Radiator Air Guide

[Dale FZ1]

Long story is I experienced some cooling issues with the R33 at track days. Had a good hard look at things, and it appears airflow through the radiator core was inhibited. I've got onto most of the fixes I can identify, with a little help/comments from a few people on SAU. I am very conscious of proper sealing of air gaps, and quality/spec of the radiator.

My R33 now has guides installed at bottom and sides of the intercooler:radiator gap, trying to establish if there is any gain in putting a guide across the top as well?

My thinking is that if I don't run one that full airflow through the grille will give the radiator a high pressure zone but effectively render the intercooler a high speed barge board. Unless I force the air to travel through the intercooler first by using a top guide.

I'm looking for comments from those people who have installed and tried out air guides between FMIC and radiator particularly for track use. I don't believe road-only experiences will be of great help simply because the road speed/engine speed/loads are sustained high enough for long enough to show up strengths or weaknesses in cooling systems.

I know this is probably more motorsport/build/fabrication related but figure posting up here is appropriate.

Comment/discuss please.

Edited February 6, 2012 by Dale FZ1

[GTSBoy]

From what I've seen, most of these top air guides don't try to separate intercooler and radiator flow. I initially thought that they wouldn't do much at all (in the context of R32s specifically), because there is a rubber seal across the radiator support panel. I thought that air was naturally stopped from flowing where it wasn't supposed to. But it then occured to me that air that flows up towards the bonnet can in fact go sideways behind the headlights and down and out, bypassing the radiator. This would be true on any car, including those that have the engine air intake over the top of the radiator support panel.

I cannot see how these top guides can fail to do "something" for controlling the amount of air that spills around the radiator - provided the other holes are all closed as well. Some still will get past, but blocking the majority of the hole has to be of some benefit.

[urtwhistle]

I found that with my R34 when I sealed the gap around my intercooler to radiator on all 4 sides that the car ran hotter. So I ended up removing the top piece then it ran cool once again. So therefore I think you might be right about the barge board theory.

[Dale FZ1]

Interesting that yours ran hotter with full ducting at sides and top.

I had in mind to leave a slot to at least let a little bit through the grille passage.

It might be a balancing act with intercooler spec to achieve decent airflow through it, and then also through the radiator core. I want them both to work at least reasonably efficiently. My understanding is that air will pass through successive cores only when there is a pressure differential on either side ie. high pressure to lower pressure.

My logic says that with no top plate the bulk of radiator airflow will surely pass through the grille and render the intercooler fairly much a loaded heat sink with nowhere to shed heat because the air isn't passing through it. I believe that my radiator had been doing that because of poorly thought-out air control and passing a cold inlet air duct unsealed into the engine bay.

Ultimately the best bet will be to try running with and without top plate, log the data and see.

There are enough SAU track runners, no way am I getting the Neil Armstrong feeling with this one. Post up some pics and ideas and share the experiences.

Edited February 6, 2012 by Dale FZ1

[wolverine]

I made a small fin to sit on top of the cooler itself which discourages air spilling over the top.

[badhairdave]

Do you have pictures of your current ducting? Does it extend to the front of the car, or just between the 2 cores?

On the low pressure area behind the intercooler; I think you are looking at an extreme but your thinking is correct. I'd be inclined to think you would have some interaction at he boundary of the air coming through the intercooler with the stuff coming over the top but it's all still going through the radiator as the pressure of the air behind it will force it through. Sticking a guide in there should help but by how much i couldn't say.

But i tend to think it's more important to get the guides as far forward as is practical to direct/channel as much air towards the cores as possible. Guides from the front of the cooler to the hole in the front bar, guides up the sides between the radiator and the grille. Maybe angle the guide between the top of the intercooler and the radiator down slightly so more of the radiator is getting cooler air?

[Dale FZ1]

This pic shows the side plates and the rubber seals if you look closely. Little bit tricky to show the lower guide but it's there.

I'm in the process of fitting a GTR replica front bar with bigger openings, and there will be further guides fitted to channel air onto the intercooler rather than allow it to spill around the sides.

[urtwhistle]

I'll try and remember to take a photo of mine. I did mine out of pure curiosity. I made it from cheap high density foam rubber and used elephant snott to glue it to the back of the inter cooler so that I could easily pull it out later on. On a 40 deg day I was driving (plodding) around with it sealed on 4 sides and my warning light on my gauges was going off as it was set at 100deg. I removed the top peice only and the water temp dropped by about 5-6 deg when idling at the lights so just enough to stop the warning light flashing.

What I noticed while looking at a race car was that they used guides on the bottom and sides. On the top they ran 2 guides. 1 ran 90 deg to the top of the intercooler to radiator and the 2nd routed air over the top of the intercooler into the top 1/4 of the radiator. that was in a s14 though.

regards

Chris

[Dajae]

Do you have the stock front undercar diffuser in place? There is a great article on http://www.autospeed.com about the subject.

Goes indepth about cooling underbonnet temps. Great read as it relates to this. Im at work right now so cant link it straight for you guys, but a quick search on the site should point you in the right direction.

Ty.

[Dale FZ1]

For interest's sake it would be great if you can find the direct link.

Initially I hadn't considered the effect of that plastic "splash guard", until I experienced overheating issues. Then I was directed towards thinking about air pressure differentials across heat exchangers, and it occurred to me that the simple plastic guard was actually helping to create a draft through the engine bay and pull air through the radiator. Simple concept, but takes some thinking through.

