Air intake plumbing for 5.7 hemi?


Well-Known Member
Motor is mildly built (cam and heads w/ large valves). Current intake is an open element next to the pass side fender on 4" alum tubing back to the TB.

Struggling with heat soak when the temps rise into triple digits. Truck runs fine while moving but, in triple digits when I get slowed by a semi or mtn areas where I'm slowed to a crawl (think loreto - mulege), she'll start burping and requires less rpm and less throttle input until i'm at a crawl and have to pull over to let heat out of the engine compartment. I had the tubing wrapped in thermal wrap with no benefit. This last trip, I wrapped the tubing in tshirts and soaked with water to help with the heat and this often helps temporarily.

I intend to louver the hood and open it up a good bit to try and get the engine compartment heat out. Hoping this could possibly make a good difference. I have no cowling at all so there's a lot of room for the heat to get out in the back of the bay when I'm moving but not so much going slow. The fender liner is trimmed away so that the open pod position gets some fresh air but mainly when the truck is moving and it's a little too high in the engine bay. My plan is either to replumb the intake to a lower point like further down the fender to grab more fresh air or potentially use a canister with a fresh air scoop, which I'd prefer.

A couple of the questions I have are:

1) is 4" tubing enough to support the motor or should I step up to 5" for some built in overkill.

2) will a single UMP canister flow enough for the motor? I don't think I have room for the 20x10 (5"in/4"out) but could possibly open up/notch the hood to allow it to sit up a little higher. Kartek suggested that the 10905 8x14 (4"in/4"out) would probably be sufficient for it as well but this seems small.

The open element has always worked super super well for the most part and where it's currently located, doesn't get overly dirty when combined with a prefilter. Moving it forward and lower into the fender area will expose it to more dust / dirt / water which I'm not really wanting to do.

The only other possibility is to try and make a custom divider to block some heat. I can't run stock airbox stuff (or aftmkt replacements) due to the upper shock mounts and I have no original intake parts. I also thought about wrapping the tubing with the heatshield insulation to lower the radiant heat onto the tubing or use silicone hose for some insulation properties.

Any thoughts would be great.
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jon coleman

Well-Known Member
a cheap quick fixx i did once is put spacer blocks on hood hinge to hood mount to lift rear of hood to let trapped heat out, 3/4- one inch worked really good.i think ' custom' air box is in your cool..