05-EVO-GSR

iTrader: (16)

Why does the factory pull back boost in the upper RPM band? Is it a safety and/or emmissions issue?

jason@NTEC

iTrader: (1)

safety precaution but a boost controller will cure that.

trinydex

iTrader: (12)

not so... the ecu also aids the boost controller sollenoid/waste gage/whatever else makes the boost taper. you need to get a stand alone or a flash that specifically takes it out. i've been askin' around for the longest time about what exactly or whats exactly causes the taper... this is what i've found so far... anyone know for sure?

plokivos

iTrader: (3)

some say boost leak, some say built in ECU prog, some say it's leaking somewhere.

I'm thinking it's the BOV not holding and I'm sure it's done by Mitsu purposefully.

It's always safer to run rich then lean.

People with MR BOV (Metal) is seeing it not taper down to 16psi.

Then again, if you know how to drive it right, your boost stays up there without tapering with stock BOV.

evo_dadi

iTrader: (13)

tapering of the boost was set from the manufacturer for warranty isues and also to cover for their butt.if it didnt taper it would mean more gas to support the boost then the emmision level goes higher which woul make the evo a non-lev.

as for a boost controller the ebc comes with the solenoids to control the boost so you bypass the stock solenoid.which in turn flexibility of controlling the boost but some of the reflashes now can control boost using the stock solenoid.

jbrown

iTrader: (17)

I have a DynoFlash, HKS EVC V, and HKS SSQV BOV and I STILL have boost taper, the facory wastegate appears to just not be capable of holding anything over 19 psi at 6,500 rpm and up. It sucks. I can make 22psi+ from 4,000 - 5,500 rpm, but after that, there is just too much pressure on the wastegate from what I have found.

trinydex

iTrader: (12)

it's not about the wastegate holding anything, it's about the waste gate opening, it would be a bad thing if the wastegate just held it all in, something is tripping it, and it might just be that it is made to trip not that it can't handle it. a failed wastegate is a wastegate that overboosts, the PROBLEM is that it CAN bleed it off and you don't want it to!

now for the bov thing, tightening hoses i've heard is crucial, ok... done... plastic bov will still leak, but some have after market, check. ebc or mbc removes boost pill in the vac lines, people have done that, check. flashed removes ecu tapering action, check. anyone have all these and still have taper? if not, then that's the recipe.

Dr. Fob

iTrader: (5)

Dynoflash cannot eliminate the tapering, it can only delay it. When my car was dynoed, the boost chart shows that at 3,500rpm, full boost kicks in, then tapers very slowly and gradually. If you sustain full boost at high rpm, then things might start to break.

jason@NTEC

iTrader: (1)

i had a works p2 on my 03 evo and it hit 20psi and just stuck there i loved that p2 flash it was great!!!

watchout

iTrader: (2)

I have heard adjusting the wastegate spring a bit tighter can help hold boost. I have not done this but have heard it suggested. My car on race fuel peaks at 26-27 and tapers all the way to 21 at redline.

Shane

trinydex

iTrader: (12)

uhm... how do you figure that if you have sustained boost at high rmp you'll break things? on any other turbo charged car on earth there is sustained boost all the way up to and past high rpm.

evo 8 ya

iTrader: (31)

The wastgate can hold as much boost as the turbo can handle. About 24 psi. You prob have something not set right with you EVC V. Cause with my old school profec b boost is rock steady 20.5 psi.

Dr. Fob

iTrader: (5)

If you sustain way-high boost (25psi +) using stock internals for a long period of time, your engine will run hot and eventually something is gonna break.

boomn29

iTrader: (47)

Do a search on the P2 and you'll understand. The P2 is a flash, but also replaces the stock 'pill' with a new line that can hold boost.

A Dynoflash, a Xede, or an MBC just try to trick the current ECU and force it to make more boost. You'll never hold peak boost with any of these unless you also replace the stock solenoid (I believe that's what it's called) to get rid of that pill.

The factory BOV is really more of a DV, but either way it's not the issue. It will hold boost up to around 24 psi I think. But, please don't try to run 24psi everyday on pump gas if you're stock...

Ted B

iTrader: (6)

Wow, that's wrong.

First of all, the restrictor pill is removed when an Xede is used, and no MBC is required either.

Secondly, a Dynoflash, Xede, and MBC are very different items. Of the three, an Xede provides the user with a comprehensive means of tuning in real time. A Dynoflash (and P2 flash) is a static reflash that is not user adjustable. An MBC is simply a mechanical boost controller and nothing else.

To say that a Dynoflash or Xede are ineffective at holding boost due to a failed attempt to trick the ECU is false. Nothing will overcome the limitations of the factory turbo, which cannot effectively provide greater boost pressure at higher cfm demand. The more air a particular setup can flow, the more power potential it has, and the greater the boost taper will be.

This is the primary reason for the boost taper.