Honest question, since these gains make every other GT4/Porsche exhaust product—and the GT4 Clubsport—look less than well engineered: How is Dundon finding this much power? It looks like, what, 12-16% more power? That makes these headers seem pretty magical, given what I understand to be the minimal losses experienced with catalysts after 40 years of development at the manufacturer level as well as the reasonable but minimal gains usually found with aftermarket headers in modern, normally-aspirated cars.

Okay, one thing we can all agree on is that the GT4 is hampered from the factory by its exhaust. So it's a rare case where there is real power left on the table.

However, the GT4 only makes 3-4% less HP than the 991-1S 3.8, which probably isn't all that hampered by its exhaust system—given what it took Porsche AG to coax another 7.5% power out of the 3.8 in X51 guise. If Porsche could have bolted on exhaust alone for another 7.5% and charged $17,000 for the option, I have zero doubt it would have done so. But it needed to develop new cylinder heads, new camshafts, a new and complex intake plenum, a new exhaust system, and (of course) new ECU maps—and then added a third radiator to make sure the engine would live.

Which brings me back to my honest question, out of a desire to understand a normally-aspirated product the likes of which I haven't seen in a modern car: How do these headers add so much power? And, what difference in gains do you see with and without catalysts on your product?

 

That's a great idea.

The claimed power number are incredible and, if they can be confirmed by a third party, become very interesting to study. They fly in the face of much of what I've known—but I'm always willing to learn something new.

 

I vote for this as well. I've seen a lot of headers in my day and it looks as if these are unicorns . How can I get a set that makes that kind of power? Where do I send payment ?

 

its the patent pending 4th tube... duh

hah

 

Hi John,

All are currently sold out. Also wish we made 510hp... 373 whp with 15% loss is 373/.85 = 438hp...

Would love to do a test with the Cargraphic Race on our side and then we can send a set your way? Haven't tested them yet... And keep in mind this is with the Dundon Pro Tune (using Cobb AP) to get to the 373...

Shoot me an email and we can set something up...
jamie at dundonmotorsports.com

 

I understand everyone's "disbelief"... Our 996 GT3 produced 26whp, 997.1 GT3 Race produced 28whp, 997.2 GT3RS headers/plenum and airbox made 40whp, 991 GT3 Race headers produced 40whp and everyone said that was impossible. Now many sets and dyno tests later it's accepted. The same will happen with these.

We're very careful in our approach and what we claim. We back our products up with 100% satisfaction guarantee. I'll do my best to explain what's going on with our systems and why they work without giving away proprietary information...

Our products are designed to harness the expansion and suction waves that are formed in a header when the exhaust valve pops open. It's more than "flow restricition" and "back pressure". If you get the timing of these waves just right, you fully evacuate the cylinder and "suck" more air into the cylinder than is possible by atmospheric pressure alone. Another name for it is resonance tuning. This means that the lengths of the tubing after the headers and the use of the factory muffler is important for our headers to work as effectively as we've tested as this is what the design constraints were.

Another thing to consider is construction, cutting corners saves money, cutting corners also costs 5whp here and 5whp there, merge collector angle is too steep, costs you power, don't want to add a step to the runner as it's too much work, costs you power... etc etc... We design our products for full power and don't cut corners on construction. They're also not cheap and we understand that, but we feel there is a place in the market for fully engineered, tested, vetted, tested, retested with most all of the testing shared while we're doing it...

One last thing to keep in mind is that the OEM's are not utilizing 100% of the engine capacity. There is exhaust gas recirculation occuring at almost all load ranges and rpms with the stock tune and stock manifolds. For the OEM this helps reduce NOx emissions by burning them over and over again. For power production on a race car this is not the main priority, so an exhuast that fully evacuates the cylinder is almost like getting a bump in displacement. We see this with the 991/981 more so than the 997.

Just look at a torque curve from a 997.2 GT3RS vs a 991 GT3 or 991 GT3RS, you can see what I'm talking about... The 991 is "lazy" by comparison...

We welcome truly independent testing using similar tools and methods. In fact anyone is welcome to come up and we can go to an independent local dyno here in Washington (a dynojet) and run the car there. Also since most don't have a PIWIS 2 to put the car into factory rolling road mode, it makes it easier to ensure the car stays happy...

As far as the catted loss question, we'll let you know when the tested is finished!

 

i'm 100% impressed. with all of it. this is the next level.

 

Amazing! Any idea when we might get some catted info/teasers?

 

Hello Jamie, I have been watching this thread with much interest. I'm in awe of the amazing results you are getting with only bolting on headers. DeMan Motorsport has the same Dyna Pack dyno you have your original results posted from and would offer up our dyno/shop/BONE stock GT4 for this independent test suggested by Pete and BGB

We have run many GT4 cars on the dyno and have a really solid collection of BASE/stock runs as well as cars with headers and tunes of various intentions (race/street) as well as seven 4.0L conversions.

If you have a used set, or have a new set to sell me, lets get this going ASAP! I'm excited for the results.

