Front-end aero mod

[donee]

Hi Cephrain,

I am a Prius driver, and do have grill blocks. The NAH is built with Toyota HSD technology. So these comments assume the NAH is similar to the Prius. The Inverters and transmission on HSD cars need cooling. The transmission is only cooled by airflow over the transmission. The transmission has the big motor and the speeder motor (socalled MG2 and MG1). Both need to be cooled. The inverters are cooled by a liquid coolant loop and radiator. In the Prius, that radiator is the lower third of the radiator assembly (both engine and inverter radiators are integrated into one assembly, with seperate chambers). Assuming the NAH is similar, you probably do not want to grill block the lower openings except when it gets below 20 F.

Assuming the top 2/3'rds of the radiator is the engine radiator, you can grill block probably the passenger side of the top grill (again leaving the lower grill open) and 1/2 of the driver side for casual commuting. Casual Commuting meaning - no mountains, no desert, no 100 F/80% relative humidity and running the AC at 70 F. The reason for this is to get air to the transmission which is assumed to be on the driver side. Whatever you do, its best to set it up to be removable and instalable quickly. Even at a red-light quick.

The upper radiator blocking will improve aerodynamics the most. It will ease the bending of the air over the top of the hood. Also, water during rain, will not be guided into the hottest portions of the radiator, giving extra unwanted evaporative cooling.

I have also moved my license plate down so that it bridges the gap caused by the lower grill.

[cephraim]

Donee,

Thanks for the info! While Nissan licensed the hybrid technology (electric engine and battery), I believe the ICE and transmission are Nissan-unique. I know I have a CVT transmission, and the standard Altima 4-cylinder ICE, for example.

So, do you believe your comments still apply?

Thanks again!
Eph

[donee]

Hi Cephraim,

Yes, the engine and transmission are Nissan unique, but similar in concept to the Prius et al HSD cars. So, yes, I think my comments still apply. The CVT is actually an eCVT. It does not have mechanically variable components to provide variable ratio. It uses a speeder motor and a torquer motor that geared with the engine in a fixed manner. The speed of the speeder motor impacts how much torque goes from the engine to the wheels, or to the electric half of the drive train. Further variation on the electric side controls how the eletricty is used (stored, or routed to the torquer motor).

[cephraim]

So, you suggest pulling out my styrofoam and going with the top radiator blocks, as you have described? Certainly would LOOK better, too!

Also, I was thinking that, since I take this car through carwashes, the styrofoam is likely to be a pain in the butt. Whereas, a block of the top grill that is positioned between the grill and the radiator will be more secure, I would think.

Thanks again!
Eph

[azraelswrd]

For slower speeds, tires are a MAJOR area to be addressed in addition to driving style and weight.

(ex: switch to low rolling resistance types, thinner tires, more pressure)

[donee]

Hi Cephraim,

There is another issue with styrofoam. If it disintegrates, it has to be picked out of the fins of the radiator. Prius grill blockers typically use polythelene foam plumbing pipe insulation. The foam tubing is either wrapped around the horizontal grill bars, or wedged inbetween the bars and held from being pushed further in by the grill uprights.

[cephraim]

Makes sense.
Oh well. Good thing it didn't take too long and cost me $zero.

I guess I'll buy some black coroplast and try the upper grill mod.

Thanks,
Eph

PS - My tires are brand new stock tires. I have them 2psi above sidewall. I did notice a big improvement when I went from placard to sidewall...