Aeromods

[theman53]

Anytime you are in gear and not on the pedal the pump limits fuel.

[TylerDurden]

No tach needed... the IP spits fuel with each revolution: with no pedal, a little at idle (e.g. 800rpm), same pedal at 2400rpm (engine braking)... 3x as much. The cc per injection doesn't change, but the number of spits does, and for nothing since you're braking.

As for aero, the blunt rear is the big offender.

[745 turbogreasel]

Fuel is limited in decel, but I think it only stops  above 300 or so.
An EGT gauge can help a  lot, and mostly driving slow.
http://cumminsengines.com/uploads/docs/cummins_secrets_of_better_fuel_economy.pdf

[theman53]

I think the fly weights on the gov shaft pull it in harder when the engine is spinning faster than idle, but you are off the pedal.

[burn_your_money]

No tach needed... the IP spits fuel with each revolution: with no pedal, a little at idle (e.g. 800rpm), same pedal at 2400rpm (engine braking)... 3x as much. The cc per injection doesn't change, but the number of spits does, and for nothing since you're braking.

It's not quite that simple because the throttle pedal is not directly connected to the control sleeve that determines how much fuel is being injected.

With our pumps, engine braking uses 0 fuel. Fuel will start being injected again once the pump RPM approaches idle speed. The reason why you would see 200F on a pyro is because of the compression of the engine, not because of burning fuel.

[TylerDurden]

Ok, that makes sense, but that would also mean that fuel consumption might not differ much between coasting and engine braking.

From the Bosch book:

Overrun
When the vehicle descends a steep gradient, or when the accelerator pedal is released at  high speeds (overrun), the engine is driven by the vehicle's inertia. The sliding sleeve responds by pressing against the starting and tensioning levers. Both levers move the shift the control collar to decrease delivery quantity; this process continues until the fuel-delivery quantity reflects the requirements of the "new" load factor, or zero in extreme cases. The response pattern of the variable speed governor described here is valid at all flow control lever positions, and occurs whenever any factor causes load or rpm to vary so substantially as to shift the control collar all the way to its WOT or "stop" end position.

[745 turbogreasel]

I don't seem to coast nearly as far  while engine braking though.

[TylerDurden]

Regarding aero-mods: trailer-tail perhaps...?

[burn_your_money]

Ok, that makes sense, but that would also mean that fuel consumption might not differ much between coasting and engine braking.

From the Bosch book:

Overrun
When the vehicle descends a steep gradient, or when the accelerator pedal is released at  high speeds (overrun), the engine is driven by the vehicle's inertia. The sliding sleeve responds by pressing against the starting and tensioning levers. Both levers move the shift the control collar to decrease delivery quantity; this process continues until the fuel-delivery quantity reflects the requirements of the "new" load factor, or zero in extreme cases. The response pattern of the variable speed governor described here is valid at all flow control lever positions, and occurs whenever any factor causes load or rpm to vary so substantially as to shift the control collar all the way to its WOT or "stop" end position.

Exactly. Coasting means you burn whatever fuel you burn at idle, which is not much.

[JerryGTD]

Duckbill and A pillar spoilers...








Rear upper spoiler...






Rear lower spoiler...

[Rising]

Woah those a pillar spoilers are wild! I've never seen those or the lower spoiler either. I imagine those a pillars might actually reduce drag a bit. Though I think the rear spoiler might increase it... Those are super rare at any rate. Wish I could find a zender 3 PC just for looks

Sent from my Nexus 5 using Tapatalk

[mystery3]

The rear spoilers decrease drag a lot, they aren't there to provide downforce. I'm really not at all a physics guy and know little about automotive aerodynamics someone explained the rear spoiler once, something about directing the airflow away from the pocket of low pressure behind the vehicle and reducing turbulence IIRC. You could probably make one or modify a common junkyard lip spoiler, e30 comes to mind, maybe the Impreza (mid-late 90's) with the spoiler just beneath the glass could be shortened?

[shorttimer]

Glad I stumbled on to this thread. I have been going to the Ecomodder site for quite some time and truly believe that mileage starts with areodynamics. The best example would be for anyone to type in 'basjoos' on google & see his 100mpg 92 honda vx. He's done just like a wing: blunt at the front & pointy at the back, so the air flows back together with no turbulence. I have been thinking if a Caddy was to do something like basjoos did, 80+ mpg would be possible, albeit it would look completely alien. A flat bottom has also been shown to be very effective and is incorporated in basjooses work. I think it will be worth a try.

[scrounger]

Most of the "aero" benefits are at the back of the vehicle. But some are available at the front. Blocking off the grill helps. I have about 3/4ths of the radiator covered. Narrow tires help. Putting spats in front of the tires helps.

Look at almost every newer SUV and van, they all have a rear window deflector. Its purpose is to help the air stay attached longer.  I have a 12" long deflector on the back window of mine.

Taking it to an extreme, this guy gets 60-70 mpg on his diesel. Besides the obvious he has a full underbody covering and a nearly full grill block.

[TylerDurden]

Perhaps y'all are familiar with Flow-Illustrator? It makes videos online, or a version of the program can be downloaded.



http://www.flowillustrator.com/

Not a 3D flow modeller, but interesting.