Newbe Ecomodder - Prius Owner
 

Well, my first mod was to block my lower grill on my '07 Pruis. I learned about this on Prius Chat. I just used the pipe insulation method. In order to maximize mileage I also reduced my speed on my commute from a max of 70mph to a max of 60mph. This has caused my mpg to jump from 46mpg up to 52+. My current tank is at 55mpg with just over 300miles on it. That has gotten me really excited. While I was happy with the 46mpg (in the northern california winters) I was shocked at the dramatic improvement I have achieved recently.

This has inspired me to install a more aerodynamic grill block. I am also considering lowering my car and or adding an air dam. I don't want my car to look too funky, but am willing to try a few mods. Then I found this site! I had no idea there was a whole forum devoted to mpg mods. I love it!

I saw a design for a grill block made of coroplast that was put on a Honda Del Sol. I think I will try that first.

Anyone know what kind of improvement I would get by lowering my car 20mm? (I can buy springs that would do that).

What about adding 2" to my existing air dam?

20mm? That's not very much of a drop at all, I would look for something more dramatic if you expect it to actually make any difference...but then I'm sure someone better on the aero aspects will chime in with better advice, ;)

Anyway, welcome to the site, don't forget to add a fuel log and garage, :)

Welcome to the site. The Prius is a great car and very capable of big numbers. I think an airdam would only increase the drag thus decreasing FE. A block heater would do wonders to increase the FE. Check tire pressures, most here run pressure at max sidewall pressure or more.

What kind of commute do you have?

Welcome fellow prius owner. Do you have a picture on what you did on our grill block. I too have the foam insulation.

Just curious, do you have a scanguage or anything to keep track of your water temp with your grill blocked.

This is the grill block example I saw. I have not done it yet. My current grill block is for the lower only, using pipe insulation.

http://www.gassavers.org/showthread.php?t=701&page=2

My commute is from Danville, CA to Downtown Oakland, CA. About 25 miles each way. Highway 680 and 24. Mostly freeway. It includes one gradual incline up to a tunnel with an elevation difference of 1000 feet. The traffic is generally not too bad. I generally cruise in the slow lane at 60 like an old lady now. Although I am only loosing about 3 min per trip due to the 60mph speed.

I have thought about getting a scan gauge, but have not splurged yet.

That is a great grill block. If you do it, do two I want one.

Haha - that GS link shows the grille block on Dan's old Del Sol. Dan owns a Prius as well, and posts here once in a while (krousdb).

By the way, welcome to the site, Winston!

If you're doing primarily highway commuting (and it sounds like you are), lowering the car will help very slightly. Lexus calculated a one inch drop reduced Cd on the LS400 (I believe) by .01. That may gain you (guesstimating) 1-2 mpg @ 60 mph.

So, don't do it for the financial impact, though there may be other motivation.

There are lots of mods you can do to a Prius in addition to these.

And it's great to read someone's surprise at the savings from just slowing down. That's priceless! :thumbup: And just the beginning - the Prius responds particularly well to a motivated right foot. There's more fuel economy where that came from!

Hmmm. That looks familiar......:p

Dan! Do you hang around in the shadows waiting for people to mention your name so you can pounce?

Yes, I am amazed at the huge impact to mpg. Everyone knows that the aero drag increases exponentially with speed, but I am still shocked at the difference. That is why I am telling it to everyone. Just to help reinforce the influence of reduced speed. I kind of think there are side benefits to my reduced speed. By staying in the slower lanes I don't have to accell/decell as much as people in do in the fast lanes.

That may be an old grill block, but it still looks great. I am wondering if he did the same thing for his Prius?

Actually, I just stopped by so I could get jealous of others here getting better FE than me. With my new tires, it feels like I am pulling a boat.:mad:

Actually, I was thnking about doint that tomorrow if I have time. I did one a few years ago with duct tape covered cardboard. That was when I lived in a colder climate. Now, a grille block for me is more for aero purposes.

Once ultra-low Cd vehicles like the Aptera to become available on the market, then this FE penalty when traveling at normal highway speeds would become a thing of the past. When you drop the Cd low enough, then you push the drag wall (the point where the drag curve starts to curve upwards fast) up to well above normal highway speeds, so travelling at 70mph causes very little drop to your mpg's (KW/mile for an EV). And if your engine gains efficiency as you increase its load, then with the proper sized engine and gearing, the MPG (or KW/mile) can be close to constant over a wide range of speeds as the slight increase in wind drag as you go from 30 to 70mph is compensated for by the increase in engine efficiency as you increase its load.

With an ultra-low Cd vehicle, the only place where the higher speed kills your mileage is when climbing a hill, since the accumulation of potential enegy with altitude is tied to vehicle weight rather than Cd, and in this regard an ultra-low Cd vehicle is just like any other vehicle. To reduce the FE penalties of hill climbing, you need as lightweight a vehicle as possible. So to keep your mileage up, you need to drive with load (DWL) as much as possible on the uphills whenever a low traffic density or low speed limit allows you to safely do it. Experimenting with increasing the amount of DWL along my route has been where I have been getting my greatest increases in FE lately.