Thats probably not how you really feel, but for the sake of getting back on topic, fair enough.

 

Well I think it's pretty obvious it didn't gain 45whp from just taking out the airfilter unless Mitsubishi put in a piece of cardboard. Meaning that other variables changed causing an increase in horsepower from the airfilter being removed. The fact that is gained 2psi and leaned out some helped probably equated for damn near 30whp. I am curious to see what it would do with just a better airfilter....maybe 10whp? Also Brian what did IX's baseline on your dyno...about the same whp but less torque correct? Does look like tuning would help alot...that powerband looks somewhat sketchy to say the least. Why is it the AFR is so rich...most VIII's and IX's ran about 10.5afr in stock form. Did they do this to account for the 23psi stock?

 

Many cars these days run abnormally rich from the factory because of new emissions standards enforced by CAFE. Now I know what you're thinking; "running rich is worse for emissions than running lean." Yes, ths is true. However, there is one major factor in this equation. New cars, especially the new evo, which earned the highest emissions rating available in Japan, use ultra efficient and restrictive catalytic converters. Now, to make the cat work it's best, the temperatures running through it have to be as low as possible. So, whats the best way to keep exhaust gas temps down? Why running rich, of course. By running overly rich, it cools the combustion chamber and reduces exhaust gas temperatures. This, of course, is bad for performance, so to counteract this the new evo runs pretty aggressive stock timing maps. Problem is that it's not enough to offset the overly rich conditions. The car really does run far more rich from the factory than the 9 did, and the heads have larger intake valves and a larger combustion chamber than the 4g63 did. So a huge part of the gains are that it is pulling far more air into the combustion chamber than the 4g63 did with a filter replacement, this seems to net about 20 hp. And of course, the boost rises by about 2 psi, which accounts for about 20 hp, but it's not a peak boost increase, it's only a reduction in taper at redline of 2 psi. This is why the peak increase in the midrange is only making it's 20 hp gain from the leaning out; because there's no boost increase. But at redline the boost increase is combining witht the gains from being leaned out, and thus the 40 hp gain. Damn I'm good.

 

Usually I thought running more fuel to offset the high boost and aggressive timing creates higher EGT's. Atleast thats how it has been on 4G63's. I am also wondering if the new evo uses Metallic Substrate or still uses Ceramic cats. I haven't seen any pictures but I know alot of the newer cars dont use Ceramic cats anymore and they produce better emmissions. Seems that the newest head with Mivec on both sides allows more timing too. I guess it would be handy to see the actual flow characteristics of the head since it has bigger intake valves but smaller exhaust valves over the IX's. I am really curious to see what boost they can push on pump if it already does 23 from the factory. I would suspect it might be possible to run 25-26psi on pump. That may be what helps it overcome the weight and be faster that other evos with its more efficient design.

 

You can see a stock IX overlayed with another stock X in this thread:

https://www.evolutionm.net/forums/sh...d.php?t=321315

That IX is on the higher side of the stock IX's on our dyno. The average is 235whp/230wtq

 

Ah so the IX's do put out a bit more power in stock form. Its amazing to see that both spool almost identical but up top theres quite a difference. Also seems that even being 4-5psi more than the IX's that its doing much good. I think with better A/F and boost holding it could be a beast.