I read someone saying that by removing the hoodliner/heatshield from the hood, it reduces engine temp. by 20 degrees? Is this true? I do see them removed in car shows a lot. Is this for temp. reduction or looks? What's its factory purpose? To reduce sound? To protect the paint on the hood from the high engine temperatures? Before removing it I just want to double check with you guys that there is a benefit and hopefully no harmful consequences. Is it even worth it? Thanks in advance.

 

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Leave it on there. If you have an engine fire, the plastic fasteners that hold it under your hood will melt, allowing the fire blanket to fall onto the engine, thus smothering the fire. It's not worth taking off...

 

Are you serious?! Is that what its purpose is? A fire blanket? I had no idea. Thanks. Anybody else have an opinion on this? Thanks guys.

 

someone said something about it ruining the paint on the hood too. is this fact or myth? thanks

 

i believe its a myth... the hood thing is only to extinguish a fire to the engine... the plastic pieces the hold up the heat shield melt and the heat shield falls on the enegine... stopping the fire..

 

I'm the one that has recorded a reduction in intake temp by 20 degrees. The shield is a fire blanket. IMO, I'd rather let my car burn then have the fire blanket save it. Damaged electrical systems are nearly impossible to fix right. I'd rahter the fire just total my car. Hopefully I'd be out of the car when it happens though.


Dave

 

very very good point. i like that idea, i'll take mine out tomorrow morning.

 

Thanks for the responce. ) So you are the one, huh? May I asked how you measured the two engine temperatures (with and without the heat shield)? Same conditions with the only variable being the shield? Multiple tests? So have you had yours off for a while now? Is the engine noise louder? (either in or out of car). No visible destress to your hood paint? Is it easy to remove? Thanks again.

 

I just took my heat-shield off. Started the same. Revved the same. Drove it. It sounded a taad bit more powerful under WOT, but pretty much all normal under regular driving. The car seemed quicker, but maybe that's just in my head.

How in the world, under daily driving, could your engine catch on fire !? It's just not gonna happen. Every car nowadays has the overheating sensor, so if the max did over heat, just turn it off and pop the hood. Thats all normal.

I have seen cars w/o the little engine blanket.

Dave is right. If the engine ever did catch on fire, the electronics would be ruined, and the engine would be a total mess anyways.

 

I totally agree with you Craig. I'm not overly worried about the blanket not being there 'IF' my car were to catch on fire. I just want to know if there is actually a benefit! Does the engine really run 20 degrees cooler???!!! I asked Dave to explain in detail his measuring proceedure and he never responded. As far as I know, he is the only one who has mentioned this 20 degrees. I don't suppose you did a before and after temp. reading, did you? Anyway, Dave if you could respond, that would be great. If anyone else has done their own measuring and can respond, that would be great. If it does in fact lower your engine temp, I will do it, I just don't want to do it for nothing. Thanks guys.

 

Hood COULD become discolored in different areas

 

No, I doubt it. I drove for about 15 minutes and it was fine. The hood wasn't any hotter at all, and the paint was absolutely normal. The blanket is a very thin fire-retardant material. I Highly doubt it will discoler.

Ptatohead, I didn't do any temp. checks before/after, but It did seem to be a little louder(more powerful sounding) at WOT, and was pretty normal at normal smooth driving. I could'ove sworn it felt a tiny bit more quick, but that might be do to the sound.

Overall its not a big deal. My mom has a Dodge Caravan, And my dad a ford explorer. They don't even know if they have a "heat shield". Last time I looked I didn't see one either.

Your engine is to complex and technology is at that point today(and in the maxima's) that it would let you know if your engine got even the slightest bit hotter.

Take it off. See for yourself. Once again I sware it feels a lil' different. Just do it. If you feel paranoid, just go down to your local nissan dealer and order another one for like 10 bucks. Hope this helps!!

 

I have seen a few burnt out cars along the highway here in Memphis, including what appeared to be a brand new BMW Z3. Judging from the burn patterns on these vehicles, all the fires seemed to have started in the engine bay, then spread to involve the passenger compartments. I don't know whether fire blankets helped prevent even worse damage to the cars and/or injury to the drivers, or not.

The point is, if a car is going to catch fire, it seems it is likely the fire will start in the engine bay. It's cheap insurance to leave the fire blanket in place, just as is wearing a safety belt, changing engine oil every 3,000 miles, or stearing around roadkills! The benefits must be significant, else the car companies would delete the fire blankets to cut cost.

