Mods for MPGs
#32
12-29-2014, 11:18 AM
I'm fairly new to the 4.3 and I have a '95 which I am not impressed with. I'm positive swaping in a worn out TBI 305 from the 80's would give an increase in MPGs.
The tune for the 4.3 overall is not efficient. You can swap all the parts you want and get a tune out out of a box but you will need to invest in something like EFILive and do it yourself. The tunes you are buying from a company are still basic and will work for someone in either Alaska or Arizona and not specific to an engine or vehicle(they just throw in extra fuel and maybe enough timing). If you want something better you will need to take your vehicle to a dyno and they can get it closer but you'll be spending shop hourly rates for work that could take days or weeks.
Even OBD1 in the 80's would cut fuel if above 25mph and closed throttle. There is a lot that can and should be done with tuning if you know how and where to look.
The tune for the 4.3 overall is not efficient. You can swap all the parts you want and get a tune out out of a box but you will need to invest in something like EFILive and do it yourself. The tunes you are buying from a company are still basic and will work for someone in either Alaska or Arizona and not specific to an engine or vehicle(they just throw in extra fuel and maybe enough timing). If you want something better you will need to take your vehicle to a dyno and they can get it closer but you'll be spending shop hourly rates for work that could take days or weeks.
Even OBD1 in the 80's would cut fuel if above 25mph and closed throttle. There is a lot that can and should be done with tuning if you know how and where to look.
Last edited by TZFBird; 12-29-2014 at 11:24 AM.
#33
01-03-2015, 12:16 PM
Hmm - adding 2 cents worth of my stuff after reading through the whole thread.
IMHO we should make sure that we are talking about the right things in the correct context.
I do around 22 mpg with my 1994 S10 Blazer 4.3 (262 cdi) V6 with TBI without particular attention to mpg.
When wanting to go further with less fuel consumption I still think the V6 can do a terrific job. Now a bit into the generalities of engine management and such.
Generalities
We need to be aware that all cars from manufacturers are designed for a purpose, built and tested to a balance in power vs. fuel consumption vs. reliability vs. cost.
What we also need to keep in mind is that if you want to go far with as little fuel as possible ist that WOT (wide open throttle) operation and such are simply out of question.
Another aspect is that some very clever people have worked for man-years to get the optimum out of what they produce. I admit that not all engineering is optimal, again this is depending on what you want out of your car. And yes manufacturing does another thing to the optimum. More later on.
STOCK vs. CAI vs. RAM AIR
One needs to understand where the fuel goes during warm-up time and during the ride. On warm-up you definitively want to have the STOCK air intake which gets you pre-heated air heats up the intake manifold faster and prevents fuel from condensing on the inner surfaces. The runners are quite long and can absorb a lot of fuel vapor. That means when running cold the engine needs more fuel during warm up time. Think "choke" on old cars. On fuel injected cars the ECU does this taking into account coolant temperature, intake air temperature and manifold pressure or such.
That said - a CAI without a means of taking in pre-heated air during warm-up will nearly for sure increase consumption and lower mpg. It may make up some during the ride.
The idea of CAI is that more dense air can burn more fuel which delivers more power. But stop! Do we really need more power?! How much HP do you need to accelerate and then keep it moving? 60? 50? Definitively less than the 160 it is capable of. CAI is for racing and WOT ops IMHO.
While the power/torque/force needed to drive around remains the same under the same conditions the requirements on the engine remain the same as well. (Simplified model assuming same conditions). Therefore we would not see any change as long as we will have the same output requirements on the engine. That means that a CAI will not make any difference on fuel consumption when delivering the same power output. As we have modern fuel injection the MAP/MAF sensor will simply adapt fuel flow to match the demanded power output and it does so taking into account the air temperature as well.
RAM AIR ducting is an aerodynamic measure, again to increase the volume of air inducted into the engine which will be matched by the fuel injection and will therefore most probably not change anything in mpg when driving below the maximum aka. WOT. RAM AIR may increase your hp output but then we convened, that hp is not the limiting factor here.
If you succeed in upping the thermodynamic efficiency of your engine then you should see a mpg increase. This is where properly designed ECU mods would work and where a solid engine rebuild will help. Approaching the optimum.
