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.

 

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

 

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.

 

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+.

 

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

 

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.

X...

 

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

 

Removing the seal will create a high pressure in the engine compartment created by "cowl induction". It will prevent air from flowing through the radiator.

 

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.

 

I agree with you about the high pressure area and that air actually enters the hood at the base of the windshield. The reason is because the HVAC system in cars has its intake there (that's what all those little vents are near the windshield wipers) so air will noticeably enter the car when it is traveling at speed. Let's assume that the hood creates a perfect seal around the top of the engine compartment. This means that all of the hot air in the engine bay is forced out underneath the car and replaced by cool air from the grill and bumper ducts. By removing the seal at the top of the hood (or raising the hood altogether like some drifters like to do with washers), air would enter like Julian said before. The hot air would still need to exit at the base of the engine bay. Thus, the cold air taken in at the windshield would have to travel down, past the engine, and then out through the bottom of the car, cooling the engine some.
So in theory, this may still have some efficiency.

 

Wargasm has also done measured testing -- it does not work.

http://www.zeroglabs.com/rx7/freecooling.htm

 

Running cool air over the top of the engine will do little to cool the engine. Coolant is needed internally to reduce temps.

 

What was the big deal a few years ago about the Japanese tuners/guys running with the rear of the hood held up a couple of inches. Wonder if they found it hurt/or helped since i don't see many pictures of it like that anymore.

Tim

 

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



X...

 

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

 

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?

 

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?

 

I've got the Greddy FMIC so my setup is much "weaker" than stock by design (Radiator) but better on the intercooler side of things. I did switch out to a Koyo, but I still need the plate so that the air flows throught the Chiller and the Radiator, and not over the radiator.

X...