The fire blanket also insulates the hood from engine heat, protecting the paint on the hood. Yes, it may trap some heat in the engine bay, but I wouldn't think a significant amount of heat will build up, especially with a car moving at speed. The engine is probably cooled more by radiator fluids than by outside air anyway... Good luck.

 

I will continue to keep a close eye on it. Maybe when I am driving for a longer period, I can then see better. I bet it's a "just in case" thing for nissan. They are probubly very cheep to make, and add very little to the overall cost of the car. They are no big deal.

Nissan doesn't use any cheap-*** paint on their maxima's, either. Any maxima owner knows this.

Dave has had no problems what-so-ever with his paint. And like I said, I don't even know if my parents have any fire blankets in their engine.

Bottem line is if your paraniod about it, don't do it. My car will be fine, though. And if I do get **** about it, like I said I'll go down to Nissan and buy another for a few bucks.

Thanks and keep the questions/comments commin!

 

I've had my car on fire before. One was my couch cushion burnout, and another was when my stereo wire shorted but the fuse saved it (on my old car). Another function of the hood liner is noise absorption from the engine. Its probably pretty insignificant though. But as for my old camry, which did not have a hood liner, over the exhaust manifold the clear coat got faded. I suppose if you wax and wash regularly which I'm sure most everybody does on this forum you should be OK. Also that car was a 1990, so I'm sure paint formulations have gotten better over the years too.

 

Told ya'll!

 

That's a 1990 Camry, bro. 5 years prior to my car. I dont think Nissan would use ****ty 5-year old paint, especially on their flagship sedan. Nooooooooooooo my brotha.

 

**** O.k., I still just REALLY want to know if there is in FACT an engine temperature reduction. I was also hoping there would be no noise increase but you say there is. I also want to know that the paint will not get hurt. It probably won't. I don't really fear an engine fire so that isn't an issue. Like I said I just want to make sure there is no paint damage and there is a heat reduction. Also, what do you mean run down to Nissan and order another?! Why can't you put the same one back on?!?! Thanks Craig.

 

Did you guys know that this HEAT shield could possibly be keeping your engine cool from the sun beaming down on your hood when sitting? Think about it, this heat shield could be more than just a fire extinguisher. I think taking it off has no effect of making the car run better or keeping the block cooler.

Dave B, have you done any testing(I am sure you have but I would like to see numbers if you have them)?

 

You can't compare the heat from the sun's rays hitting the top of your hood to the internal heat produced from a running engine. Besides, you want your engine cooler while it is running, there is hardly a benefit to keeping it cooler while it's parked. If anything, it would be beneficial to keep your engine warmer longer while it is parked as cold starts are one of the worst things for an engine. I don't think that's an issue to worry about.

 

Good point. I just got back from the movies(Damn Rush-Hour 2 is funny. Anyways here is the complete and final truth now that I have suffecient experiance:

There is no noise increase when driving normal or a little bit speedy. Only when really pushing it hard you can here the engine's powerfullness just a taaaaad more. Kinda like addin' more icing on the cake.

Now for the paint. Like I said Nissan wouldnt use some ****ty @ss maaco paint. Like most car's nowadays they use quality paint. It has been fine and will be fine. And I will wash it regularly and wax it every-now-and-then so it will be better than fine.

Now for the Speed factor. I think that taking the shield off allows a LITTLE better ventilation. But damn it's hard to tell with a Maxima. Their so fast it's hard to tell little increases.

So, do what you gotta do. But, I, and my Maxima, will be just fine.

PeaCe

 

The heat shield is made to block heat. It is not a good conductor of heat, therefore resisting heat and I believe it acts as a type of insulator for the hood to resist outer heat from entering the engine bay also. If heat will build up in your car from sunlight, what makes you think it can't have the same effects under the hood? If you took off your roof paneling from the inside of your car do you think the inside of your car would get hotter than if you left it there? I definitely think so.

The only way to get cooler temperatures under the hood is to open you fenders with more ventilation, run a bigger radiator and run a lower temp thermostat.

 

Deezo, That aint a new car for you, is it ? (Your Sig Pic)

 

I should leave you all in suspense.

 

OK, nobody flame me, but quite honestly the Nissan paint blows. How many here have complained about the chipping hoods and other stuff like paint that doesnt match cause of the thin nissan paint? I wouldnt be surprised if when brand new the Toyota 90 paint is better then my Nissan 97 paint. Even after 12 years in the sun, outdoors, and not always waxed the Camry paint is not bad (and its got 185,000 mi on the clock). I wouldnt take a chance with the Nissan paint especially if you plan to keep that car for a while.

