Drafting with grill block

Safety aside, unless your coupled to the trailer like a train, I would think there's still a lot of air flowing behind the vehicle you're drafting.

 

Drafting requires tailgating - never a good idea.

BlackBerry 9930 ?

 

I partially grill block (about 2/3 to 3/4 of the bottom grill). I've driven behind big rigs and have not seen a noticable increase (or any increase) in engine water temperature and inverter temperature. I would say that drafting a big rig will not harm your engine due to overheating.

There are other safety concerns, that I'm sure you are aware of (and were pointed out here) that you do risk.

 

Wind does not give your engine manifold air. That air is around the engine, the car, you at all times. So no problems there, period. I have seen no effect on the temperature on my Scan Gauge from from the grill blocking.
Drafting can be dangerous, that said, I have drafted my way from Washington state to North Carolina and back with the Prius six times. With my Adv Tech Package 2011 Prius (two of those trips) I set the Radar Cruise Control on 100 feet and have remained there allowing the RCC do all the work, to and including a few near stops. Gives me about 2-3 mpg advantage. I pick trucks that obviously have light loads and do not slow down on hills. Seems to keep me out of other traffic situations too. Often wondered what the drivers think but none have shown any bad behavior and a couple as they were leaving the highway and I passed have waved back at us as we gave them a "thank you" wave. I am not endorsing this as something others should do.

 

The radiator is likely sized for cooling the engine when it's sustaining peak (or near-peak) power, at altitude, and/or on a very hot day. (It might not be able to keep up with all three of those at once, but I'd bet it'd do OK with at least 2 of the 3 without grill blocking.) When drafting, you're reducing the load on the engine, so it needs less air to keep it at a reasonable temperature. Not to mention, it's not really blocking that much air - put your hand out the window sometime and feel how much is still going by you. I wouldn't worry about it.

And as for the safety aspect, I assume by "drafting" you mean "following a large vehicle at a safe distance", not "trying to count the number of dust particles on the rear bumper". Even following at a safe distance can still save fuel. (I sometimes follow a truck at about double the "normal" following distance in this area, and I easily gain a couple mpg.)

 

Not at all.
When you wham into the ICC bar the grill blocking might come in handy if you use thick enough pipe insulation.
Those bars that hang down from the rear of a semi trailer are officially called ICC (sometimes DOT) bumpers, but they used to have a different name.
They called them Mansfield bars.

 

I don't get it... the Prius already gets 50+mpg... why would you put yourself, the trucker and other drivers that share the roadway in a potentially dangerous situation by following closely (and being blind) behind a 60' object moving at >60mph? How much could you possibly save on gas?
Even if your fuel consumption went down to zero- it still wouldn't be worth it...

 

I do not draft, but that is not the question you asked. Your car, like many, is equipped with a device that comes on when normal airflow is not adequate to cool your radiator passively, it is called a fan and it protects the coolant temperature when drafting, or more likely, cruising through the drive thru. It has been some time since I heard of a Toyota that could overheat with the fan running.

(I drove to Phoenix in a Corolla with the heater on full blast so we could replace the water pump when we got there, in 1977)

 

Drafting a semi could possibly save you a few cents on fuel, but I doubt you'll ever save enough to pay your ins. deductible when he throws a cap or he straddles a chunk of rubber that takes out your under side. Dumb idea.

 

Until he's cut-off by some texting jerk-wad in front of him... or he gets a blowout, or something hits his windshield, etc... then it's a full panic-stop that you cant anticipate!
It's a risk vs reward decision- do you want to risk $1000's of dollars of damage to your car, maybe lawsuits from other drivers and injuries to save literally a few pennies worth of fuel?

 

'Typically' isn't good enough. There are more than enough atypical situations to drastically shorten the life expectancy of drivers who depend on not encountering anything but typical.

While loaded trucks typically stop slowly, an empty or lightly loaded truck can stop much faster in an emergency. Add in a few distracted truck drivers who rear-end a stopped truck ahead -- I can think of a few nearby local cases in the last couple years, which turned very tragic for the car caught in between -- and you'll find that trucks will sometimes stop faster than a tailgater can typically react. And don't count on that North American ICC or 'Mansfield' bar to adequately protect your car from submarining beneath the trailer and decapitating the occupants.

Note that 2 car (Prius) lengths at 70 mph is less than 0.3 seconds of following distance. I doubt that most drivers will react quickly enough to avoid one of the trucks that can stop fast, let alone to serious debris emerging from beneath the higher clearance rig ahead.

 

I'm planning a trip to the Dallas area soon. If I assume my car will get 48 mpg average without drafting and 51 mpg with drafting, then over 700 miles, I could save 0.85 gallons of fuel. Figure $4.00/gallon, I could possibly save $3.40. For my money, I'll try to keep the 2 second following distance minimum whenever I can. It lowers my stress level compared to my younger, more aggressive driving habits. The wife stays happier, too.

 

^Good plan!

A happy CFO is a happy home!!

Besides....I talk to OTR drivers occasionally.
Great bunch of folks on average!
However (comma!)
You wanna know what one of their favorite tactics are for clearing their baffles?
They ride along with the old CC engaged until they see something like an "interstate snake" lying on the road, and then all they have to do is make sure their rear tires (Tyres...if you drive on the wrong side of the road...) send the aforementioned object airborne.
Works every time....I'm told.

For those of you who aren't particularly cultured...an interstate snake is usually the de-laminated tread from a re-cap or other piece of fod that you see occasionally on the interstate. You see...tractor trailer tires are usually fairly large...and there are a bunch of them on your typical 18-wheeler - hence the name. They're also expensive. No....not just because they're big, although that doesn't help.
Passenger and some light truck tires carry the "P" designation...When a tire size begins with a "P," it signifies the tire is a "P-metric" size that was designed to be fitted on vehicles that are primarily used as passenger vehicles. This includes cars, minivans, sport utility vehicles and light duty pickup trucks (typically 1/4- and 1/2-ton load capacity). The use of P-metric sizes began in the late 1970s and they are the most frequently used type of tire size today.
TRUCK tires are constructed to withstand the rigors of interstate duty with heavy loads. They're also expensive because we live in a country that's infested with sniveling, bed wetting, bottom-feeding, ambulance chasing, liberal voting attorneys.
So....guess what? Since Retreads are significantly cheaper than new tires they are widely used in large-scale operations such as trucking, busing and commercial aviation.

That's where the interstate snakes come from.

The next time you have some free time to kill.....go pick one up.
Heavier than you think....aren't they?

Now....imagine one getting flung at your car while you're dozing behind the wheel in interstate traffic.

It doesn't have to be because some disgruntled OTR driver is sick and tired of having idiots on his (or her) tail. I've been behind a truck when it gave birth to an interstate snake.
It will make you a believer in the lunacy of hanging out in the shade of a tractor trailer at 80-mph!

Normally....I'm a live and let live kinda guy. I like the beneficial side effects of natural selection, especially when MORONS self delete their genetic material from the pool before they're able to procreate but since we all have to share the same roads....it's probably best for now that we just enforce tailgating laws and let the idiots out there wonder why.

Personally?
I think that it would be fun to have a special lane for idiots, drunks, and aggressive drivers. We could call it the The Darwin.....or maybe the Mad Max lane.
No rules.
No ambulances.
No first aid.
Cameras every 500' or so (for YouTube revenue )

Get so many points on your license????
You have to use the Darwin lane or mass transit.

 

Love it! Around here- that would probably turn out to be the most popular lane.
Give the Alpha-Hotel's their own lane for madness and mayhem!
Kind of like "The Running Man" TV show... but this time- they won't be back (not even in a re-run)!