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Dundon Street Header (catted) Testing on 991.2 GT3RS

 
Old 03-16-2019, 10:02 PM
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Default Dundon Street Header (catted) Testing on 991.2 GT3RS


We installed our Long Tube Catted Street Headers and a Lifetime Black muffler on this beautiful 991.2 Lizard RS



Let's start with the pull away video



And the dyno video




And now onto the discussion

Stock the 991.2 GT3RS is stout, making 467-468whp peak on our dyno. To put this in context:

997.1 GT3 rated at 415hp makes 360whp
997.2 GT3 rated at 435hp makes 385whp
997.2 GT3RS rated at 450hp makes 400whp
991.1 GT3 rated at 475hp makes 400whp
991.1 GT3RS rated at 500hp makes 430whp
991.2 GT3 PDK rated at 500hp makes 445-448whp
991.2 GT3 Manual rated at 500hp makes 455-460whp
991.2 GT3RS rated at 520hp makes 467-468whp

You get the idea... 991.2 GT3/RS and 991.2 GT3 either have incredibly efficient drivetrains as the losses are much smaller than the 991.1ís or more likely are making more power than their rating says they are (nice work Porsche!). One thing to note on the stock dyno trace is past 8100 the engine loses 70whp... Our Catted Street Headers make a significant difference is helping this!

So here's the results of the testing:
Stock Runs had intake air temps in the low 53-58F
Dundon Street Header runs had intake air temps 71-73F
The ECU will start trimming power levels back at 68F intake air temps, so we bet there's more in it than this with just the headers, but this is enough for now.

40lbft at the wheels at 4300rpm
30whp gains from 8200-9000rpm
16whp peak gains

Some of you may see the Purple line above the other traces. This is the results of our Prototype Big Throttle Body and Airfilter box we have in development starting with the 991 GT3/RS.
50lbft, at 4300rpm, 25whp gains peak, 40whp gains with the combination. This is all without a tune...

Once the prototype parts are ready, we'll announce, but wanted to let you know that while everyones worried about what sounds best, we're over here working on getting this engine to run the best and make the most power!


991.2 GT3RS Stock, Street Headers/Loud Muffler and Prototype Airfilter Box and Larger TB

And for those curious Race headers made about the same gains, a little less peak than the Street headers, and a touch more in the midrange. And yes the TB/airfilter box testing was done with the Race headers, but since race and street gave very similar results, we're confident the TB results carry to the Street headers (had to deliver the car back to the customer so couldn't test this combo, yet...)



Last edited by [email protected]; 03-17-2019 at 01:04 PM.
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Old 03-16-2019, 10:34 PM
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Good stuff Dundon! Since the .2gt3 and gt3rs both have the same engine I believe do,you know why the RS makes so much more power? Factory tune or any difference in engine internals?

also how is everyone getting around a CEL running heads with no cats?

thanks much!
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Old 03-16-2019, 11:20 PM
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Originally Posted by mdrums View Post
Good stuff Dundon! Since the .2gt3 and gt3rs both have the same engine I believe do,you know why the RS makes so much more power? Factory tune or any difference in engine internals?

also how is everyone getting around a CEL running heads with no cats?

thanks much!
These are our 200 cell catted headers, and it's just tuning in the 991.2 GT3RS that's the difference (and ram air at speed), engine is the same.




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Old 03-17-2019, 12:19 AM
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Originally Posted by Jamie[email protected] View Post
These are our 200 cell catted headers, and it's just tuning in the 991.2 GT3RS that's the difference (and ram air at speed), engine is the same.
Oh wow...didnít know these are 200 cell cats on your header...wow thatís even more awesome. You guys got it going on for sure!
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Old 03-17-2019, 01:19 AM
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Awesome work!.... though no surprise you guys are killing the power game!
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Old 03-17-2019, 02:36 AM
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Originally Posted by [email protected] View Post

997.1 GT3 rated at 415hp makes 360whp
997.2 GT3 rated at 435hp makes 385whp
997.2 GT3RS rated at 450hp makes 400whp
991.1 GT3 rated at 475hp makes 400whp
991.1 GT3RS rated at 500hp makes 430whp
991.2 GT3 PDK rated at 500hp makes 445-448whp
991.2 GT3 Manual rated at 500hp makes 455-460whp
991.2 GT3RS rated at 520hp makes 467-468whp

You get the idea... 991.2 GT3/RS are making more power than their rating says they are (nice work Porsche!).
997.1 GT3 rated at 415hp makes 360whp: 55 hp loss (13.25%)
997.2 GT3 rated at 435hp makes 385whp: 50 hp loss (11.49%)
997.2 GT3RS rated at 450hp makes 400whp: 50 hp loss (11.11%)
991.1 GT3 rated at 475hp makes 400whp: 75 hp loss (15.78%)
991.1 GT3RS rated at 500hp makes 430whp: 70 hp loss (14%)
991.2 GT3 PDK rated at 500hp makes 445-448whp: 52 hp - 55hp loss (11%)
991.2 GT3 Manual rated at 500hp makes 455-460whp: 40 hp - 45 hp loss (9%)
991.2 GT3RS rated at 520hp makes 467-468whp: 52 hp - 53 hp loss (10.19%)

I don't understand how you can say the .2 GT3RS makes more hp than its rating suggests. Can you explain?
Are you implying that the power loss is more than 10.19%? For example, if it were 12% instead, then the "on paper" rating wouldn't be 520hp, it would be 532hp.
How can you determine what the actual power of the engine is without pulling it out of the car and dyno testing it directly?
How can you come to the conclusion that the 520hp rating is sandbagged unless you actually know what the parasitic loss is through the drivetrain?

