Plastic Parts..

[toocrazy2yoo]

So, if GM fitted a plastic intake manifold to certain of it's V-6 engines, causing considerable trouble at some point in the life-cycle of these cars, how does Hyundai square the use of plastic/nylon/whatever cam-covers on their 4-bangers? My 92 Elantra's cam-cover was Al. Why plastic on the newer ones? Not sure when the practice started, but the "new" 05 Accent GT I bought this winter has plastic. I may have asked this a long ways back, but didn't follow up the question.

Should I expect leaks in the near-to-distant future owing to the non-expanding plastic vs. the expanding aluminum head? Something has to give on the plastic cover through fatigue at some point, yes? No?

 

[punisher]

Not really. Plastic is used because of NVH concerns as well as reducing cost and weight. I have worked on countless engines starting in the late 80's that used plastic valve covers and haven't noticed any more problems with leakage as compared to aluminum covers. Certainly less leakage than stamped steel covers.

 

[labman]

Most plastics expand more than aluminium.

 

[T-Keith]

Most major car companies use plastic intakes now. The 3800 intake problem does not effect every one and newer ones have it resolved.

-T

 

[Tosh]

If you don't have a grip on QC, it doesn't matter what material you use: steel, aluminum, titanium, carbon fiber, plastic, whatever, it's not going to last. Conversely, with proper design and QC, you could make it out of wood...

 

[Kestas]

Cost, weight, NVH, life, ease-of-assembly, able to do the job, underhood appearance - these are just some of the considerations when designing an intake manifold.

I believe the popular plastic intake manifolds are glass-reinforced nylon.

 

[Dark Jedi]

they have a plastic intake manifold on the DODGE 4.7L V-8. never had a person complain about a leak or anything. I have had my 4.7 dakota with the plastic intake and either plastic valve covers or are the composite. I cant remember but anyways never had a problem with them and had the vehicle for almost 3 years.

only thing is watch how you use nitrous. seen a guy blow his in his dakota. guess they cant take a big shot lol.

 

[JTK]

quote:

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Originally posted by toocrazy2yoo:
..Should I expect leaks in the near-to-distant future owing to the non-expanding plastic vs. the expanding aluminum head? Something has to give on the plastic cover through fatigue at some point, yes? No?

---

On the GM vortec 4.2L I6, the cam cover and IM are plastic. GM advertizes the cam cover as "full floating" where any fastener bolts are mounted through, but not to the cover. I'm sure it all boils down to cost. All aspects of the plastic are less costly.

Joel

 

[Master ACiD]

they can take as big of a shot of nitrous as any other manifold. the problem is when you get a nitrous/fuel backfire. that usually blows the manifold up. the only problem is that it usually blows up aluminum ones too.

 

[Matt_S]

quote:

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Originally posted by T-Keith:
Most major car companies use plastic intakes now. The 3800 intake problem does not effect every one and newer ones have it resolved.

-T

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Yeah, they resolved it by going back to Al.

 

[Audity]

Porsche has been using plastic intake manifolds on their flat-6's for quite a while (no, I don't have one...) I don't know it they use them on the twin-turbo versions.