Yes, it's cheaper, and that's the word I'd say would be best to describe the value of them. Even if it's the fault of a design flaw, what it takes for plastic to crack and warp is much less than that of a similar aluminum intake. Actually I can't think of ever hearing of an aluminum intake cracking or warping from a design flaw (not saying it's impossible, nothing really is), a gasket yes, but not the intake.

I admit there's performance gains to be had, and when designed right they work and work well (even better with an aftermarket insert), but it will always be an uneasy thought in my mind that a major part of my engine is plastic.

What was the reasoning for the L26's intake change? Could GM not design a plastic intake that was reliable for the L36 or what? I don't know why the choice was made to go aluminum on the L26, though I don't think it unfair to think the problems with the L36 plastic intake might have had something to do with that.

 

This sure is getting to be a heated back and forth conversation with many, many great points.

My plenum cover is simply held on by the oil tube and one screw/cap. If you look in the center of the striping on the plenum cover, there is one screw that holds it in place.

I agree with bumpinMonte tho, when he says that it just cleans up the engine bay a bit. As I stated before, on vintage and classic cars, plenum covers are a ridiculous idea, but with SO many things under the hoods it cleans up the bay, and keeps things covered. My 2008 Mustang is soon to be ROUSHcharged, and the s/c has a flat black painting and won't compensate a plenum, so that car wont' have one. But i can sure see both sides of the story... However in my case, I just don't like the sloppy mess of wires and the dingy color of the s/c on my Monte, so i'm gonna stick with the plenum cover.

My folks have a 2001 PT Cruiser, and if anyone has seen that engine bay, it's AWEFUL! It's nothing but plastic... you can't see a thing! The entire bay is black plastic, and the dipstick, hood prop and the oil, radiator caps are all higlighted in yellow... causet that's the ONLY thing you can touch under the hood. That's quite a sad sight.

Just be glad none of you have a BMW! They lock there engines with plenum covers so that NO ONE can get inside the engine bay. The only way to get in, is to bring it to the dealership!

 

IMO, that's an old school opinion of new technology. More performance, lighter weight, less cost- as long as its engineered properly, there is no problem at all- its a win-win. Plastics are the way of the future, and there is no reason why an intake manifold has to be made from any kind of metal.

That's what I mean- even metal intakes have design problems which make them cause problems- it all boils down to how well engineered the part is for the application.

I imagine it was something people though too when they went from iron intakes to aluminum- its going to be a fact of life, and they're just becoming more common every day.

No idea- I'd personally bet the EGR routing posed the biggest problem. The heat from the engine alone is something the plastic can tolerate just fine- but exhaust gases can get pretty hot. No idea why they didn't try and design it differently- I'd imagine they found the design flaw on a 10 year old engine that was destined to be scrapped soon- and wanted the quickest and cheapest solution.