so first of all i searched but couldnt find an answer to my particular question.

i understand when installing a TBE on an EVO8 that boost will rise. mine is an 05 so i around 24-25psi. (NO MBC yet)

so heres the timeline:
installed Apexi GT spec (6months ago) - spiking to 22 psi
installed UR TP (4months ago) - spiking to 24-25psi
installed Tanabe DP (2days ago) - back to 22-23psi?

in that order i went up then down on boost. now i have been using a mix of 91/100 octane 50/50 (loving company gas cards =)) so im not worried.

I checked for exhaust leaks, and found a small one. (gasket after the TP, cheap POS, came w/ UR TP)
I did a boost leak test, none. (DIY tester found at this site)
Have a hallmanRX MBC not installed yet, but i was just curious why boost would fall instead of rise again. not that its all that bad anyway. anyone care to chime in?

 

bump

 

Fixed exhaust leak.....same thing, anyone have an idea? BBUUMMPP

 

still 22-23psi......im on a stump bump?!?!

 

sounds strange it will increase the boost but that sounds like a lot 4-5 psi more it's safe though it should be fine does it bleed off on the high end

 

remember these cars were restricted by the manufacturer because for the 280hp rule in japan all cars must be 280 hp or less and the filter and exhaust is the easiest way to do it like the skyline if you just bolt off the catback and remove the filter you pick up 4 psi of boost and about 60-80 hp.

 

That is very strange. Maybe you saw the bigger increase in cooler months and are now seeing less in the summer months? The boost is affected by air density. I highly suggest installing the MBC (not sure why you haven't yet) so as to keep the boost right where you want it. A constant 91/100 mix means you're safe, but if you were ever on straight 91, I'd be a little concerned.

 

say wha? if i remember correctly, they dropped that law/rule a year or two ago. unbolt cat back? remove air filter? 60-80 hp? what you smoking? hook a brotha up.

 

thanks for a better response.

even in the "heatwave" we have had. (100+degree weather). In day or night i would hit 24-25psi before i put in the DP. MBC going on in a couple days, just waiting for the cockpit cable. In the mean time, just for my piece of mind. Im running straight 100octane.

Just curious if anyone else has had this problem or know whats up?

 

Without the MBC the turbo has a tendency build boost up then down. With a MBC you can some how maintain the boost higher longer before it goes down.

As far is the leak after the test pipe, I wouldn't even worry, it should affect the performance much at all.

Carlos

 

carlos,

thanks.....i know about taper, when i was spiking to 24-25psi, it would taper to 20-21psi by redline.

but its wierd after installing my DP i thought atleast it would stay spiking to 24-25psi, but instead dropped to a 22-23psi spike instead, tapering to 19-20psi.


i figured the exhaust leak was no biggie, but fixed it anyway. (couldnt stand the smell w/ windows down)

 

When I did the exhaust on the Evo 9 I gained 3psi (peak). Basicly it helped the turbo to build boost rapidly. Get the MBC install and let us know, that might fix the issue.


Carlos

 

The MBC should have been installed before the TBE so you chould adjust the boost. I never had a problem like that on my car with mysetup. I had the MBC first, then installed the TBE and didn't even have to readjust the MBC because it still boosted the same 20-21 PSI peak. I think if you have running 100 octane you should be tuned for that. BTW what boost gauge do you have, maybe its not reading correctly?

 

prior to my TBE, i probably should of got a MBC.
im pretty sure i dont NEED to be tuned to run a 91/100 mix.....yes it may be better, but no need.
my boost gauge is a defi-d, i tested it on 2 different sources for accuracy and were dead on. i tried my friends autometer on my car and read the same as well.