40whp and 30wtq gains with Dundon Motorsports Headers, no flash required!
#136
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From: Gig Harbor, Wa
Those are some amazing quarter-mile times for a naturally aspirated non-four-wheel-drive car (991 GT3 The traps speeds are very impressive as well.
I know that the 991 RS is not designed for straight-line speed but it would be interesting to see what the 991RS would be able to run with the dundon headers in place for the 1/4 mile. Would the extra HP of the 4.0 motor negate the more aggressive down forcing of the RS?
Motor Trend tested a stock RS in the quarter-mile at 11.1 at 125 MPH
I know that the 991 RS is not designed for straight-line speed but it would be interesting to see what the 991RS would be able to run with the dundon headers in place for the 1/4 mile. Would the extra HP of the 4.0 motor negate the more aggressive down forcing of the RS?
Motor Trend tested a stock RS in the quarter-mile at 11.1 at 125 MPH
#138
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From: Gig Harbor, Wa
#139
Here's a plot of the ideal shift points on a stock 991 GT3. The dyno plots from the first post in the thread for the headers suggest a power curve larger similar in shape to stock (but boosted up), so I suspect the ideal shift points with the headers are similar.
#140
#141
So you are saying 9000 in first three gears then 4th@8850, 5th@8750 and 6th@8700 did i get that right?
Last edited by GT3 KSA; 04-12-2016 at 03:18 AM.
#143
The 991 C2S and GTS share the same base engine so they physically would fit. I will just have to do the needed testing on the dyno before being able to fully produce them. The GTS has the x51 power kit so I would want to do separate testing to see if that setup wants a specific header design compared to what the regular 3.8 would want.
#144
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From: Gig Harbor, Wa
Got some time sheets from 991 Gt3. Customer said no time differences with muffler bypass or side delete and Ti center muffler. Then he tried Dundon Race headers. Was a big enough difference they pulled him out for a tech inspection looking for Nitrous!
This is same tires, same pressures, same launch, no wing etc. as apples to apples as it can get. Left is Dundon Race Headers. Right is stock/center delete/side and Ti muffler
This is same tires, same pressures, same launch, no wing etc. as apples to apples as it can get. Left is Dundon Race Headers. Right is stock/center delete/side and Ti muffler
#148
Hopefully they fix this up for the next iteration.
Well done on the 1/4mile slips. Thats a tangible improvement! You will have my money and my order very soon Charles/James!
#149
Great work on the graph! I did the same couple years ago but lost the file since. The car does seem to shift short of 9000 after 3rd gear in auto, so the gearbox programming most likely takes that into account. When shifting manually, I'd shift at 8500 or earlier because no one is 100% precise, especially without proper shift lights, and bouncing off the limiter even once costs more time than shifting 200-300RPM short of optimal.
#150
Great work on the graph! I did the same couple years ago but lost the file since. The car does seem to shift short of 9000 after 3rd gear in auto, so the gearbox programming most likely takes that into account. When shifting manually, I'd shift at 8500 or earlier because no one is 100% precise, especially without proper shift lights, and bouncing off the limiter even once costs more time than shifting 200-300RPM short of optimal.