Best of Both Worlds

[Sentientbydesign]

We all love our Gs.

We all love the power.

We all prefer to pay less on gas, get more miles per gallon, and/or have cleaner air.

Here's the plan :

Devise a system by which significant fuel economy can be gained without sacraficing the potential for power.

The questions:

What options are available or can be devised to increase the fuel efficiency on the G (when you want to drive conservatively), yet still allow you to open the car up when you want to?

Are turbos only efficiency boosters on small displacement diesel engines?

Can a stand alone fuel management system be setup to run very lean and very rich with the switch of a button?

My goal isn't to create a savings where one doesn't currently exist. My goal is to reduce my environmental foot print on the earth, while forging ahead and also increasing my fuel tank range (in miles).

[zozoka1212]

Maybe having 2 car would solve the problem. Having a car what you are using for everyday commuting and one beast for the weekend.

The concept is not new. People are doing it for various reason. Some probably for the same reason you think of. Some for the daily comfort drive and the weekend sporty drive.

zozo

I've ben thinking to get a 2 seater for weekends. Just for constant weekend abusing.

[Sentientbydesign]

Hmm, I'm lazy and I very spontaneous. I couldn't afford to go home and get the other car when a situation arose.

Anyone else?

[rn79870]

Here is another cite for one of those 300MPG carbs. (Don't hold your breath)Scroll down to the answer by Cecil Adams for some good information written by a SDSAB member. (Cecil Adams is a fictitious, the SDMB is not)Where several ideas and possible future technology is revealed.

In other news, they are forecasting $4.00/gallon gas here in SoCal by spring. If you're looking for a good SUV I'll bet there will be a backlog on the dealer lots by then. Backlogs on dealer lots is not good news for the economy, neither is $4.00 a gallon gas.

[TJMaxx98]

Does anyone know why only GM has tried limiting the number of cylinders working at a given time on their v6 and v8 engines? It's like power on demand, but otherwise you would be getting the benefits of a 4 banger? If Chevy can do it why not Nissan/Infiniti?

Why not, we have CVT why not CVE (constant variable engine)?

[rn79870]

Does anyone know why only GM has tried limiting the number of cylinders working at a given time on their v6 and v8 engines? It's like power on demand, but otherwise you would be getting the benefits of a 4 banger? If Chevy can do it why not Nissan/Infiniti?

Why not, we have CVT why not CVE (constant variable engine)?

There was a Cadillac a while back. It was called a V8/6/4. It was a disaster. The purpose was to improve fuel economy. I understand that the new system is better, but I'll reserve judgment for a few years. The purpose is again to improve fuel economy. Nissan is probably waiting and watching, IMO.

[Sentientbydesign]

This is a ridiculous claim, but what we really need is variable volume cylinders.

Or maybe to move away from cylinders all together.

[joe603]

Rotary engines are not much better. The RX7/8 doesn't get good gas mileage.

Now a fuel cell...that would be different.

[telcoman]

We all love our Gs.

We all love the power.

We all prefer to pay less on gas, get more miles per gallon, and/or have cleaner air.

Here's the plan :

Devise a system by which significant fuel economy can be gained without sacraficing the potential for power.

The questions:

What options are available or can be devised to increase the fuel efficiency on the G (when you want to drive conservatively), yet still allow you to open the car up when you want to?

Are turbos only efficiency boosters on small displacement diesel engines?

Can a stand alone fuel management system be setup to run very lean and very rich with the switch of a button?

My goal isn't to create a savings where one doesn't currently exist. My goal is to reduce my environmental foot print on the earth, while forging ahead and also increasing my fuel tank range (in miles).

I believe we will be seeing more Diesel engines here in the US in the not too distant future. They are already widely used in Europe where gasoline is over $6 per gallon.My 1980 VW Rabbit Diesel was up to 246k miles when its oil pump failed & I decided to get rid of it. At a steady 55MPH it got 55 MPG. The problem was that during the 1979 oil crises diesels were in short supply & I could only get it with a 4 speed manual. Had 5 or even 6 speed manual transmissions been available the MPG would have been even better.We need more and better public transportation in this country. How many of us sit in bumper to bumper traffic with only one person in each vehicle.

Telcoman

[C-Kwik]

My friend's old Envoy had this technology (dubbed Displacement on Demand). It wasn't a significant boost in economy if at all. He was still only getting about 15 mpg average.

