The turbo inlet is extraordinarily close to the radiator. The GT2860RS has a 3" inlet and is currently only sporting a mesh screen. I'm not to comfortable with that. In order to get a filter on it I'm going to have to remote locate it using silicone elbows and aluminum tubes. I may have to go to 2" and back up to 3" to get the snake behind the radiator. The best filter looks to be an APEXi 500-A026.

I'm concerned I may strangle the turbo for air and cause issues.
It's a B18C Type-R, stock, running just under 300hp at about 6psi. It's a daily driver and I only do a track day now and then. The car weighs 1700 pounds and the engine hardly knows it's there.

 

It'll take a bit more than 6psi to make 300whp. but yes, to make a "snake-like" inlet to use the turbo would be needed for your specific application. As for the APEXI 500-A026, its a VERY nice filter, but there are plenty of others to choose from, if needed.

 

For cramped quarters, you can't beat this filter:

http://www.knfilters.com/search/prod...x?Prod=RU-3700

 

Ok, so it may be more like 275...the car is almost too quick now. I'm crazy happy with the way it runs. It's so much more pleasant to drive.

I'm a bit worried about going down to 2" and back up to 3". I guess I'll see pretty quickly if it likes it or not.

I saw this test between K&N, APEXi, the HKS Mushroom and Blitz. They attached a vacuum cleaner to them and the results look relatively convincing.
http://www.mkiv.com/techarticles/filters_test/2/
I was a bit surprised by the poor showing of the mushoom.

 

I have to come off the turbo with a 3" 45 degree silicone elbow reducing down to 2" and then run a 2" aluminum pipe behind the radiator and then back out to 3"'s. At that point I can fit a fair number of filters. But I need to make a turn and get a wee bit smaller to make it between the engine and radiator. I wish it wasn't so but I can see no other path.

http://www.mkiv.com/techarticles/filters_test/2/ It's interesting that K&N did pretty well. I have read nothing but negative comments about K&N being unable to filter well.

 

Take it to a shop and have a 3 inch intake made for the turbo. It will cost some cash but it will be well worth it. Having the turbo suck in hot air from the radiator can increase AIT by over 10 degrees and that is some whp lost just from hotter air.

 

I actually agree here.

 

They make filters even more narrow than that. Think motorcycle. In plenty of builds we have used various types from the K&N book to achieve tight spot filtration.

 

That is an excellent idea. I had not considered a Motorcycle filter at all. I had a Rickman Cafe Racer years ago. The engine was a 1978 Honda F2 with 29mm Mikuni Smoothebores....and those were considered "big" carburetors at the time.

 

Just go on K&N's website and go to town. They have a million sizes and shapes

 

K&N's motorcycle site has a cabillion flavors. To be clear, I wasn't going to run the filter directly behind the radiator. I wasn't sure why, but it just didn't seem to be a good idea.

It looks like the best option (please tell me if this is stupid) is to come off the 3" turbo to a 45 degree silicone elbow that reduces it to 2". This will get me between the radiator/engine. Then I can attach a 2" aluminum pipe that will run completely behind the radiator to some free space I have behind the right front headlight...back up to a 3" silicone connector to some sort of filter that fills the space.

The filter/intake will not get any air that had to flow through the radiator. However, going down to 2" has me concerned that the turbo will feel like it's trying to suck through a straw.

 

I love K&N for this reason. If you use a K&N make sure to call their techline and get the flow rating for that part number. You need to make sure it will flow enough air for the HP you are making.