Radiator Air Guide

[Dale FZ1]

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

So do you have something installed under the engine, or a splitter on the front bar?

[badhairdave]

The plan is to eventually run a splitter/undertray extending to the engine cross member. That's more for aero than cooling though. Nothing right now.

The skyline under trays that i've seen start at the radiator support which IMHO is less important that ducting from the front of the car. One of my first ever posts on this forum (when i was still BHDave so 03/04ish) was asking whether i was missing the front half of mine as it didn't make sense to me to start at that point. The factory intercooler had a nice plastic duct running to it but the tiny single core radiator got no help....

[badhairdave]

Out of interest Dale; Are you running a tube and fin or bar and plate intercooler?

[Yeedogga]

I had similar thoughts to the OP...

I made a diversion panel which effectively blocks off the grille airflow to the radiator and means all frontal air must pass through the intercooler before it gets to the rad.

Spose it means the grille air is just going into the engine bay/intake snorkel.

I also ran some alloy sheet under the cooler so there is now a sealed undertray from cooler duct (series 2 r33) right through to the plastic radiator undertray.

I have no idea if it works or not, but it does look pretty :-)

Havent noticed any difference in engine temps but i only have the standard gauge so who knows!

[GTR_JOEY]

I had similar thoughts to the OP...

I made a diversion panel which effectively blocks off the grille airflow to the radiator and means all frontal air must pass through the intercooler before it gets to the rad.

Spose it means the grille air is just going into the engine bay/intake snorkel.

I also ran some alloy sheet under the cooler so there is now a sealed undertray from cooler duct (series 2 r33) right through to the plastic radiator undertray.

I have no idea if it works or not, but it does look pretty :-)

Havent noticed any difference in engine temps but i only have the standard gauge so who knows!

Would really love to know if this makes a difference, positive or negative

Buy an after market temp gauge so we can get results

[Dale FZ1]

That's more for aero than cooling though.

The skyline under trays that i've seen start at the radiator support which IMHO is less important that ducting from the front of the car... it didn't make sense to me to start at that point.

Dave, I have had to make cooling the priority because I was thoroughly peeved with not getting a full run in each time before the ECU failsafes started kicking in, and also the potential reliability woes with it running hot.

I agree it makes most sense to combine the undertray/splitter as one unit for aero and cooling.

Either the cooling engineers know something more than us, or the production accountants worked out they could pull costings down without affecting stock performance. It would seem to me that the stock plastic tray from the lower radiator support - front crossmember would give a decent return on investment for cooling, and they didn't worry as much on the aero side given the GTR is the hero model. Would be good to have a close look at a dead stock GTR and see what tricks the factory used.

[Dale FZ1]

I made a diversion panel which effectively blocks off the grille airflow to the radiator and means all frontal air must pass through the intercooler before it gets to the rad.

I have no idea if it works or not, but it does look pretty :-)

So is yours 100% road use, or some track work included?

At this stage it's rated as bling only?

[Dale FZ1]

Out of interest Dale; Are you running a tube and fin or bar and plate intercooler?

Bar and plate. A bit heavy, but it's served a reasonably good purpose to date. Unknown just how restrictive those things are to the airstream.

[Dajae]

It would be more beneficial to have *some* airflow directed to the radiator, so its not getting the pre-heated air from the intercooler. Perhaps a 70/30 split?

While i dont think it would kill the cooling capacity to have 100% second hand air through the intercooler, there would definately be improvements in a different setup. I'll try and dig up photos of the do-luck R34 gtr setup.. Seems to have a lot of thought put into it..

Air vents in the front bar ducted straight to the top portion of the rad, with the intercooler dam ducted on the sides. The bonnet had a vent up and exactly back from the top side of the rad, with a air guide plate sitting across the top of the rad to the front of the car. The car also had a diffuser under the front, that tapered downwards towards the rear. In the intake ducts in the front bar, 50% was directed towards both intercooler and rad, the other 50% flowing to brake ducts and oil coolers.

This in theory would create a MASSIVE pressure difference across the heat-sink surfaces.. Critical for efficient cooling. The diffuser and vented bonnet would also help to create low pressure zones in the engine bay *behind* the cores.

Ty.

[Dale FZ1]

I like the idea of a bonnet vent to relieve air from the engine bay post-radiator. Might be worth looking at in due course.