 

Deezo, all you did was repeat yourself man. It's as if you didn't read what I wrote. Once again, you can't compare the sun's rays to engine heat. The sun will heat your engine bay up to maybe low, low 100s, your engine will cause the temperature in your engine bay to be hundreds and hundreds. So, I don't think the sun could ever possible do any damage to your engine with the heat shield off, trust me. And, once again, it would be better to keep your engine warm while parked! And to answer your question about if your interior can heat up, why can't the engine bay, the answer is simple. Glass! It's called the greenhouse effect. Trust me, your trunk will not be nearly as hot as your interior on a hot, sunny day. so anyway, I don't think that would be an issue. I am worried about the paint though. I also am dying to know if there really is a temp reduction. If I don't hear from Dave I guess I'll try it myself and report back to you guys. Mom won't notice her oven thermometer missing for a few hours - lol.

Also, Craig, you never answered me. Why can't you put back on the old heat shield?

Thanks guys. Have a great night.

 

Oh sorry bout that bro. Those little plastic peices are a ***** to get off. I broke the thin little "shield" into 3 peices before getting it off. That's why I'd have to get a new one

Damn seriosly though, this shield is VERY thin. It probubly does a good job retarding flames, but it seems way to thin to have any effect on your outer paint, at all. Unless the fibers are some brand new technology (95, Car, (I dont think so) )

So anyways everything is a-o-k for me, DAVE needs to respond. Keep me informed,too, ptatohed!

 

i belive Dave tested it with a air flow tempeture meter...i can't remember what he said for sure...as for the paint his paint is perfect on the hood and i think he had it off for like 2 years or so not sure.....dave knows what he is talking about....good guy...wont' lead you wrong...
later

 

**** That's great! Thanks so much Dahnrman. I think I'll go for it. I'll do a temperature test myself and let you guys know what my results are.

Hey Craig, are you sure it can't be removed in one piece? Looking back now, do you have any advice for someone wanting to keep it all intact?

Thanks so much.

 

you know, I'm still pretty young, and I'm at the point where I kind of argue with most of the things my dad says. He has this one phrase that he always repeats to me if I think about "modding" a car. He says "Nissan made (whatever I'm interested in modding) for a reason, and they've done studies on it and it's effectiveness."

While with some things I disagree, this underhood heat shield seems like it makes perfect sense why it's there. I agree with the person that said it wasn't really worth it to take off. Think about it...yes, you probably do get a reduction in heat temp. in the engine bay, but it's still the same amount of heat being generated, correct?

so if the hoodliner was removed, the amount of heat reduction reduced (20 degrees, right?) probably got distributed throughout the engine hood. I read that there wasn't a noticible difference at all when the hood was touched after 15 minutes, but isn't it possible that over time (a few years), the quality of the hood paint would be worse that that of a hood with insulation under it?

man, it's getting really late at night right now 2:30am, but I just want to make my point that there probably is more good in just leaving the hoodliner the way it is. Personally, I added an extra layer of heat shield insulation (foil backed) under that, and I noticed a good difference in sound reduction (I'm an audiophile). I wouldn't take a risk to ruin my paint (any further, ha ha) in the course of a few years. But simply, wouldn't you just feel a lot better if you had that nice blanket protecting that super microscopic thin layer of clear coat? (espeically on those 95-96, sheesh)

 

Originally posted by ptatohed

Dude, stop trying to start a fire. I read what you wrote and it doesn't prove anything thats why I asked for Dave B to post his numbers so I can look at them. I know Dave has it together and we have conversed in the past so I'll believe it when I see the numbers. I DON'T believe it does anything for performance and I think Dave B did this because of his Pop Charger dragging in the hot engine induced air. He also designed a sheild for the Pop charger to block the hot air.

I have been in the midwest in the summertime. Prove your point on this. I have a temp gauge that says my underhood temps have gone up to 130 degrees by sitting in the sun, on hot days while I am at work (about 9 hours).

???????? If you are looking for more power, the engine releases more power when its cold. I thought you knew that?

I disagree. I have gone into my trunk and it has been hot as hell in there. So the Greenhouse effect doesn't effect steel enclosures huh?



I would like to repeat myself again, the only way to get cooler temperatures under the hood is to open your fenders with more ventilation, run a bigger radiator and run a lower temp thermostat.

 

Ptatohed, all you have to do to take them off is pry REALLY hard. They pop right out. I was just impatient and dumb and ripped some of the insulation.

I have had it off for 'bout 3 days now, and have noticed no difference in the paint. It's not gonna do anything to your paint. Keep waxing it regularly and it'll shine just as good as ever. No dis-coloration at all.

