tonsoffun300zx

so i got myself a z31 hood scoop, and was wondering if i should put it facing forward to bring air into the engine bay, or facing backwards venting hot air outwards. any ideas before i cut into my hood?

NismoPick

The answer would be found in my following question:

How is it stock?

skib

its a vent stock.

its like the 280zx "turbo" style hood vent on the N/A's
its designed to let hot air out after your stopped, not take air in.

tonsoffun300zx

i see thanks nismo and skib

AZ-ZBum

Good GOD! Who let the non-z31 owner answer questions in the Z31 section?

Look at the thing. It faces forward to scoop the air while moving. Open the hood. It has some ducting to help direct air over the turbo to help cool it.

tonsoffun300zx

i have an 88 turbo

AZ-ZBum

Then it won't fit on the hood like it would stock. Do whatever you want with it.

hoov100

Actually the low pressure area in the scoop and in the engine bay will keep the high pressure air flowing over the top of the hood from actually going in the scoop at speed. That and it's too small to have any real measurable effects, let alone actually help cool a turbo that is crammed in the bottom of the engine bay.

My guess is they added it to help with vapor lock and hot air venting when parked to prevent heat soak.

tonsoffun300zx

ok cool thanks guys, and hoov did you ever use dupli-color on the car? if so do you remember the code? the hood scoop is black right now i want it to match the hood.

hoov100

The guy who owned it before me painted it. any paint shop should be able to match the color though it's not a special color.

tonsoffun300zx

ok cool thanks and i finished the install and cutting the hood. i was thinking about putting something on the edge of the hole to try and keep as much water out as possible

tonsoffun300zx

what if i put the hood scoop like this?:

what do you think would be the effects as compared to facing forward?

yes i stole the pix from another thread sorry if it offends anyone.

AZ-ZBum

Correct me if I'm wrong, but wouldn't air want to flow from the area of high pressure to the area of low pressure? Thus, forcing air into the engine bay via the hood scoop.

And then that still doesn't answer the question of why there are ducts and heat shields in the engine bay that help divert air onto the turbo and O2 elbow right there.

Yes. I'm guessing as well. But my guess has logic behind it. Otherwise, why wouldn't they just leave an open vent like on the 280ZX and why would they face it forward to meet oncoming air?

hoov100

They put it on for aesthetics, just like those ugly *** fender flares on the AE's and like those stupid little lips on the 84-86T's. All the z31 body/chassis really is, is an updated version of a 280zx.

If memory serves there aren't any ducts directing air from it to the turbo and if I remember correctly the scoop sits forward of the turbo, heat shields are meant to keep heat in. Also wouldn't you want to keep the exhaust housing on the turbo hot to a degree so that energy from the exhaust isn't lost heating up the exhaust housing?

If you have pictures of the ducts it would greatly appreciated if you could post them, but I have never seen one.

AZ-ZBum

Scoop sits directly over the turbo. The actual inlet sits directly over the rear half of it. The metal shields are what I was referring to when I mentioned the ducts. You'll want to have cool the air as much as possible after it exits the turbo.

Next, you're going to be telling me that the scoops on the 200ZR don't do anything to direct air over the intercoolers. The inlet for the 200ZR scoop isn't any bigger than the one on the 300ZX.

The spoiler and lips on the turbo models absolutely did something. The drag co-eff suffered slightly for it as well.

The body may be an updated version of the 280ZX, but it's completely redesigned and doesn't share a single piece in common.

The wider fenders and fender flares of the AEs allow for wider tires and wheels to be fitted.

tonsoffun300zx

i think im going to go with az-zbum on this one hoov sorry. i agree why would Nissan put the heat shields directing cool air onto the turbo unless it actually worked, and on a side note i want to say that 84-85 the turbos were air cooler oil lubricated correct?

skib

the 280zx turbo scoop had ducting towards the turbo too.... dosent mean it actually works.


both are exit vents.

tonsoffun300zx

what if i faced it backwards?

skib

still going to be letting out air and not taking it in.

put it on how ever you think looks best


if you want a scoop that actually takes in air look into properly designed NACA ducts

AZ-ZBum

NACA ducts are just more efficient and reduce the drag on the area around them.

All Z31 scoops were designed to bring fresh air into the engine bay. They may serve as vents when the car is stopped, but when moving, air goes into the engine bay through them.

tonsoffun300zx: The 1985 models saw the addition of coolant lines to help cool the turbos. Prior to this, they were just air cooled/oil lubricated, hence the need for the scoop.

tonsoffun300zx

the letting air out is just fine with me i just want the most functionality out of it as possible you know. so in your opinion which would help the car out more forwards or backwards?

tonsoffun300zx

oh ok thanks az-zbum for that i guess i was wrong.

AZ-ZBum

You can't mount it in the proper place to gain the full functionality to help cool the turbo. You can put it somewhere else to direct air over whatever part you want to help cool, but it's not going to be as effective as it would have been on the early model hood.

AZ-ZBum

BTW: The 280ZX turbo scoop is a NACA duct.



280ZX turbo hood scoop:


NACA duct:


I believe that's called being PWNED!

tonsoffun300zx

i understand that and appreciate the input from all you guys but now i have 8 holes in my hood and a big 6X8 one for the air to move around in i just wanted to drop engine bay temps as much as possible with the hood scoop.