Hey all. 996 noob, but have a 930.
Question, for a daily driver, how much horsepower can be made with the stock exhaust? Anyone have k16 billets, 3.5 intercooler, injectors, 1 bar spring, 5 bar fuel, and a tune to run 1.3 bar or so, but a stock exhaust? How much power do you make?

 

HI,,I don't think anyone has ever run a stock exhaust on that type of set-up because not only being way to restrictive BUT it would be a waste of that build also..

 

Why so much love for the stock exhaust?

 

Let me rephrase. If I wanted to keep the car as quiet as stock or quieter, how much horsepower could I make with k16 billets, 3.5 intercooler, injectors, 1 bar spring, and a tune to run 1.3 bar or so? Is there another exhaust as quiet or quieter than stock that I can use?

 

Milltek and cargraphic systems are quiet but for the most gain you'll want a 3" system. I'm sure 911 tuning can build you system that is pretty quiet.

 

I would not do a Cargraphics because it is on the restrictive side.
I had a Cargraphics ,,and even went from 200 to 100 cats,, I gained noticeable power when I went to the 100 cell Milltek on my 18g set-up, as I have past threads on this..

 

there are plenty of exhausts... you need to open it up to let it breath...
otherwise it will be counter productive...

 

I run a RUF exhaust on my car with K16/997GT2RS hybrids, 997GT2RS ICs, injectors, 1.3 bar ECU, RUF intake manifold, and RUF turbo intake pipes. The exhaust has 100 cell cats and is just a bit deeper than stock with zero drone and a high pitched whistle on the top end. Previously ran the same exhaust with RUF K24/26 turbos as the car came from RUF with. No issues...

 

Europipe quiet. Call Steph

 

[QU buy opening of the exhaust.OTE=MARKSKI@911tuning;4132771]there are plenty of exhausts... you need to open it up to let it breath...
otherwise it will be counter productive...[/QUOTE]

Thanks for the feedback, all. I understand I could get a bunch more horsepower relatively cheaply by opening up the exhaust.however, that is not my objective.my objective is to get as much horsepower as I can for a reasonable sum well keeping the car as quiet or quieter than stock. unless the laws of physics have changed since I was an automotive engineer,power output will be roughly proportional to intake air density, with a little bit of adjustment for increased work by the exhaust turbine to increase the density. If I can get the turbos to produce 1.2 bar, and I can get the post intercooler charge as cool as the stock charge, then I am going from 1.8 bar absolute to 2.2 bar absolute or a little over a 20 percent increase in power, assuming my injectors and turbo can supply that level.from what I've dug up the recently, it sounds like the lower rpm torque levels are kept artificially low by constraining boost pressure. So, my increase in torque should be greater than 20% even with the stock exhaust.also, it looks like the whiskey Springs or a little weak to support higher levels, so those might need to be addressed, particularly given a higher boost pressure.what am I missing here?

 

[Thanks for the feedback, all. I understand I could get a bunch more horsepower relatively cheaply by opening up the exhaust.however, that is not my objective.my objective is to get as much horsepower as I can for a reasonable sum well keeping the car as quiet or quieter than stock. unless the laws of physics have changed since I was an automotive engineer,power output will be roughly proportional to intake air density, with a little bit of adjustment for increased work by the exhaust turbine to increase the density. If I can get the turbos to produce 1.2 bar, and I can get the post intercooler charge as cool as the stock charge, then I am going from 1.8 bar absolute to 2.2 bar absolute or a little over a 20 percent increase in power, assuming my injectors and turbo can supply that level.from what I've dug up the recently, it sounds like the lower rpm torque levels are kept artificially low by constraining boost pressure. So, my increase in torque should be greater than 20% even with the stock exhaust.also, it looks like the whiskey Springs or a little weak to support higher levels, so those might need to be addressed, particularly given a higher boost pressure.what am I missing here?][/QUOTE]


SAY WHAT?? LOL..

 

Take the stock exhaust knock out the cats and redo some piping inside the oem exhaust and call it a day. Stock exhaust has 400 cell cats. No go.
Open up the exhaust and it will run well. Your choking it with back pressure

 

This is just weird! I got that Singer to stop following me as soon as I could!!!

 

I looked into this a little while back. I like the idea of having an extremely quiet sleeper. You have a few options IMO:

1. You can use the stock exhaust and only get 70% of your potential hp- 700hp if you have the potential for 1000. Probably more if you modify the stock exhaust.

2. Run external waste-gates. Your spool will be effected, but once you reach your peak boost and your wastegates open, then the restriction goes away. Basically its an open header at that point. You'd be going from stock restriction all the way to ear-shattering header dump! :P

3. Buy a very quiet exhaust system. Europipe quiet is of the highest quality, and one of the least (if not THE least) restrictive for how quiet it is.

Good luck!

 

I'm not sure this is going to help, because the wastegates dump the exhaust before the turbo. If you're flowing enough exhaust to spin the turbine wheel to produce 1.3 bar of boost, then the stock cat/muffler will not flow as much exhaust as the turbo, still creating back pressure.

Later, Steve