[QUOTE]Originally posted by MrAWD
[B]

Hmm, if you calling a guessed boost drop for the one or more RPM ranges, than you are correct. From my end, to be able to control something, you need to know more about the stuff that you are trying to control, and here we don't have that.

Mitsubishi can do the same thing to reduce the boost pressure RPM dependently instead of knock sensor count dependently. For instance when RPM's reach above 5000 RPM the ECU closes the bleed path on the wastegate solenoid valve therefore allowing boost pressure to be controlled to mechanical limits of the actuator spring alone.

Or by using a larger solenoid valve with larger ports to bleed more air they could get by with still a 10 or 12 psi actuator can and bleed enough air to achieve 19 psi at lower rpm's and above 5000 rpm start cycling the solenoid valve to reduce pressure to the 16 psi at redline. If knock were to occur the could close the valve fully and reduce the pressure to actuator pressure only.

Fact is that the turbo can flow much more than 16 psi at redline, for some reason it doesnt. That is why the aftermarket exists and people tinker. Just like with the 2G DSM, with the leak O.E. boost bypass valve, the aftermarket responded and the tinkering shops developed retrofits to the old 1G steel Bypass valve that would hold boost. Interesting fact is that with BOV replacement alone and Catback exhaust the 2G would spike up to 16 to 18 psi depending on the weather and then drop down to 12 or 13 at redline. The could have built in a guesstimated amount of overboost (or spike) that occurs when the turbo spools to full boost. Who knows?



The thing is that Toyota (not sure about the Mazda) is using MAP system instead of the MAS and they have a fuel cut defense that is activated at the certain amount of boost (not the amount of air as DSMs have), so any attempt to raise the boost will result in the fuel cuts. That is why you need to replace the ECU code! there is no requirement on the DSM side to do such a thing, since simple system as the AFC can trick the ECU on how much air is entering the system. G-FORCE DSM ECUs didn't do much (if anything) for our cars!


The Supras use a MAP to monitor absolute pressure in the intake manifold, but they also use a MAF sensor to calculate engine load and fueling. The ECU monitors MAF voltage and at 2.0 BAR absolute pressure the fuel cut comes in. The DSM use the MAF hz to determine that the engine is injesting too much air at a certain temperature at that given RPM. If you have RPM, temperature and mass of the air, you can calculate pressure using the ideal gas law:

PV = mRT

P= absolute pressure
V= volumetric flow rate
m= mass flow rate
R = gas constant
T= absolute temp

m,R,T are known and V is calculated by knowing that a 2.0 L engine consumes 2.0L ofair per 2 revolutions of the engine (RPM/2) this assumes 100% volumetric efficiency (and Mitsubishi knows the vol efficiency of the 4G63 motor at different RPM's).

The don't measure it exactly but they know it. This is how the boost gauge on the DSM works, they estimate the boost pressure by the MAF voltage, temp, and RPM.

Speed Density systems like the HKS VPC and some JDM motors use Pressure and temperature only to calculate "m" in the ideal gas law. The RX-7 3rd Generaton uses this type of setup as well as most hondas.

Brian

 

while I don't have a DSM, I have frequented this site for 4G63 mods done to a buddy's 2G.

http://www.vfaq.com/
as well as
http://www.dsmtalk.com

however as MrAWD said, the EVO may be a different car regarding mods even though they both have the 4G63...

 

Obviously, like other have said, we're just guessing at this point because we don't know for sure how the US Evo will be setup, but based on modding a DSM 4G63 we can make some somewhat educated guesses.

More than likely an ECU upgrade isn't going to get you much bang for the buck. A free flowing exhaust (cat-less), high flow intake, boost controller, and AFC will probably take you a long way (probably to the limits of the stock fuel system). Boost controller is definitely a must when you start modding, and a MBC is usually the best (read: cheapest) way to go. Doubt you'll need an external wastegate for the 16g. Oh, and with the twin scroll design of the stock turbo, it sounds like the Evo will come with a decent exhaust manifold design and "headers" probably won't net you any gains. Anyway, its all speculation at this point, but its fun isn't it?

-Loris

 

This is always a welcome mod on turbo cars. Sometimes, too open exhaust might hurt low and mid range a bit, but 2.5" system is usually good for most applications. Headers are on the other hand not that important mod on the DSMs (especially 2Gs), since they are pretty good stock and after a bit of porting right where most people need them to be. Usually people with frankenstien turbo combinations have to have something else, so headers are way to go! Still, not saying they would not help, but they might be good enough for most of us!

Hallman Boost Controller is one of the best MBCs that I know of and you can find one on my car too!

ECU has no control of the boost that would be useful for the aftermarket use!

16G turbos are in general pretty good and don't need external wastegate. In some application, we had to port wastegate opening a lot and even replace the flapper valve on the turbo to make sure that boost creep will be tolerable. EVOs have even bigger 16G than those that we could find over here in the US, so I don't believe that will be the case!

See 2 from above!


Fedja

 

Lets just face it.

The first mod we need is an EBC. I'll set it to 19psi and HIT 19psi in EVERY single gear all the way to Redline =)

The beauty of the stepper motor... ahh profec B here I come again

 

Wouldn't be great if things would be that simple!!


Fedja