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S130 bonnet/hood vents


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Have you done anything about stopping water coming in through the vent though? that's the side with the brake booster and clutch master cylinder is it not?

 

Since it's just the brake & clutch masters it doesn't worry me. As with Richard mine is mostly driven to the track and only occasionally sees rain ... or a bath. You notice I didn't do the same on the other inspection lid. That's because the engine computer and fuse box is under it. Even the few times it gets wet I dont want to risk shorting out the ECM.

 

Cameron

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Can't get over how effective the new vent has been. Drove the car in moderate traffic again including some lengthy stops. Previously the thermo fan would have come on several times, now it does not come on at all and the temp stays at 85C.

 

Effective area of the vent is 140 x 200mm.

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  • 1 month later...
Can't get over how effective the new vent has been. Drove the car in moderate traffic again including some lengthy stops. Previously the thermo fan would have come on several times, now it does not come on at all and the temp stays at 85C.

 

Effective area of the vent is 140 x 200mm.

 

Thats really interesting mate - I had some pretty annoying cooling issues when I had a turbo RB30 in my car, worried I will have the same issues once I get the Z back on the road with the 1UZ, I wonder if you findings would be transferable to an S30 with a V8?

 

Just curious - do you think something like this would be as effective?

 

Big massive cowl with the whole end of it open (part facing the windscreen)

 

01032009818640x480.jpg

 

It makes life easier for me as I think I will have clearances issues with the 1UZ's manifold!

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The critical thing seems to be the location of the vent immediately in front of the V motor. Assuming a V motor is set back close to the firewall, there will always be a fair space between the radiator and the front of the motor which means that the vent will be located part way along the bonnet away from the high pressure area at the front.

 

So yeh, it should work on a S30 with a V motor.

 

As to the shape/type of vent, seeing its for air exit it should face back a bit with preferably a lip in front to direct oncoming exterior air up over the vent. The vent could be located in a 'power bulge' as long as it follows the 'rules' above, I think :)

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  • 6 months later...

See if we can revive this. So did anyone do any additional testing as was discussed? Jon - did you get those mounted? I just bid a on gauge to do some testing this spring. I also bought some 280 hood vents so need to decide where to put then on my 240 hood. I think it will be pretty far forward but we'll see after testing.

 

Cameron

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See if we can revive this. So did anyone do any additional testing as was discussed? Jon - did you get those mounted? I just bid a on gauge to do some testing this spring. I also bought some 280 hood vents so need to decide where to put then on my 240 hood. I think it will be pretty far forward but we'll see after testing.

 

Cameron

 

 

I'm just about to go out and do some more testing, for now, here are some pictures of a bonnet i got for nothing and had a crack at with a jigsaw:

 

http://smg.photobucket.com/albums/v621/Tommo560/Datsun%20260Z/Bonnet%20Venting/

 

 

 

And here is some video i took a while ago of airflow patterns over the bonnet and why opening the latch at the back doesn't let air in or out of the bonnet:

 

 

 

I will update this post when I get the butchered bonnet on the car and do some more videos at speed and testing overheating while stationary. Unfortunately there is not an event for a while for me to test these vents on the track, but we'll see how it goes at low speeds and if it looks promising I'm just gonna go ahead and probably louver the bonnet in the position I cut the holes anyways.

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Isn't the video with your bonnet opening, predominantly showing air entering the engine bay? The wool moves left to right but doesn't really appear to come back out of the engine bay.

 

It's a hard angle, but the wool shows a small amount of air entering the engine bay overall but the wool tufts were actually flicking in and out constantly, there was no constant flow of air either in or out.

 

 

 

**UPDATES FOR TODAY**

 

I put the bonnet on the car and you can see in the pictures that the vent is immediately behind the radiator. The pictures are all in the same folder that i linked to earlier:

 

http://smg.photobucket.com/albums/v621/Tommo560/Datsun%20260Z/Bonnet%20Venting/

 

P1000075.jpg

 

P1000076.jpg

 

P1000078.jpg

 

You'll have to excuse all the masking tape, the bonnet is not the best fit and so i sealed all the edges to replicate how my other bonnet properly fits on the car.

 

I went for a test run but didn't have a camera man and by the time i found someone to help the tabs were pretty frayed, so not the best video but you can see on the drivers side (right for you americans) that the tabs stick upwards. The tabs i placed inside the bonnet stick up out of the hole and the tabs situated toward the windscreen from the hole are even sticking up in the air. Very positive results. I reccommend watching the video in HD (uploaded at 128x720) to get the clearest image. Video is here:

 

 

For some physical testing I sat the car at idle without the thermo fan engaged. The temperature SLOWLY (about 5 or 6 mins) crept up to about 95 DegC. I engaged the thermo fan at this point and whilst the creeping stopped, when i brought the revs up to 2000 the needle kept moving up to about 100 DegC. You could still feel the heat coming out of the vents. With the fan on a surprising amount of air exits from the vents too.