As my work progresses the oil and power steering coolers will have ducts feeding them from the outer openings on the front bar. Pics will be posted up once the cardboard templates morph into metal.

On the undertray/splitter, I've thought that a small lip from plastic on the trailing edge may/should work to further reduce airflow to the rear of that point. (it's not lost on me that it will probably cause turbulence as well). Perhaps that might assist with creating a bigger pressure differential through the engine bay and exhausting/drawing air through the heat exchangers at the front of the car.

[Dajae]

The only real drawback to having a vented bonnet is the fact of water getting to the engine bay, but with thoughtful design consideration, this can be minimized.

If you can mould the trailing "lip" in such a way that it makes the outline shape of a plane wing (which basically means an upside wing), then the turbulence created (from the result of restriction of airflow to back inside the engine bay from underneath the car - our sought after "low pressure" zone) can be turned into something extremely useful... Downforce.

By having a flat under car arrangement that goes from say, firewall to rear diff, then it would only add to this effect.. This entire under tray would act as one big upside down wing. Because our "lip" extends further down than the body tray (if only by a small margin) this creates a low pressure zone the entire length, because of the blocked air flow.

Better still to this setup, having a rear diffuser in addition, shaped much like the front one, would help to keep drawing that air to the rear of the car, where it can join the air stream off the top of the car.. By doing so, we reduce the "wake" of air that is created by the movement of the car.

I really cant wait to get my car back on the road! Will be able to put all this theory to good use

[Dale FZ1]

I know the thread is about air guides etc, but on reflection it's about management of total airflow.

These pics apparently show a stock undertray/diffuser, and a sheet aluminium version.

I'd still like to see pics of any stock guides around the GTR intercooler and radiator sides/top

Edited February 10, 2012 by Dale FZ1

[Dajae]

Definitely one of the more interesting threads on offer

That sheet version is very similar to the design i had in mind.. Only difference is i would have it curved on all trailing edges.

[rob82]

You've answered your question you need to create a pressure differential. Best way to do that is using a lip to cause a low pressure path for the airflow. You need a 60mm flap at 45 deg angle that stops just before the bottom of the radiator. Works best under the car as the air velocity is a lot higher under the car but the pressure is slighty higher.

Was trying to find it but Mazda under car aero on their rx7 or rx8 is a work of art - air dams at brake points and oil coolers.

[Dajae]

I remember reading about the Mazdaspeed aftermarket aero parts. Were similar parts used as standard? Time to trudge through google images..

[Yeedogga]

So is yours 100% road use, or some track work included?

At this stage it's rated as bling only?

The car does see some track duties and is a weekender only at this stage.

To be honest though, it was really designed to obscure the intecooler and piping and to tidy up the engine bay. That said, I did vainly hope that it would improve cooling.

I am considering buying an aftermarket water temp gauge anyway, so if i ever do i will report back with results.

[Dale FZ1]

I am considering buying an aftermarket water temp gauge

I've been running the stock gauges, and would never have known that it was an overheating issue. It was only that I do my tuning, and knew the failsafes I had written into the tune. But it still took a bit of looking to confirm my suspicions. A decent calibrated gauge would have helped shortcut to the problem.

I want to stay on-task with this thread, but dug up this effort at a full undertray on an RX7. Way beyond my plans and resources, but interesting to see. Fish-eye lens shows full-length view but sadly gives no real idea of what is done around the front bar leading up to a basically flat undertray.

I'm pretty interested to get some input from a few of the SAU people with a motorsport profile who are prepared to comment and/or post up some pics of their setups. Hopefully a few PMs will encourage them to share their experiences.

[Dajae]

That's freakin' awesome! Thanks for posting that up. However, not too keen on encasing the exhaust like that..

Take a look at honda prelude front ends. Not sure which year it is, but it came with some sort of air guide over the radiator, with two ducts on the inner edge of the headlights, flowing *over* the guide. Scavenging effect perhaps?

Indeed, i shall stop whoring your thread..

[badhairdave]

The undertray on the mazda will only be telling half the story. He'd have to have some pretty extensive vents in the bonnet to let trapped air/heat out.

[Dale FZ1]

Very true. I have first hand experience in a gravel rally car with a 3/4 length, sill-to-sill bash plate. Worked awesome but needed vents to get rid of exhaust heat. Started frying the floor, burning paint, the works. Very uncomfortable .