I've got some time set up this Saturday to get my 2005 CTT on a dyno. I've got quite a few mods and want to see what kind of power it's making. Talking with the owner of the shop though he mentioned they have a Dyno-jet machine and once in awhile have issues with PSM on all wheel drive Porsches.

I know the PSM button switches the system off but not totally from what I've read. At any rate, I just wanted to see if anyone has experience running a CTT on a dyno, specifically a Dyno-jet unit and if so did you have any problems?

If so was there a workaround? What I'm thinking is switch PSM off, A/C off, suspension in sport and low. Anything else?? Oh, and also make sure they have the biggest fans possible aimed at the intercooler intakes to keep intake air temps as normal as possible.

Thanks and I will post my results when done.

 

Also, looking at the specs for my 2005 it seems that neither 4th or 5th gears are that close to 1:1 ratio. 4th is supposed to be 1.16 and 5th .86. So it would seem 5th gear should be used since it's slightly closer to 1:1.

 

I'd be concerned about doing it in 5th due to the load its going to put on everything by doing a long pull in an overdrive gear.. More potential for knock or something otherwise to go wrong being under the higher load for that amount of time.. Not to mention the physical wheel speed, ~115 mph in 4th vs ~155 mph in 5th at 6400 rpm.


BTW, I think I'll be by there at some point ~11. My fiancé has an appointment in Kirkland that morning so its a win/win for me to drive her there to score some good guy points and then I can swing by and check out what's going on. Still not sure if I'll do a pull or not though.

 

Good points. Cool, will be good to meet up. We should be there until at least 12:00 or 1:00.

 

Missed seeing you Chris. Don showed up with his 957. Mine disappointed me running 365awho and 384tq. Don's did much better.

Pretty convinced I should have been north of 400 so I need to finish checking the rest of the vacuum lines. Got to be a leak there somewhere. Was still fun. Some nice cars there too. A Pontiac G8 with a bunch of mods put down somewhere around 550rwhp. Beastly.

 

When I dynod my 957 s I put down 305 awhp. I had bypass pipes and intakes. We did the pulls in 4th with sport mode on and traction control off. Tuner let off right as the tranni is about to shift.

 

That sounds like a healthy S.

 

I had issues while en route to meet up with you guys. I did my fuel filter swap on Friday evening so that I'd be comfortable doing some pulls (not nearly as bad of a job as I read.. I'd dare say it was quite simple/straight-forward since I had the correct tools for the job, other than I missed a little detail on my reinstall that screwed me for the day).


She started up and ran fine immediately afterwards, no worries at all so I go to bed pleased with myself and excited to see what she makes. As I was leaving to meet you guys around 1015, I got maybe 2 spaces down from mine in the parking garage and she dies. Try to start, turns over, won't fire.. Obviously not getting fuel. Someone helped me push it into the nearest non-reserved spot in the garage and I rip it all apart again.. The connection of the drivers side fuel pump came off and took an electrical connector loose with it. Snapped it back in, now she still wont start. Won't even turn over. Like an idiot, I realize I forgot to disconnect the battery this time and working with the doors open plus repeated starting attempts has made the battery go flat. So I call my fiancé who drove herself to her appointment, by the time she gets back and can jump start the thing its close to 1. Get it running again, idling fine, then it dies again after about 5 minutes... Luckily I hadn't put it 100% back together, just enough to give it a test... Take it apart again, same line has come loose. This time I realize something is going on with that fitting, so Im inspecting the connection and the disconnect tab is stuck down inside the rubber boot of the fitting, so while it clicks and locks onto the filter housing, its not strong enough of a connection to hold 4 bar fuel pressure.. I bent the tabs back into place, she clicks in and locks on, battery's gone flat again, jump start again and shes back to life and runs great and has ever since. Its past 230 by this point so I didn't expect you guys to still be there so I didn't make the drive . On the plus side, the idle and throttle response and overall smoothness is 10x better now that thing is replaced.


Shame about the numbers, have you researched what other 955s with similar mods are doing to confirm how much yours is down? Can't really compare our trucks to the 957s, they have much better turbos and intake track than we do. I would've expected you to put down more than that considering yours is E81 though. Really wish I would've made it up there to compare. You didn't happen to log by durametric during your pulls did you? I was planning to log my pulls to gather as much data as I could for comparison purposes.

 

Well that sucks but glad you figured it out and it solved your issues. It would have been great to have another 955 to compare. I don't seem to be able to find any E81 955's but it should be basically the same as an '06 CTT. Should be 520hp at the crank stock. Even figuring (what I think is a high) 30% drivetrain loss that means with all the mods I've done mine is right at stock.

I didn't even think about data logging. My P3 gauge is still not showing the right boost levels but I also don't think I'm making 14psi like it was. I think there are still vacuum leaks and one may be in the line to the gauge. I can't figure out why else it would be showing such low levels.

More work to do! After driving around a bunch yesterday though I'm also fairly well convinced that Alex maybe didn't have something set right when he ran it. With both mine and Don's he kept saying it was shifting at the upper end and I didn't hear either hit the rev limiter. With PSM off and in manual mode it shouldn't shift.

So One of these days I still need to tear the thing apart to get the power steering pump done and that will also give me better access to the rest of the vacuum lines I didn't get to last time.

 

Yeah Im beyond pleased with the change this made in the car. It feels stronger when on boost, sounds more aggressive, I think it was being held back by a clogged fuel filter and then the faulty check valve was causing the difficult starts. It hasn't ran this well in at least a year.


I'm convinced the E81 package in the 955 is kind of rare, may be best to compare with the CTT-S as you said. Yours is actually the only one I personally know of with the E81 package, but I'm sure others are out there. Yeah if its in manual mode via the console shifter and PSM off, it wont shift at rev limit. If its in manual mode because of shifting with the thumb buttons, it will still shift at rev limit. Wonder if he was only using the thumb buttons?


Vacuum leaks definitely can kill the power. Sounds like you are in for a hunt . Any luck on the intake manifold conversion you were looking at?

 

Excellent news. It's great when a fix make things feel like new again!

Yeah it seems like it was pretty genius marketing on Porsche's part to make the upgrade and actual model designation with the "S". Funny that people wouldn't have a problem paying $20K more for "the next model upline" but not many elected to get basically the exact same thing as a $20K option package. Smart!!

I really want to chase down the vacuum leaks and go back and run it myself.

I haven't had time to do anything with the intake.

 

My recommendations: Use 4th, not 5th gear. Spray down intercoolers with water in between runs. Use the wiring harness on the passenger side for a coil pickup if they do not have the OBDII sensor. Also get the native .DRF Dynojet file so you can keep it for future reference using the dynojet free analysis software.

Moving this thread to the new Cayenne Turbo section with a permanent redirect...

 

Do you recommend using 5th gear in the 958?

 

No, According to this Porsche 958 Cayenne Turbo Gear Ratio PDF document, 6th gear is exact 1:1. As such, use 6th gear.

 

Thanks for the info! I tried 4th and 5th gears. 6th gear would be too fast for the dyno .