Funny this comes up, in 2013 I put a pressure sensor in a exhaust and made a thread about the "smash X exhaust" not being good for higher HP and man I got trolled hard by all the smash exhaust fanboys and guys that make these things.


Facts are facts and the more people try this on their own and add some sensors to see what is going on the more good info there will be. What I found back then was that using 6262 PTE turbos at 22psi of boost there was 6psi of back pressure after the turbo and before the X merge.... that is huge. My car still made 780whp like that but 60whp was being robbed by the exhaust.

 

Yeah, I'm late enough in saying this that the crowd who likes to spend $5-$8k on exhausts and compare them as their primary mods to their cars are gone from the 997.1 market. At least I'm probably not going to get flamed for saying it .

All of my data would suggest yours is spot on.

 

Dare you to post in the 991 forum lol

 

Steve is a very good source for any thing Porsche, he has kept my car running for several years with out a rebuild in 5 to 6 years. A huge accomplishment for a car that make around 1300 hp to the wheels.

 

LOL!! Your bad man!

 

 

Congrats Dan

 

Just having some good clean fun. Obviously the 991 is a phenomenal machine. Maybe I’ll upgrade one day when doctors start throwing them away like my 997 lol.

 

Yeah, I bought mine in 2010 for less than 50% of MSRP and 3,000 miles on it. It's my baby. My wife asked me the other day which car I was going to sell in order to get a Tesla and I couldn't control myself and laughed.

Obviously she won't let me get a Tesla yet, or a 991 Turbo still working on that. The 997.1 was a unique package, the 997.2s aren't quite there. The 991 is close, maybe the successor will be such a clear cut upgrade I'll have to get one. The funny thing is all I really want is a NA 6 cylinder Cayman that I can floor the entire time I drive it. Driving slow cars fast is very entertaining compared to 1100whp+ that is scary every time you hit it .

 

lol

Must be US doctors, us Canadian docs are on the receiving end of the throwaways. Come to think of it, I think my car was owned by a US doc and it was a low mileage nicely discounted car. She turned 10 this year, and is still a keeper.

 

I rescued mine from a Porsche dealership where the doctor traded her in as the down payment for his wife’s Macan. He also ordered a 991 turbo for himself. True story.

Luckily for this 997 she has been fully rehabilitated

 

I hear you.. I bought a 981 Cayman S with SC & PSE about a month ago and I just sold it to a guy in south Texas.. I'll tell you the story over a beer sometime, but I really digged that thing in Sport+ mode w/ a PDK tranny..

 

We should get coffee sometime soon. Damn thing is noticeably quicker than when we drove it on the Tollway. All tuning and fuel too

 

Here's a video of the dyno.

Basically what I learned is this: X-Pipe with a lot of interference is bad for backpressure.

Of course, everything that goes wrong will go wrong. My exhaust backpressure sensor failed, so I couldn't get data. I also didn't get to dyno the car after the new exhaust (Protomotive) went on.

What I was able to do however was correlate some things in the Syvecs datalogs - Mainly that the car would make a maximum of ~27psi of boost up around 7200-7800rpm with the BBI X-Pipe. With an open exhaust the car made around 30-31psi up top.

Once I had taken the car off the dyno, fit the Protomotive exhaust and ran it at the half mile it used approximately the same amount of fuel and ran the same 30-31psi up top. I'm sure no exhaust (straight pipes) is better than any exhaust, but I didn't really see any penalty in performance from the datalogs.

 

Either no X or as close as possible to 1D and on big power the straighter the better IMO as well.