Jan Erren is a gentleman. Generally Manthey's policy is not to discuss details over the phone or even email. But if you visit them and you have done your homework, they are great to deal with.

PS. Toby, nice post.

 

i remember the letter he wrote in one of the magazines once...

 

i don't even own a turboed car but that was a really cool read - go RENNLIST!

 

+1. Very interesting thread.

Definitely information worth sharing.

 

I've been tracking my GT2 with RS tuning 600hp kit for a year or so now , from my previous experience the heat soak is alot and i mean alot less than my previous 997tt.. i dont know if this comes down to the expansion intake or because i am running a catless exhaust.. which reduces back pressure... or possibly the tune?? My IATs are not the best even with the GT2rs coolers and get pretty high in the 60C range but power is consistent especially at the track??? where my previous 997tt will heat soak in 1 or 2 3-4th gear runs and go into limp mode...

Regarding power loss , it is also consistent in a 30C trackday power is lost a litte but my shift points from 4th-5th stays the same lap by lap !!

While on a cooler day the shift points are earlier but also the same each lap and i reach a higher speed on the straight..

Another problem in the 997.1 GT2/TT is the EGT sensor which as GT-TT pointed out that it reads higher EGT values than what it actully is... the improved EGT sensor carries part number 99760625005 which i beleive is from the TTs and GT2RS? For the first TT cars the part number ended with 001...

 

R+C, **** maybe a bit harsh but I found him too know it all when in reality after some light grilling the BS was seeping at the seams

Pic of the standard length 997tt.1/GT2 intercoolers sticking out 4cm from the GT2RS lower intercooler duct... the RS/997tt.2 intercoolers have shorter cores to allow better end tanks and fatter


MM
Expanding a bit more on it, the VTGs start spooling fast at 2000rpm and produce maximum torque at around 3000rpm which can be held until 5000rpm, this is so much work that it is easy to envisage how much heat they must produce........with the VTG engines much more than in other Porsche turbos of the past the tuner must precisely adjust the boost so that its curve does not produce too much heat low down and kill the hp further up the performance range, the only way to do this is having a facility (track/road) where the car can be taken up to 300+kph since 5th and 6th gear produce a lot of heat......

I would wager that there are many VTG engined Porsches out there which are very quick up to 200kph and then as slow as stock from 200 to 300kph......the awesome thing today is we can all check our tunes with Durametric, measuring 60-130 did its job in the last decade, now its data logging and interpretation

 

Did you have problems with the EGT and went with this new EGT in your car?

 

No Never im just going to get these new sensor to make the car run more efficient.... my EGTs where always below 880 degrees even at the track i dont know how some people are seeing 900 degree EGTs ?? could the catless exhaust be doing all this?

Toby , so i guess thats a reason why my IATs are a little high with the .2 coolers since my ducts are the 997.1 so this means the ducting is short by 4cm and not that efficient..???

 

Guys, I believe they are on yet another version of EGT sensor, mine was blowing them during shakedown testing in June and they told me that the latest sensors they received had new part numbers indicating a change......maybe this is related to the extreme VTG heat 980c ?

 

Mo, your .1 ducting with be too large so air will escape around the sides..... this is 100% worth getting right , it makes a big difference, why not just buy a set of .2 ducts top and bottom so the sealing is correct where it meets the core (this is the important bit).

 

Blowing them?

What does this mean, is there some way to see if there not working?

Newer version for our cars or are you getting the GT2RS stuff?

 

Blowing them means they were showing up as faulty on the PIWI I guess so if you have no faults showing yours are OK...

I've no idea what the actual part number was, is the RS sensor different ? anyone seen the PET ?

 

Toby the part number is 99760625005 as GT-TT ( George ) stated on a 6bling thread..
I beleive our cars part number end with 001 or 002..

 

Yes GT-TT here, had the 001 and changed to 004 (latest part at the time). Power came back immediately at high rpm. Interesting thing is that the power loss started before i got the error message so that means that it is a bit like that air mass issue with the 996tt were you would quietly lose power with no message until the sensor got completely destroyed..
On the power loss issue discussed here we have to also consider that when we are pushing 700 hp with large compressors and small turbine wheels effectively the latter are bringing backpressure that raises temps all the way to the cylinder heads. So I dont think it is possible to have more than 650-680hp or so on a track lap after lap with VTG turbos. Maybe more on a very cold day, but not on a 30+ deg day no matter what mods you have. For more power you need different turbos but then you lose response etc etc
In my car i tried every trick we knew to get the backpressure/ IAT issue reduced (wider lobbed cams, ported heads, expansion intake, larger GT2 turbos, 100 cell cats with flaps, 2RS coolers with spray. ). The interesting bit is that in my car i get a lot of torque from 3-5.5k then it flattens to 6.5k and then there is a lot of power coming until limiter at 7.8k. However at that last bit the increase in power is actually coming with LOWER boost and HIGHER ignition timing. I think this is because of the expansion intake cooling things down so power comes more with ignition timing (25-28 degrees), a bit like a NA car.
On the topic of ICs above it is worth mentioning that ambient temperature is only one parameter that influences performance. My tuner has measured 3-4% power loss every 10deg celcius and that is with out ignition pulling. The other parameter though is ambient pressure. Has anyone noticed how sometimes the engine feels stronger on a sunny day with 33+ degrees than an evening with similar or even lower temps? The reason is pressure of oxygen density. And there is nothing any IC can do about that..

 

all the time same story, lower boost is required.....or bigger turbines producing big amount of air at lower boost.
I talked with engineer responsible for cores design, he was also working on porsche turbo....he told me that the biggest problem of this car is intercooler position, there is not enough air passing the core and that's why it's never ending story.. he also told me that the best intake temp he ever noticed was 24C over the ambient.He mentioned about 996 turbo race car with 3 intercoolers, third one was on the top of the engine covered by special bonnet something like gemballa. 24C above the ambient was recorded during the race in summer.

Ps. Toby nice middle radiator core, I'm using same core as heat exchanger for liquid cooling system I have.