Improving Engine Efficiency & Performance

[geoffinbc]

Looking for better efficiency? Don't use iron heads. And don't drive a truck with the aerodynamics of a shoe box. I'm wondering what kind of mileage I'll get this weekend, mostly highway over rolling hills at 55-65 MPH, with three additional passengers. But also about 40 miles on rough access roads.

I've been looking at getting a Malibu, and would be content with getting near 30 MPG with a 170 HP engine. I've heard up to 38 MPG in some of the smaller cars (http://60degreev6.com/forum/showthread.php?t=40101). For a V6, that sounds pretty darned good.

Ha ha I hear you man. I just went 4 wheeling yesterday and on the highway doing 100Km/h (60mph) I was at 3000RPM but the throttle angle wasn't very high. However I have got to get that 2.8L out of there. I couldn't pull any kind of hill in 5th. No torque! So the 3.2L is looking sweeter and sweeter every time I drive. With a high torque engine and some 35's I should be able to get the RPM down to a respectable level. Yea I know the weight of 35's don't help mileage but it should be a descent balance with reduced RPM. My Buddy was with me in his Jeep and he burnt $10 more in gas than I did.

[IsaacHayes]

Yes if your cat is rattling it's probably broken up and clogged.

[SappySE107]

http://youtube.com/watch?v=f5xXBb_mrYc

If you make it all 36 minutes, congrats Interesting but could have been 1 minute and more details on how to do it.

[Canyonero]

Ha ha I hear you man. I just went 4 wheeling yesterday and on the highway doing 100Km/h (60mph) I was at 3000RPM but the throttle angle wasn't very high. However I have got to get that 2.8L out of there. I couldn't pull any kind of hill in 5th. No torque!

I put new O2 sensors in right before the trip. That Trooper pulled all the hills in 5th at 55MPH, I was very pleased. I'm just running 31x10.5s at 40PSI (bumpy ). Mileage is looking improved. Same or better than I was getting with my 2.8L. I'm going to finish up the tank with my usual mixed semi-rural driving an see what happens.

[Rhedalert]

I've been researching and experimenting for a while to bump up fuel economy, and the one thing that helped big time was advancing the ignition timing on the highway. This engine would not get above 23 mpg when commuting to work, which is about 80% highway (going 70+mph). Light load, cruise speeds had about 40 degrees advance stock, I'd calculate between 21-23mpg. I bumped this up to 46-48 degrees and now the car has consistently averaged 24-26 mpg. Granted there's many variables but I have NEVER been able to hit 25+mpg territory before.

My cam has a LOT of valve overlap, I calculated 43 degrees. This may allow me to run higher timing #'s especially if I'm getting a natural EGR which I think I have. However this extreme duration may be detrimental to my fuel economy to begin with.

Getting back to what was mentioned earlier how it's ideal to have your peak torque at around cruising speed, I recently read an article about Oldsmobile in the late 1960's producing a Cutlass Supreme "Turnpike Cruiser". The engine was a standard 400ci Olds engine only with a special camshaft with smaller-duration and advanced timing. Coupled with something like a 2.55:1 rear they were able to increase fuel economy from the mid-teens to the mid 20's. Link to the article Here

[CobraCDR]

Finally thank you Brian for some meaningful input to this otherwise worthless thread of rambling. Too bad I missed you I was at Larry's helping him move over the weekend. Guess you are just going to have to join us out at Island Dragway soon! Take care.

Ken

[Bones]

http://youtube.com/watch?v=f5xXBb_mrYc

If you make it all 36 minutes, congrats Interesting but could have been 1 minute and more details on how to do it.

Hilarious video. I love how he says engines with 4 valves are less efficient and yet his engine has 4 crankchafts!! And it's only one cylinder! haha. Oh well, it takes all kinds...

The part about his dads '41 Cadillac a the dog was great too... and the part about liquid nitrogen cooling the exhaust...too funny

Nice to see our tax dollars going twords something useful...

[SappySE107]

Yes, it takes all kinds. Now that you are here, i suggest learning a bit before sharing your uneducated comments.

[Bones]

Yes, it takes all kinds. Now that you are here, i suggest learning a bit before sharing your uneducated comments.

What was uneducated about my comment? The engine design this guy is talking about doesn't do anything different than a normal diesel engine. The part about having a second connecting rod and crank to reduce side load on the piston is neat but the frictional loss of having the piston pressed against the cylinder is pretty small, probably less than spinning the extra crankshaft. The thing that makes internal combustion engines so inefficient is that there's still a lot of heat and pressure in the cylinder at the bottom of the stroke when the exhaust valve opens and it all blows out the tailpipe. Unless someone finds a way to tap into that lost energy there's never going to be a revolutionary improvement in efficiency.

