help me build an intake

[MainFrame]

Okay, here's the deal.. I'm going rotated, GTX35R (4" compressor inlet), etc. The car is set up on speed density, so no need for a MAF sensor. I am pulling vacuum to my catch can from a custom exhaust e-vac scavenger kit, so no need for any fittings on the intake what so ever. Really, no need for an intake. I could run open turbo but for two reasons. I don't like my engine sucking sand, and I would like to be able to at least somewhat isolate the intake air from hot under hood temperatures (cold air box).


The name of the game here is as little resistance as possible. I'm planning on using an AEM Dryflow filter with a 9" element (big ass filter).

The Supra guys seem to be all about velocity stacks.. so what if I were able to at least somewhat mimic a velocity stack with a filtered short ram? I got to thinking, I could run a filter with a 6" inlet, attached to a short pipe (possibly PVC?), then use a 6" to 4" silicone reducer coupling to attach to the compressor inlet. That would kind of mimic a velocity stack, while remaining filtered. The problem is I can't find anyone that makes a 6" to 4" reducer. There are 6" to 5", and 5" to 4", but multiple steps seems like it would ruin the flow and cause turbulence. I suppose I could just go with a 5" filter and reduce it to 4" at the compressor.. but 6" just seems better.



Thoughts? Suggestions?

[teflon_jones]

I don't see why you need to go that large on the intake. That size piping will flow more air than your engine and turbo will really need. I'd just stick with 4" piping throughout which will reduce any turbulence due to the same size throughout. I thought the AEM filter has a 4" outlet size correct?

[MainFrame]

Yeah, AEM filters come with all sizes of outlets, I could just get a 4" filter and call it a day. I realize 4" isn't going to be much of a restriction, and being forced induction it's not going to make much difference one way or the other.. but with the way it's set up now there's no reason not to go a little overboard, especially if it's not going to cost much more.


A rough calculation says my engine will theoretically consume ~980cfm at redline and max boost (my compressor map says I should be around .77 efficiency).

The pressure drop for 6" pipe will clearly be less than with 4" pipe, and the air flow should benefit (albeit not much since the compressor inlet is still 4".







Plus, won't a 6" intake just look better?

[Donkey]

Some conical filters have a velocity stack in the base.

[teflon_jones]

I just realized when I reread your post that you put SRAI in there as what you're looking at. I'd skip that idea entirely and go with a fender well mounted filter for sure with a heat shield. Is there any reason you don't want to do that?

Given the compressor inlet is 4", I still think it would be best to go 4" throughout the system. If you taper from 6" to 4" anywhere near the inlet, then you're introducing a ton of turbulence at the worst possible point. If you put the taper further out, you're eliminating the benefit of using 6" in the system to begin with. So I stick with my thoughts of going 4" for the entire thing.

[MainFrame]

Hmm.. hmmm. I'm thinking you're right about the taper introducing turbulence right at the inlet.


For one thing, I'm not sure if I can even fit a filter that size in the fender well. I could compromise on size a little to get a more consistent charge. Then again, if I put the filter in the passenger side fender well, that means it will be sitting right on top of the FMIC pipe as it exits the compressor and heads to the core. That pipe is going to be HOT under boost, so the fender may not be the coldest air anyways. Plus I don't want to have to worry about ingesting water. And I'm not sure how I will angle the PVC pipe to enter the fender in the first place.

I was planning on making it a short ram and blocking off engine bay temps with a custom made plastic box while funneling colder air into the box using the OEM ram air intake fitting..



Help me brain storm on this a little more.. I've got probably three weeks to a month before I have the car running and back in my hands.

[Oh! Snap!]

Did you figure out a set-up yet ? Dont use PVC, thats a hokey as hell. The guys over at KS Tech make some nice stuff and its done here in the US. They have different lengths, diameters, with/without speed density, top mount, and front mount.

As far as velocity stack goes you should have to worry about that on your rotated set-up. They are used mainly to straighten air out if you were to run through a mas air sensor for consistent measurements... or for a regular stack injection intake.

[Donkey]

Velocity stacks don't straighten air. They Increase it's speed. Hence the name "velocity stack". Air grids straighten air. Like the "honeycombs" some OEM MAF's use or say the straightening grid that Cobb's intake uses.

[MainFrame]

Did you figure out a set-up yet ?

Not exactly.. I talked to my tuner and he said they have extra couplers and several different intakes made for rotated setups laying around that he would just give to me if I wanted one. Right now the plan is to get it all together and the custom IC pipe fabbed up, then once it's running we will look to see what will fit and figure out something that will work with the huge AEM filter I'm wanting to use. I may just grab one of their extra intakes and modify it, or I may make something out of PVC and silicone couplers (I don't see how it would be hokey, from appearances you wouldn't be able to tell the difference between it and a metal intake, and it wouldn't heatsoak like a metal intake).

[pizzazombie]

Yeah, I disagree about the pvc being hokey. As long as it's got a decent coat of paint it'll look fine. I don't have any real suggestions, but I just want to say that you should definitely post pictures of your work along the way. Or at least the end results. I'm really looking forward to seeing it.

[Oh! Snap!]

They pull it in more smoothly and evenly. You can run a velocity stack without a straightening screen and have the same results. They're nothing new and have been around for decades. Bell mouths in an inclosed log type ITB manifold arent increasing the speed they are straightening everything out before the air runs down the intake runners.

MainFrame - It sounds like you have a decent amount of money into your set-up and if your getting custom IC tubing done then you might as well do it right and have a nice correct intake made. It can always be wrapped in a thermal reflective material. Some stuff reflects up to as much a 90%

Just helping you brainstorm like you asked.

---Joe---

[MainFrame]

Yeah, I was considering wrapping the intake tube in that gold reflective tape. I forget what it's called, but that stuff is pretty effective at blocking radiant heat. If I used PVC I was planning to prime, prime, sand, paint, paint, sand, paint, gloss, sand, gloss, gloss.. no one would be able to tell it's plastic.