5th generation civic hatchback - improving aerodynamics

[aerohead]

Originally Posted by steffen707

There's also a big gain from having the throttle plate open further at a given speed, because it reduces pumping losses from the engine, I'm not sure how to explain that, but this thread has good info on it.
http://ecomodder.com/forum/showthrea...rence-529.html

*Yes,the throttle plate is like a sheet of plywood,flat into the airstream at low throttle settings,with Cd 1.11.Ouch!
*At wide-open-throttle the Otto-cycle engine approaches the volumetric efficiency of a Diesel,lacking only the 10-11% Btu advantage of the Diesel fuel itself.
*Gasoline Direct Injection engines dispense with the throttle altogether,running at WOT just as with a Diesel,doing all the fuel metering with the electronic fuel injection.
*During the era of the 55-mph national speed limit,some car makers (HONDA) designed their carburetor's 2nd barrel to operate at WOT during cruise,with the 3rd barrel for passing and climbing,achieving mileage like today's hybrids.

[some_other_dave]

Originally Posted by aerohead

*Gasoline Direct Injection engines dispense with the throttle altogether,running at WOT just as with a Diesel,doing all the fuel metering with the electronic fuel injection.

I do not believe that this is the case. Gasoline engines don't tolerate the immense swings of mixture as well as diesels do, so there is more need to restrict the air flow into the combustion chamber than with a diesel.

I'm pretty sure that most GDI engines still have throttles. Some may only be used for warm-up (I think I've read that somewhere) but I am pretty sure that most do control the engine load with a throttle mechanism.

-soD

[Stan]

Originally Posted by some_other_dave

I do not believe that this is the case. Gasoline engines don't tolerate the immense swings of mixture as well as diesels do, so there is more need to restrict the air flow into the combustion chamber than with a diesel.

I'm pretty sure that most GDI engines still have throttles. Some may only be used for warm-up (I think I've read that somewhere) but I am pretty sure that most do control the engine load with a throttle mechanism.

-soD

I wondered about this, too, but according to this article aerohead's comment appears to be true, at least for current state-of-the-art GDI engines. The best of all ICE worlds, as it were.

[GTR]

This was one awesome thread full of great info! Definitely going to use some of it on my VX.

I want to comment on the fact that seems rather unbelievable to me. The story about the plexiglass window flying off at high speed not once, but twice, and absolutely no mention of very real danger everyone else was put in and that for some mods some attention to safety perhaps should be a little higher on the list.

If that window had hit a (motor)cyclist, it could easily kill them. It could cause anyone to veer of the road, swerve, cause accidents, or do serious damage to someone else's car....and I doubt your insurance would pay for it, either.

I'm all for modding and experimenting and going crazy, I'm just flabbergasted nobody said a word about it?

[Ahaley88]

Great read. I have learned quite a bit.

[aerohead]

Originally Posted by GTR

This was one awesome thread full of great info! Definitely going to use some of it on my VX.

I want to comment on the fact that seems rather unbelievable to me. The story about the plexiglass window flying off at high speed not once, but twice, and absolutely no mention of very real danger everyone else was put in and that for some mods some attention to safety perhaps should be a little higher on the list.

If that window had hit a (motor)cyclist, it could easily kill them. It could cause anyone to veer of the road, swerve, cause accidents, or do serious damage to someone else's car....and I doubt your insurance would pay for it, either.

I'm all for modding and experimenting and going crazy, I'm just flabbergasted nobody said a word about it?

This is a very late response, however, I wanted to point out that, even NASCAR required Chrysler Corporation to install safety lanyards on the rear wing of their Dodge Charger Daytona in order to qualify for competition.
Kinda like safety tethers on modern surfboards. And having been skegged in the head as a teenager, it's probably a really good idea.

[freebeard]

I have a VW Golf wing that has an internal lanyard.

More to the point, the Charger got braces to keep the window from popping off.


http://www.dodgecharger.com/forum/in...topic=132072.0