For the next event that guard will be back in place, unless I have enough time to fit a diffuser direct to the bottom of my front bar.

[Dajae]

I wont be back home until later tonight, but i'll post the direct link as soon as i can.

Agree 100%.. With our R33's, even though there isnt much in terms of good aftermarket aero modifications, i think JUN have a good universal diffuser that can be fitted without too much hassle.

While the stock one is good, there are other little tricks to improve the performance of pressure differentiating..

It will be illustrated better when i get that link for you

[Dale FZ1]

What I noticed while looking at a race car was that they used guides on the bottom and sides. On the top they ran 2 guides. 1 ran 90 deg to the top of the intercooler to radiator and the 2nd routed air over the top of the intercooler into the top 1/4 of the radiator. that was in a s14 though.

That info could be gold, Chris.

Ignore the chassis being used, the issue is managing airflow through two different height heat exchangers and making them both work well. That would have effectively given two different pressure zones at the radiator core, and make the intercooler core continue do its thing at speed as well - theoretically at least I wonder how well it worked?? It might be a challenge to the cooling efficiency of the radiator if only a portion of the core gets exposed to full airflow but sounds ok.

It may be that I only need a horizontal divider from top of intercooler height, and sealing against the radiator. The bonnet should work well enough as a top guide plate, with good sealing rubber mounted on the support panel.

Hopefully someone can post up some pics of their work. Good ideas are one thing but the devil is in the detail.

Edited February 7, 2012 by Dale FZ1

[GTSBoy]

It may be that I only need a horizontal divider from top of intercooler height, and sealing against the radiator.

That's a good idea. Otherwise the air from the grille will flow down behind the cooler and upset the low pressure that you'd want/need there to make the cooler flow properly.

The bonnet should work well enough as a top guide plate, with good sealing rubber mounted on the support panel.

As per my first post in this thread - I don't think you can rely on the bonnet for that task, as the air can go upwards to the bonnet, then sideways over the headlights and then down behind the lights. The top divider panels will take care of (most of) that.

[Dale FZ1]

Do you have the stock front undercar diffuser in place? There is a great article on http://www.autospeed.com about the subject.

After this info I had to check for myself Ty.

Is this what you were referring to?

http://www.autospeed.com/cms/A_2160/article.html

Makes for interesting reading, I just don't have heaps of time ATM to go road testing with a manometer. I followed a fair bit of info written by Edgar when he kicked off Zoom Magazine, even back then he was big on testing and validation. Clever stuff that proves why something works.

[Dajae]

After this info I had to check for myself Ty.

Is this what you were referring to?

http://www.autospeed.com/cms/A_2160/article.html

Makes for interesting reading, I just don't have heaps of time ATM to go road testing with a manometer. I followed a fair bit of info written by Edgar when he kicked off Zoom Magazine, even back then he was big on testing and validation. Clever stuff that proves why something works.

Haha yeah thats the one. Sorry couldnt post it for you, got tied up.

True.. I dont have the time either.. But i figure that this same theory can be applied "universally" without similar, if not better results. When i get annual leave mid-year, i'll go about doing some real road tests

[badhairdave]

Hopefully someone can post up some pics of their work. Good ideas are one thing but the devil is in the detail.

Obviously not an R33, and not a road car so no reo in the way of air.

This one shows the guides for the intercooler extending all the way forward and the top guide for the radiator. The radiator guide extends to the front of (what used to be) the radiator support to give it a cleaner run at the core. When i originally made the top guide i measured it to run to the headlights, but it just doesn't fit as the bonnet drops down in front of the radiator support so i figured it would do a good enough job of guiding the air at that point.

I don't know if you can see it in the photo but the guide for the intercooler is wider at the front to make the most of the gap between the headlights.

This one just gives a view of how i have everything laid out. I have a gap between the intercooler and radiator of about an inch due to the oil cooler being in there. There's about 10 rows of the oil cooler hidden behind the IC. It's up high to minimise the area with 3 cores, couldn't go higher and close the bonnet. Still no side guides in it, i ran out of time before it's first track day and it seemed to do ok without them even on a 35 degree day. They are on the to do list.

Here's a work in progress of building the bottom guide. The centre bit was eventually shortened and is bolted to the lower opening on the front bar. You can see the 2 bolts in the top pic if you look closely.

[Dale FZ1]

Nice work Dave. I agree that multiple heat exchangers makes getting decent airflow that much harder. Interesting to note that even without side plates you got a good result.

Does the S13 run a front bar splitter or the splash guard underneath the engine?

[badhairdave]

Yeah they run a guard underneath from factory, but i have never seen one....or at least never noticed one before.

The mounts for it look the same as the r32 so it'll be pretty similar, starting at the bottom radiator support and running to around the swaybar/front of sump somewhere

[GTR_JOEY]

Has any one tested/tried this type of diversion panel

Any results, what do you guys reckon the benifit if any would be

I recently purchased one, purely for asthetics though

[Dale FZ1]

That's the top lid or plate that I was looking to make.

But purely if it was functional, as per the thread title.

It appears that running the top plate from top of intercooler and sealed against the radiator roughly at two-thirds height is something that would work.

GTR running an OEM intercooler with (presumably) less restriction to the airstream might make things different.