Bonnet Scoop Advice

[John_D4]

I’m thinking of getting a bonnet scoop and mounting it directly above the turbo to help both keep under bonnet temps down, try not kill my deep cycle battery too quickly. I was talking to a guy in Melrose this year who did this and noticed benefits.

I’m thinking about 1 of these but I’d love soon feedback as I’ve never fitted something like this before. My bonnet needs a respray anyway.

4X4 TOYOTA NISSAN MITSUBISHI UNIVERSAL BONNET SCOOP | eBay (https://rover.ebay.com/rover/0/0/0'mpre=https%3A%2F%2Fwww.ebay.com.au%2Fulk%2Fitm%2 F153038579753)

MULTI UNIVERSAL FIT BONNET SCOOP MADE FROM ABS SUITS TOYOTA HILUX KUN/LN/GGN/TRD | eBay (https://rover.ebay.com/rover/0/0/0'mpre=https%3A%2F%2Fwww.ebay.com.au%2Fulk%2Fitm%2 F262992519578)

[trout1105]

There is another thread on this .
Will a bonnet scoop reduce heat in the engine bay? (https://www.aulro.com/afvb/discovery-1-a/257694-will-bonnet-scoop-reduce-heat-engine-bay.html)

[John_D4]

There is another thread on this .
Will a bonnet scoop reduce heat in the engine bay? (https://www.aulro.com/afvb/discovery-1-a/257694-will-bonnet-scoop-reduce-heat-engine-bay.html)

Oh right. Thanks. I’ll go there

[John_D4]

So from what I’m reading:

Forward bonnet scoop = increased engine bay pressure causing decreased air flow through the radiator.

Maybe ceramic coating is a better idea.

[laney]

I'd have a look on e bay at rear facing bonnet vents

[Mick_Marsh]

So from what I’m reading:

Forward bonnet scoop = increased engine bay pressure causing decreased air flow through the radiator.
No. If placed in the right spot, it will increase the airflow in the engine bay and reduce engine bay temperature.

[John_D4]

Well that was becoming confusing. I read 98% of the entire thread & it was becoming difficult.

I would have thought that a scoop similar to a Hilux design, a few inches forward of the turbo would direct air downwards and rear wards, bouncing off the firewall and past the large air gap between the trans and passenger side chassis. This should take turbo heat along with it. I am going to ceramic coat the manifold when I redo it. Additionally, after reading the thread I’m also going to make a Saudi grill modification. Not sure about the bonnet vents tho. That part was confusing.

My water temps sit high 80’s to low 90’s and maybe 92-93 when stationary in traffic. I bought my nanocom after summer so I don’t know what the summer temps are so I don’t know if radiator temps a concern or not. I haven’t towed our 1.6t jayco since buying the nanocom either, so I don’t know how that effects things either. Let alone Summer plus jayco!

[trout1105]

The scoops on the Hilux and the cruisers direct the air into a pre cooler and not just to the top of the engine.

[John_D4]

The scoops on the Hilux and the cruisers direct the air into a pre cooler and not just to the top of the engine.

Agreed, I know. I was referring to the hilux style instead of some other funky style

[gavinwibrow]

Well that was becoming confusing. I read 98% of the entire thread & it was becoming difficult.

I would have thought that a scoop similar to a Hilux design, a few inches forward of the turbo would direct air downwards and rear wards, bouncing off the firewall and past the large air gap between the trans and passenger side chassis. This should take turbo heat along with it. I am going to ceramic coat the manifold when I redo it. Additionally, after reading the thread I’m also going to make a Saudi grill modification. Not sure about the bonnet vents tho. That part was confusing.

My water temps sit high 80’s to low 90’s and maybe 92-93 when stationary in traffic. I bought my nanocom after summer so I don’t know what the summer temps are so I don’t know if radiator temps a concern or not. I haven’t towed our 1.6t jayco since buying the nanocom either, so I don’t know how that effects things either. Let alone Summer plus jayco!


I too have heating concerns cos i tow a big heavy brick on occasions. Normal non towing summer operating temps are 88 - 93.
However, I'm reliably informed that the TD5 can safely operate at coolant temps of up to 120 celcius, so you have quite a bit of leeway.
As long as you can monitor EGT and coolant (temp and ideally coolant alarm for unforeseen loss of coolant) you should be pretty right.

[Pedro_The_Swift]

Not sure if this helps,,
but with no front bar or spotties there is a "no" pressure area at the back third of my bonnet in the rain at 100 kays.
The rain just pools there.
[bighmmm]

[John_D4]

Fair point. The slope of the windscreen prob forced the air upwards from the last 1/3.

Not sure if you’ve helped or hindered my question tho!

[DiscoMick]

It's confusing, but from what I can figure, for the radiator to function at peak, the air pressure behind the radiator should be lower than in front, so air is sucked through the radiator to try to equalise the flow.
Adding a front facing bonnet scoop might force air behind the radiator, raise the air pressure there and reduce the flow through the radiator.
To lower the pressure behind the radiator, a rear-facing scoop might vent air and lower the air pressure, increasing radiator flow.
This is counter-intuitive, so it's hard to take in. Have fun working this one out.

[Mick_Marsh]

It's confusing, but from what I can figure, for the radiator to function at peak, the air pressure behind the radiator should be lower than in front, so air is sucked through the radiator to try to equalise the flow.
Adding a front facing bonnet scoop might force air behind the radiator, raise the air pressure there and reduce the flow through the radiator.
To lower the pressure behind the radiator, a rear-facing scoop might vent air and lower the air pressure, increasing radiator flow.
This is counter-intuitive, so it's hard to take in. Have fun working this one out.
So, Mick, that's what you have done on your Defender. And it works?

[djam1]

Just ceramic coat the exhaust manifold and turbo

[John_D4]

Yeah, that’s where I’m thinking also. Turbo also? Haven’t heard that before

[DiscoMick]

So, Mick, that's what you have done on your Defender. And it works?No, I'm leaving mine alone. Only thing I might do is remove the driving lights, which the light bar has made redundant, to increase airflow.

[Pedro_The_Swift]

so when money is no object,, and you want cooling,,
https://www.aulro.com/afvb/images/imported/2018/06/159.jpg

an original GT40--


https://www.aulro.com/afvb/images/imported/2018/06/160.jpg

[RobMichelle]

Wonder if the water pools in the black one [emoji12]

[John_D4]

Wonder if the water pools in the black one [emoji12]

Only if you get it wet!

[billsdefender1996]

I’m thinking of getting a bonnet scoop and mounting it directly above the turbo to help both keep under bonnet temps down, try not kill my deep cycle battery too quickly. I was talking to a guy in Melrose this year who did this and noticed benefits.

I’m thinking about 1 of these but I’d love soon feedback as I’ve never fitted something like this before. My bonnet needs a respray anyway.

4X4 TOYOTA NISSAN MITSUBISHI UNIVERSAL BONNET SCOOP | eBay (https://rover.ebay.com/rover/0/0/0'mpre=https%3A%2F%2Fwww.ebay.com.au%2Fulk%2Fitm%2 F153038579753)

MULTI UNIVERSAL FIT BONNET SCOOP MADE FROM ABS SUITS TOYOTA HILUX KUN/LN/GGN/TRD | eBay (https://rover.ebay.com/rover/0/0/0'mpre=https%3A%2F%2Fwww.ebay.com.au%2Fulk%2Fitm%2 F262992519578)

Hi There, just read your thread on the bonnet scoop.
Just two things to bear in mind when fitting one, it needs to be positioned with the intake in the front half of the bonnet, as the futher back it is positoned the less effectice it will become due to the aerodynamics. The back half of the bonnet is an aerodynamic low airflow area due to the air being forced up by the windshield.

Second while the scoop can be positioned any were to the left or right of the center line it is probably not a good idae to place it over the turbo, as this would result in even more rapid cooling of the turbo charger and inlet manifold after long climb followed by a descent. This rapid cooling causes the manifold to distort and pull bolts out of the alluminum clyinder head. Put it in the middle/drivers side if possible. it will still help to lower the temp under the bonnet.

Cheers Bill

[John_D4]

Hi There, just read your thread on the bonnet scoop.
Just two things to bear in mind when fitting one, it needs to be positioned with the intake in the front half of the bonnet, as the futher back it is positoned the less effectice it will become due to the aerodynamics. The back half of the bonnet is an aerodynamic low airflow area due to the air being forced up by the windshield.

Second while the scoop can be positioned any were to the left or right of the center line it is probably not a good idae to place it over the turbo, as this would result in even more rapid cooling of the turbo charger and inlet manifold after long climb followed by a descent. This rapid cooling causes the manifold to distort and pull bolts out of the alluminum clyinder head. Put it in the middle/drivers side if possible. it will still help to lower the temp under the bonnet.

Cheers Bill

Thanks for your reply Bill