Releasing Engine Air

[rudypoochris]

I just came up with an idea. Would it make sense to create some holes leading form the top of the firewall into the space where the windshield wiper motor is? This would prevent pent up engine compartment air from creating lift and all kinds of bad things. The only two reasons i can think of not to do this would be:

 

1. Windshield wiper life could be shortened from excessive heat

2. Effects on windshield condensation (someone who knows more about this chime in but i think it might acctually act like a defroster in effect which is a double bonus....)

[Synlubes]

Actually air is sucked into the vents on the cowl panel not exhausted.

 

I closed off two of the three vents on my cowl panel, leaving the small vent on the pass side open to pull air into the cabin.

There is as much air flow with just the one vent open as with all three vents opened.

 

You can see some pixs here

 

Pulling air from the cowl panel would work great for cowl induction!

[TheNeedForZ]

Looks like synlubes beat me to it. Anyway this is what I posted :

 

Afraid not, air will actually go into engine bay from the wiper motor area, depending on how fast the car is going. This is because when the car travels at speed, a high pressure area forms at the base of the windshield.

 

There used to be a great article called "early Z aerodynamics" I tried to search on google hoping to find a link but it is gone.

 

here's part of it :

 

"....The high pressure continues all the way to the windshield at station 60, which is why ventilation air intakes are located just in front of the windshield, and also why opening the hood slightly does not result in significant venting of hot air from the engine bay. One would think that such a large area of high pressure would push the hood and windshield down, but lift generated by the air dammed up by the front of the car is greater and the net vector is upward....."

[Synlubes]

Here is the link

 

Early Z Aerodynamics

[rudypoochris]

Argh so i guess best is going to be venting into the wheel well. Thank guys, cowl induction is an idea though.

[DAW]

Rudypoochris, I was thinking like you and was checking out my Maserati Biturbo Spyder wanting to lower the underhood temp. I found two rubber plugs about 2x3" each at the trailing edge of the underside of the hood. These plugs were located over the cowl/wiper linkage area but the space they plugged comunicates with the space between the hood surface and the structural webbing (which is like a ductwork since it is open to engine compartment air in some places).

 

Long story short; after removing the two plugs in my hood which established ducting between the top of the engine compartment and the cowling area, my underhood temperature is lower than before removing the plugs as evidenced by the less frequent operation of the automatic thermostatically-controlled electric fans at shutdown of the engine. Prior to removing the plugs the fans used to run for 3-5 min after shutdown; now they seldom run at all. I do note that the in-cabin ventilation is not as fresh (not surprising since the vents are now sampling underhood air instead of 100% outside air). I'll run it like this for top-down weather and replace the plugs for colder weather. Something tells me that the two plugs weren't arbitrarily put there. DAW

[2003z]

One would think that such a large area of high pressure would push the hood and windshield down, but lift generated by the air dammed up by the front of the car is greater and the net vector is upward....."

Which is why, when the hood latch broke on my previous 240, I couldn't drive it. Over 20mph and the hood was pulled open!

 

 

DAW, what year biturbo do you have? I had an 85 E coupe!

[280Zone]

Have you seen these hoods?

 

http://forums.hybridz.org/showthread.php?t=101130

[sab12373]

I really liked the article on aerodynamics. Some things in it that I hadn't thought of.

 

Thanks

[rudypoochris]

I like the stock look though so i do not want to go with a cowl induction hood. I think i will simply route it from the windshield wiper area.

[DaleMX]

Couldn't you put deflector just before the end of the hood (by the windsheild) like 6 to 8 inchs back and about 4 inchs high sloping at the angle of the windsheild and create a vacuum behind it to pull the air. It might even keep the bugs off.

[TheNeedForZ]

The windshield of the Z is like a giant airdam in itself. It accumulates a lot of pressure when going at speed. any deflector big enough to work is going to disturb the line of the car.

[rudypoochris]

I decided that either I am going to create vent in the hood with an angled lip or I am going to use a front diffuser that stops 6-8" before the firewall to effectively suck out the engine compartment air.

[y-not]

This is how I Vented the heat from My 302 powered 250 GTO replica.

I cut out a flap in the area where the battery was and on the other side. They line up with the GTO's body side vents. Side vents on a Z would sure be different.

[SHO-Z]

Chevy has used cowl induction on the old Z28 camaros. I did a calcuation on approximate pressure gain at 100 mph for a friends Z28 drag car. If I remember right it was around 2 psi. One option is to cut a hole vent wheel well. Toyota truck and 4-runners us a small electic fan for ther AC condencer. This way you can turn it on and off when needed.