[ds968]

The hoodliners I had on my 944 ( a pure foam one first, then a silver "reflector shield" faced one ) caused the temps in the engine bay to surge, at least one full bar higher on the temp guage. So the first thing I did was to rip off the liner on the 968 when I bought it, but I understand they SHOULD have just the opposite effect, actually pushing the hot air trough the bottom of the bay, leaving the entire enclosure cooler <img src="/forum/images/smilies/968/blink.gif" class="smilie" alt="" /> I'm thinking about putting one back in, but puzzled by the reason behind what will undoubtedly be the same hotter temp reading, as was the case with the 944... ? Is the sensor picking up something which has little to do with the actual operating temperature of the engine ?

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[Lim Yong]

Didn't think the 968 have hood liners....I am also interested in the answer. Does a hoodliner reduce/increase

under hood temp?

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[ds968]

[quote name='Lim Yong' post='55759' date='Jul 2 2008, 08:31 PM']Didn't think the 968 have hood liners....I am also interested in the answer. Does a hoodliner reduce/increase

under hood temp?[/quote]



The P.O. put one in.





May be it depends on the type of liner you get ( not sure there are all that many choices out there to begin with.. <img src="/forum/images/smilies/968/blink.gif" class="smilie" alt="" /> ) , I think their primary purpose is to muffle engine noise so the engineering may not at all factor in the heat effect <img src="/forum/images/smilies/968/unsure.gif" class="smilie" alt="" /> But again, if these silver faced ones act in the same way as the windshiled sun screens the heat is pushed down into the engine bay and flows out while driving... or does it ?! Sure as heck did not on my 944.

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[Lim Yong]

Wonder if the increase temp under hood also increase engine temp? do you notice with the temp gauge?

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[SILVY968]

the black hood liner dampens hi freq noise and is supposed to lower hood temp.

my 968 seems to be cooler running, but I have not measured.

The hood liner is very warm after a fun-run, whereas the metal hood was less warm before the liners went in.

Brian

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[Larry Currie]

where did you buy you buy your hood liner?

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[ds968]

yes, it does lower the HOOD temperature.. so it that sense it may protect the longevity of the paint, definitely a plus there, but I'm focused on what it does to the engine bay below and the engine's operating temp.. which in my case was reading substantially higher.



Performance Products ( ex-Automotion ) used to carry the liners, custom cut for the car and IIRC, Autoanything.com also had them..

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[gryphon]

The hood liner is an insulator, and as such will not lower engine compartment temperatures.



Tom

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[SILVY968]

[quote name='Larry Currie' post='55795' date='Jul 4 2008, 06:46 AM']where did you buy you buy your hood liner?[/quote]



Larry,



I bought it at Jager Engineering. They have lots of cool stuff.



http://jageng.com/garage9/product_info.php...6ca9936b5b8fb6c



Here is what they saw about the liners:

"These heat shields will hold up much better than the OEM hood pad, keep the exterior of the hood cool and will not reflect engine heat back down toward your intake."





Brian

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[ds968]

Brian, thaks for reminding me about Jager, they do have fun stuff.. <img src="/forum/images/smilies/968/smile.gif" class="smilie" alt="" /> I just ordered the blue LED gauge kit for the instrument panel.



Still on the fence about the hoodliner though.. I know they claim it does not increase heat on the engine, but I'm not so convinced... yet.. <img src="/forum/images/smilies/968/blink.gif" class="smilie" alt="" />

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[flash]

ok - i'm puzzled - i love the idea of deadening the sound, but the heat thing has me perplexed and concerned



how can something keep the exterior of the hood cool, while not reflecting heat back down toward the intake? it's not like the heat is coming from outside - the real source of heat originates from the engine - the hood might possibly see a max of 140 degrees if it was baking in the hot sun and was black - underhood temps though can easily go over 200 degrees

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[SILVY968]

wild guess...

the dark liner material absorbs the heat and radiates it to the air slowly. The lid is cooler, but only in some spots as the liner dissipates the heat over the entire surface area.

My engine does run a bit cooler on hot days when I run it up at 4-5K most of the time.

Even if it does not get rid of heat, it certainly does not make the engine compartment hotter.( as far as I can tell )

It does add a deeper tone to the engine sound and it does keep hood paint in better shape.

Brian

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[flash]

i'd love to conduct some tests (pardon the obvious pun)

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[ds968]

deeper tone to the engine ... hmmm, that's not a bad thing, especially for those of us with the air box mod which generates a very slight but still audible pitch at wot. a more muffled tone could be an improvement.



back to the heat ; there was no mistaking the silver faced liner being solely responsible for increasing temps because the very moment I ripped it off, the temp gauge dropped by an entire bar, and stayed that way.. I don't recall the exact effect of its predecessor ( the simple black foam one ) but pretty sure that one raised the temps also. However, technology of the materials used in these new shields is probably so advanced by now, they

may indeed have found a way to deal with the heat distribution <img src="/forum/images/smilies/968/blink.gif" class="smilie" alt="" />

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[flash]

insulation layers should keep heat from penetrating them - that's the job - that's good - an insulation layer on the underside should prevent heat from the engine bay escaping through the hood - that's bad - if it stops sound from escaping, it probably stops heat too



i've been playing around with heat sheilds and such lately, and have had some successes - choosing materials and locations has been critical to that success - i'm doing more this week



i love the idea of reducing sound, and hood liners do a great job of that - i just lined the hood of the denali with dynamat extreme (lain in between the factory foam hood liner and the sheet metal - did great things for the noises - but i would not do this on the 968 at the expense of increasing heat that i've been working so hard to reduce



as i said, testing and measurement required - should be easy to tell though

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[Lim Yong]

Bump...any results???

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[flash]

i haven't had any on the hood liner, as i have not done it, but i am getting good results from the new heat shield and header wrapping



i'll call brian and see what he has noticed

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[jimmywhisker]

[quote name='SILVY968' date='Jul 5 2008, 04:46 PM' post='55837']
wild guess...
the dark liner material absorbs the heat and radiates it to the air slowly. The lid is cooler, but only in some spots as the liner dissipates the heat over the entire surface area.
My engine does run a bit cooler on hot days when I run it up at 4-5K most of the time.
Even if it does not get rid of heat, it certainly does not make the engine compartment hotter.( as far as I can tell )
It does add a deeper tone to the engine sound and it does keep hood paint in better shape.
Brian


Brian,

You have now had these for a couple of years now. How have they held up and would you still recommend. I really don't like the effect of the heat on the paintwork but definately don;t want increaed engine bay temps. It can get pretty hot here in summer.
Thanks,
Peter

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[DayDreamer]

+1
I have a set of the Jager liners sitting waiting to be fitted, but am a bit unsure as we have very hot summers and hot winters. I'm also curious on the long term use...

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