What really makes you go further with less fuel?
From my experience working the engine to optimize a design can make a difference as long as you succeed in making the same amount of fuel per hp/rpm do more hp/rpm than before which in turn makes you release the accelerator a bit to get the same performance from your car. Now we are at the place where you can make a difference. It is not a CAI or modding your air intake. Just put a clean air-filter in your car can bring the mpg up by 1. Add cleaning out dirt from the ducting, keep your service intervals, change your oil according to specs and keep your car overall happy, including a good battery which takes less charge. Don't forget the spark plugs, wiring, and vacuum system.
Now what really makes a difference!
Stop using your A/C in AUTO mode. Switch it off when not needed. Maybe an advice from a European knowing Americans very well (used to live there and have friends over on the west-coast). Just because you have an A/C able to cool to 60F doesn't mean you have to. On a hot AZ day with outside temps in the 100's an interior of 85F even 90F is just fine and will save a lot of fuel. The very same goes for houses btw. the energy needed to cool 1 more degree increases over proportionally. The compressor simply runs less of the time.
As already mentioned in the thread the usual things will help as well:
Aerodynamics is your worst enemy on the Chev Blazers. So it is a very very bad idea to lift your car, to put bigger tires on it, to add roof racks, to add any kind of stuff to the exterior. We should once meter the 4.3 V6 on a test bench in various accelerations and power outputs to figure the optimum acceleration in time vs. output vs. acceleration vs. fuel flow. Normally when accelerating it is best to use 80 % throttle opening just make sure it does not shift down. High rpm is high fuel flow. Make it shift early and use the OD. Try to ride at speeds when the clutch closes and locks out the torque converter. This may be 1 mile more or less on what you are used to. Terrific results on mpg.
Try to figure the speed for best endurance which normally is somewhere around 50 mph. Look ahead and release the accelerator early. Try to keep the kinetic energy (momentum). Keep the junk out of your car. Every pound extra mass takes extra fuel to accelerate.
Tires can make a difference too. Go with the best compromise on thread width and keep the size according manufacturer standards. Inflating to a bit higher pressure than required but keeping it within tire specs helps as well. And please when comparing mpg it's useless when mounting different tires/wheels without proper adjustment of the VSS.
Lights and all electric equipment put a load on your alternator which in turn uses up hp which need fuel to be generated. Maybe LED daytime running lights would be a nice add on.
If you have other useful tips please expand and I stay corrected if I've got something wrong. TZFBird has summed it up quite nicely.
Happy fuel saving.
IMHO we should make sure that we are talking about the right things in the correct context.
I do around 22 mpg with my 1994 S10 Blazer 4.3 (262 cdi) V6 with TBI without particular attention to mpg.
When wanting to go further with less fuel consumption I still think the V6 can do a terrific job. Now a bit into the generalities of engine management and such.
Generalities
We need to be aware that all cars from manufacturers are designed for a purpose, built and tested to a balance in power vs. fuel consumption vs. reliability vs. cost.
What we also need to keep in mind is that if you want to go far with as little fuel as possible ist that WOT (wide open throttle) operation and such are simply out of question.
Another aspect is that some very clever people have worked for man-years to get the optimum out of what they produce. I admit that not all engineering is optimal, again this is depending on what you want out of your car. And yes manufacturing does another thing to the optimum. More later on.
STOCK vs. CAI vs. RAM AIR
One needs to understand where the fuel goes during warm-up time and during the ride. On warm-up you definitively want to have the STOCK air intake which gets you pre-heated air heats up the intake manifold faster and prevents fuel from condensing on the inner surfaces. The runners are quite long and can absorb a lot of fuel vapor. That means when running cold the engine needs more fuel during warm up time. Think "choke" on old cars. On fuel injected cars the ECU does this taking into account coolant temperature, intake air temperature and manifold pressure or such.
That said - a CAI without a means of taking in pre-heated air during warm-up will nearly for sure increase consumption and lower mpg. It may make up some during the ride.
The idea of CAI is that more dense air can burn more fuel which delivers more power. But stop! Do we really need more power?! How much HP do you need to accelerate and then keep it moving? 60? 50? Definitively less than the 160 it is capable of. CAI is for racing and WOT ops IMHO.