 

My car's ready and waiting for delivery/install at Olsen Motorsports, I can arrange pre/post dyno, though it's a bit of a pain as they'll have to transport to Schaumburg and back for each set of runs.

 

There might be an easier way, weather permitting: Know anyone local with a stock GT4 who can meet you at a track or private road where you can do a straight roll-on drag race? Say 2nd gear and 3rd gear pulls at WOT from a predetermined rpm or speed on up?

The results, especially if supported with video, may be as or even more informative than dyno results. I have spent way too many a day dyno testing aftermarket stuff only to find it doesn't make the power it needs, needs endless adjustments to get to where it advertised to be, or the dyno itself is adjusted "incorrectly" and is thus yielding high or low numbers.

 

On a different topic I'm taking my newly acquired 2015 991.1 TTS to Dundon Motorsports next week to get rennline grill screens installed. They do other things too. :-)
Leaving my GT4 at home but will check out their new shop. They did test fitting of their GT3 exhaust system on my 2015 with an "F" engine.

 

We're flattered and humbled that more of the established shops are interested in our products. We certainly have no problem with folks independently testing our products. We expect it and encourage it.

HOWEVER ...(sorry, here comes a little rant) ... where we tend get a little puckered is when competitors, importers, and partners of large competitors say they want to run our products for "independent dyno verification." If that is truly all it ever was we welcome that ... however, the history in this industry says that is not always the case. Please bare with me in this as I generally believe only the paranoid survive, and as a small shop just getting started, we have to remain a little paranoid because we have created a design that the industry has never seen before and it is this design that is giving us these tremendous results. When larger, more established companies ask to run our products to help "demonstrate that the gains we achieved are real" it can mean multiple things. We're hopeful this means the requester is looking to add our products to their lineup in order to provide a competitive advantage to their customers' racing endeavors, but the devil on my shoulder, as well as what I have seen through the years in this industry, is that their request to "test" a set comes laden with other non-spoken objectives. And it is these unspoken objectives that cause us the angst.

Further, no other company we can find, on Rennlist or elsewhere, has provided even a fraction of the data and testing results for their products that we have provided on our from day one. In some cases dyno charts are nowhere to be found. It seems that simply because they are established and recognized companies all they have to do is make a claim of XXhp and everyone just accepts it and comes running. We have yet to see the level of scrutiny for our competitions products that have been applied to our.

It kind of feels as if the only ones being asked to "prove it" is us...and we have "proven it" all along the way with all the real data and results for the world to read at their leisure.

Okay ... Rant Over

I know everyone is excited to see that what we have shown is "real." And soon you will as right now 20 systems are in the process of shipping throughout the USA. Any of these owners can (and likely will) test the systems and report back, We are hopeful they do.

I think the best course of action until we have more systems to sell is for shops looking to test our product is to contact one of the current owners and offer them an install and "before and after" dyno data at a discount? I'm sure owners would be interested in that!

 

Sorry Pete, have to really disagree here...

This is not the right way to do a scientific comparison of products to understand the difference. In a roll race can you tell if the car that lost, lost due to losing traction, or the traction control intervening, or was it just not as powerful?. Too many variables, driver, tires, tire air pressure, driver skill, conditions, traction, suspension setup, reaction times etc...

If someone wants to do 60-130 times that's great, but illegal in all places that you can do it and dangerous, don't condone it and it still has driver error incorporated into the results.

Want to go to the drags, awesome do it, that's a great way to show real world results, trap speed can be backed out to HP very easily using basic physics, but there is still error and doesn't give you the full picture a well run dyno does.

A dyno is a repeatable scientific tuning tool, when used correctly it is very precise. Many companies incorrectly use them as marketing tools and don't use air temperature correction or intentionally have them calibrated to read higher. Even then a before and after on the same dyno is normally enough to show the relative change.

We have provided this data over and over and over and it becomes exhausting trying to illustrate that a dyno chart is a repeatable, unbiased and scientific method of demonstrating power gains... This is why we've looked for others to publish them, and rarely find them. And why we have published all of ours for public scrutiny...

OEM's, race teams and engine builders don't go out in the parking lot to run against another car, they do things on the dyno in a controlled fashion.

Your experience on dyno days is exactly our point. If it doesn't bolt on and make power then what was the point...

Sorry if this post comes off as frustrating, but it does get old having people look over your shoulder and second guess your methods to say their way is better and "the" way to do things...

 

So I'll take that as a no......

I understand your position about being a newcomer and protecting your IP, but I could have just signed up and purchased a set and did the tests without your consent or blessing.

I will say I'm on sceptable side of things here but I welcome your efforts and would champion your work if they did produce the power you claim.

We have the same equipment, dyno, testers, COBB pro tuner software and I have dynoed just about every header made on the GT4. I am not on these forums bashing or knocking down anybody's claims and just want to verify that these do make that kind of power then I will send every one of my customers for a set.

So if you won't loan a set for a few days, then this is my official order for a set that I will use on my personal car.

I'm really just trying to help and support your efforts, I hope you can see that as well.

Thanks for listening

Rick DeMan