Got me an Insight...

[samwichse]

P0420 is a cat efficiency code.

Also: I flip the snorkel over like that for the coldest part of winter. But! I find the gas engine seems to have significantly less low-end torque when I do that, possibly do to the loss of the resonator...

[Natalya]

Is the resonator the piece of plastic that normally goes in front of that tube? (The one on top of the radiator.)

[Ecky]

Yeah. There's also a plastic hose that goes down to an air box below the driver headlight. Both are part of the tuned system.

[NoD~]

Before removing the resonator, I did a "butt dyno" difference (just A-B) with and without the resonator. i just simply disconnected and blocked off from the intake tube. I couldn't tell enough difference to justify keeping it. I haven't seen anybody do an actual dyno or anything. Be very curious to see one, if anybody has done it!

Reading on the forums, it seems that with the resonator, there's a few RPM's that get boosted, but some that get hurt by it. I'd have to see if I can dig that one up...

I may give this HAI a try, then maybe revamp it with the resonator box and see what it does.

[Natalya]

Would a possible work-around be sticking an air hose from the cat to the resonator?

[Ecky]

That's what I did over the winter, with some 2" RV ducting. Due to engine vibrations it fell apart after a while, but it worked nicely until then.

[NoD~]

Originally Posted by Natalya

Would a possible work-around be sticking an air hose from the cat to the resonator?

I'm 99% sure it would not. The resonator is a sealed chamber. The tube is a specific size and length to that chamber as well. Intake systems works much like sound, with specific sizes and lengths and such that are most efficient at a specific frequency. The engine RPM defines that frequency. The only consistent thing by replacing that resonator hose with another to anything is the distance down that intake pipe it gets connected, which should be one of those factors. It takes a smarter person than myself to understand it all, though.

There's been dyno tests done with various lengths of intake tubing, finding that the longer, the more low end you get. Finding the perfect length for the perfect RPM bump... not really sure how to do that other than trial and error.

As for my drive this morning, the intake temps didn't get over 85*, so definitely not doing as much as I hoped (my drive is only 3-1/2 miles, though. I did hit full engine warmth in that first mile). The aluminum intake tubing is touching the cat shield, so it can't get a whole lot closer. Maybe take out a hole in the cat shield and having it pull from there?

[Xist]

I do not know how relevant this is, but many people in this thread say they lost power deleting the resonator from their Jeeps. The OP used a dyno: Dyno test....Stock Resonators + MagnaFlow VS Resonator Delete + MagnaFlow = WTF! - Cherokee SRT8 Forum

[NoD~]

Xist... Close! Those are exhaust resonators. We're talking the intake resonator.

[Natalya]

What if you just hot boxed the entire engine bay?

I know this sounds insane, but hear me out:

Get coroplast underbody panels, affix some aluminum foil to them facing up, or buy the aluminum one sold on Insight Central. Then you do what Ecky did inside his front wheel wells, more plastic sign crap in there with aluminum foil. Get some extra weatherstripping for the hood, and switch to an upper grille block + partial lower grille block. Cool air comes in the bottom, only the hot air at the top ever makes it to the stock intake thing. Also maybe use some aluminum around the exhaust to exhaust tunnel gap below the first cat to seal the air in down there. And aluminum foil on the underside of the hood.

I bet you could get air intake temps of at least 120°F and still have the stock intake setup.