Removing seal b/w firewall and hood is bad for engine temp
#1
Removing seal b/w firewall and hood is bad for engine temp
I have seen posting about removing the seal will cause air to flow into the engine bay instead of outward.
It just happens that I removed the seal years ago and never paid too much attention to water temp coming out of the block as I was running EG and Water.
Recently, I installed NPG+ with a VDO gauge mounted to sense temp at the filler neck. NPG+ doesn't have as much thermal mass as water so you can see variations immediately (that's why it needs a bigger radiator core and increased flow rate). Well, as I've reported in other posts, the car coolant temp got hotter the faster I'm travelling (not under heavy boost either). I couldn't figure out why and the last thing was the seal.
Last night, I put the seal back in. This morning, same drive to work, the temperature stayed rock steady at 195 despite increasing the speed. Not 100% proof but another data point on supporting the theory that there is a reversal of air flow if you remove the seal.
It just happens that I removed the seal years ago and never paid too much attention to water temp coming out of the block as I was running EG and Water.
Recently, I installed NPG+ with a VDO gauge mounted to sense temp at the filler neck. NPG+ doesn't have as much thermal mass as water so you can see variations immediately (that's why it needs a bigger radiator core and increased flow rate). Well, as I've reported in other posts, the car coolant temp got hotter the faster I'm travelling (not under heavy boost either). I couldn't figure out why and the last thing was the seal.
Last night, I put the seal back in. This morning, same drive to work, the temperature stayed rock steady at 195 despite increasing the speed. Not 100% proof but another data point on supporting the theory that there is a reversal of air flow if you remove the seal.
#3
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Originally Posted by obviousboy
I honestly removed to help flow incase of an emergency (over heating)
I could pop the hood while driving and get alot of great flow through the engine bay
I could pop the hood while driving and get alot of great flow through the engine bay
FYI, with the hood popped while driving you *probably* get even less air flow through the radiator. You increase the pressure in the engine compartment which decreases the pressure differential across the radiator.
#4
Rotary Freak
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Originally Posted by pomanferrari
I Well, as I've reported in other posts, the car coolant temp got hotter the faster I'm travelling (not under heavy boost either). I couldn't figure out why and the last thing was the seal.
#5
Originally Posted by moehler
How much hotter did the coolant get? I have never noticed this on my pfc with the strip removed... temps are always very stable and constant regadless of mild accelerations.
10-15 degrees higher. You don't notice this because you're running standard coolant and water. I'm running Evans NPG+.
#6
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Originally Posted by turbojeff
So you removed the seal to allow the engine to run hotter normally, that way when it overheats you can pop the hood while driving to allow more air flow?
FYI, with the hood popped while driving you *probably* get even less air flow through the radiator. You increase the pressure in the engine compartment which decreases the pressure differential across the radiator.
FYI, with the hood popped while driving you *probably* get even less air flow through the radiator. You increase the pressure in the engine compartment which decreases the pressure differential across the radiator.
my radiator and intercooler are ducted seperately (actually enclosed)....this from knowledge would isolate it..
At the point (which hasnt happened) of over heating yes popping the hood will work..(for me)
Air would flow in the front grab the warm air and flow it out.....
Now there would be a cold spot, warm engine air would fill this and repeat...
I could be wrong but it made sense to me
#7
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Bump
This sounds wrong to me, taking that weather strip above the firewall off seems like it would allow more air to get in/out in that place. I know there is usually air flowing in that way when the speeds go up (cowl induction-ish) but that shouldn't hurt the radiator, as long as the front is sealed up top and bottom.
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This sounds wrong to me, taking that weather strip above the firewall off seems like it would allow more air to get in/out in that place. I know there is usually air flowing in that way when the speeds go up (cowl induction-ish) but that shouldn't hurt the radiator, as long as the front is sealed up top and bottom.
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#8
Rotary Freak
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This makes sense. Cars have a high pressure zone in front of windsheild, thats why air ducts are there to fill pass comp. Raising underhood pressure would reduce inflow from front. Air is not being froced in, air flows path of least resistance, i.e. into low pressure zones, our goal, for cooling, is to provide air a lower resistance path into radiator and IC and out bottom than over top or under car
#10
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when air passes fast enough ontop of the car, it creates low pressure under, and inside the engine bay... having low pressure inside the bay is a good thing, it sucks the air inside. Now, when you open the rear of the hood, it creates turbulance and equally pressurise the bay, making a wall of air, and harder for the air to travel inside, it travels either above or below the car.
#11
Originally Posted by Julian
This makes sense. Cars have a high pressure zone in front of windsheild, thats why air ducts are there to fill pass comp. Raising underhood pressure would reduce inflow from front. Air is not being froced in, air flows path of least resistance, i.e. into low pressure zones, our goal, for cooling, is to provide air a lower resistance path into radiator and IC and out bottom than over top or under car
So in theory, this may still have some efficiency.
#12
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Wargasm has also done measured testing -- it does not work.
http://www.zeroglabs.com/rx7/freecooling.htm
http://www.zeroglabs.com/rx7/freecooling.htm
#13
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Originally Posted by obviousboy
my radiator and intercooler are ducted seperately (actually enclosed)....this from knowledge would isolate it..
At the point (which hasnt happened) of over heating yes popping the hood will work..(for me)
Air would flow in the front grab the warm air and flow it out.....
Now there would be a cold spot, warm engine air would fill this and repeat...
I could be wrong but it made sense to me
At the point (which hasnt happened) of over heating yes popping the hood will work..(for me)
Air would flow in the front grab the warm air and flow it out.....
Now there would be a cold spot, warm engine air would fill this and repeat...
I could be wrong but it made sense to me
#15
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Maybe it only makes a difference if you raise it a lot where the air can really flow in under "higher" speeds, and flow out when you are going at lower speeds (vent like) Sounds like either way it's not doing much. I am working on making a plate to cover from the IC to the Radiator like others have done and hoping that this will help. I don't exactly live in a warm climate (Buffalo, NY) but it is still upper 80s all summer, and it's cool to be cool
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#16
Rotary Freak
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Originally Posted by aREX4X
I am working on making a plate to cover from the IC to the Radiator like others have done and hoping that this will help.
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#18
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Originally Posted by KevinW
if there is a big problem with this then why do people run Cowl induction hoods on hotrods and such and dont have overheating problems?
The cowl induction is typically ducted to the carb, it doesn't vent the engine compartment in general.
I think what people are saying is that it won't improve cooling so then why remove the seal?
#19
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So what about venting the hood with holes, and not having a lip?
As if you where to cut slits or holes into the stock hood, with no ramp type lip in front of the holes?
I was thinking of making a steel template and cutting a slit above the engine belts to vent the intercooler, and make some slits above the brake booster and the ABS to exit under hood heat when the car is stationary.
Would this greatly affect my driving cooling?
As if you where to cut slits or holes into the stock hood, with no ramp type lip in front of the holes?
I was thinking of making a steel template and cutting a slit above the engine belts to vent the intercooler, and make some slits above the brake booster and the ABS to exit under hood heat when the car is stationary.
Would this greatly affect my driving cooling?
#20
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Originally Posted by Julian
What will the plate do?? our cars are sealed in from of radiator and IC is ducted in front of it. Maxiimising volume aft of each is required to reduce pressure, air flows "downhill" from high pressure to low pressure, and remember lower pressure air takes up more space, make the space, don't bottleneck it
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