Hi Everyone,

I'd like to thank those who have helped me out with choosing an exhaust system for my newly arrived 993 turbo.

My car has just arrived and I drove it for the first time. I was a little disappointed however with the acceleration. I had a ppi done before I bought the car and the independent specialist assured me the car was great. I bought the car without seeing and test driving it first. The car has 23K miles and the car feels to have some turbo lag. The boost maxes out at .8 bar at approx 7,000 rpm. I was expecting more turbo thrust at the 3-4,000 rpm range. It reads about .2-.3bar at 3-4,000. Am I being realistic? Talking to two specialist if the turbos hit .8 bar the turbos are fine. There are no leaks and the car is mint. Reading numerous articles this car is rocketship quick. I am fairly dissapointed so far about the performance. Can someone please assure me that I made a good purchase and not a dumb one. I am currently not driving with a grin but a frown.
Thanks for your input.

 

Buy a Performance Driftbox and do some 60 to 130 runs or book some time on a dyno..

You should be seeing the turbochargers spool up quicker than what you are saying.. Do you have any CEL's? Vancouver Washington or BC? You could have a failed or stuck bypass valve which would bleed boost.

 

kevin5889, dude sorry to hear that u r frowning... I bought mine unseen almost 3 yrs ago and never frowned on performance... fyi mine hits .8 at around 4000rpm and definite kick in the rear...

 

CEL's ? car is stock, Vancouver, B.C. Thanks

 

Kevin you should be hitting 0.8 bar at around 4k RPM in third gear under WOT.

If not, I would check leaks first.

 

CEL = Check engine lights.

Not to alarm you.. If your mechanic has checked for all the boost leaks including the intercooler to throttle-body (common leak also) ie stripped bolt... Are engine has ceramic exhaust port liners.. They are cracking with age, when the crack the ceramic chips off and enters the exhaust stream. The turbochargers are turning up to 175,000RPM's. The ceramic knock the turbine blade tips off.

 

If you don't have a smile on your face everytime you drive your car, there is something wrong. I'm not an expert but could offer to let you ride/drive my car for comparison. I'm in Kerrisdale area, could hook up some time and could take a peak at your car...

Ryojo

 

Thanks for your help Kevin, BTW No check engine lights are on. When I get my car fully insured I will get it to another independent specialist for an opinion and let them know what you think. Does having the air conditioning on have that much of an effect on the turbos? Ryojo-I will definetely meet up with you when I get my car fully insured, its in the importing process.

 

You can't even tell the A/C is on.

 

Kevin,

I'm a 993tt owner as well, located in Vancouver. Not sure whose advice you sought in Vancouver, but MCL Porsche has a technical supervisor, first name John, last name starts with a B. who is a 993tt guru. He modified his own 993tt to 700 HP, provides race driving lessons, etc. He might be a good person to talk to. Steward, shop forman at Weissac, also knows turbos backwards and forwards, having worked on them for 17 years. Don't think he owned or modified one himself, however. If you'd like to talk, drop me an email:
rshaw1@shaw.ca

Good luck, Paul

 

Have a read here:
http://993tt.com/buying.htm

 

Related question:
Is it normal for boost to hit .8 bar as it should and then bounce down momentarily to .7 then back to .8 as RPMs continue to climb? Is that just due to the OE boost sensor? I hear they aren't real accurate.

Boost sensor is new.
Turbos refreshed about 10K miles ago

 

See post 12 in https://rennlist.com/forums/showthread.php?t=137547; that's the shape of the factory boost curve.

 

MarkD, check pages 3 and 4 of this thread:

https://rennlist.com/forums/showthre...ferrerid=41998

You may have a sort of ECU "hiccup" where a faulty frequency valve allows the turbos to overboost in the low RPMs (even if it's overboosting, the factory gauge only reads to 0.8bar), which results in the ECU pulling timing around 4100-4300 RPM. The boost then settles and and the car should pull strong from ~4700 to redline.

 

Thank pehlix and whb, great info.
Mine is behaving exactly like the chart phelix posted. The "dip" in boost happens at just over 5K rpms, as displayed by the guage anyhow. The guage seems to have a slight delay in boost changes so it makes sense.
It doesn't hit .8 bar at 4K rpms, takes some revs to hit max at close to 5K, then a dip to .7 then back to .8
Seems that is normal.