The problem is, the weight of the 'dead' cylinders are still being carried by the working cylinders. From my understanding a limited amount of compression still occurs, but that is probably offset by the spring effect the compressed air will have as it decompresses. But there is still friction and weight to deal with. Frankly, I can't make much of a strong case for it.

The two technologies I'm most interested in is direct injection and infinitely variable valve actuation. The G37 is using a version of the latter, but it's hard to quantify it as it is using it on a bigger motor. And from photos, it appears it may make for a heavy valvetrain. But in theory, the valves control the intake of air so you reduce the need to choke an engine with a throttle to reduce airflow. It can also maximize volumetric efficiency at all times if applied correctly.

Direct injection has shown to have great results on power and economy, but last I heard, it's biggest promise to ecnomy, which is the lean burn capability, introduces a high level of NOx emissions due to the higher combustion temperatures associated with leaner burning.

Both can offer some measurable benefits without sacrificing power (To some extent, it may increase it).

[Sentientbydesign]

My Father-in-law has a VW diesel rabbit from the 60s. He drives slower than the big rigs and gets 50 mpg.

I was hoping for someone like ckwik to come to the rescue on this matter, but it seems moot.

The rotary engines are terribly inefficient. They don't always complete a burn and have heavy pollution problems.

It's too bad that compression is essential to a combustion engine. I have dreamt about rotary style engines that spray and blow.

[TJMaxx98]

Ok what about hybrids? I like how Lexus combines the gas and electric motors together on the RX 400h. 0-60 time in 7.3 and MPG of 27 city and 24 highway for the front-drive models. I could live with that level of performance.

How about putting a simular setup on a G35 vs a SUV with a Curb Weight of 4190 lbs?

If we could keep current performance numbers and average 30 mpg or better, I would not mind the combo gas/electric.

[Sentientbydesign]

Ok what about hybrids? I like how Lexus combines the gas and electric motors together on the RX 400h. 0-60 time in 7.3 and MPG of 27 city and 24 highway for the front-drive models. I could live with that level of performance.

How about putting a simular setup on a G35 vs a SUV with a Curb Weight of 4190 lbs?

If we could keep current performance numbers and average 30 mpg or better, I would not mind the combo gas/electric.

You're missing the point. The idea is to improve upon the platform we all own, not to give Nissan idea for future cars.

[TJMaxx98]

You're missing the point. The idea is to improve upon the platform we all own, not to give Nissan idea for future cars.

Sorry, I got off on a tangent there... You're just asking what mods we can buy to make the G more fuel efficient.

I have noticed some improvement with the 5/16 spacer, before I was getting around 350 miles of HWY driving, the last road trip I was at 400 miles, before having to stop for gas. That was also with the Stillen intake too.

[Jacko3]

Yep! I noticed gas mileage improvement as well when I added the spacer and Stillen exhaust and JWT pop charger. The problem is, the new set up causes me drive the car like i stole it. So, what am I to do? When I drive it normally, the gas mileage is really impressive, even in lower gears, and at RPMS up to 4,000RPM. yes, the mods really do work for pwer and fule efficiency. Very much worth it! Best thing ever. Why did infiniti not think of this in the first place? ***Scratches head*** and

The G-35 coupe is a real toy. Nothing practical about it. Very rugged and yet cormfy in some ways. That's why I have my little Nissan, which is a real car--30MPG. But I still drive my G a lot more than the little Nissan.

[Sentientbydesign]

Just for the record, is your "little Nissan" a Sentra or an Altima?

I guess I'll just start in the dark and see if anyone wants to comment on my ideas as I go along.

1st up is that damned intake. That stupid silencer has got to go. Does the z-tube have that on it?

How about the other intakes? Are there any that connect directly to the MAF/Throttle?

Also, what's the concensus on the plenum texture? Does it provide any REALISTIC benefit or was it just a bi-product of production?

Jacko, that bolded, underlined term up there was directed at you

How about ignition timing? Let's say for the heck of it that the car is always fed premium octane fuel. Does there exist any fuel savings by advancing or retarding the timing? If so, can a stand-alone fuel management system be programmed to make this change on the fly?

