rawkus

iTrader: (16)

Hello all,
I used to be able to hold boost (21-22psi) from about 3700-3800 to redline. After I installed an EPM Dump and TME 6.5 turbo (ported and coated by MAPeformance) boost falls off to 18-19psi near redline. The car "feels" faster than before, but I can't 100% say for sure. The previous turbo was just a stock Evo 8 turbo. Could this be an effect of having less back pressure?
Dan

Fast_Freddie

iTrader: (50)

Which 02 housing did you have before? Also did you set the wastegate preload on either turbo?

Evostacio

iTrader: (1)

humm very interesting

sspaladin28

iTrader: (25)

Funny cuz when I had my MAP o2 dump my boost creeped so badly I couldn't run it

bustriajb

iTrader: (27)

Wouldn't you need to re-tune after changing those parts?

sspaladin28

iTrader: (25)

After two changes that major, you would indeed want a tune to maximize the setup and adjust for the new variables

rawkus

iTrader: (16)

Completely forgot about this thread.

I was running a stock o2 housing before with 3" downpipe and exhaust.

I did adjust preload on the wastegate, but I want to double check after things have been driven a while.

And we are going to retune the car soon, awaiting a new Wideband to arrive. I will try and remember to keep everyone up to date.

Dan

mrdevo

iTrader: (4)

Not having a tune and running a more eficient setup could lead to boost falling off more than before. You hear how people with with just a boost controller and tune can hold 20+psi to redline no problem, but the ones who are more modded can't hold it...its all about efficiency in every individual setup. Your turbo is making more power but not working as hard..

sparky

iTrader: (1)

Try preloading the WG to 17-18 PSI. Are you running a cat or a catless exhaust?

Did your car´s original turbo have a 9.8cm turbine housing, whereas the new one has a 10.5cm housing?

rawkus

iTrader: (16)

I am running with a cat and yes, I went from 9.8cm to 10.5cm. More updates soon.
Dan

sparky

iTrader: (1)

Based on my experience with porting my Green turbo and having seen the quality of porting done by MAP, I would say that yes, quite possibly that drop could be due to a decrease in backpressure.

MAP does excellent work judging from the little I've seen. They port the turbine discharge area of the turbine housing and this work if done properly can definitely reduce backpressure by about 3-4#. Reducing backpressure at the outlet improves the overall efficiency of the turbo due to a more favorable pressure differential between compressor and turbine.

andrewzaragoza

iTrader: (6)

yes just like what the other people said, tighten up your preload. make sure you do this before you get a tune atleast you could get the full potential of your new upgrades.