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


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[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?


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[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


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[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

[threedogs]

Have a search , you may find the fan only benefits sand driving at higher speeds the fan blades may block air flow.
Be it from fitting the fan to the top or below the IC, I would not fit one too many con's as to the pro's

[jack180]

Have a search , you may find the fan only benefits sand driving at higher speeds the fan blades may block air flow.
Be it from fitting the fan to the top or below the IC, I would not fit one too many con's as to the pro's

Did that, but still not finding a consensus

Fitted the bonnet protector today v- and did the ribbon test again
Hardly any difference to my first test - which was a suprise, but a good result i thought.
OK airflow into the intercooler below 70kmh, but at 100 i reckon its not getting much

Which for me, kinda goes against the thinking a fan us only useful for sand and slow work.

My take is that at slow speeds its getting airflow, but at 100k is not.

So, the question for me is will the fan help or hinder at 100ks.

How can i test this? Gonna have to put my thinking cap on and use my brain - which is likely to hurt lol

Cheers,
Jack

[FNQGU]

Jump onto the ARE website, if you haven't already, and read up on Richard's research. He has done a stack of testing and has shared a lot of his info. I found it quite informative, and he is considered one of the industry experts. He is a busy guy, but will also generally answer emails when he has the time, and I've had a couple of chats with him on the phone too.

[threedogs]

Did that, but still not finding a consensus

Fitted the bonnet protector today v- and did the ribbon test again
Hardly any difference to my first test - which was a suprise, but a good result i thought.
OK airflow into the intercooler below 70kmh, but at 100 i reckon its not getting much

Which for me, kinda goes against the thinking a fan us only useful for sand and slow work.

My take is that at slow speeds its getting airflow, but at 100k is not.

So, the question for me is will the fan help or hinder at 100ks.

How can i test this? Gonna have to put my thinking cap on and use my brain - which is likely to hurt lol

Cheers,
Jack

your EGTs should show any results with or without
a fan at 100 kph, a 7"-9" fan wont break the bank either

[Col.T]

G'day FNQGU,
coupla questions mate.
1) just how quick is your GU?
2) I can't find a ARE site. You can't mean ARB 'cause E and B aren't even close on the keyboard.
Can you give a full web address please?
Regards,
Col.

[jack180]

http://www.are.com.au/Inter/topMountIntercoolers.htm

[threedogs]

I have an A.R.E scoop with the louvers and a Tigged OE IC, but I dont feel Im
acheiving 71% efficiency, or for that how it would translate in real world figures.
I have also filled in the gap between the bullbar and the bonnet with a piece of perspex

[the evil twin]

Hiya TD... I get what you are saying.

I have no doubt at all that the 71% quoted by the manuf is correct.
I have no doubt that the product is of excellent quality
Neither do I have any doubt that the average punter in his average truck on an average day would, on average, notice bugger all difference
Or at the other end of the scale, that a Finke Desert Racer gets an extra 15 kW and 10 KPH or whatever and the rest lie in between.

E.G. the 3.0 Litre Leaking Factory I/C debate.
I had a leaky factory cooler (I think they all do from day 1 actually and just get worse with age)
IMHO it was an average one IE I saw some significantly worse but mine was sama sama most others

Just before my old truck was about to go out of warranty at 6YO I had it replaced.
Change in boost observed - 0 (PSIA on Scangauge)
Change in EGT - I reckon it dropped maybe 10 possibly 20 degrees at most (calibrated VDO EGT gauge) but an ARE would get more
Change in Fuel consumption - none that could be quantified IE same before and after (scan gauge and also GPS distance plus calibrated Odometer check against fuel used)

Reason why nothing noticeably changed on my truck IMHO is that the boost pressure is set by the ECU (or Dawes if Nad'd) after the Intercooler.
All that happens is the VNT angle increases for a bit more flow to get the same pressure which compensates for leaks pre-boost sensor.
That will happen up until the VNT maxs' out which is quite a large leak.

Yes, if the charge air is cooler at a given pressure it is more dense so has more Oxygen by volume but unless you punch in more fuel then so what?
Remembering that the ECU senses;
Inlet air temp and flow at the MAF prior to Turbo and I/C,
Boost at the I/C plenum afterwards, and,
doesn't know the EGT, then
the ECU has no way of knowing that the engine now has a kickarse charge air system.

Bottom line, IMHO, is to get the biggest or even a noticeable bang (other than a drop in EGT) out of the excellent quality aftermarket gear around then a punter needs to remap the ECU or crank up the Chip.
That is why the CRD's love cold weather and hate hot... the MAF so therefore the ECU knows there is more oxygen available.

[threedogs]

All noted I did however notice when I changed fuel from Caltex to BP.
For a joke Id say about 10% increase as in more zippier, now if I got
70% Id be doing a 14 sec Qrt mile or 400mtrs for the youngin's,
and we all know that wont be happening with a ZD30 ,,,,,,lol

[the evil twin]

You can do a sub 15 400 metres in a ZD... the cliff just needs to be at least 410 metres high...

Flame suit on and up, up and away....