[justjuiceit4]

I briefly watched the video for this product: http://www.preignitioncc.com/HCM/index.htmThe current HAFC unit seems very gimicky, but could have some merit for improving gas mileage, but not exactly the way that they describe. I remember Smokey Yunick mentioning something about pre-heating fuel for some fuel economy gains. It appears that they are using some kind of additive to the gas tank which claims to clean out the carbon in your engine. This also acts as an octane booster. My guess is that the main computer of this system bumps the timing to make the engine more efficient and/or leans out the fuel (hence why a qualified technician has to tune the system!).

I am too lazy to do the calcutions for how much hydrogen gas would be required to actually offset the use of gas, but I doubt it it does much.

Just some food for thought, I am interested to see what C-Kwik has to say about this!

[Beancooker]

Advancing the timing will improve your fuel economy slightly. You can use an Emanage Ultimate, and have all sorts of settings saved. So yes. you could switch from performance to economy, on the fly. Advancing the timing, as we all know, requires you to use higher octane gasoline, to prevent spark knock.

I see the small displacement diesels with a turbo, a good source of low emmissions transportation. If you use low sulfer diesel, you are no longer spewing the black cloud of death.

Biodiesel is up and coming, but needs some kinks worked out. There are some upsides, like no need for crude oil, and it burns really clean.

There are a lot of downsides too. If it gets too cool (below 40ºF) it starts to gel. Also it is prone to get a groth of bacteria, which will cause excessive foaming (think vapor lock) and fouled/ruined injectors. It is also a solvent, much more than standard diesel, so the need for a high quality fuel filter, and more frequent filter changes is needed.

We used to run our fleet of delivery vans on biodiesel. It was okay, until the repairs in one year exceeded $15k. Then we switched back to standard diesel.

[Jacko3]

Sentientbydesign:

I shall leave the mystery of my "little Nissan" up in the air.

As for the spacer and the mrevv2, what I have nnoticed is that when the temperature is really cool. It makes the car even faster and a littel quieter.

When it is warm, then, it seems to behave normally. It seems to me that throttle response also affects how the spacer and mrevv2 delivers air into the combustion chamber. Sometimes, it would feel as though so mouch air is being accumulated and not enough pressure or force is available to get all that air into the combusting chamber at once.

Thus, it might apppear as if there is a lag in some instances when immediate power is required. So, I have learnt that the way I step on the throttle and at what RPM, determines how much power I get from the mods.

Slow but steady acceleration will cause all the stored air in between the spacer to be used up quickly, and so, when you need the sudden power at that point, there isn't enough air to produce the power you need. So, I am careful not to accelerate slowly.

On the other hand, when i suddenly stomp on the car in higher gears, it sometimes feels like it takes forever for the car to respond. So, the trick is to accelerate fast in low gears, and then take it easy in higher gears. This is how I get much of my power form the mods. Perhaps I have high expectations about the mods.

So, the mods do work. I found the third gear at RPMS over 5K to be the most beneficial. Before I had the mods, this same phenomenon was in my 4th gear. I now dribe with the 3rd and 4th gears a lot more wit the mods, than in 4th and 5th gears without the mods. However, they do work if one masters the art of when and how to get the most power. It maybe different for others, but this is how it feels to me. And, i maybe wrong in my description. Also, remeber, i have a revised VQ engine as a result of the oil consumption issues I had int he past. So, this may also be playing a role in my experience.

[adren77]

The problem is, the weight of the 'dead' cylinders are still being carried by the working cylinders. From my understanding a limited amount of compression still occurs, but that is probably offset by the spring effect the compressed air will have as it decompresses. But there is still friction and weight to deal with. Frankly, I can't make much of a strong case for it.

The two technologies I'm most interested in is direct injection and infinitely variable valve actuation. The G37 is using a version of the latter, but it's hard to quantify it as it is using it on a bigger motor. And from photos, it appears it may make for a heavy valvetrain. But in theory, the valves control the intake of air so you reduce the need to choke an engine with a throttle to reduce airflow. It can also maximize volumetric efficiency at all times if applied correctly.

Direct injection has shown to have great results on power and economy, but last I heard, it's biggest promise to ecnomy, which is the lean burn capability, introduces a high level of NOx emissions due to the higher combustion temperatures associated with leaner burning.

Both can offer some measurable benefits without sacrificing power (To some extent, it may increase it).

