vented hood: any problems so far?

[dark_knight]

i have to be honest. not so sure if this was to go in the 'engine' section or the 'body' section as i've placed it.

i not-so-recently vented my hood and have been loving the look and improved cooling that the bay now gets coz when the rad fan cracks in, you can feel the epic heat venting away from the engine bay through the 'vent'.

i was just wondering, has anyone else had any problems whatsoever..? i've been a little worried about rain going in through the vent and especially messing with the igniter since it's right there at the firewall and with little protection. also, i'm still running the TMIC and it's now slightly separated from the rubber sealing that is mounted on the hood even when completely shut -- i don't think it affects air flow much but it doesn't hurt to ask. the other minor problem i had was having to adjust my windscreen sprinklers but i got over that..

ps: my hood is elevated 25mm at the hinges on aluminium spacers..

 

[mech5107]

Mine is vented for a year now...

No problems, either with rain or car wash.
I'd say it would be better to seal somehow the tmic so all air passes through...

 

[GTnomez]

Bloodyhell thats quite high! That would create drag (just like opening a window at high speeds) as well as allowing heat out!

I wouldnt worry about water getting in somewhere important as it would trickle off between the fenders if anything. You will get a build of crap though in those corners because you've exposed it more so.

Youve got more of a chance of a misfire happening through bonnet scoop (specially with a FMIC) that the back.

 

[dark_knight]

how high would you vent yours GTnomez..? if you are not already vented..?

 

[GTnomez]

Mine 'used' to be a couple of washers then after a while i decided it looks a bit naff so i removed it. Use heat reflection tape & reverse scoop to help with the heat anything.

Lifting the rear would create drag as your interrupting the air flow so air would go over the bonnet and up and over the roof, most of it will go into those gaps you have created.

Up to you really, keep it if you think it works! In answer to your question, i doubt you will be putting the coilpack in danger due to water ingress.

 

[dark_knight]

so at what point/speed does the turbulence become a concern..? i seldom do over 70mph.. car never sees the freeway much, nothing but traffic jams..

 

[GTnomez]

Sorry i couldnt answer that question.. Im no Nasa apprentice but if its traffic driving you do then i guess it would help!

Besides its not really something to be concerned about anyway, just thought i would point it out. Try using heat reflective tape, heatwrap and even knock up a small heatshield for the mani if you dont have one.

 

[dark_knight]

not a problem GTnomez -- it's just in the name of sharing knowledge..
i have the stock heat-shield on the mani but the place still really boils over.. will try the reflective tape although my idea behind venting is to keep the entire bay cool, and not just the intake as is the primary agenda behind most custom builds..

 

[Rev]

not a problem GTnomez -
i have the stock heat-shield on the mani but the place still really boils over.. will try the reflective tape ..

Still figuring it out but would think heat shield on the manifold is a poor idea ( distinct from heat shield on intercooler pipe to manifold.) .
It seems to me the heat that is conducted from the block to the manifold would build up excessively if the manifold is shielded because Aluminium is working as a very good conductor to shed heat to the engine bay. There are issues of thermal layereing inside the inlet manifold and such also to be considered.

 

[dark_knight]

phenolic spacers

Rev, how about phenolic spacers at the inlet mani..? i think that works best, but only limited for a time as i would suspect after sometime they also get heat-soaked..? of course depending on how thick they are.. & their thermal properties as well..

 

[Rev]

Rev, how about phenolic spacers at the inlet mani..? i think that works best, but only limited for a time as i would suspect after sometime they also get heat-soaked..? of course depending on how thick they are.. & their thermal properties as well..

> From whats been said before, phenolic spacers will need ventilation to work best but when engine temp is max ie at idle , there is little air movement - so would say a fan that blows cool air onto the inlet at idle would be worth a try but logically on a hot day you would be just blowing hot air with reduced benefit.

> Having thought about this I wonder if a little spray of water ( distilled ) on the inlet when it is excessively hot may be the answer.

> Also I find my Aluminium radiator seems to be pulling more heat from the water system so this may be worth checking out for better cooling and this is working the way the engine has been designed to control cylinder heat. Unfortunately for me that heat goes back into the engine bay.

> Finally on phenolic spacers I am unsure how these will perform over longer periods , I think that after the initial intake cooling period ( that drag racers benefit from) the spacer would probably keep a little more heat in the block in a localised way near the fuel inlet but whether this is significant I dont know ?

 

[dark_knight]

Rev, wait. i thought phenolic spacers are more like insulators so how come you mentioned that they are best under vetilated operation..?

 

[Rev]

Rev, wait. i thought phenolic spacers are more like insulators so how come you mentioned that they are best under vetilated operation..?

The insulators prevent heat being conducted through the metal at block to manifold. Although initially a good insualtor the air eventually becomes a conductor as temp rises and transmits heat to the manifold easily as the manifold is highly conductive aluminium.

> Ventilation that keeps temp down will greatly reduce the airs conductivity. ( You may also recall in thermo dynamic terms heat radiation is proportional to temperature squared )
> Secondly there is the effect of wind, while Aluminium gathers heat easily it also gives it up easily so just as we get cold in the wind as heat blows away from us the manifold will readily lose heat this way. A priviso is how to cool the manifold without disturbing the heat layer that is close to the engine which may add too much heat, that is partly why I thought water cooling may be a possibility if ventilation was not sufficient.

 

[dark_knight]

good one on the manifolds' thermal properties. very true. so then my vented hood works perfectly..

 

[Rev]

It seems a good measure for hotter climate like ours you will see more as summer peaks

 

[dark_knight]

my climate is sweltering hot almost 10 months in the year.. so this is definitely the best cooling mod i can think of. running green-stuff coolant on the stock rad.. de-tuned my boost to 0.7bar for a bit.. will keep an eye on the engine. hoping to get some gauges to keep an eye on things too..

 

[Rev]

Yea I just looked at a map for Kenya. Gauges sound a good idea.
I have issues with over heating manifold but I am usually thinking about preignition as I higher boost around 1.5 so am thinking greatest risk is a blocked injector so want to install aircraft temp gauges. I don't know if anyone has done that before but seems logical to me.
They monitor the temp of each cylinder individually so you can see discrepancies.

 

[dark_knight]

i'm curious Rev.. how are you going to install the individual temp gauges in each cylinder..? or will you take the reading from the exhaust runners right after the block..? i.5bar on a td04..?

 

[Rev]

i'm curious Rev.. how are you going to install the individual temp gauges in each cylinder..?

K1 I see you want all my secrets.....

Simple this probe fits under the spark plug!

 

[dark_knight]

hmm.. so you thread the plug through the probe prior to threading it into the head..? looks interesting. how soon are you planning to get this done..? can't wait to see build pix..