Shiv,

With the normal Stage 0 maps, why would the performance of the car degrade if you have a cone filter (with airbox eliminated) on your car? If anything, you'd run slightly more lean than you would if you had the airbox. Correct?

-M

 

Yes...it has been found that the MAF signal gets messed up with a different filter...the stock filter is very capable..

 

I don't mean to be a pest, but this doesn't make sense. How exactly does the MAF get messed up? If this was the case, why is it that the EVO can get power from the filter cone? If it messes up the MAF signal, it would mess it up with the stock computer. I've been running with one for weeks now with no problems.

-M

 

The readings with cone filters are fairly inconsistant. Sometimes they overshoot the actualy reading, other times they undershoot it. It makes it fairly hard to predict what it is going to do, thats why we recomend pnd of the following....

1. Take it off.
2. Come in for a custom tune.
3. Take it off, but still come in for a custom tune.

The first and third choices are the best of the of the three. Even on our 600 HP shop evo we run the factory air box. I wouldnt discount how good the factory air box actualy is.

 

Well, since I've already spent my money on the cone, I'll opt for #2.

Also, even though they cause the MAF to read higher or lower readings than the actual air that is entering the engine, what are the actual HP increase numbers? Can you show me that a stock EVO with the airbox is making more HP than a stock EVO with a filter cone?

Thanks for the input,

-M

 

You shouldn't see much difference with a filter at all on an otherwise stock engine. The stock airbox is a controlled environment, and a WAI like what you have will get much hotter underhood air at times.

Regarding the MAF, you take out the factory air filter, and your A:F ratios get leaner, simple as that. Ever see a stock Evo on the dyno with the panel filer removed from the box? leaner conditions. Shiv's baseline maps are tuned to the stock airbox, because its much more of a controlled and repeatable environment than all these different types of open elements will produce. Since the stock airbox is still in place in their 500+HP One Lap car, its definitely up to the task. Just remember that the maps are made where the MAF sees the stock airbox.

I've seen custom tuned cars with an open conical filter make less whp on the dyno than the stock airbox several times. I've also seen a couple of custom tuned conical filter WAI cars make less than another identically modded car with the stock airbox.

The point of the matter is that the airbox and filter are not a restriction on the Evo, and even though changing them makes a cool BOV venting out of the filter sound, they often hurt performance.

 

Exactly. Since the fuel maps of the stock ECU are, in fact, too rich and when you tune you are essentially adjusting the fuel maps for a leaner condition (to retreive the extra HP), this is what you want without going too lean. Correct?

So essentially are you saying that because your numbers fluctuate with an open airbox, you opted to keep the controlled environment of the airbox? Does this mean then, that you are unable to get higher HP numbers with an open air filter.

Sorry for this long discussion, but physics tell me that the airflow with the airbox is more restrictive than an open air filter. Yes, you will get more heat coming into the intake but the added flow condition should give you more HP. Of every turbo car I've ever owned, I've never been recommended NOT to have an open air intake. It's like saying don't change your catalytic converter out for a test pipe because it won't yield any more of a performance advantage since it "controls" the flow of exhaust better than not having any CAT.

Buscher tested with an open air filter and got 4WHP and 13WTQ from this alone. While I'm not trying to go into a debate on this, it seems that Shiv just decided to go with the stock airbox for consistant reasons moreso than it being actually harmful and getting less HP.

The only way for me to tell whether the WAI is harmful for my car HP-wise is to take it up there and dyno with and without it. I would certainly be more inclinded for you to tune my EVO with XEDE and with the WAI even if the numbers grow inconsistant from time to time. The numbers we get will be lower than what we will get in the real driving world anyway since the air will be much denser at night and will tend to increase the A:F ratio with cooler air hitting the intercooler.


-Marlin

 

Shiv obviously can get around it, that's what the custom tune is for. But then you get into different types of air filters with different shapes and different filtration potentials.

