It will actually stay at 15psi through redline in normal mode--and 17psi in sport.. All the way to redline.. The tune makes the tt a TOTALLY different car...

 

A great tune from a reputable tuner is the best money well spent with almost a 100% headache free guarantee...

 

all tuning talks aside....

in STOCK form, the car should be at 13-15psi in NORMAL mode all the way to redline correct? it should NEVER drop to 6psi in normal mode for a STOCK car, am i correct? this is what I am trying to figure out

 

No. ... LIke I already stated..

"This is a very simple answer.....

Stock ECU lowers boost as revs climb above 4500.. Revs up---Boost down.

Nothing wrong with your car. (I thought the same thing about mine)"

Boost will vary, However it will NOT Stay at 13-15psi past 400-4500rpm.. It will DROP as the revs go up..

 

I'm pretty sure on the 997TT the boost drops as you reach redline.

On the GT-R, the same thing happens where boost is high and then once I reach around 5000rpm's, it tapers way back. Even with a tune, it cuts boost back by about 5psi at redline from the max boost I get at the lower RPM's. I have datalogging on the GT-R so I watch this happen all the time. I don't have a tuned 911 Turbo but I'm assuming the tuners do the same thing so that the VTG turbos stay efficient and safe?

I'm also sure a datalog will show everything and that different tuners take different approaches as far as boost levels go.

 

ttdude posted his datalog which shows boost at different rpms on his modded car, it's in another recent thread...

 

997.2 Turbo's have diverter valves like the 996 Turbo's

Edit: I say that only because Brian has a 997.2 Turbo, although we're talking about a 997.1 Turbo

 

You have a problem for sure!!! you should not be seeing less then 10psi at redline in a stock 997, did this just start when the plugs were changed?? if so I can almost guarantee they took the electric WG actuators off and something did go back on right I have seen this first hand. Do you have a durametric cable?? If so log requested boost vs actual boost.

good luck getting it fixed keep us updated.

Chris Green

 

Yep, you're absolutely correct. DFI 3.8s have gone back to the diverter valve system.

I was responding (like you noted) to the OP.

bob

 

Hi guys help me out here... The 997.2 Turbo still incorporates the same identical VTG type chargers? If so why a change in boost valve replacement?

Furthermore I'm still trying to understand the BRV.

I know about "blow off" and "diverter" type differences but how does the BRV differ?

Is not the BRV a closed loop system as well???

Can someone share the mechanics of a BRV versus DV? Differences?

 

chris i do not have a durametric cable. what are the WG actuators? is this something I can go under my car and hook up simply? or is this an ordeal to do? I am only getting 3-6psi at redline. I had my spark plugs changed and an intercooler replaced at the same time due to broken mounts(nothing wrong functionally with original IC) I thought I was supposed to be at 10-12PSI at redline, now I just need to figure out what is wrong

justin

 

Answer this did it do it before the plugs and ic's were changed??? wastegate acutuators on the turbos, little hard to check yourself find a good porsche shop in your area and have them check it out.

 

i dont remember, i never paid too much attention to the amount of boost prior, but i feel now i am missing power in the higher rev range which is sparking these questions. Looking back I wish i knew how it acted prior to the work, this uncertainty is what is killing me... i thought the 997.1 turbos do not have wastegates??

 

They are VTG turbos so they dont work like a standard turbo but easiest way to describe them is WG's. They are electic box's with a rod just like a WG that controls how the turbo controls boost. In most cases people take them off to change plugs thats why I am saying have them looked at.

 

most times only the problem is posted and no one hears the solutions...so for future people searching this topic...here goes

First off i would like to thank Quantum and Chris Green. Chris Green lives 2000 miles away from me, i have never bought anything from him and we talked about no products to buy from him and he still spent 20 mins on the phone with me...very impressive service right there. Next Quantum, he lives 20 mins from me and was nice enough to drive to me and hook up the durametric to my car and also talk to other porshce mechanics to try and help me steer my dealership in the right direction. What came out of this was a soft fault code "P9902 : Turbocharger underboost" This code throws no lights or anything, only way to see it is to hook up a durametric or a PIWIS to the car. So now it goes back to the shop and even with the code they still dont think anything is wrong, i insist they recheck...welp just got the car back and this baby hauls again. There was a cracked "O" ring on bank one turbo outlet pipe. I was loosing boost pressure through this.

Now i get full 14psi in normal mode all the way to redline and it pulls hard. Before i would get 14psi and then around 4500 rpm it would drop down to 6psi. To reiterate this car is BONE stock. Hopefully this helps someone in the future

thanks again quantum and chris green