nooo midrange dip at 700whp using 996tt intake.


no midrange dip at my 900whp power level too using 997tt intake. the 6.5k drop in power is my car running out of fuel pump and fuel pressure dropping then pumps catch up and power sarts climbing back.

 

i doubt you did this with a canned tune, and you spent or someone spent alot of time working on that over the years learning how to remove the dip, correct?

 

I would never run that much power through a "canned" tune on my car, thats silly IMO.

 

Yea you have a tune catered to your specific car, and with extensive mods, and time you have a nice linear curve, and im sure great drivability.

my point to the post i made is there is a HUGE difference in who tunes your car, and also how much time is spent logging, dynoing etc. and how many mods are on the car play a big role also. if you want a cheap flash, you wont get the same product as one that spends more time and effort into trying to make that tune specific for your car.

case in point i have a turbo dune buggy that has a standalone and i bought it this way, well the tune sucks, its very bad, terrible throttle input response and lean even in closed loop. The person behind the Tune is probably the most important decision to your motors life in the future.

 

Thanks for the inputs, now this is getting somewhere.

Some speculation: if the reason is not intake manifolds or even the tune, could it be possible that there's some fluid dynamics (=gas flow) issues before the TB or after turbos? Something that causes standing wave at certain frequency (6 cylinders pulsing @ 6000rpm)...what comes to my mind is divided vs. x-flow exhaust...or tubing diameter.

 

IMO there are some large restrictions in the intake system of the 996tt. both on the inlet pipes side of the air flow and after the intercoolers, especially if you upgrade any leg of the piping, say new inlet pipes to the turbos, new intercoolers, and new Y pipe now the bottle neck is the throttle body and the plenum behind it, etc.

I dont have any data to back it up just observations following these cars and tuning and dyno sheets.

 

Holy resurrection, Batman!

I had completely forgotten this, but I'm happy that this came up. For I have something to say about my original question myself. Solution to this problem - at least in my case - has mostly been opening up the airflow, secondary the tune. While I still do have 996 turbo's longblock, the airflow in and out has been extensively upgraded:
-997 turbo's air filter box
-do88 silicone tubing to turbos
-997.1 VTG turbos
-do88 largest ICs for 997 turbo and silicone tubing for those
-do88 Y-pipe and plenum
-997 turbo's TB
-997 turbo's intake manifolds
-100 cell cats and 3" exhaust with center outlet

The dyno chart is from last October, 4th gear, 98 oct (Euro) fuel. Crank hp & tq. No dip whatsoever. 1.1 bar boost, external boost controller and tq curve's shape between 3 and 4k is on purpose, to save my rods.


997.1 VTGs, do88 Big Pack, 100 cell cats and 3" exhaust.

 

It's time to resurrect this thread again, because John gracefully shared his experiences in the mysteries of VarioCam tuning here: Rennlist thread
So there's a decent explanation for that hp/tq dip at RPM range I was pointing out. It may be either exaggareted or diminshed with parts installed on the engine.