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P71
P71 Reader
7/4/08 9:55 a.m.

Rotary engines are more efficient

This guy is a total BS'er though, his main brace doesn't even work as well as the other ones and his claims range from 50-110MPG depending on what forum he's trying to make money on.

ignorant
ignorant SuperDork
7/4/08 9:58 a.m.

I will say the current trend in engines I am seeing from europe are tiny boosted 4's. I'm very interested because my house is paid for with turbo money.

http://www.caranddriver.com/reviews/hot_lists/high_performance/vw_audi_performance/mini_test_review_2006_volkswagen_golf_gt_car_news

We'll see.

ProDarwin
ProDarwin Dork
7/4/08 11:56 a.m.
ignorant wrote:
ProDarwin wrote:
ignorant wrote:
ProDarwin wrote: Thermodynamic is about 35-40% for most gasoline engines already
source? last time I looked at it.. gasoline engines are in the 20's with most diesels being int he 30's-40's. http://www.isuzu.co.jp/world/technology/clean/diesel_gasoline02.html isuzu quotes 25-30 for their Gasoline engines and 30-42 for their diesels. I'd love to see a practical 40% efficient gasoline engine. I'd love it in my honda.
I'll check my powertrain book when I get home, that number may be a tad off. I thought atkinson/miller cycle engines were definitely above 30. Regardless, 38% is not the maximum efficiency of a gasoline engine. The second law of thermo says max efficiency of a heat engine is given by 1 - (Tc/Th). Do some math (70 deg = 294k, 1500F = 1088k), and you end up with a number a bit higher than 70%. Granted, we are far from a frictionless engine, but that's the theoretical maximum. Not necessarily utilizing the otto cycle though.
Ohh Ok.. Miller cycle. Yes those are more efficient, but there has never been a commercially viable one in the states. S/C 2.5 mazda v6 was a bit of a loser.

True, but there are millions of cars in the US using the atkinson cycle.

SVreX
SVreX SuperDork
7/4/08 2:59 p.m.
John Brown wrote: Since it is impossible to have a 0 friction IC engine, let's focus on what he could do to reduce internal losses, then maximizing HP versus fuel consumption, then minimizing suspension losses. Could a crankshaft be built that would utilize (1)roller bearings for rods and mains and (2)use end loading to keep it together and stay together for industry testing and capable of taking 500hp? Can a spiraling teflon swiper seal be used in place of steel rings? Can electrohydraulic lifters be packaged in the head? A unit that opens the valve and also ats as the spark plug would improve cylinder and chamber design for rapid intake and exhaust. That guy is running 17" Cobra Rs, not a light wheel by any means, and likely not skinny as well. Maybe this needs to be it's own thread ;)

You are discussing internal mechanical changes.

He claims most of the changes are electronic.

Sounds like a crock to me.

wlkelley3
wlkelley3 Reader
7/4/08 4:53 p.m.

IMO, definitely not obtainable during normal driving but could be possible at cruise. Back in the early 80's there was a guy around Seattle-Tacoma area that modified his late 60's Chrysler Imperial w/440 to get around 60 mpg at cruise. Someone I worked with bought his plans and shared. He ran a coil of fuel line through the upper radiator hose before going into the carb to preheat the fuel which was supposedly good for an increase of >5 mpg. Next he ran an extension cable off of the fuel/air mixture screw to inside the car and added some gauges that I don't remember what they were. At cruise speed, set cruise control then lean out carb till speed starts to decrease and cruise away. Not too good for hills and have to richen back up for normal driving. Some of you pilots might recognize this, it's common on aircraft with recipricating engines. In aircraft at cruise, lean out carb till cylinder head temp starts to increase and stop. With modern technology/electronics; pulse ignition, blocking off cylinders and leaning out cruise should do something close to what he claims. But only at cruise, non of this would work for normal stop & go driving.

iceracer
iceracer New Reader
7/4/08 6:09 p.m.

Cruise and coasting are the easy part. It's acceleration and hills that are the problem. Maybe his test was downhill all the way with a tail wind.

JohnGalt
JohnGalt New Reader
7/4/08 11:06 p.m.

neon4891
neon4891 HalfDork
7/5/08 12:48 a.m.

+1 that windsors are week blocks from the factory. get a dart alloy eagle in 4.125 bore. that could be fun

Wall-e
Wall-e SuperDork
7/5/08 9:35 a.m.