I live in central florida, and my max is black. When I pull up at school at 8am, and get back to my car when school's over at 2:40pm, DAAAAAMN my whole car is like a sauna. But that's becuase I live in Florida, its summer, and my car's black.

I live 25-35 minutes away (in traffic) from my school. Today I went to school, back home, and back to school. (I felt "sick" ) Anyways, I popped the hood and everything was normal. The engine gets too hot to tell just by feeling.

But anyways, Nothin's gonna happen (for the worse) if you take it off, unless you get a fire which will never happen under everyday driving, and doubtfully under any other curcumstances.

But anyways, it is cheep insurance and if I had to do it all over again, I donno what I would do.

But my maxima is as quick as ever. Man, what a great car.

 

so what is the verdict? is your max running a little better now or what ? cause in my maxima theres huge difference in performance beteween a crisp cool morning and a 95 degree afternoon, 20 degrees would be noticable in my car . if just a little.so if you had to call it , just in the head ? or a little something extra?

 

Wow!! I'm sorry for missing this post for a while.

I've had my underhood liner off for about 4 months now. I've had absolutely no problems with fading or bubbling paint. I live in Kansas City and the average temp for the past 3 months has been over 80 degrees with nearly a month of 95+ degree and extremely sunny days. I also drive a black Maxima. This is about as extreme as you can get.

The underhood liner is a fire shield and a noise barrier. If a fire broke out under the hood, the tabs would melt and the liner would drop over the engine and potentially put out the fire. HOWEVER!!!! After talking to Dahryman (Bryon), it is clear this fire shield doesn't do much because he saw three Maximas at a junkyard that had been hit and broke into fires. All front ends and dashboards were complete toast, literally. Nissan went to great lengths to make the Maxima quiet with lots of resonators, underhood liner, soft engine mounts, and a super baffled muffler.

In a quest to lower underhood intake temps, I removed the liner. I recorded 20 degree lower intake temps on a 85 degree day. At a stop, there is little change in temp between having the liner and not. Once rolling, the heat quickly disappates without the liner. My temps were measured with a high grade digital BBQ thermometer with the display mounted in the cabin. Heat soak is far less dramatic. I noticed no noise increase with this setup. It is my guess the liner served to muffle high rpm noises which is all, but impossible with a POP style intake on a VQ.

My setup to reduce underhood intake temps by over 30 degrees is as follows:

1-POP charger (HKS)
2-use stock lower airbox with OSCAI tubing
3-custom made heat shield around POP
4-no hood liner

Adding heat extractors to the fenders and/or hood would help things out. However, adding a lower temp thermostat and larger radiator would do nothing for the VQ. For optimal performance, you want the engine HOT and the intake charge cold. When you see guys icing their intake manifolds with the car running, they are trying to keep the intake cold and the heads nice and hot.

Do the hood liner mod at your own risk. Honestly, if my car catches fire, I'm letting it burn. Once the electrical system burns, you can never fix it right. Electrical gremlins will plague the car for life. To make you feel better, nearly every stock Honda I've seen doesn't have a hood liner.



Dave

 

Dave you consider the Throttle Body Coolant Bypass? This does not help under the hood temps, but it should decrease the intake charge temperture. When I first did mine, I noticed the idle was alot higher then before. I then closed the air control valve all the way down and it seems to idle just like it did before so I solved that problem.

I _may_ try the removal of the under the hood liner. First I notice there is like a 1 square foot hole that isnt even there in the hood liner, and infact it might just sit over the front exhaust manifold... I noticed this when it reaches the dewpoint outside and theres this one area on my hood that does not collect moisture. I'll look into this tomorow. I will probably buy a remote thermometer from Radioshack, theres a good black one there that can show outdoor/indoor temp (since my automatic climate doesnt have it in 97...) that I can probably use to track the intake temp.

 

Where were you bro.?! We needed you - lol. Seriously man, thanks a million. You are the man. Thanks so much for the detailed responce. Your testimony is enough for me, I'm sold. Thanks again. Have a good one.

 

the maxs i saw in this graveyard made me wonder things....if that is a fire shield.....it is not a very good one....as sublime so nicely sang.....wannna let it burn...cause im not going to stop it.....ill just get a new max.....

 

Eric-

I've never done the TB bypass because I know it did little to nothing for the Mustangs and F-Bodies. Can you tell a difference between the heat soak before and after the bypass mod. What all needs to be done to perform this? I'm assuming you pull two coolant lines off the TB and bridge them. The only reason the coolant goes thru the TB is to keep the throttle blade from icing in the most extreme climates.

Dave

 

BAAAAAAAAAAAAAAAAAAAAAAM !!! (Shakes the haters off).