[torq455]

you ever turn an engine over by hand without the spark plugs in? try spinning it at 500 rpm manually. too much work and can't do it huh? hmmm....no pressure still built up after combustion since YOU are doing the work. that means there is a lot of friction there. that's why an internal combustion engine is so inefficient. not to mention the fact that is has to overcome compression forces.

wow! "NEVER never going to be a revolutionary improvement in efficiency." soooo since the eairly 1900's, the engine has seen no improvement? variable cams including lift and duration (electronically controlled), variable intakes, EFI, computer designed camshafts, ceramic coatings, anti-friction coatings, more efficient flowing exhaust systems (metal catalytic converters) , direct injection, turbos, lower friction synthetic motor oils in thinner viscosities, and there has even been a running concept of a variable compression engine. with more research and technology involved, compression ratios have been rising making the engine more efficient alone.

initially, i did think SappySE107's comment of sharing uneducated comments was a little harsh. however i'd say that i have to agree with him 150%!! please research first.

[pocket-rocket]

Actually in the mid 70s when the emissions situation hit, compression ratios took a nosedive. Back in the muscle car era it was nothing to have a compression ratio in the double digits up until the switch to unleaded gas. I read about a Camaro that came with 12.0:1 compression stock. Cars today stock haven't hit that mark either. Not the 08 Z06, Viper, or the Enzo.

[SappySE107]

I guess he skipped the part on direct injection and the higher compression possible from 2 pistons moving at each other vs 1 piston moving against the cylinder head. Frictional losses increase with RPM, so the more you have to spin the motor to make more hp, the more you lose. The crank spins on a thin layer of oil. Most of your friction comes from the rings and piston in the bore, not the rotating assembly.

At 7k, you lose roughly 56hp on a 3400 due to frictional losses (according to dynomation 5). While there are multiple areas to address to increase efficiency, the friction loss is more significant than you think.

[Bones]

you ever turn an engine over by hand without the spark plugs in? try spinning it at 500 rpm manually. too much work and can't do it huh? hmmm....no pressure still built up after combustion since YOU are doing the work. that means there is a lot of friction there. that's why an internal combustion engine is so inefficient. not to mention the fact that is has to overcome compression forces.

Maybe I can't do it by hand, but the electric starter motor doesn't have any trouble doing it, and it's only a couple horsepower, maybe 5 at the most. The source of the inefficiency in an engine is NOT friction. Pumping losses however are. Like you said it's easier to spin an engine with no plugs because you only have to overcome the friction and not the pumping losses. Even so if the average engine is 20% efficient then that means a 200 HP engine is burning 1000 HP worth of gasoline (in terms of the actual chemical energy stored in the fuel) and I can assure you that it doesn't take even close to 800 HP to spin a non-running engine at 6000 rpm.

Internal combustion engines make power by turning chemical energy stored in the fuel into heat energy, which is then turned into mechanical energy. So any heat energy that dissipates into the atmosphere without being turned into mechanical energy is considered waste. That includes heat that goes out the exhaust, heat from the radiator, the block, etc. In thermodynamic terms it's all wasted energy.

I'm not saying that there haven't been improvements or that there won't be more improvements in the future, but those improvements tend to be evolutionary rather than revolutionary. The only exception that I can think of is the Crower 6-stroke engine which is an attempt to reclaim the energy that is normaly wasted through the radiator.

Anyway, we all know what they say about arguing on the internet...

[Bones]

I guess he skipped the part on direct injection and the higher compression possible from 2 pistons moving at each other vs 1 piston moving against the cylinder head.

Diesels have always used "direct injection", they have to be to prevent pre-ignition. And the 2 pistons moving away from each other is another gimmick. A cylinder head doesn't absorb any energy, so there's no loss assoiated with using one. The pressure in the cylinder is pushing on two pistons but in order to do a direct comparison the pistons can only move half as far as a single cylinder with the same bore size. If the pistons moved the same distance the engine with 2 pistons would have twice the displacement so it wouldn't be a fair comparison.

edit: next you'll try to convince me that his "electric supercharge" is a valid technology? I'm not trying to be an argumentative dickhead, but all the ideas this guy is trying to sell are bunk. you could probably dig up thousands of old patents for ideas just like these.

[SappySE107]

So the cylinder head doesn't absorb any heat energy? Right. And 2 pistons moving at each other is a gimmick? Only because you don't understand or have any desire to open your mind to concepts you haven't heard before.

pumping losses are 10hp at 7k and frictional is 56hp. Thats through simulation software, which is based on a lot of real world testing and math. Please provide some proof of your claim that pumping losses are greater than friction. So far you are only concerning yourself with thermal losses.