Dundon 991 GT3/RS Street Header (catted) Update
08-05-2016, 01:56 PM
#16
I am really interested in a catless or catted version, my biggest concern are the db limitations on the European tracks. If someone with more knowledge could comment on this and would it be possible to get on most tracks with DMS.
Another question is in case of heavy db limitations can the valves be kept closed?
Thanks!
Another question is in case of heavy db limitations can the valves be kept closed?
Thanks!
08-05-2016, 02:09 PM
#17
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And this is why we test everything extensively...
Got the dyno results yesterday and the midrange power is not where we want it to be. We had our new centerlock adapters overnighted and we're forgoing a car show to do the R&D necessary to get this dialed in for everyone. Adapters will allow us to dyno the car on our dynapack right next to our fab area so we can test a number of changes on the exhuast very quickly. For example on the GT4 we tested 6 versions of exhaust and over 32 tune revisions in a week...
I'm working with our Tuning partner to get the map packs as well so that we can be equally as quick!
I understand most won't want a tune, just bolt on and go... But others will want it!
The current configuration is very quiet on track, I didn't get a dB reading but if we can keep it like this may be winner for those at dB limited tracks...
Answer to Asco, turn down tips are far better than keeping the valves closed, that much restriction on the track will likely damage the engine...
Stay tuned, more next week!
Got the dyno results yesterday and the midrange power is not where we want it to be. We had our new centerlock adapters overnighted and we're forgoing a car show to do the R&D necessary to get this dialed in for everyone. Adapters will allow us to dyno the car on our dynapack right next to our fab area so we can test a number of changes on the exhuast very quickly. For example on the GT4 we tested 6 versions of exhaust and over 32 tune revisions in a week...
I'm working with our Tuning partner to get the map packs as well so that we can be equally as quick!
I understand most won't want a tune, just bolt on and go... But others will want it!
The current configuration is very quiet on track, I didn't get a dB reading but if we can keep it like this may be winner for those at dB limited tracks...
Answer to Asco, turn down tips are far better than keeping the valves closed, that much restriction on the track will likely damage the engine...
Stay tuned, more next week!
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Dundon Motorsports
Gig Harbor, WA
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jamie@dundonmotorsports.com
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Dundon Motorsports
Gig Harbor, WA
253-200-4454
jamie@dundonmotorsports.com
www.dundonmotorsports.com
Facebook.com/dundonmotorsports
Instagram @dundon_motorsports
08-05-2016, 08:39 PM
#20
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That's easy stuff... We'll get those knocked out in the next few weeks.
Getting this thing happy with making race header midrange and have cats on it is the trick.
Also came up with some ideas for a robust center muffler as well...
Jamie
08-06-2016, 10:58 AM
#21
Would be nice to have some cool looking tips for running the stock center muffler.
Strong midrange will be difficult with the shorter primaries dictated by adding cats but you guys seem up for the challenge so thumbs up! I can't wait to see what you come up with. Is there room for winding around some longer tubes that end in the same location like many equal length headers have to do?
Strong midrange will be difficult with the shorter primaries dictated by adding cats but you guys seem up for the challenge so thumbs up! I can't wait to see what you come up with. Is there room for winding around some longer tubes that end in the same location like many equal length headers have to do?
08-06-2016, 03:52 PM
#22
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Would be nice to have some cool looking tips for running the stock center muffler.
Strong midrange will be difficult with the shorter primaries dictated by adding cats but you guys seem up for the challenge so thumbs up! I can't wait to see what you come up with. Is there room for winding around some longer tubes that end in the same location like many equal length headers have to do?
Strong midrange will be difficult with the shorter primaries dictated by adding cats but you guys seem up for the challenge so thumbs up! I can't wait to see what you come up with. Is there room for winding around some longer tubes that end in the same location like many equal length headers have to do?
The factory tune isn't setup for performance everywhere, emissions is king, and traditional rule of thumb for "short" primaries vs "long" isn't always how the car ends up performing. Our catted system primaries vs the race primaries are only about 9% shorter, so pretty close to what we wanted! We have some proof of concept tests to run on the dyno that aren't related to primary length on Monday that will be very telling either way they work out!
Will keep everyone updated!
08-09-2016, 04:22 AM
#26
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Jamie what kind of TCF are you estimating for the 991 GT3 to get rwhp to crank? I have quite a few hours experience on the dynapak 4000 with a 911 with one of the foremost operators here (its a NZ designed and built machine). Hes a rally and race prep shop, old skool, and we were using a 1.09 TCF on a 6 speed G50 with lightweight FWC and pulleys. Curious as to where you guys see the TCF with the PDK-S on the GT3. Looking at your numbers Im thinking 1.15?
P.S. That result is much better than I would have predicted for the cats...great work boys!!
P.S. That result is much better than I would have predicted for the cats...great work boys!!
Last edited by Macca; 08-09-2016 at 09:02 AM.
08-09-2016, 08:22 AM
#27
Macca, I am no expert in any way but witnessed many tests. Both road Dynojet and Maha. Maha is the most accurate dynometer out there however I believe that the road dynometer (provided their algorithm is correct) would provide real condition measurement. Real air feeding, drag froce, transmission loss, etc. It just lets the car roll in N and checks it's deceleration. Later it subtracts that loss from the Gross result and you have 100% accurate crank result.
Both devices calculate drivetrain loss themselves. There is no need to shoot any numbers which would be just inaccurate. Why you guys talk about that parameter if its measurable?
Both devices calculate drivetrain loss themselves. There is no need to shoot any numbers which would be just inaccurate. Why you guys talk about that parameter if its measurable?
08-09-2016, 08:25 AM
#28
08-09-2016, 09:01 AM
#29
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Macca, I am no expert in any way but witnessed many tests. Both road Dynojet and Maha. Maha is the most accurate dynometer out there however I believe that the road dynometer (provided their algorithm is correct) would provide real condition measurement. Real air feeding, drag froce, transmission loss, etc. It just lets the car roll in N and checks it's deceleration. Later it subtracts that loss from the Gross result and you have 100% accurate crank result.
Both devices calculate drivetrain loss themselves. There is no need to shoot any numbers which would be just inaccurate. Why you guys talk about that parameter if its measurable?
Both devices calculate drivetrain loss themselves. There is no need to shoot any numbers which would be just inaccurate. Why you guys talk about that parameter if its measurable?
08-09-2016, 09:29 AM
#30
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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... 