I'm no tuner. But it's my understanding (albeit limited) that a dyno is useless for determining the power of a car because there are too many unknown variables. And a dyno's real value comes from doing a before/after comparison on the same car to test a modification or tune. So it really doesn't matter what the numbers on a car are until you examine that delta.
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Old 03-17-2019, 03:00 AM
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Jamie, how come there is an extra 5% drivetrain loss for 991.1 vs 991.2 with PDK?

Side note, the sound/purr that RS makes on throttle lift off is sublime...

Last edited by bigskyGT3; 03-17-2019 at 03:22 AM.
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Old 03-17-2019, 03:22 AM
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Originally Posted by bigskyGT3 View Post
Jamie, how come there is an extra 5% drivetrain loss for 991.1 vs 991.2 with PDK?
There isnít more drivetrain loss. The 991.1 GT3 pdk is a bit optimistic in itís rating and the 991.2 GT3 is a bit stronger engine.
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Old 03-17-2019, 03:26 AM
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Roger that.
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Old 03-17-2019, 03:33 AM
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Originally Posted by FourT6and2 View Post
997.1 GT3 rated at 415hp makes 360whp: 55 hp loss (13.25%)
997.2 GT3 rated at 435hp makes 385whp: 50 hp loss (11.49%)
997.2 GT3RS rated at 450hp makes 400whp: 50 hp loss (11.11%)
991.1 GT3 rated at 475hp makes 400whp: 75 hp loss (15.78%)
991.1 GT3RS rated at 500hp makes 430whp: 70 hp loss (14%)
991.2 GT3 PDK rated at 500hp makes 445-448whp: 52 hp - 55hp loss (11%)
991.2 GT3 Manual rated at 500hp makes 455-460whp: 40 hp - 45 hp loss (9%)
991.2 GT3RS rated at 520hp makes 467-468whp: 52 hp - 53 hp loss (10.19%)

I don't understand how you can say the .2 GT3RS makes more hp than its rating suggests. Can you explain?
Are you implying that the power loss is more than 10.19%? For example, if it were 12% instead, then the "on paper" rating wouldn't be 520hp, it would be 532hp.
How can you determine what the actual power of the engine is without pulling it out of the car and dyno testing it directly?
How can you come to the conclusion that the 520hp rating is sandbagged unless you actually know what the parasitic loss is through the drivetrain?

I'm no tuner. But it's my understanding (albeit limited) that a dyno is useless for determining the power of a car because there are too many unknown variables. And a dyno's real value comes from doing a before/after comparison on the same car to test a modification or tune. So it really doesn't matter what the numbers on a car are until you examine that delta.

The drivetrain takes a certain amount of power to accelerate and there are losses associated with the drive train.

For a pdk as you calculated,
991.1 GT3 and 991.1 GT3RS are 70 ish HP
991.2 GT3 pdk and 991.2RS are now 52 and 53 HP with the same transmission, axles, hubs etc?

If we apply the same 70hp drive train loss as the 991.1 GT3/RS for the 991.2 GT3 it makes it 515hp, and the RS is 538hp. Both stronger than advertised

or use the counter, and decide the 991.2 GT3 is correct and the drive train is really only about 50hp losses

That means the 991.1 GT3 is 450hp and the 991.1RS is 480hp

Since the pdk, axles, etc are all very very similar between the 991.1 and 991.2 cars you can assume that similar drive train losses should apply. Which one is correct? I’d say the 991.2 is underrated and is actually stronger from the factory.

Once our cylinder pressure monitor arrives we will build this data base as well and will have a direct measure of pressure/temperature in the cylinder and will be able to further illustrate an engines strengths and weaknesses.

In the end you’re correct that a dyno is used for relative measurements, but it is nice that we have a library of all of the cars mentioned above from our dyna oack dyno.




Last edited by [email protected]; 03-17-2019 at 02:30 PM.
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Old 03-17-2019, 03:45 AM
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My headers are flying to Italy :-) can't wait to install them ad have the car dynoed on a dyno very similar to the dynapack.... I can say that the dundon communication was great during the 2 months wait ...
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Old 03-17-2019, 10:26 AM
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^Street headers or Cattless??
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Old 03-17-2019, 11:40 AM
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Street headers
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Old 03-17-2019, 11:53 AM
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Originally Posted by [email protected] View Post
If we assume...
I think that's my point. Can one assume?

or use the counter, and say the 991.2 GT3 is correct and the drive train is really only about 50hp losses

That means the 991.1 GT3 is 450hp and the 991.1RS is 480hp
If you re-dyno any of these cars two months later, will the dyno yield the same numbers?

In the end you’re correct that a dyno is used for relative measurements, but it is nice that we have a library of all of the cars mentioned above from our dyna oack dyno.
Yes, good data
I just wonder if you can truly draw concrete conclusions from it.

Last edited by FourT6and2; 03-17-2019 at 12:22 PM.
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Old 03-17-2019, 12:12 PM
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Originally Posted by cox1974 View Post
Street headers
Very interested in your thoughts after 30 days.

I am on the fence but if I am going to spend $5000 plus it is not just going to be for sound for sure
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