+1

Both VVEL/Valvetronic and Direct Injection can potentially increase efficiency because they can eliminate throttling losses due to butterfly valve. Butterfly valve can be entirely eliminated since the load is controlled by either valve lift, or amount of gas injected through DI. The reason for higher NOx emissions in DI engines is not necessarily due to lean combustion. High NOx comes from the fact that stratified fuel injection will cause localized combustion (rather than premixed homogeneous) which causes higher peak temperature. Also DI engines gain on efficiency due to higher compression ratios since knocking happens under different conditions. Higher cr = higher thermal efficiency.

Using infinitely variable valve timing can be used to increase efficiency. You can program the valves to open/close at certain time that would make expansion stroke larger than compression stroke. This makes the engine more efficient because less energy is wasted through exhaust part of the cycle. Some cars actually utilize this.

[C-Kwik]

I briefly watched the video for this product: http://www.preignitioncc.com/HCM/index.htmThe current HAFC unit seems very gimicky, but could have some merit for improving gas mileage, but not exactly the way that they describe. I remember Smokey Yunick mentioning something about pre-heating fuel for some fuel economy gains. It appears that they are using some kind of additive to the gas tank which claims to clean out the carbon in your engine. This also acts as an octane booster. My guess is that the main computer of this system bumps the timing to make the engine more efficient and/or leans out the fuel (hence why a qualified technician has to tune the system!).

I am too lazy to do the calcutions for how much hydrogen gas would be required to actually offset the use of gas, but I doubt it it does much.

Just some food for thought, I am interested to see what C-Kwik has to say about this!

Frankly, it's a bit hard to really discuss it as there is no hard data on what the product does. At least the specific processes. I can't imagine water being broken down into Hydrogen and Oxygen atoms not taking a toll on the electrical system for the amounts that would be needed to have any real effects on gas mileage. Think about this. Several car manufacturers have been trying to come up with realistic hydrogen powered cars, investing a lot of money, including subsidies from the government. It's highly unlikely that an effective solution is this simple.

The site claims to use magnets to ionize the gas. As other magnet devices have generally been thought of as fraudulent devices, even using such a device should point out where their intents are.

For some good reading about fuel saving devices, I'll point you to the site I referred to in the octane discussion:

http://www.fuelsaving.info/catalysts.htm

But as a general rule, just think about this. If the manufacturers of automobiles, who likely have huge staffs of engineers and scientists (likely very good ones at that) aren't implementing even some of the simpler devices, do you really think they work?

If you really want better gas mileage, get a more economical vehicle. the solutions to make our existing technologies aren't going to be cheap or easy anymore. Our level of understanding of science is well beyond the point of simple solutions. It's likely, in fact, that there are many solutions in the pipelines. The problems, to name a few, are typically in making them affordable, making them reliable (or long lasting), or making them work with current or impending emissions regulations and infrastructure (alternative fuels).

[C-Kwik]

The reason for higher NOx emissions in DI engines is not necessarily due to lean combustion. High NOx comes from the fact that stratified fuel injection will cause localized combustion (rather than premixed homogeneous) which causes higher peak temperature. Also DI engines gain on efficiency due to higher compression ratios since knocking happens under different conditions. Higher cr = higher thermal efficiency.

Absolutely. As for the knocking conditions you speak of, it would perhaps point in the direction that the fuel may be combusted as it is being injected (similar to a diesel). This is something I was thinking would have been a huge plus, but I didn't throw in any thoughts of higher compression into the equation. The higher CR would be a huge plus. Being that car manufacturers have been bumping up compression incrementally, with existing fuel delivery systems, it would seem to me that DI could offer a huge step in this regard. Hopefully they can get a handle on the emissiions issue though so we might see this technology become more widespread.

[justjuiceit4]

But as a general rule, just think about this. If the manufacturers of automobiles, who likely have huge staffs of engineers and scientists (likely very good ones at that) aren't implementing even some of the simpler devices, do you really think they work?

If you really want better gas mileage, get a more economical vehicle.

I have several engineer friends at the "Big Three" and they fool around on the internet a lot!

This thread was started because someone wanted to get better gas mileage with their "current" vehicle! Not everbody likes little 4-cylinder econoboxes.

I think Mercedes-Benz is working on something very interesting that gives the best of both worlds.

Luckily with my Sentra, I was able to get 38mpg as a high and still run 13s in the quarter mile!

