I decided that I wanted to install a heat shield of some sort on the under side of the intake manifold. I'm not looking to get every ounce of power out of this 350 I'm working on but still want to try many different things to see how well they work for future builds. If it works well and in the process increases power so be it but in the end it is only a short cam low rpm 350 so there are limits. What I'm really looking for is as much effeciency and tuneability as possible with the side effect being power.

The performer 2101 aluminum dual plane intake looks to be a very effecient absorber of heat. The entire lower intake tract is fully exposed to all the hot oil splashing about in the lifter valley. It will dissipate it well also (right into the intake charge) but if it absorbs less then it does not have to dissipate as much either.
The shield I came up with I hope will help to keep the intake charge cooler even if only marginally. The sheet metal should absorb the heat from the large oil droplets striking it and then radiate that heat off of it's surface hopefully to be carried away by the various air currents in the lifter valley. That's the idea anyway.
I needed to come up with a way to attatch the sheet metal to the manifold without creating a FOD hazard to the engine internals should it come loose. I decided to use a bolt through the crossover heat and another through the water passage into the area just below the thermostat. The one in the crossover is red locktited in place. I then used large washers to support the sheet metal and welded them to the bolt so should something come loose it could not fall into the crank area. I have some concerns with a piece of the weld popping off and getting jammed somewhere but don't know how to avoid that other than insure that it has decent penetration to keep that from happening.
Here some pics of what I did. Not installed on the engine yet, still thinking on it.

If anyone knows of a good way to fasten this thing that I'm not using and known to work I'm looking for a better way. No real confidence in epoxy's, at least any I know of, staying put, pop rivets could possibly come loose and vibrate out. Don't think brazing would penetrate but I've never used it so open to opinions on that. Would rather insulate it with some expandable foam then how to seal the foam? Porcelin coating to many $$.


Underside of intake.
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This weld worries me a bit.

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many companies sell a lifter valley cover already made. i would worry about that shield for a number of reasons

 

I spoke with a company that makes the lifter valley cover and none are made to work with roller cams. What are your concerns with this shield? I'm open to input.

I'm not really happy with this design yet. I'll need to tweak the attatchment points to something more secure. The weld looks like cr*p too.

 

i would be concerned with it interfering with the valve train. i think a flat piece of thicker aluminum would be better and really just needs to be under the plenum and doesn't need to cover every square inch. with a single plane or an air gap you don't need it. on a street car i think its a waste anyhow. i would never drill a water passage in an intake locktite or not, aluminum can crack and then you have real trouble real fast.

 

I bet it holds just fine who cares how it looks you cant see it

make sure the pushrods and lifters dont touch it.

 

I did consider what you suggested either aluminum or steel. My concern with that is that the plate would vibrate at certain rpms and put a lot of stress on whatever attachment points I had and that may cause it to crack the intake at those points. With the thin steel sheet it can flex and vibrate and twist to absorb the various frequencies at different rpms and not put stress on the intake itself. The shield does not extend to either edge of the intake just the center section. I contoured it so that it could push against the intake and not just flex up and down on the long sides.

Neither of these fit under my hood.

Many would share your opinion, I do not. It is quite hot under the corvette hood. Any effort to cool the intake charge is worth consideration to get a more consistent running engine at all temps.

I drilled a hole into the crossover heat and that has the loctite to secure the bolt. The crossover heat is going to blocked off. There is a nice large boss just below the thermostat housing. The metal through that boss is about 1/2 inch thick. The bolt through that boss is not under significant torque and has thread sealer on it. Cracking while a possibility is remote I think.

Clearance is more than adequate with push rods and lifters. Lots of room under there really.

All of your points make good sense and I've considered many different options. So far this is the best I've come up with.

you're right of course doesn't matter what it looks like. May try to get a better weld just to put my mind at ease.

 

i think it is an interesting idea.....as you say every little bit helps.
if its a new manifold , you could possibly weld some aluminum round stock to the underside , then drill and tap for attachment of the shield.

 

Not a bad idea. I may have to look into that. I don't know much about welding cast aluminum. I know cast iron can be a real pain.

 

i guess i'm lucky..........my brother is a very good welder,he used to work at a power plant,my dad ( who is 86 ) is also a great welder,he can weld cast iron and magnesium, he welds stainless and aluminum like i weld steel.compared to them i'm an underachiever

 

I made and installed one long time ago. I used a piece of galvanized vent pipe that I cut in half and shaped around the ports. (The half round came out nicer than yours, but as noted, no one can see it.)

I don't recall if I tapped it or used JB Weld for front and rear bolts to hold it in place, but once it's in place, there is really no where for it to go as it wedges in fairly tightly.

I've never had any interference issues with a hydraulic cam.

 

That looks fine. I would make another though and start with a cardboard template and get it tighter around the port areas.

 

So do you think it did anything for you? There is probably no good way to measure that other than dyno runs or a temp probe in the intake tract.

These ones are closer than shown in the pic I actually bent them in a bit thinking if I left them out they might flutter against the intake ports on the heads and chaff some aluminum away.

 

The only way dyno runs would tell is if they were immediately back-to-back.

But........

Couldn't hoit!

Don't forget to block your intake manifold crossover pipe or this is all for naught.

 

Yes for sure that will be done.

I had planned on using a thin piece of aluminum sheet metal a little bigger than the hole in the head, to do that. Does it matter if it's on the head side or the manifold side of the gasket? I figured on putting it on the head side since that's where the heat is originating from. Securing it in place with some rtv then sandwiching it in there with the gasket. The metal pieces that came with the manifold gasket are just restrictors not a solid piece of sheet metal.

 

It will work and it was a common item 30+ years ago before the rise of the aftermarket.

http://www.speedwaymotors.com/Small-...affle,584.html

 

probably would do more than the splash cover.

 

It will at least cause no harm. For a scratch-built unit, it's a pretty good effort.

There's not a lot of splash going on in the lifter valley. Most of what's happening there is oil misting from crankcase blow-by and general air movement in the crankcase.

Valley trays were to help divert crankcase vapors to the road draft tube in most of these applications and, later, to make crankcase evacuation through PCV systems more efficient by trapping the heavier oil drops before they reached the PCV. They seem more common in engines with more volume in the lifter valley.

Factory intakes also use a shield under the heat crossover under the plenum. This isn't to keep oil mist from reaching the heat riser -though it no doubt does make a contribution there- but to contain coked oil and keep the carbon cinders from falling into the valley.

Aluminum has a specific heat value twice that of cast iron. This means that it conducts (and radiates) heat much faster than iron. As far as manifold heat goes, an Al intake will come up to temperature much faster than iron, making the heat riser super efficient on cold starts. It also makes the heat riser less necessary in the moderate climates due to the speed it will absorb heat from the rest of the engine. Oil temperature is usually not significantly higher than the heat in the engine so most of the heat in the intake would be there regardless. BB Chrysler and Pontiac used "air gap" intakes from the factory and those got hot as well. So it's not the oil doing a number on the intake that you're going to see some substantial improvement.

Again, a good effort.

 

I installed one of these many years ago when I switched manifolds. I'd forgotten all about it.
Duane