I heard on the radio that Big Turbo is to blame for pushing up oil prices to make everyone buy small turbo cars.

John Brown
John Brown SuperDork
7/7/08 9:52 a.m.

Nice ;)

ignorant
ignorant SuperDork
7/7/08 10:03 a.m.
Wall-e wrote: I heard on the radio that Big Turbo is to blame for pushing up oil prices to make everyone buy small turbo cars.

hush

Raze
Raze New Reader
7/7/08 11:03 a.m.
JohnGalt wrote:

who in the world is John Galt? and amen to the meter, you sir are spot on...

dimarra
dimarra None
7/7/08 3:07 p.m.

Iceracer's probably nailed it.

With my F150 SuperCrew's Scan Gauge set to instantaneous mpg, I regularly show 60+mpg.

...when I let off the throttle.

This guy's probably basing his... ahem... "improvement" on a similar measurement.

Keith

HappyAndy
HappyAndy New Reader
7/8/08 7:56 a.m.

what we need is to desgn an engine that will run on this limitless source of bullE36-M3! Its rich in carbon so it is possible.

JohnGalt wrote:
HappyAndy
HappyAndy New Reader
7/15/08 12:06 a.m.

OK this has been stuck in my head for days now. Basicly I think that this guy is full of bull E36 M3, because of his claim of 400 hp & 80mpg on E85, but I can;t stop wondering what his secret electical upgrades are.

Here is what I think could yeild serious mpg improvements and also yeild some power too. For starters, ditch the conventional valve train and switch to an electro magnetic or electro pnuematic valve system that is completly adjustable by a computer on the fly. It could otto cycle, atkinsin cycle, or miller cycle (this stang is turbo'd right) depending on what was optimal at that moment. This system could easily shut of some cyls while cruising, and would eliminate alot of parisitic losses from the mechanicly driven vale train.

The next thing would be direct injection, I understand that this offers improvements in both economy and power.

Some kind of electric starting assist would also help. Manual steering, no A/C and an electricly driven water pump would also push the mpg up a bit too.

I remember reading about a very high out put alternator, or possibly generator that had fairly low power needed to turn it. something like this could power the whole electical system, or wheel hub motors could provide the electric assist at start up and charge up batteries with regen braking. These motors need not actuly be on the wheel hub like on heavy equiptment, but could be hidden in an inboard part of the drive train, like on the back of the trans or on the rear axel/diff housing. This is all existing technology, and some one with the right know how could probably combine it all together and make it work; but not to the tune of 400HP & 80 mpg. Maybe 250HP and 65 mpg? That still sounds pretty good to me.

Raze
Raze New Reader
7/15/08 9:45 a.m.

Look, I've been telling my friends for years the best way to reduce overall fuel consumption until battery/high discharge capacitors obtain the required power densities (material/cost limited for now) is to runn hybrids w/a very small turbo diesel to recharge the pack, oh wait both VW, Peugot already fielded demonstrators that broke 100mpg, hell Dodge had an Intrepid that was a killer hybrid returning close to 80MPG with a projected cost of $30k/unit in 2003. And let us not forget the Volt will have a battery pack with a 1.0L turbo engine (does anyone smell swift/firefly) gasoline engine to recharge the pack, accelerate pretty quick and have decent range. The reason to do this is simple, if you do the math the losses normally associated especially with city driving is due to the engine not running at most efficient RPM. With it as a generator it will ALWAYS run at peak efficiency, and can even be electronically leaned out to improve economy further so long as the internals can take the heat. But there are losses associated with mechanical to electronic conversion, it is not however higher than the mechanical losses due to engine rpm vairation over a typical drive cycle, especially when you factor in regenerative braking to recover spent power. If you peg the engine to run at peak efficiency, incorporate regenerative braking, high discharge capacitors for spirited acceleration, and a decent battery pack to maintain power you're going to get good results, maybe not amazing, but damn good for any hybrid. It just requires car manufacturers to let electrical engineers have a big say in the design and mechaical engineers hate that :)

John Brown
John Brown SuperDork
7/15/08 10:20 a.m.

At what voltage and amperage do electric motors work best? Is it possible to develop a low voltage low amperage motor capable of producing 95 equivelant horsepower?

Raze
Raze New Reader
7/15/08 11:05 a.m.
John Brown wrote: At what voltage and amperage do electric motors work best? Is it possible to develop a low voltage low amperage motor capable of producing 95 equivelant horsepower?

