Reducing intake take and engine bay temperatures

i've been doing some research on here and otherwise...trying to determine how to effectively reduce engine bay and intake temps
now i realise i see some common items keep poping up as aids to this process
- heat reflective tape for cooler piping between the cooler and TB
- heat wrap for the manifold and downpipe
- heat shield for the manifold
- intake manifold insulator
- turbo blankets

what are your opinions on these items? have you used any of these? do they work?

did you notice any measurable drop in intake temps or engine bay temps?

all opinions and expereinces welcomed

if you have any other recommendations that may help in these areas....please feel free to post them
 

weeJohn

Lifer
I think engine bay temps are hard to keep down without a constant flow of cool air through them, bonnet vents are probably the best way for that. Heat wrapping the cooler pipes will help the pipes from absorbing heat and transferring it to the air inside, but the real heating gets done in the inlet manifold as its bolted to the head and the heat transfer is large.

A Honda owner who drags here fitted the thermal gasket between the head and the inlet mani and he noticed a drop in his intake temps, but after the car sat at idle for 10 minutes it was nearly the same as before until he switched the engine off and opened the bonnet.

I logged intake temps drag racing 1 day, about 28-30 was normal for idle, about 20-24 was normal under boost.

It dropped to 10 with Nitrous going through it lol.
 

Texx

Super Moderator
How about sealing off the underside of the engine bay and adding extraction vents that scavenge air out of the engine bay into the low pressure area beneath the car?

Similar to what you see on most modern cars when you look underneath i.e miles and miles of plastic trays.
 
thanks texx and weejohn
yeah,,,it seem due to the compact engine bays..temps really rise when the car i stationary for a short time

in theory, the insulator between the head and intake mani should really help...but then i guess it again depends on how long you sit idle with the car on

i think someone on tercelonine made these and did a test...i'll try to find the link and post it
 

Rev

Member +
I have heat issues as sera engine bay seems poor.

My experience so far -
1 Sometimes pipes between intercooler and intake get very hot -
>> Heat from radiator fans blow onto these pipes and heats them badly.
>> I removed bonnet insulation - So on hot days bonnet heats the intercooler pipes .

2 Couldn't agree more with wee John -
>> The air intake sucks heat from the block and mine gets heat from through the bonnet also .
>> Moving air on hot surfaces makes a big difference but low pressure behind radiators and intercooler should be maintained so air passes easily though them.
>> I read a technical paper that said the same , max engine heat load is at idle. The other day I found I could get 100rpm more by filling oil ( 10w 30 ) from just below half to just below fulll this is a sure way to reduce heat.

>> I have celica racing air temp sensor. WIth hotter weather now the car is dropping up to 200 rpm at idle because of the intake heating up makes the ecu pull timing. The other day when this happened I pulled out the sensor and the car recovered revs and idled fine.

3 Under car presure-
>> I find when I stop the air under the car is hotter on the drives side this is where it exits most, I think this is because the radator fans pressurise the passenger side so I am planning to try to increase this natural flow.

4 Insulation -
>> I have been testing insulations - I bought special engine bay heat shield ,double aluminium with rubberised shield between. - Total failure shields only for a short time till it heats up. Looks like it is designed to absorb heat so willl need air flow on one side to keep cool.

>> Best so far I put reflective gal sheet with about 3mm felt glued on the cool side.
The sheet has limited mass so does no hold sufficient heat to push heat through the felt.
So the cool side remained reasonably cool even after a long exposure to heat.
At about 50+ deg C some glue failed so I am retesting with high temp silicone soon. ( fire retardent felt may be necessary )
 
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well ive recently raised my bonnet 47mm with a kit i bought from ebay and i have noticed a huge difference in engine temp just from doing that alone
 

Paul_JJ

Member +
Well, I have heat wrapped all the intercooler piping as well as cold radiator pipe. And it seems to help but as already mentioned the inlet mani gets very hot as it is, but even then when I touch the cold pipe next to the TB it's cold, because it's heat wrapped, where is before it was warm. So makes the difference. The cold radiator pipe was heat wrapped because it goes next to the hot IC pipe and I don't want it to absorb extra heat.

To fight temperatures I would recommend to relocate the Air Filter in front of the radiator - does an awesome job.

Also I read somewhere that to make the radiator most efficient it must have some kind a tray underneath to hold the air.

Like Tex mentioned all the modern cars have loads of plastic I would assume that's for a reason, also that reduces the noise -)

What I have on my car is I have no Top mount but still got the hole for it in the bonnet, well I've taken all the rubbers of it (under the bonnet) so it blows the cold air right on the inlet manifold/cold IC pipe and of course when the car is idle - it's used to get rid of the heat inside the engine bay.
 

dark_knight

Member +
fact or fiction

i can attest to the reflective tape, heat-wrap and exhaust manifold heat shields giving you some degree of heat reduction -- or rather, directing the heat where it does less damage so-to-speak. having a FMIC also helps as it's a longer route, where the intake charge will loose some heat to the ambient air.

i haven't tried phenolic (thermal) spacers that go between the block and intake mani but a friend has them on his boxer engine and he gets pretty impressive IATs, so i'd say they count for something.. :)

contrary to popular belief, raising the hood's rear end does not aid in cooling as this is a low-pressure zone & instead creates a vortex (suction) effect drawing air in so what you have is just turbulence more than smooth airflow to the windscreen.
 

Paul_JJ

Member +
Forgot to mention, Heat wrapping the mani and the downpipe will increase the risk of cracking. I know they do it for the race cars, but they replace a lot of parts pretty often.
 

dark_knight

Member +
phenolic spacers

i've heard of some people go the extreme route and swap out the stock intake mani bolts with extended ones then layer on a phenolic insulator as thick as 15mm for extra heat rejection.. definitely sounds like a plan.. but i doubt i'd have the supplies to make this happen.. :D
 
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after more research...it seems some people are of the view that all the heat wrap, insulators, etc dont really make much difference to air intake temps
it seem that the air is travelling relatively fast through the intercooler piping, TB and intake manifold so it does not get much chance to be noticeably heated from the surrounding surfaces

any thoughts on this?

interesting the things you find on the net huh?!?!
 

Rev

Member +
after more research...it seems some people are of the view that all the heat wrap, insulators, etc dont really make much difference to air intake temps it seem that the air is travelling relatively fast through the intercooler piping, TB and intake manifold so it does not get much chance to be noticeably heated from the surrounding surfaces any thoughts on this? !?!

Just thinking

> When injectors close the air doesn't move much ?
> I find if the air sensor is heated by manifold at idle, timing is effected even if air is cold.
> Would be intereseted to Know why weeJohns example is happening ie. phenolic spacer working but then stops working.
- Is it heat from the water in the throttle body?
- Heat transfered through the metel bits like brackets?
- Heat Conducted heat through the air, ie engine bay?
- or direct Radiant heat from the engine block building up in the throttle body?

The former seem manageable and if it is direct radiant, a heat shield may help.
 
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