While the power/torque/force needed to drive around remains the same under the same conditions the requirements on the engine remain the same as well. (Simplified model assuming same conditions). Therefore we would not see any change as long as we will have the same output requirements on the engine. That means that a CAI will not make any difference on fuel consumption when delivering the same power output. As we have modern fuel injection the MAP/MAF sensor will simply adapt fuel flow to match the demanded power output and it does so taking into account the air temperature as well.
RAM AIR ducting is an aerodynamic measure, again to increase the volume of air inducted into the engine which will be matched by the fuel injection and will therefore most probably not change anything in mpg when driving below the maximum aka. WOT. RAM AIR may increase your hp output but then we convened, that hp is not the limiting factor here.
If you succeed in upping the thermodynamic efficiency of your engine then you should see a mpg increase. This is where properly designed ECU mods would work and where a solid engine rebuild will help. Approaching the optimum.
What really makes you go further with less fuel?
From my experience working the engine to optimize a design can make a difference as long as you succeed in making the same amount of fuel per hp/rpm do more hp/rpm than before which in turn makes you release the accelerator a bit to get the same performance from your car. Now we are at the place where you can make a difference. It is not a CAI or modding your air intake. Just put a clean air-filter in your car can bring the mpg up by 1. Add cleaning out dirt from the ducting, keep your service intervals, change your oil according to specs and keep your car overall happy, including a good battery which takes less charge. Don't forget the spark plugs, wiring, and vacuum system.
Now what really makes a difference!
Stop using your A/C in AUTO mode. Switch it off when not needed. Maybe an advice from a European knowing Americans very well (used to live there and have friends over on the west-coast). Just because you have an A/C able to cool to 60F doesn't mean you have to. On a hot AZ day with outside temps in the 100's an interior of 85F even 90F is just fine and will save a lot of fuel. The very same goes for houses btw. the energy needed to cool 1 more degree increases over proportionally. The compressor simply runs less of the time.
As already mentioned in the thread the usual things will help as well:
Aerodynamics is your worst enemy on the Chev Blazers. So it is a very very bad idea to lift your car, to put bigger tires on it, to add roof racks, to add any kind of stuff to the exterior. We should once meter the 4.3 V6 on a test bench in various accelerations and power outputs to figure the optimum acceleration in time vs. output vs. acceleration vs. fuel flow. Normally when accelerating it is best to use 80 % throttle opening just make sure it does not shift down. High rpm is high fuel flow. Make it shift early and use the OD. Try to ride at speeds when the clutch closes and locks out the torque converter. This may be 1 mile more or less on what you are used to. Terrific results on mpg.
Try to figure the speed for best endurance which normally is somewhere around 50 mph. Look ahead and release the accelerator early. Try to keep the kinetic energy (momentum). Keep the junk out of your car. Every pound extra mass takes extra fuel to accelerate.
Tires can make a difference too. Go with the best compromise on thread width and keep the size according manufacturer standards. Inflating to a bit higher pressure than required but keeping it within tire specs helps as well. And please when comparing mpg it's useless when mounting different tires/wheels without proper adjustment of the VSS.
Lights and all electric equipment put a load on your alternator which in turn uses up hp which need fuel to be generated. Maybe LED daytime running lights would be a nice add on.
If you have other useful tips please expand and I stay corrected if I've got something wrong. TZFBird has summed it up quite nicely.
Happy fuel saving.
Last edited by error_401; 01-03-2015 at 12:28 PM.
#34
01-03-2015, 02:27 PM
Excellent job! I have to agree on the CAI, totally worthless. The theory is well understood, and that's what the manufactures capitolize on, but reality is the deciding factor. To burn fuel efficiently, 4 things must occur, in order:
#1 Atomization, (break it up into small particles). This is done when the pressurized fuel exits the injector in a mist. (Where's that "cold air"?).