Depends what you're trying to do and how big the motor is but their efficiency is tied to their internal design and materials composition (as well as ability to reduce heat buildup), acceleration requires much more power and since we're talking less time to accelerate you need higher current, I've seen numbers suggesting a 50-75HP gasoline/diesel engine is sufficent to recharge the batteries while at cruise while providing enough energy to do the actual cruising for a 2-3000lb car. The real limitation right now is in the acceleration cycle, people are so used to petrol based accel curves they think anything that accels slower is slow. There is alot of work right now to develop high discharge capacitors capable of storing enough energy for excellent accels but you would only get a couple every few minutes so it would not perform like a race car...

Paul_VR6
Paul_VR6 New Reader
7/15/08 12:33 p.m.

You can get some very lean burn cruise even on typical combustion chamber shapes (17:1 and leaner). However the big problem by doing this is emissions. NOx and CO drop but HC skyrockets until you go even leaner (20:1 and greater). There are some mfg's that can do this and it shows up well in their mileage ratings (Honda i-VTEC cars are a great example) and the fact that they still have power. There are times you can tune around the lean surge with timing and some careful playing with accel enrichment settings, etc but it's definitely challenging. Still got a 2L 4cyl to make 193whp on pump gas without vtec/vvt at 12:1 comp ratio and get 32-33mpg average in a 2800lb car with a 4.24 final drive. Take some gear away and that'd jump a ton.

tuna55
tuna55 New Reader
1/7/09 12:19 p.m.

Careful, sounds like some of you are proposing a motor that makes more power than it takes to drive it. There's no free lunch - an electric water pump takes the same amount of power to run as a mechanical water pump. Normally far more because of losses. Power is power, whether measured in watts or hp. Volts * amps = watts period. You can't change that. There is no such thing as an alternator that takes less power to spin than it produces. Likewise, no such thing as a motor that takes less volts * amps than it produces in power.

Also, in regard to the solenoid valve activation thing, solenoids don't last very long, like 10 million cycles at best, which put the run life in hours for an engine. Good idea though.

This guy is full of it, if he wasn't, the entire world would be driving 80 mpg 400 hp fox bodied mustangs right now. -Brian

Salanis
Salanis SuperDork
1/7/09 12:50 p.m.
matt_fulghum wrote: Yes you might be able to get 80 mpg or 110 mpg or whatever this guy says out of an 87 Mustang... with a tiny tiny tiny engine and radical gearing. No way in hell could you get it out of a full size 400 horsepower V8 though. :P

No, you couldn't. I don't think any mechanical voodoo could get that car to produce that mileage. It is still subject to wind resistance and rolling resistance.

It is still an angular Mustang body, and it has big wheels with wide sticky tires.

Compare the platform to any of the competitors. Engineers on other projects are taking care to to make the cars as aerodynamically clean as possible. They design special pockets for the windshield wipers. The cars use thin wheels, cover the wheel wells, and make aerodynamic undertrays. They are building special ultralight chassis.

dj06482
dj06482 New Reader
1/7/09 1:09 p.m.

Fox-body Mustangs are about as aerodynamic as a brick. I know, I've owned two. My '92 GT would get around 24 MPG in mostly highway driving, but that was driving very reasonably with a 3.08 rear axle ratio. I find 80 MPG to be very unbelievable, there are just too many aerodynamic issues on the car to make it possible.

DJ

slantvaliant
slantvaliant Reader
1/7/09 1:26 p.m.

[sing] It may be so for all I know but it sounds like BS to me ... [/sing]

Did I miss it, or did the article specify what kind of engine is in that Mustang? We seem to be assuming SBF, but lots of engines will fit under the hood. All he said was that it was a "rod and piston" engine. Hybrid with a Briggs and Stratton?. Then, again, he may be gaming the heck out of whatever system is giving him the 80 MPG reading. Remember that Dart Lites and Feather Dusters had an EPA rating of 36 MPG in 1976. That didn't mean they could actually do it.

Xceler8x
Xceler8x HalfDork
1/7/09 2:21 p.m.

OooooooOoooOOoOoooooooo

Zombie thread!

Back from the dead!

ignorant
ignorant SuperDork
1/7/09 3:33 p.m.
Xceler8x wrote: OooooooOoooOOoOoooooooo Zombie thread! Back from the dead!

indeed..

this guys a crack pot.. let the thread die.

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