seems to me you are saying a dirty 15000 mile stock filter causes no vacuum. something tells me there is something wrong with your experiment. wouldn't you agree removing the filter element would increase air flow?

 

I don't think you understand what I am trying to show. I am taking a vacuum reading from the intake pipe after the MAF and before the turbo. If there was any restriction at the MAF, airbox, or filter I would have seen vacuum in the pipe from the turbo trying to suck in air that isn't there. If I would of seen some vacuum then I was going to remove the filter to see if it would get rid of it. Of course, I didn't see any vacuum so I didn't go any further.

 

There is definitely increased vacuum from a stock filter to a better filter, I just don't think your test has enough resolution to see it. I remember logging baro pressure (in the MAS) on the DSM with two different filters, one small and dirty, the other larger and brand new, and the difference on the log was huge. Because of the scale though it turned out to be a not so huge difference in reality. Certainly measureable though. I wish I could remember the numbers, but it's been too long.

The DSM MAS was small enough that going to a GM MAF in blow through was worth several hundred rpm improvement in respool after a shift on the logger with a 35r sized wheel, but the EVO seems to be bigger. As far as what the EVO can read up to, the data that is available to me says it's good for 57-58 lbs/min, IIRC. Which works out well in my opinion, since a 2 liter at 8000 rpm, 30 psi, and 100% VE is going to move around 55 lbs/min mathematically and from experience, and that's about as far as I will end up going on this car for some time, and I like using the stock MAS as long as possible... Hertz numbers are relatively worthless if not from the same type of MAS, which I only mention because I've seen people try to compare the values to those from DSM sensors.

I think it's also worth mentioning that a turbo is a pressure multiplier, so while the pressure drop across the stock airbox/filter/MAS may be small, but depending on the PR you are running at it may add up to something worthwhile. The fact remains though that at 300 whp and less the gains from "intakes" tend to be pretty small compared to what another 1 psi of boost will add.

 

what would removing the screen from the MAF do.i,m sure it would increase airflow but would it screw with the way the car runs even if you get it tuned without the screen?

 

I call mistake somewhere in this test. There would definately be vacuum even on a stock turbo. Zero vacuum. No way.

 

Jesus christ people, all he is saying is that there was no vacuum in the intake tube between the turbo and the air box, which means that there was no shortage of air. This is in no way affilliated with intake manifold vacuum.

 

I would not recomend it. I ran with a "hacked" MAS for years, but the benefits were minimal. The problem is that the airflow metering is completely uncalibrated, and even worse it's not a linear change relative to RPM. For example, the change was 30% at 1000 rpm, and like 5% at 4k rpm. Testing with the DSM MAS and DSMlink shows however that removing certain honeycombs would give a 14% gain in metering capability, raising the limit from 50 lbs to 57 lbs, and with DSMlink's MAF comp tables it can properly be compensated for. I'm sure the same is true with the EVO MAS if poeple with engine management systems or poeple doing flashes can properly compensate for it.

I might be missing something, but I don't see evidence of anyone mistaking this point. Obviously manifold vacuum is not what we are talking about. I maintain my point that there was certainly some presure drop there, just not enough that he could measure within the resolution of his test and equipment.

 

how about saying, I saw no vacuum indicated with my uncalibrated gauges.

no on is questioning your general point, that the stock system is fine.

 

Honestly, i think the best test to see if a stock maf is a restriction is to have a Speed density tuned car on the dyno. Make one pass on the speed density , then make another pass with the maf as an intake(still on speed density). This will only measure the restriction due to the honeycombs and not the restricted resolution of the maf sensor.

 

honeycombs are not restrictive. they "smoothe out" the air flow...

 

A year or two ago someone sucked the honeycomb till it collapsed I'll try to find the image

 

That was Smogrunner at Tunning Technologies with his 35R last year.

I think they found a couple of beer bottle caps in with the MAF

 

Here it is:
https://www.evolutionm.net/forums/sh...+honeycomb+air

Look at post 3

 

I did the test again w/ 2 different gauges, one being a 0.5% accurate over full resolution compound gauge, and still could not get any measurable vacuum readings. Both gauges are in increments of 0.5 inhg.

 

They can be restrictive if the airflow demand of the turbo is great enough.