Heat soak - vented hood options that are not "louvered"

SouthArk370Z

Thanks

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phunk

If you drive with your fuel pump access covers off, you will generally feel very warm air coming in. This is because the air under the car is the air that came in through the radiator and around the engine.

I think that a scoop on a hood is a bad idea unless it is used to feed the air intake filters in a sealed manner. Vents will relieve pressure in the engine bay, allowing heat to escape out the top, hopefully allowing more air through the bumper/coolers while reducing air pressure under the car. A scoop will just try and cram more air in, and if it does, it will probably only serve to increase engine bay pressure, possibly reducing radiator flow, and putting more air under the car.

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phunk

I also think that louvers are used rather than just openings in attempt to create a venturi effect. Seeing as how most louver designs actually bulge up just before the vent, then the dip down for the opening... creating a little high pressure area that transitions quickly to a low pressure air with an opening... well that's the formula for a venturi. If successful, these louvered vents at speed should be pulling air out quite well.

How technical it gets after that is probably the type of stuff that would hurt the brain. My personal belief is that further spaced gradual louvers like the Siebon TS will have a more effective venturi effect, and that steeper more rapid louvers will have superior airflow volume with less venturi effect. I have really good reasons for thinking that, but I dont want to say it aloud and then have someone who is way smarter come in here and make me look like an idiot

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Chuck33079

At this point, I think you've earned the right to say pretty much whatever you want without someone calling you an idiot. We're spitballing here, so let the unfounded beliefs and wild-*** guesses fly.

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fuct

would it be wise to check out what nissan did to the GTR? im not saying they are super similar but the basic ideas are the same. twin turbos placed in almost the same location as a TT 370z. both have a radiator and IC mounted in front..... maybe something like they did on the GT3 car. albeit ugly...

dmhenderson

That hood looks godawful. Perfectly fine for a race car but there's way too much "stuff" going on there.

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dmhenderson

Man I sure opened a can of worms. My initial question was innocent enough!

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fuct

i agree, but im also sure its full of R&D with wind tunnel testing.

phunk

Well... I think that each vent in a steep louver will hurt the venturi effect of the louver in front of it by putting another high pressure area too close. But, if you think about it... you may not need a venturi effect anyway.

I think that it depends on the scenario. If your car has a problem with too much air pressure in the engine bay and under the car, then you dont even need a venturi to get the air to leave that hood vent... its going to just leave because of the pressure differential. Aggressive venting would be fine for that.

But if your car doesnt really have an issue with pressure in the bay and forcing pressure under the car... then mass hood vents may not even do anything at all... there is pressure on the hood already, so the pressure in your bay better be higher than the pressure on the hood otherwise air is not going to be leaving hood vents without a vacuum effect from a venturi.

I think the GTr posted above sort of supports my theory. I am willing to bet that the steep louvers in front are ducted from the radiator allowing mass airflow... so there is minimal pressure in the engine bay because of this, and then behind that ducting they use the venturi louvers to pull air out above the intake manifold to reduce pressure under the car and reduce underhood temps.

maybe???

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theDreamer

There is this hood on some of the 370z in Japan racing:

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Chuck33079

I'd also assume there's ducting under the hood to make full use of all of those vents.

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phunk

and I wouldnt be surprised to see those front NACA ducts possibly headed straight to the exhaust manifolds to help them get fresh airflow cooling even though that air will just end up under the car.

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theDreamer

Doing more digging on those hoods from Japan. Here is the best underside shot:

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SouthArk370Z

Go for it. So far, I've seen no true experts respond. A few with some very good practical knowledge, but no PhDs. I was an Instrument Tech many years ago and have some familiarity with gas flow but I'm certainly no expert. If we can test your theories, we'll see how good of a guesser you are.

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Sh0velMan

lol funny you mention this.

There's a few mounting holes on the tranny tunnel near the shifter area that blow air up into my forearm at speed. Freaked me the **** out the first few times I drove it at speed hahaha.

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