[Beancooker]

Can a stand alone fuel management system be setup to run very lean and very rich with the switch of a button?

Sorry, I got lost in the other posts, and never answered your question. Yes, just as with the timing, with the EManage Ultimate you can set up different fuel air maps, and switch them as you wish, provided you have a laptop hooked up.

[lucidd]

great subject!

let me say this first ... nissan made a great motor : vq... lots of hp... but they've used "heavy tuning" to achieve this, instead of utilizing "latest" technologies such as direct injection. almost seems like they've rushed it a bit to fast - although they've been able to match the big boy's output (ie lexus, audi, honda) ...at what cost to the consumer? answer: fuel economy, high engine db (loudness) etc... is there anyone else that shares my views?

I don't mean to bash nissan; cuz I love my g... but I knew its drawbacks when I got it... with its highly tuned symetrical intake and exhaust---- this 306hp 2007 vq engine is extremely loud! but I like it,,, and with its agressive engine mapping/ tuning- performance oriented - it sucks as much gas as my audi s4.v8 w/awd!.. of corse, at almost half the cost cuz like I sed, it doesn't have the "latest" tech.think about this, let's dobthe comparison that I did when purchasing... the lexus is350 has same hp, more torque cuz it has direct fuel injection; and of does 0-60 in slightly faster.... then we have the audi s4- the original 04/05 4.2,v8 makes 340hp... then with direct injection and tuning- it makes 420hp in the rs4•... what I'm saying is that the g is missing di, but will come soon I bet... cuz nissan introduces this technology in the gtr.

I guess this makes for an interesting future

[lucidd]

oops got a little off topic... but get what u pay for/// the is350 is like 10k more$, so solution?, unless u know how to put direct injection into the g, try this:

may work for the 6manual better: use your fuel economy computer as a tool to monitor your fuel usage... it will get you more aware of ur mpg... try to coast in neutral as much as possible•then in city driving, look ahead///far ahead- cuz if you know that the light ahead is goin to change... don't accelerate-furthermore, slow down enuff so that there is a chance that by the time u get to the lite, it may turn back to green... ( yeah I know- it'll piss off the ppl behind u- so ) • for goodness sake- take the rite lane!//that is what that lane is for. • use the realtime fuel economy gauge to control that lead foot.

measure your fuel economy by trying this for a month... if you can LOL,,, and compare gas bills to last month,,,, it should be minimum 10% less,,, my results show a 25~30% difference... so this will make the g's 20mpg 26mpg- and this is close to the desired 30mpg standard!

try?..

then u can go back to ur normal style; I did LOL

L

[Sentientbydesign]

Lucidd,

What you're suggesting is a mild form of hyper miling. Most of the hybrid fanatics use this and get their huge MGP numbers.

It's definately an option.

I was also doing some searching and I found a symetrical dual intake design for the 350Z that might fit the G35. Not sure if any fuel economy improvements can be had from it, but I'll do some research.

[adren77]

Absolutely. As for the knocking conditions you speak of, it would perhaps point in the direction that the fuel may be combusted as it is being injected (similar to a diesel). This is something I was thinking would have been a huge plus, but I didn't throw in any thoughts of higher compression into the equation. The higher CR would be a huge plus. Being that car manufacturers have been bumping up compression incrementally, with existing fuel delivery systems, it would seem to me that DI could offer a huge step in this regard. Hopefully they can get a handle on the emissiions issue though so we might see this technology become more widespread.

Anybody hear about HCCI (or PCCI), Homogeneous Charge Compression Ignition? A lot of research is being done on this. The point is to get a benefit from both Gasoline and Diesel engines. Gasoline engines have nearly constant volume combustion, while diesel engines have a lot higher compression ratio which. Both of these aspects contribute to higher thermal efficiency in the engine, which are combined in HCCI.

[BigWill]

Here is another cite for one of those 300MPG carbs. (Don't hold your breath)Scroll down to the answer by Cecil Adams for some good information written by a SDSAB member. (Cecil Adams is a fictitious, the SDMB is not)Where several ideas and possible future technology is revealed.

In other news, they are forecasting $4.00/gallon gas here in SoCal by spring. If you're looking for a good SUV I'll bet there will be a backlog on the dealer lots by then. Backlogs on dealer lots is not good news for the economy, neither is $4.00 a gallon gas.

Hey rn... what site? There's no link.