Yes, BR made 4whp on a FWD dyno on a car without any fuel management. The thing you aren't paying attention to, though, is that all the stock maps are programmed for the stock airbox. Sure, there is a margin of safety built in, but use a WAI on a map that isn't designed for it, and you might go lean in a spot, det slightly, and pull timing. Hence, you lose power.

Next, I can't think of a better compliment to bestow on a tuned car than run to run consistency. IMO, that's the #1 reason why WAIs suck in a MAF equipped car. Think about drag racing: You run down the track, sit in line and let the heat cook under your hood and blow all over and into your WAI, and your next run is slower. The IC isn't heat soaked, the WAI is injesting much hotter air. To me, why would you sacrifice run to run consistency for BOV sounds from your WAI?

Every **custom tuned Evo/WRX I've seen makes the most power when the stock airbox is in place. On a stock car that is pig rich up top, there is a chance that in good conditions when the car is cold you can make more power, but that's not always reality.

Try this one for science: Turn the dyno fan on high and dyno the car with the hood closed with the stock airbox, then with the WAI. The WAI will lose power as the car heats up. To me, conistency is front and center when it comes to importance. Why are you so hooked on the open element? Show me a car that has at least a full exhaust that is custom tuned for the airbox and the warm air intake, and I bet the stock airbox makes more power. The difference between us is that you view the airbox as a restriction. I'm telling you that when the car is custom tuned, it is an asset, whereas an open element is a liability becasue it throws consistency out the window.

 

PS: I had an open element filter on my Evo. I've since pulled it and sold it, as I made more power with the stock box and air filter.

 

Noize,

Thanks for the comments. Is this Brett by any chance??

It's not that I'm hooked on an open air element, it's just that I've not seen an OAI be a hinderence in HP on any turbo car. I did mention that it could get heat soaked, but you didn't address that even though it could get heat soaked, you'd still gain some extra HP by the simple loss in restriction. You can't deny that the airbox is less restrictive than an open element. It's just not true.

Thinking about this more, it seems that the trouble (or handicap) is with the Mitsu's MAF. My Probe GT Turbo with MAF and my old RX7 T2 with MAF never had these problems with inaccurate readings. A Lot of DSM owners admit that they can't even vent to the atmosphere with their MAFs..whereas most other cars (non-MAP sensor equipped) can.

We'll see what we can in July. Do you always carry the XEDEs in stock or do you have to order them?

Cheers,

-M

 

Noize is just a customer of ours. His name is Seth. We usually have about 5-6 Xedes on the shelf, order about 15 each new shipment. Sometimes there can be a 1-2 week wait depending on inventory.

 

I'll give you guys a call when I'm ready to come up to the Bay Area next month.

Cheers,

-M

 

Ok, sounds good

 

Look at the highest HP per liter engines. Look at a brand new Yamaha R1. Motorcycle engineers are always looking for the smallest edge over the competition. Do they use open air elements, no, every year they are looking for a way to make the airbox bigger. Formula one cars to not use open elements either and those vehicles use the most advanced engines ever developed. That's right, they use air boxes. Why? Some of the reasons have been discussed already and they are all valid. You might say that you cannot compare these naturally aspired vehicles to our turbo Evo. I say you are wrong. Remember, the concept of air flow is still the same whether the air is being fed into the turbo inlet, or directly into the head, such as on a NA engine. The air doesn't care and acts the same way regardless. Besides, the Evo's airbox design is great and as a bonus, it had some ram air pressurization at speed, just like the R1 and F1!

I think the REAL debate with the airbox for the Evo should not be whether or not to keep the box, but whether or not to use a drop-in filter.

Lambtron, Shiv, please chime in on the drop-in filter. We all know you guys support the use of the air box!

CPT Evo

Iraq...

 

Yep, I'd like to hear a debate on this topic ... even more so, since I chose to go with an HKS drop in filter for now. I've had my car on a dyno with the stock air filter and with the stocker removed (dyno sheet), and while it picked up ~5whp, it also ran ~1 point leaner up top. Based on that, I don't really expect to gain much, if anything from the HKS, other than better sound from my BOV.

l8r)