So today I did some extensive testing on some variations I had been messing around with of our EVO X - GST Open Filter Kit we will be releasing soon.

We had the car we did testing on before come in again. He had recently got the "Factory reflash" from Mitsubishi for the Evo X.

Here is a new baseline for this car. 100% stock, stock airbox, stock filter:



These are the "average" of three pulls for each.

Dotted lines are before off the showroom floor, before the new "factory reflash" came to be.

Solid lines are now with the new "factory reflash"

As you can see the new reflash really smoothed everything out and also gives a nice horsepower and torque increase over the powerband.

Peak gains from the "factory reflash" are 11whp/0wtq. Horsepower and Torque area under the curve however has increased throughout.

Next we put the "final" design of our EVO X - GST Open Filter Kit on the car:



These are the "average" of three pulls for each.

Dotted lines are 100% stock Evo X.

Solid lines are with the GST Open Filter kit.

Little less total increase than before which was +22whp/+22wtq. However, the car is stronger 100% stock now from the "factory reflash" so do keep that in mind.

Peak gains from the kit are: +15whp / +13wtq. Larger increases in area under the curve do occur at around 6,000 rpm.

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After this I tried out a couple different things with our kit.

The first one was using a different type of cone filter. For the kit above we where using a normal open cone filter with no "velocity stack". Basically a flat top filter with the filter element on the side much like K&N open filters. I switched this out for a filter with a "velocity stack" on it, which means it also has a opening on the top of the filter that comes down like a pyramid into the filter.



Dotted lines are 100% stock Evo X.

Solid lines are the GST kit with the different type of filter with "velocity stack"

The Evo X did not like this design at all. Smoothness was gone, jerky powerband and it lost peak power of -18whp / -8wtq from the stock airbox and -33whp / -21whp from the GST filter kit with other filter design above, with even larger decreases in area under the curve.

Amazing how such a small change in filter design can have such an effect. Throw this type of filter in the trash.

Next we tried this same filter with "velocity stack" and also a 45 degree silicone coupler. The idea here was to move the filter element as far away from the engine as possible, and if it worked, to re-engineer our heat shielding to work with this. It did indeed move it further away from the motor, the filter was nicely tucked behind the drivers side head light.

How did it work?



Dotted lines are 100% stock Evo X

Solid lines are the GST kit with the different type of filter with "velocity stack" and 45 degree silicone coupler.

Even worse. -23whp / -19wtq from the stock airbox with even larger decreases in area under the curve and really lumpy powerband.

What we learned with all this is the Evo X hotwire maf is very picky with the type of airflow going through it and you have to be aware of this when engineering a filter kit if you want it to work well and see gains.

 

Great info. You want to go with a product that has had some R&D behind it and as been proven. Can't just buy things blind thinking it'll work for whatever reason or because it's the new "in" thing that has worked on other cars. You guys proved this.

 

what do you think about the apexi filter??

 

Great info! Thanks for the report. Keep us updated, I am sure a lot of people are interested

 

I was looking at the agency power intake kit. It appears to have a filter with the "velocity stack" you were talking about (i think?), but they seem to have found success with that filter. Is the one you were using the same?

 

Yes that filter is the same type. However they are also using a different MAF housing. We are using the OEM one.

 

i thought that any open cone filter would work? how come the filters with the VS suck so much for the OEM MAF? so would kn filter be alot beet with flat top?

 

Excellent. Solid R/D to filter out the posers

 

Very interesting, great R&D! Do you have pictures of the intakes? Did you keep the MAF at the filter, or did you put it down stream in the pipe?

 

yes a price and pics would be nice. If it's in my budget I'm all over it

Paul over at DB Tuning in Roseville speaks highly of you guys...I'm starting to see why

 

Just took out my filter and it has a velocity stack it seems. The top of the filter is open and comes down almost 3 inches getting more narrow at the bottom. If you flip it over and look through the larger end, there is a pyramid with a circular cap or top. Do I have a crappy filter thats holding me back? I made 380whp with all the boltons and meth(30psi) but couldn't get any higher, but my torque was 430lb ft? It just seemed that something was holding my setup back..

 

We especially like the testing of the factory reflash for 11whp MD gains. That's good info.

This is exactly why we have chosen to wait before piling a bunch of untested parts on our X. This is the type of testing we plan on doing with the X also.

Good work fellas.

 

Question: did you guys reset the ECU after each change? Multiple reports on forums state that the cone filters felt terrible until resetting the ECUs after which the cars felt to spool turbo just as quickly as before but pull harder until redline according to the butt-dyno.

If by chance you guys did not reset the ECUs after each filter change it is possible that you could be getting the false negative results like what others have reported from their butt-dynos.

And can we see some pics of your "final" design?

 

I really like this post, especially on the cone filter part. Right after I got my car, I tried a modified IX filter with a homemade adapter plate and could tell it lost a TON of power from the butt dyno.

Question for you: Can you show fueling on those runs?

Thanks so much for the info.

 

I swapped mine from the velocity stack to the old style soild end cap but no change in performance or surging . seems Identical. I did reset the ECU with the intial filter change but not switching back to the old style . my info from my car.