#2 Vaporization. This is done on the back side of the intake valve where it's nice and warm, and the fuel instantly vaporizes. When that "cold air" enters the plenum, it is heated, (the air has not been introduced to the fuel yet). When the intake valve opens, the air and fuel are drawn simultaneously into the cylinder, (how cold do you think that "cold air is now?). A little side note here: Chrysler designed the "Hemi", (hemispherical combustion chamber) back in the 60's. Ford came out with HSC, (High Swirl Combustion) in the mid 80's. Honda came out with CVCC, (Controlled Vortex Combustion Chamber) in the late 70's. GM's answer is the "Vortec". They all accomplish the same exact thing, in the same exact way: mix the air & fuel together. The "mixing" is done in the cylinder, both on the intake, and the compression stroke. We're still waiting for the benfit of the CAI here.
#3 Compression.
#4 Ignite it at the correct time.
The "cold air" theory is blown to pieces on step #2. Save your money.
Another overlooked fuel saving factor is wheel alignment. If the tires aren't all going in the same direction, mileage will suffer substantially. Instead of the tires rolling down the road, they are being dragged down the road. If there is noticeable irregular tire wear, (not smooth) on the tread, it's costing you money in fuel. Go to a specialty front end shop, not a tire store or a dealer. You'll spend a little more, but it be far less than a CAI system
There's my 2 cents, who's next?
#1 Atomization, (break it up into small particles). This is done when the pressurized fuel exits the injector in a mist. (Where's that "cold air"?).
#2 Vaporization. This is done on the back side of the intake valve where it's nice and warm, and the fuel instantly vaporizes. When that "cold air" enters the plenum, it is heated, (the air has not been introduced to the fuel yet). When the intake valve opens, the air and fuel are drawn simultaneously into the cylinder, (how cold do you think that "cold air is now?). A little side note here: Chrysler designed the "Hemi", (hemispherical combustion chamber) back in the 60's. Ford came out with HSC, (High Swirl Combustion) in the mid 80's. Honda came out with CVCC, (Controlled Vortex Combustion Chamber) in the late 70's. GM's answer is the "Vortec". They all accomplish the same exact thing, in the same exact way: mix the air & fuel together. The "mixing" is done in the cylinder, both on the intake, and the compression stroke. We're still waiting for the benfit of the CAI here.
#3 Compression.
#4 Ignite it at the correct time.
The "cold air" theory is blown to pieces on step #2. Save your money.
Another overlooked fuel saving factor is wheel alignment. If the tires aren't all going in the same direction, mileage will suffer substantially. Instead of the tires rolling down the road, they are being dragged down the road. If there is noticeable irregular tire wear, (not smooth) on the tread, it's costing you money in fuel. Go to a specialty front end shop, not a tire store or a dealer. You'll spend a little more, but it be far less than a CAI system
There's my 2 cents, who's next?
Last edited by Captain Hook; 01-03-2015 at 02:31 PM.
#35
01-03-2015, 02:55 PM
All your points are valid but what really opened my eyes was pulling a 2.5 out of a 1985 Fiero listed as 25mpg combined. Put in a 3.8 out of a Camaro, swapped the cam to a slightly larger lift and some tuning. After a couple days of tuning it was getting low to mid 30's. The larger displacement even got better than 25mpg from Denver and up in elevation(passing everyone but a Corvette on the way up). I wish I had the ability to do some tuning because I am very interested to find out what can be done for mileage on the 4.3.
#38
01-03-2015, 05:49 PM
Not so! The system voltage is regulated by the gap at the plug. As soon as there is ionization at the gap the system resistance goes down drastically thus the voltage sags until system energy is depleted. Voltage is only enough to fire the plug. Rated voltage is only developed when voltage cant overcome resistance. Ref: "Ugly's table"
Last edited by LeWhite; 01-03-2015 at 05:51 PM.
#39
01-03-2015, 07:03 PM
dump the clutch fan and put an electric fan on the radiator free up a few hp and may increase mpg. As far as that goes make sure your fan is turning freely when it cold.
#40
01-03-2015, 07:11 PM
LeWhite, exactly correct. If a plug requires more than ~7Kv to fire, there's something wrong. No reason to waste money on "high performance" ignition coils. Factory coil output is ~40Kv waaaay more than enough.
screwdriver, Fan clutch must have resistance when cold. If it spins freely cold, it's bad. That's why they roar when cold.
screwdriver, Fan clutch must have resistance when cold. If it spins freely cold, it's bad. That's why they roar when cold.
Last edited by Captain Hook; 01-03-2015 at 07:21 PM.