After reding the EVO's brochure got some ?'s
 

The dealer gave me the EVO8's brochure,more like a newspaper biggest brochure i have seen so far. After skimming thru it, have some question.

Whats dual-mode muffler with variable back-pressure valve(whats the purpose of the variable back-pressure valve??) whats the consequence If i replace the stock muffler with aftermarket w/out the variable back-pressure valve, would i loose torque??

Another thing, why does the boost change from 19psi@3500 to 16.5 psi@6500??

I don't know if :mitsu: has said any definitive reasoning behind the two things you mention, so this is just conjecture.

The dual stage muffler is for low sound volume when just tooling around and not getting on it. It opens up to be free-flowing when the engine is really being worked. This lets the system be unobtrusive, sound wise, around town, w/o much of a performance hit. Turbo cars don't want or need any backpressure in the exhaust, it slows the boost curve and decreases the peak boost level.

The boost levels dropping is almost certainly a design for better reliability. 19PSI at 6000RPMS is much harder on the engine than it is at 3500RPMS, and it is also more likely to encounter detonation with high boost and high RPMS. Also, because a lot of people are dumb and run 87 octane in performance cars. They spend 30K+ on a car and then complain about an extra $.10-$.20 a gallon for gas. And then you have California which has high octane gas at only 91 octane in most places. The engines have to be tuned to run in this environment.

Well said Seattle.... I miss 13 coins....sigh...

You forgot about the worst part of the brochure, the fact that three pages are dealing with modification, and of course the Grand Turismo video game. I can't help but complain about this. I am a non asian, but I love Japanese cars. I also love tuned Japanese cars, and of course naturally love the EVO. HOWEVER, in a sales brochure, there is no reason to make almost half of teh sales information about modified cars, that of course naturally have no warrenty, and show asian models (who look very good) that have nothing to do with the car. Also there is a sentance on the last page that states, "Go forth and Modify" if you look closely, in the bottom right of the page, it states that no modifications are allowed under the warrenty. With a car so beautiful with such a performace capability already from the showroom, why waste pages in what is essentially a marketing tool, with needless crap?

I dont think :mitsu: really cares how the exhuast sounds. The '02 eclipse exhuast sound like aftermarket, is not loud but have a tone to it.

If 19psi@3500 then 16.5psi@6000, when does the boost start tapering off(5000rpm or a big dump at 6000?)? @7000 the psi is still 16.5???

Mean TT: I agree, they could have put the 0-60 or slalom instead of the worth less crap filler they put. They could have at least put some ralliart parts, if they have any.

BTW, is it true that on GRAN Turismo the EVO is the most powerfull. Hmmm, last time i played i cant find any car that can challenge the F1 car :D .

:lol: :lol: :lol:

No they care, somewhat. There are like 5 resonators between the last cat and the muffler. The stock exhaust system sounds nice on the eclipse w/a v6.
From what I hear they added all these resonators after the 00 model cause people were complaining about the sound being too loud.

Sorry this is soo OT but just thought I would chime in on what I know about mitsu exhust systems. {thumbup}

what the hell is with the grand turismo ad?? i dont get it:dunno:

Yes I would have to agree. That brochure is pretty lame. They should have done it right or not done it at all. Big newspaper full of lame as phrases catering to 12yr olds who can't even drive.

It would have been nice to see a normal brochure like Subaru did w/ the wrx.

Some of the 3000 GT's, I dont know what year models, had the variable backpressure valve. Im pretty sure it was only on the VR4's :yum:

actually 3000gt had an active exhaust which if i remeber correctly had a speaker and a michrophone to have the sound wave made rplicated in the opposite direction to cancel out the sound.(i amy be wrong)

the dual stage muffler actually provides more back pressure for low RPM torque and open up more more high RPM horsepower(same concept as on the maxima exhaust or intake.. another example is the GTS eclipse with variable intake).

as far as the boost i am going to guess its for reliability. or due to the small sixze of teh turbe it is not as efficient at the pressure at such a high rpm. remember a turbo can make 40 lbs of boost but only be effecient for 10

small? the 16g can hold like 22-26psi reliably i belive

While this is true for a non-turbo car, it does not apply in any way to a car with a turbo.
The reason it works on non-turbo cars is because of the effect of the exhaust pulses timed with the opening of the exhaust ports. If tuned properly, the exhaust pulse from the other cylinders can cause partial vacuum pressure when another cylinder's exhaust valve opens. This helps scavenge the cylinder, and also means that the engine isn't pushing the heated exhaust out, it is getting sucked out. Naturally this type of tuning can only happen over a narrow RPM range before the pressure wave pulses are out of sync with the exhaust valves again.

On a turbo car this doesn't work. The turbo's compressor wheel blocks any sort of pressure wave from returning after the compressor. So from the turbo back any pressure wave trying to return stops when it gets to the compressor.

Also, the turbo itself works not only by the exhasut gas flowing past the wheel, by the pressure differential between the area before the compressor and after the compressor. So you want very high pressure, high temp, high velocity, air before the turbo. On the outlet side of the turbo you want as little pressure as possible. The greater the difference between the two sides, the faster the turbo spools up, and the higher the level of boost the turbo will be able to produce.

This is why you see much smaller diameter tubing used for the exhaust header than what is used after the turbo. The smaller tubing raises the exahust pressure before the turbo.

:usflag:

:mitsu: :karate: :mitsu: Yeh Really funy.... :lol: :lol: :lol: