Bonnet Protector Airflow

[jack180]

Hi All - tried using the search function but only found a little bit of chat about this.

Recently purchased a 2011 GU 3.0
About to upgrade the inter-cooler, thermofan, catch-can, egr ect.

I also just purchased a genuine Nissan Smoked Bonnet protector, but haven't fitted it yet.

I noticed when the car gets wet, the water beads on the bonnet hardly move - hence i get why we need to put thermofans on the inter-cooler (i get that), but was wondering what further effect putting a bonnet protector on also creates.
I'm guessing not much air is getting rammed into the inter-cooler scoop.
What are others thoughts/findings?
Will it disrupt too much airflow, or still be ok with the thermofan installed.

My stock Intercooler already has signs of leaks at the corners, so a full upgrade is on the cards.

[Wizard52]

Agree that any change to front of vehicle alters air flow to intercooler.
IMHO even the bull bar has some effect. The photo of my intercooler after trip to the Cape last year shows front half perfectly clean but back half a nice dirty red from the dust. My theory is that front half has very little air passing through so is next to useless. Whether this is a result of bull bar and or design of scoop is the question. There has been considerable debate on the forum about fans for the intercooler but I don't have the answer.

[my third 256]

some have said on here that an intercooler fan is only useful up to speeds of about 25 kms and are mainly for low speed driving eg 4wd

[threedogs]

The rear of the intercooler is dark as there are no vanes to direct air to the front of the IC.
I have the taller ARE scoop fitted which has vanes to direct air to the front.
Agree having a bullbar may make your IC work at higher speeds.
The ARE scoop allows the IC to cool at 65kph compared to 80kph std
Blue tack some cotton on your bonnet you may be surprised.

[jack180]

Agree that any change to front of vehicle alters air flow to intercooler.
IMHO even the bull bar has some effect. The photo of my intercooler after trip to the Cape last year shows front half perfectly clean but back half a nice dirty red from the dust. My theory is that front half has very little air passing through so is next to useless. Whether this is a result of bull bar and or design of scoop is the question. There has been considerable debate on the forum about fans for the intercooler but I don't have the answer.

Thanks.
I have seen the larger scoops on eBay as well, but I'm not keen on adding a larger scoop.
I have a bull bar as well.
Yes as you say considerable debate, so it's hard to find real data on the subject


Sent from my iPad using Tapatalk

[jack180]

some have said on here that an intercooler fan is only useful up to speeds of about 25 kms and are mainly for low speed driving eg 4wd

Interesting comment. So I wonder could fitting a fan actually worsen flow at higher speeds by disrupting flow?


Sent from my iPad using Tapatalk

[jack180]

The rear of the intercooler is dark as there are no vanes to direct air to the front of the IC.
I have the taller ARE scoop fitted which has vanes to direct air to the front.
Agree having a bullbar may make your IC work at higher speeds.
The ARE scoop allows the IC to cool at 65kph compared to 80kph std
Blue tack some cotton on your bonnet you may be surprised.

Yep good tip. Will try the cotton test this weekend


Sent from my iPad using Tapatalk

[blocko05]

I will be interested in seeing the results of the cotton test.

[threedogs]

I will be interested in seeing the results of the cotton test.

Now its warming up a bit and some insects are flying around,
you'll be surprised how many "miss" the scoop, I have fitted
a piece of plastic to fill the gap between the bullbar and bonnet.
Havent seen any difference well not huge difference anyway
I bolted some perspex to these brackets

[jack180]

Well I went for a drive today. Used blue tack to hold some ribbon on the bonnet in a few positions to try and assess if air actually flows into the inter-cooler at all.
Have a bull bar but have not yet fitted the bonnet protector

Whilst the front 1/2 of the bonnet shows little sign of air movement, to my surprise, fair bit of air movement into the scoop.
Seem like the air flow is much stronger from about 1/2 way up the bonnet

I can see by the ribbons that air is flowing into the scoop - not sure how else i could measure how much or what sort of flow, but its definitely going in.

However ... the flow going into the scoop looked stronger below 70km than above

And at 100kmh i think it kind of swirls and not as much goes into the scoop, rather over it.

Which is a worry as i really think its at higher speed when the engine is working a bit more and the boost is up you would need more cool air

The good thing i take from it is that 100km although i don't think as much, it is still going, so i would assume fitting a fan would assist this further

Fitting the bonnet protector tomorrow, and will try it again to see if the result looks different.

Cheers,
Jack