 

I then jumped in the car with the fan going and went for a spin. Within 400m the temperature was back down to about 90. At this point i disengaged the fan again and drove at 40kph at 2000rpm. The temp dropped quickly (500m) to 85. I upped the speed to 70kph at 2000rpm and the temp dropped to around 80. Re-engaging the thermo fan made no difference to temperature.

 

After coming back home and stopping it was interesting to note how hot the bonnet was around the radiator and above the motor, but so much cooler behind the vent, about 15 DegC difference. This says to me that the vents are moving a significant amount of air.

 

I am concluding from this testing that these vents are sufficient for my purposes to keep the car cool on the track which is where I am having issue on hot days. Last weekend it was about 40 DegC (100+ F) and i had to short shift at 6000rpm to keep the coolant inside the radiator, which really just irritates me. These vents should solve this issue. I also plan to louver the front guards behind the front wheels and louver the inspection lid on the passenger side (left) to promote cool air flow past the carbies to avoid the current heat soaking occurring on the 3rd carburetor.

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Well I wasn't totally satisfied with that last video, so with both the stock and new vents in the bonnet and before i removed it i figured i would do one more test.

 

This time i used white wool so it is much clearer to see them moving.

 

Here are some static pictures:

 

P1000108.jpg

 

P1000107.jpg

 

P1000106.jpg

 

The video is here:

 

 

 

 

 

My observations from the two vents are that the front vents start moving air at lower speeds and seem to allow more through by the way the tabs flick around so much. As you can see in the pictures, the rear woolen tabs are actually situated INSIDE the bonnet. If no air was moving, then these tabs would not stick up.

 

The rear, stock 280z, vents do not move air through the front portion of the vent, only the middle back. You can see the front tabs lying flat with the vent. This i suspect is due to the fact that the front vents upset the pressure over the bonnet and thus doesn't suck air through the front of the vent. That, or the vents are just not as efficient, but when i tested them by themselves without the front vents i remember all the tabs sticking up slightly. Sorry, no video :(

 

I still stand by my conclusion that the vents up the front are the better ones and this time whilst running the car, the temperature gauge didn't move above 75 DegC with the fan disengaged, the thermostat operating temperature.

 

In the new year i will be taking my good bonnet to a panel beater and having him louver the bonnet where the front vents are located and also the passenger side inspection lid to promote air flow past the carbies.

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From the video I'm not sure where the air is going with the front vents, with the stock rear ones it is definately exiting. The main thing is that its working so thats good.

 

Going to try blocking off the grille opening above the bumper next? Not picking on you, you are trying things, but bugger me S30 owners in AU are slack when it comes to aero improvements.

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Not picking on you, you are trying things, but bugger me S30 owners in AU are slack when it comes to aero improvements.

I am normally always function over form, but man I like the look of the standard front end. Whoops, did I just say that? I might have to go sign up to zcar with those sort of comments. :-)

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  • 2 weeks later...

Yeah it is hard to tell where the air is going, other than out with the front vents. I think that has to do with the large opening and nothing directing the air. With the rear vents the gaps are quite small and all the air is neatly directed up and back, with the front vent there are no deflectors.

 

What is the significance of closing off the front of the car? I just went to all this effort to get MORE air into the engine bay... I have read and seen people closing the front end off but still don't understand the logic.

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You don't need more air into the engine bay with a S30, you need less with better air exit from there. Reduces drag and lift, improves cooling. There is a fair bit on the subject around here, typically the radiator opening above the bumper is closed off for a start.

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I will give it a try then. I'm about to go put the original bonnet back on, i'll give closing off above the bumper a shot tonight and see how it goes without vents.

 

Currently trying to source an Aluminium radiator. I tell myself it's to help cooling but really i think i'm just trying to lose the weight... and they look soo pretty :P

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  • 1 month later...

Well I said I would do it, and this is what I was getting at after how well the big gaping bonnet holes worked.

 

Here are the pics of the conversion:

 

 

 

 

 

 

The first test will be this saturday at the local track. Forecast is for mid 30C (~100F) temps, this will be the real test. I'll post back about how it performs.

 

I'll also take some better pics of the bonnet on the car.

 

Tom.

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IMAG0045_thumb.jpg

IMAG0049_thumb.jpg

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Cheers mate.

 

Not so much a track day, just a shake-down before the trip to bathurst. The car is at the mechanic now getting the new diff mounts (broke front and rear at the drags two weeks ago :P) fitted along with a diff change from 4.4 to 3.9.

 

Then it's getting new brake pads, bonnet fitted and new slotted rotors on friday night and then it's bombs away saturday to see how many laps I can do to make sure everything is up to scratch for the long straight.

 

Considering last time, with 10hp and 35Nm less than now through a SHOCKING 3.5 diff we were clocking 235k's+ down conrod, I want to make sure nothing is going to fail.

 

Btw, this will be my first in 4 months....

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Well I said I would do it, and this is what I was getting at after how well the big gaping bonnet holes worked.

 

 

Hey Whittle im from WA also .Where did you get your vents done and how much did they set you back. I really like the inspection lids. Nice work

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