It appears that my air filters may be a bit of a resistriction at the 25 psi level. With no other changes than removing my filters, I got the following results:

With filters:

60' = 1.78 (spun, pedaled it)
1/8th = 6.28/123.3 mph
1/4th = 9.46/154.2 mph
Boost = 24.5 psi
A/F average about 10.2

Without filters:
60' = 1.73 (spun, pedaled it)
1/8th = 6.01/127.4 mph
1/4th = 9.08/158.7 mph
Boost = 26 psi
A/F average about 10.7

Interesting that removing filters increased boost and leaned out the air fuel. Anyone else had similar results?

Rob

 

I've seen that when the filter was a restriction. The added boost = + power and required more fuel flow.

 

I noticed a big difference just on the street. I dont run filters anymore, Just screens. That is a HUGE difference!!!


Jeremy

 

What filters are y'all running?

 

Wow thats a huge gain! I wonder if it had alot to do with the amount of boost that you are running? I doubt that someone would have similiar gains only running like 10lbs. What type of filter are you running?

-Pete

 

I run a couple big K&N conicals.

 

my friend ran a screen on his car. removing it (no other changes) went from 153 to 158.
on the dyno, another friend removed his small filter and picked up 40rwhp.

 

front mount turbo FTW!
i bought the biggest k/n filters i could find and fit back when i had twins and i agree, they were a restriction at 25 psi too. used em on the street and off at the track.

 

That MPH is great. You sure are picking up some speed after the spinning.

 

Where you been? What's up with that monster?

 

My 9.08/158 run is at 5:00 mark in this vid:
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Rob, mind putting a vacuum gauge in front of your turbo to see how much vacuum it draws for kind of power loss ?

 

I've been watching/waiting for something like these without the extra stuff to pop up on ebay to use as a track only ram air set up under the bumper. they also have larger CF pieces for coolers that you maybe able to find a square filter to fit.
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Interesting . That is huge ! Did you always run filters at the track before ?

I've always wondered about my filter . Its far from your traditional conical filter , but I think it flows well . I'm going to do this test when i get a chance .

I've never used it at the track . :noidea: It would be nice to have a smoother transition like I marked in the second pic .

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i also wondered what would be the best flowing air filter for turbos for street use would be. i hear those greddy ball type filters that supras run flow pretty well.
like these

 

Amsoil has a washable filter that doesn't use oil and claims a year or serivce that I will look into when I redeploy.

 

Those Jap filters are complete turd, look at the area of it, they not big at all. They CAN flow big power, but they are restrictive as hell.

You know why all Jap cars run solid metal boost pipes from filter to turbo and usually run none at all when dragging? Because the vacumn from the restrictive filter will suck a silicone/rubber pipe shut.

We did a practical test once, the biggest Jap filter we could get, a Blitz one you see on these 1000bhp supras etc. On a 700bhp car with a silicone inlet pipe it sucked it shut on full boost. With one of the larger K+Ns (not even the largest cone, but way larger than any of these crappy jap ones) it was fine and didnt suck the hose shut.

A rubber hose is the simplest way of showing if your inlet is restrictive- if it shuts, its too small.

There are K+N cones capable of flowing 700bhp+ with no restiction, maybe more, but I do notice, mostly due to lack of room maybe, a lot of cars run far far too small filters.

Im running nothing but a screen on a 6in alloy trumpet at mo due to lack of room.

Be warned about having long itake pipes too, even if they are the same diameter or even a little larger than the turbo inlet, they seem to lose power. Id always try and neck out the turbo inlet to 4 or even 6in right from the compressor inlet as it seems to restrict it- its like the turbine outlet but backwards- a turbo might have a 3in outlet, but if you ran a 3in downpipe its restrictive as HELL.

 

Even the screens can be a restiction. One day I tested with and without the screens and picked up 4mph with no other changes. My car is a 10.0 car on BFG DR's and the boost was 17psi with a T4 76mm with 3 inch DP.

 

Back when we had the 70mm on our 363ci, we went to the dyno to see why it made less power than the stock 302 and a 62mm What i did at the dyno was dump the wastegate in to the air...didn't change waything so, i by-passed the intercooler...gained 1psi... kinda of a suprise (thought it would've used more) What we found out was the turbo was to small and it made 525rwhp at 10psi (Stopped pulling at 5k) we set the boost to 15psi and made the same power (stopped pulling at 4500)

At the end of the day, the guy asked about the air filter and if i had removed it, i said no cause it was just chicken wire over a pipe with a thin sock pulled over it. He told me that he wouldn't charge me to run it again, so i did. The car was already set back to 10psi and when we went again it made 13psi no power change cause of the turbo but i couldn't believe it. You could see throught it

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dom, would you be so kind as to share how you made your red grommets? Ive never seen any for sale that size