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PIWIS2 got here yesterday, 74mm flaps are to be delivered by Friday. Won't be long now until we get some Vid's with flap on and off, and dyno's of our 321SS setup!
Already have deposits in from a few non-rennlisters...
3" bypass valves landed today, should have them in Peter's exhaust Monday and Dyno Tuesday/Wednesday next week...
We'll have Peter (seapar) weigh in on what it sounds like and Charles will get some video with the flaps closed around town. Also post up the dyno sheet as soon as we have it!
We did some work today confirming some small tweaks to our 997 3.6L headers, figured I'd share here for you all as well, while we get the 991GT3 dyno's ready.
Take a look at the stock vs Dundon/RK 3.6L headers/exhaust
This is an untuned car, with stock air box and air filter. These were our test headers in mild steel, our 321SS is thinner and will make about 3-4whp more than the mild steel... Also we've logged the Cobb AP on the dyno and will be building custom off the shelf (OTS) maps for our headers in collaboration with Rob Harper from Rob Tuned.
To show what we mean by tuned length headers here's our 3.8L headers vs 3.6L headers on John's 997.1 GT3RS 3.6L. One would assume the headers from a bigger engine when put on a smaller engine should make more power. As you can see, this isn't the case, at high RPM the 3.8L headers make about 5-6HP less than the 3.6L. The takeaway is the midrange torque that is lost by using a "bigger" set of headers on a small engine. It's not one size fits all, we tune them specifically based off of the cylinder pressures expected for the engine.
Stay tuned for 997.2 and 991 data (will have to go over the 991 GT3 board, but I'll share here as well)
This is super exciting! I wonder what the drone is like driving around town at low RPMs without the valves. One of my biggest pet peeves is the annoying switching of the valves, but if it were seemless, my guess is it would be better for driving around town.
This is super exciting! I wonder what the drone is like driving around town at low RPMs without the valves. One of my biggest pet peeves is the annoying switching of the valves, but if it were seemless, my guess is it would be better for driving around town.
How I do my setups with flaps is instead of using a big bulky side muffler, I use a smaller pipe around 2" diameter so when the flap is closed the main flow of exhaust (and sound) has to deflect off of the flap and has to reflect inside the exhaust and the smaller pipe restriction helps keep the low rpm drone from exiting the exhaust. When the flaps open in my setups it is very smooth and most people don't notice it or can't tell. It's really nice. Just gradually gets louder.
Would love to see the before and after on the 991 GTRS...I'm in if I can get 25 hp with 50 lbs off the back even of the car.
We'll be doing a 991 GT3 first part of this week. Finding a GT3RS is tricky, we have an acquaintance with one but he's in Vancouver about 2.5 hours north of us... Will have to wait a bit longer for one to show up here in the Seattle/Tacoma area! We're very sure the gains we see with the GT3 will just be as good or greater on the RS...
We'll be doing a 991 GT3 first part of this week. Finding a GT3RS is tricky, we have an acquaintance with one but he's in Vancouver about 2.5 hours north of us... Will have to wait a bit longer for one to show up here in the Seattle/Tacoma area! We're very sure the gains we see with the GT3 will just be as good or greater on the RS...
Hey Jamie. Small world. John Chan mentioned you. I've sat in your 7.1 RS when Erik still had it in FL. He sold it to you when I sold him my first 7.2 RS.
Gerber did my coolant pipe welding on my 7.2 GT3. Charles did a great job.
Will ping you on FB next time I am heading down south. Looking forward to your 991 GT3 results.
Hey Jamie. Small world. John Chan mentioned you. I've sat in your 7.1 RS when Erik still had it in FL. He sold it to you when I sold him my first 7.2 RS.
Gerber did my coolant pipe welding on my 7.2 GT3. Charles did a great job.
Will ping you on FB next time I am heading down south. Looking forward to your 991 GT3 results.
Funny how small a world it is... Maybe you'll sell me your 1.1 RS
Looking forward to getting a set of pipes on your RS and seeing what she does!
Just dropped my car off this morning for dyno testing stock and with dundon custom exhaust systems for comparison. Had a nice hour drive session (power lunch) at Pacific Raceways with afternoon lapping group yesterday.
65 degrees and good till the rain came in.
3 GT3s ; sapphire blue , GT silver , and black one (Kyrocks) former car , recently driven back from Texas with LWB. There was a red Ferrari 458 Italia there as well. Even a Hellcat and a Tesla S to make an eclectic mixture of cars.
The tesla was noisy around the corners due to tire noise. LOL.
10-16-2015, 10:40 AM
