Novaz Nissan Laurel aero-build thread

[lunarhighway]

you'r airdam looks a little 80's to me, makes the car look a bit like a bmw from that period form a distance...
however i think it could be better aerodynamically when you lengthen it a the sides to warp around the bumper all the way to the wheels... sinde ther's going to be a low pressure behind the dam those gaps in front of the wheel might actually suck in air...

On the other hand you might actually want to raise the airdam slightly in the middle... especially when you're considdering an undertray... although this had been used before it's an often sited feature of the calibra with a 0.26 Cd but a lot of curent cars roughly have this form.
ideally the raised portion in the middle would make a smooth curved transition to the undertay to prevent flow separation... if there's no undertray a ridge about an inch high is what most cars with that configuration seem to have.

the idea is that since you can't get the dam all the way to the road to get an airtight fit some air wich hits the car in the middle on the dam, has little alternative but to go underneath the car anyway, and the dam will just make that even harder to do, and even is part of this air is still be forced around the car this is also an engergy robbing process wich at some point may be worse than going underneath, even with a rough underside there.

on the other hand the front wheels and wheelwells generally seem to be regarded as potential high drag places and most cars have some sort of device to direct the air away from them, confusingly some cars than have holes or ducts added to provide some air to the brakes for cooling, but these don't help to reduce drag.

[i_am_socket]

I'd be surprised if the airdam is "causing" the wind noise around the mirrors. Perhaps with the reduced engine noise you noticed the noise of the mirrors is standing out more.

Kooky idea, but how much drag do you think that hood ornament maybe causing?

[Novaz_nz]

Originally Posted by Dust

I would think that a turbo would help you out a bit, as would using veg oil.

I am in the process of sourcing turbo exhaust manifold for it at the moment - again it's a tricky item to find as they weren't sold with that option here in NZ or in Japan. Have got a friend on the lookout in Aussie, where they were plentiful (albeit in a 4wd chassis). Shipping will be the kicker!

i think it could be better aerodynamically when you lengthen it a the sides to warp around the bumper all the way to the wheels...

Yeah, I thought about that at the time - but only had enough signage left over to do one side I'll see how this goes, and can always add to it later. Ideally I need to win the coroplast lottery and make an undertray for the car, flowing back from the lower edge of the air dam. After a few tanks I'll try hacking out the middle as you say, and see if I can see a noticeable difference.

Kooky idea, but how much drag do you think that hood ornament maybe causing?

Quite a bit I imagine. I look at it often when driving and think about it's removal, and then think better of it. It's mounted with an elaborate bracket that pierces all the way through the bonnet in multiple places, and kept upright by a piece of steel cable and a meaty spring.
Besides, if I took it off, where would I tie my wool tufts to for "draft testing"?

[Novaz_nz]

I had another idea this morning on the way to work. Just looking at the roof lines of newer cars, they all seem to be quite tall and most seem to be high at the front and taper off to the rear.
The Laurel however has a nice flat roof. Would I see any benefit from carving a polystyrene buck to alter the profile of the roof? Or would the extra overall height negate any benefits?

Excuse the crappy picture - hopefully you can see the red and green lines that show where I'm heading with this. Is there a better profile?

[lunarhighway]

It's an interesting idea, but very difficult to say for certain. it's very likey requirements such as headroom, crash safety regulations and the state of glass and metal construction at the time the car was designed had as much to do with the shape of windshield-roof transition than aerodynamics.

and while more modern cars seem to feature increasing smooth transitions
some pictures in this article suggest that the airflow stays attached pretty wel to even more aggressive angles.

autospeed

yet even if the new angle is superior the added frontal area might offset the gains...so some very carefull balanceing needs to be done.

on a more realistic note, if you had the resources to build such a structure, why waste them on the smoothest part of the car, when simply smoothing out the underside would improve the aerodynamics immensly.

[Novaz_nz]

Wow, that looks like an interesting article - I'll read that when I get a bit more spare time. The reason I was thinking about the roof line is that it's clearly visible (at least for other cars) while I'm driving along. Making a buck to stick on the roof will be fairly easy (I know where there is acres of high density polystyrene).

I intend to smooth out under the car at some stage also, but need to find a cheap source of sheet metal, or reasonably tough plastic. I doubt anything less would pass the 6 monthly warrant of fitness inspections here.

Other ideas I'm mulling over at the moment are to extend the roofline some, extend the boot lid, or raise up the bonnet - as well as the usual items like side skirts and wheel covers. Cost is the main factor (isn't it always)

[Sean T.]

oh! take the hood ornament off! I just noticed that. It won't help a ton, but it will help a little.

And maybe a clear air dam that goes in front of the grille and lights, so that it will be flush with the front-most edge of the bumper? In the winter, you could even create a full front block like this, looking something like this:

(sorry, it was the only pic I could find...)

[Novaz_nz]

I like the idea of reshaping the front, however blocking any of the air access to the radiator is a no-no for me until winter rocks around again. I only had an upper grille block in place, and in (mild) 20°C heat the temperatures were just peaking at 95°C.
Heat is a known head-warper for these engines, so sacrificing some FE for longevity is something I have to accept.

The hood ornament I would like to remove, but it's a fairly tricky item to deal to, and would leave 5 great holes in the bonnet. Might save that one 'till last.

The rear mudflaps will be the next item to go. Quick and easy.

[Sean T.]

Not sure if you can find it in New Zealand, but they sell white duct tape here, and you could simply put a piece of that over the holes in the hood until you have time/money to patch the holes...

And you could also do the full-front block but with a gap for the top grille (and maybe the lower ones)

As for the back, a cheaper option could be to create a rear semi-boat tail (white lines), with a panel that hinges up to allow the boot to open all the way (orange line).

[Novaz_nz]

Along the lines of a boat tail, I have already thought about fabbing up a lock-box that would sit atop the boot, but that is mounted to the towbar. Ideally it would swivel out of the way when access to the boot was required. Only downside is losing rear vision.
The plan would be to increase storage for camping gear, etc (without using the roof), and hopefully shape it to improve FE.

I am planning a round the South Island trip in March/April next year, around 7000km worth (~4300 miles). That's pretty much the deadline for me to get everything sorted out, working, legal and known to be improving FE.
For now, small steps - get over 30MPG!