Goz Posted October 21, 2008 Report Share Posted October 21, 2008 Hello, I was wondering is there any purpose to the under-bonnet insulation, apart from perhaps noise reduction? Would the engine be better off without it, ie, cooler? I read a thread on a Saab forum where the guy was thinking about removing it (from his Saab) to help his engine run cooler, but someone said that the insulation is there to protect the paint form the heat of the engine. I guess our '8s run a bit hotter than a Saab? Is the paint really that vulnerable to heat? Hoping to squeeze every bit extra HP with simple mods Thanks Link to comment Share on other sites More sharing options...
Mook Posted October 21, 2008 Report Share Posted October 21, 2008 It won't make any difference to the cooling - it's purely for noise insulation As for the paint being affected - methinks someone's been talking bollox Link to comment Share on other sites More sharing options...
Goz Posted October 21, 2008 Author Report Share Posted October 21, 2008 Thanks, I thought the bit about the paint melting was fishy. I'm still thinking it should help with cooling even if its only a tiny little bit because the metal of the bonnet will conduct the heat away quicker without the insulating pad in between? Does anyone drive around without the insulation pad under the bonnet? I'm still not sure if I should take it off, maybe it serves some other purpose, stopping condensation dripping onto the engine perhaps? sorry, I know its not a very exciting topic. Link to comment Share on other sites More sharing options...
mkoneman Posted October 21, 2008 Report Share Posted October 21, 2008 id say its down to the classic line "if it aint broke dont fix it" i dont see any gains of reducing the temp under the bonnet the only time that would effect it would be sat in traffic, are you experiencing the engine running hot then? Link to comment Share on other sites More sharing options...
Ska Posted October 21, 2008 Report Share Posted October 21, 2008 These engines run hot any way just touch the side wings after a good run and you'll see how warm they are. I'd be more inclined at creating a Al foil baffle between the airbox and air intake pipe from the rest of the engine as that'd make more of a difference to performance. Link to comment Share on other sites More sharing options...
Sven Posted October 21, 2008 Report Share Posted October 21, 2008 I'm with Ska on the cool air intake. That's where you might gain some power, not by removing the insulation. I'd leave that in place, not only for sound dampening, but there is certainly a degree of truth in the fact that it might affect your paint. It won't melt the paint, but it might discolour, fade or give clear coat failure in the long run. Ask any detailer about heat affecting paint... Link to comment Share on other sites More sharing options...
Goz Posted October 22, 2008 Author Report Share Posted October 22, 2008 Thanks guys, I'm going to leave the bonnet insulation alone. I have been readin your posts about insulating the airbox and intake and would like to give it a go, whats the best material to use for this? I thought about aluminium foil too, but isnt that only good for reflecting radiated heat? I bet there is lots of heat being transferred to the airbox via convection as well, whats a good all-round insulating material? How about spraying the airbox+tubes silver as well Thanks Link to comment Share on other sites More sharing options...
Mook Posted October 22, 2008 Report Share Posted October 22, 2008 Covering the airbox will make zero difference. The only way to get colder air through the filter is to fit a cold air intake, which means housing a free flow filter, like a conical K&N behind the front bumper. I used to run one on my R32 and it made a difference to the already tuned engine (310bhp to 312bhp or 314bhp depending on the air density). I was considering fitting one to my S4 but there's not enough room to run the piping. In all honesty Goz, if you're after more power from your car, you should be thinking about a remap and a much better flowing exhuast. Adding a cold air intake to a stock A8 or S8 will make zero or negligible difference. Sorry, but that's just the way it is Link to comment Share on other sites More sharing options...
Goz Posted October 22, 2008 Author Report Share Posted October 22, 2008 sorry Mkoneman, forgot to add, engine is running fine, I'm just playing around, seeing if I can get rid of any bits that dont serve any useful purpose. Link to comment Share on other sites More sharing options...
Ska Posted October 22, 2008 Report Share Posted October 22, 2008 (edited) Covering the airbox will make zero difference. The only way to get colder air through the filter is to fit a cold air intake, which means housing a free flow filter, like a conical K&N behind the front bumper.I used to run one on my R32 and it made a difference to the already tuned engine (310bhp to 312bhp or 314bhp depending on the air density). I was considering fitting one to my S4 but there's not enough room to run the piping. In all honesty Goz, if you're after more power from your car, you should be thinking about a remap and a much better flowing exhuast. Adding a cold air intake to a stock A8 or S8 will make zero or negligible difference. Sorry, but that's just the way it is Shielding the air intake wasn't an attempt to conjure up theoretical Horses it was more about driveability of these cars (if there is such a word). When they get hot especially the 2.8's they get sluggish and on my car the air box/inlet pipe are hot to the touch and seeing as the AIT sensor sits there as well it can only be a good thing to try and reduce the temp. in that area. Whether or not you get the desired reduction remains to be seen but I'll try it using some of that insulation aluminium & some of the wife kitchen foil and report back. That said a better option than the bonnet sound baffle. One thing’s for sure right now with the general colder temperature outside my car goes very well. Edited October 22, 2008 by Ska Link to comment Share on other sites More sharing options...
Mook Posted October 22, 2008 Report Share Posted October 22, 2008 I'm with you there, Ska Unfortunately, there's so little room and about zero air flow through the engine bay, that heat's always going to build up, regardless of the car. Link to comment Share on other sites More sharing options...
Ska Posted October 22, 2008 Report Share Posted October 22, 2008 I think manufacturers need to design some sort of semi-permeable (spelling) membraned bonnets in the future:grin: Link to comment Share on other sites More sharing options...
Mook Posted October 22, 2008 Report Share Posted October 22, 2008 I've got a circular saw in the garage you can borrow... Link to comment Share on other sites More sharing options...
Ska Posted October 22, 2008 Report Share Posted October 22, 2008 I was thinking of a Homer Simpson solution putting speed holes in with a shot gun or similar but thanks for the offer anyway Mook:roflmao: Link to comment Share on other sites More sharing options...
Mook Posted October 22, 2008 Report Share Posted October 22, 2008 You can always borrow my shotgun... Link to comment Share on other sites More sharing options...
Tobes49 Posted October 22, 2008 Report Share Posted October 22, 2008 Does anyone drive around without the insulation pad under the bonnet? Yes, Paint work is fine, Even after a thrashing on a trackday. Link to comment Share on other sites More sharing options...
Goz Posted October 22, 2008 Author Report Share Posted October 22, 2008 Thanks Tobes! I'm now really tempted to get rid of it. Link to comment Share on other sites More sharing options...
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