Proven: in materials of the same thickness, plastic transmits heat quicker than metal. Add to this the fact that a metal intake tube will most often be twice the thickness of plastic, and you begin to see the problem. Thinner, lighter plastic will (and does), eventually crack on the seam. I've seen tons of radiator overflow and windshield washer bottles with cracked seams - and they don't even sit on top of the engine where the intake will be...

The stock HHR engine cover was not designed for performance, so we're talking apples and oranges here. It was constructed plenty thick to prevent cracking and is surely durable enough to last almost the life of the car.

Of course, it doesn't provide peak performance either, and that is the point of installing an aftermarket intake...(insert name of whatever brand you prefer here). :lol:

Get em Howdy.. some people live in fansty world... and should stick to the sales world.. and leave the technical aspect to people who actuall work in the engineering / manufacture world..

that will probably put the cost over 300.00 to add that deflector..
will the costs ever come down ???
it should go for 200.00 lets hear it for $200 for that system

I'm not taking either side, but I see lots of plastic AND metal parts inside the engine compartment in that pic. Can't either material be suitably engineered to perform a specific job reliably?

Ths all started over a discussion about heat and cracking.

From a quick Google search (all "Heat Resistant" parts too):

From Lexus Owner’s Site:

I have an interesting problem, for about a week now my car has been running hard. It initially sounded like road noise coming from the tires. However, the noise (engine) is so loud that it sounds like I am riding in a jet airplane. I thought it was the spark plugs so this past weakened I changed them out. When changing the sparkplugs I notice that the plastic intake tube has a bad crake in it. The car idles perfectly and it is not throwing any codes. After the change of spark plugs there is no difference, still the same load noise coming from the engine. It feels like the car is losing power after 40mph, it shifts perfectly and at high speeds the rpm never goes over “3”.
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I have experieced the same problem with our Crown Vic. The car only has 70k miles and a cloud of white smoke comes boiling out from under the hood. It turns out it is a crack in a plastic intake manifold that has a coolant bypass tube molded in to it. It is clearly a manufacture defect I mean who ever had an intake manifold to crack like that before.
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Consumer Complaint 1999 Buick Regal:
Component: ENGINE AND ENGINE COOLING:EXHAUST SYSTEM:MANIFOLD/HEADER/MUFFLER/TAIL PIPE
Details: THE PLASTIC INTAKE MANIFOLD MELTED BETWEEN EGR PORT AND WATER JACKET. THIS ALLOWED COOLANT TO FLOOD THE MOTOR. THREE WEEKS AFTER THIS $1200 REPAIR I SPUN A ROD BEARING $2700 LATER.
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1997 grand marquis-plastic intake manifold cracked
ford moter co knows about this problem.the repair kit has an aluminum crossover section on the intake manifold right where the plastic one cracked.
the repair cost me 940 dollars.i havent received any information but i think there is a lawsuit pending. i would appreciate any information you may have
about this.
I own a 1996 Mercury Grand Marquis. While out of town the plastic intake manifold developed a 3 inch crack behind the alternator. This has happened on many vehicles that ford has made including the crown vic's, t-birds, mustangs and others. Many of these were replaced without charge and unfortunately not mine. They say it is a vehicle specific process. What does the vehicle matter if it is the same motor, same intake. cracking in the same place.
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My intake cracked on my 97' GT about 3 months ago, about 2 weeks after I bought it.....Go Figure.... I bought my intake from Advance Auto parts it was like $289.00 with the Alum. front but the Ford dealership wanted to put a complete plastic one back on it and charge me $589.00 for it plus $310.00 for labor.
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Ford has lost a class action lawsuit dealing with the Plastic Intakes on certain Models. The following link will break it down by the Year and Vin numbers:

http://www.fordmanifoldsettlement.com/index.html
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Got some possible bad news...At Perkins Chrysler in Crestwood Ky. That is just to the easy of Louisville....They have had three PT Turbos in the past two months with cracks in the Plastic Manifold. The craks are occurring where the lower bolts up to the upper part of the manifold. There are metal o rings that are in the plasice and the cracks are occurring around the o ring...These were all 2006 modles. Might want to keep an eye on this....apparently it is causing a slight vacuum leak that causes the check engine light to come on....
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But don't mind me...I'm just a "Sales guy" who's "Making things up." :lol:

That is what happened to my HHR. Where the bottom bold is the whole thing was borken right off. I'm still waiting for the replacement. Only about 1 week away now. Been waiting for 3 so far. I Know it's not the intake, but air box. I hate all the plastic on cars now days.

A few people complaining about isolated problems on older model cars is proof? :lol: Look at how much plastic is used in your engine and that should be proof that plastic is safe to use without any worries. ;)

Ya but that was the first thing to "F" up on mine was the Plastic.

But how many other HHR owners have had the same problem? I have never had and problems with plastic parts on any car I have owned. I see plastic used for many high heat applications on a daily basis. This whole metal versus plastic debate is crap. If you research it you'll find that plastic is better suited for the job.

Where is this proven? Perhaps you should specify the TYPE of plastic and metal that this was proven with as well. It's all relative. You've stated you have lab results. Why not link em?