt it was held back during the Dyno runs, so I expect to see more power on the Dyno now. We shall see, and I will certainly update you.

All and all, it was a great experience and I am really impressed with the Dundon team. Really first class individuals. Keep up the good work. Mark

mqandil

I thought I would share this text message I received earlier today and that was sent by my next door neighbor. I took the car for a short drive and ran onto them on a deserted backroad close to home, and he sent me the followings messages.. mark


������ that was insane me and my brother lost our minds over the sound of your car I wish I had that on video

Lol. Merry Christmas

I didn't know it sounded like that though ��

morjo02

Nice honest write up. Thank you for sharing the info and looking forward to the end results and HP and Torque. I haven't decided on which headers to pursue for my GT4 in the early spring time.

gac1077

Thank you Mark for your honest review, I can't wait for next year to get the headers. Happy Holidays.

RaceDevelopementCenter

Cargraphic is the way to go