Jamie@dundonmotorsports

Hi Guys,

Thought I'd start a new thread to record the further development of the Dundon 991 GT3/RS Street System.

We learned in the last iteration that the car was down on power in the midrange and had a slight drone.

We redesigned the system and will update with Dyno Results and the transparency you've come to appreciate from us!

Running on the dyno today and at the track tomorrow on the Stock ECU, going to put it through it's paces and see how the car/ecu behaves!


Here's a iphone pic to get an idea.

Dundon 991 GT3/RS Street Header System v2 with valved side deletes.

PhilT3 (PT3)

Nice. Keep up the great work!

Kobalt

Jamie,

When you have time: Do you have the possibility to measure the db's produced with original system and with your catted system?

Jamie@dundonmotorsports

How far away are you looking for a dB reading? And at full throttle I assume correct?

Kobalt

Good question - I'll try to do my homework and get back to you tomorrow.

0-60 freak

Nice, Question, why is the third center muffler still used, versus a center delete pipe?

horns

See post 51 for his answer.

https://rennlist.com/forums/991-gt3-...he-dyno-4.html

bmwtye

Maybe do the db measurements like I did on my car way a log time ago when I just had a bypass. Instead of stock you could just do catted and race:

Here is the dB info I measured at 1 meter behind the car at a 45° angle.

Idle:
Stock 77 dB
SW 81 dB

3000 rpm:
Stock 87 dB
SW 96 dB

4000 rpm:
Stock 93 dB
SW 100 dB

5000 rpm:
Stock 99 dB
SW 106 dB

6000 rpm:
Stock 101 dB
SW 108 dB

Jamie@dundonmotorsports

So you don't have to look
1. Drone elimination. The stock center muffler has two paths, a long one for when you want it quiet and a short fatter one when you need more flow.
2. More power and torque. This I won't explain throughly as a few shops are trying to copy our designs. Flattery and all that. Needless to say it helps and we have the data to show it if you're interested wil explain via PM...

Jamie@dundonmotorsports

Only issue is the car is louder under load than free revving...

Kobalt

Hi again,

The Porsche Club Sweden measures sound like this:

Standing car
Behind at 45 degrees angle, at the height of the exhaust pipe
RPM: 4500


That would be interesting in my case

(This is done before a trackday to make sure that we don't upset the track owner too much, then there might be other sound measurements being done during the day which might lead to an too early ending of the session anyway.)


And as you mentioned: "Full throttle down the front straight" would be interesting too but it will be less scientific of course...

Jamie@dundonmotorsports

For those looking for the power of the race with cats and lower decibels, I think we have a winner!

meaker

Will you be doing a db reading of race header compare to catted header? Would like to know how much difference between the two

Jamie@dundonmotorsports

Were reluctant to do dB readings as they're very subjective to the way it's measured, the weather that day etc.

That being said we can get the 4500rpm differences between the two for everyone that Kobalt was looking for!

nxfedlt1

group buy time. I'm in.