Weight has very little to do with MPG, true enough that you will need more HP to accelerate the car from a stop but after the car is at speed weight means almost nothing. Funny thing is depending on how you drive that you can get back some of the fuel lost in accelerating a heavier car because of ability to retain speed with the weight after you let off the gas (just don’t use your breaks to stop!).
Once up to speed the only difference in weight is a slightly increase rolling resistance, this is 10ths of a %.
Food for thought:
If the top speed of a car is 200 mph and weighs 1000 pounds the top speed of an identical car that weighs 2000 pounds is about 197 mph (3 mph less).
If you want an easy (and cool) way to get better MPG is to lower the suspension.
Every inch lowered the cars CD (coefficient of drag) decreases .01% this means that a 3” drop will yield a .03% improvement. This may not seem like much but you will get less air under the car as well…..this can be good for another .03%.
Total=.06 improvement in Cd.
This can make a car getting 22 mpg go to 30+….and your car will look sportier as well.
ALSO:
Get a turbocharger, you will get better MPG with one of these as well. (providing you keep your foot out of it!)
Keep the subs.
Once up to speed the only difference in weight is a slightly increase rolling resistance, this is 10ths of a %.
Food for thought:
If the top speed of a car is 200 mph and weighs 1000 pounds the top speed of an identical car that weighs 2000 pounds is about 197 mph (3 mph less).
If you want an easy (and cool) way to get better MPG is to lower the suspension.
Every inch lowered the cars CD (coefficient of drag) decreases .01% this means that a 3” drop will yield a .03% improvement. This may not seem like much but you will get less air under the car as well…..this can be good for another .03%.
Total=.06 improvement in Cd.
This can make a car getting 22 mpg go to 30+….and your car will look sportier as well.
ALSO:
Get a turbocharger, you will get better MPG with one of these as well. (providing you keep your foot out of it!)
Keep the subs.
I think he already has a turbocharger, and hence has 20mpg.
His engine (if I understood correctly from above):
http://en.wikipedia.org/wiki/Nissan_SR_engine#SR20DET
A turbocharger on a gasoline engine of equal displacement CAN increase efficiency and in theory always should, but in reality the efficiency gains don't often materialize (because of engine tuning and design tradeoffs for more power rather than optimum fuel efficiency).
A diesel engine on the other hand nearly universally benefits in efficiency from turbocharging (because of the reduced pumping losses compared to a throttled engine); they are really the ideal match.
For a gasoline engine, the RPM of the engine dominates the fuel requirement for the engine. Pressing the throttle down further at lower RPM actually increases the efficiency of the gasoline engine to an extent (because of reduced pumping losses against the more open throttle). The extra fuel added to enrich the mixture at higher throttle inputs is small compared to the fuel required to run the motor at a higher RPM.
-David
His engine (if I understood correctly from above):
http://en.wikipedia.org/wiki/Nissan_SR_engine#SR20DET
A turbocharger on a gasoline engine of equal displacement CAN increase efficiency and in theory always should, but in reality the efficiency gains don't often materialize (because of engine tuning and design tradeoffs for more power rather than optimum fuel efficiency).
A diesel engine on the other hand nearly universally benefits in efficiency from turbocharging (because of the reduced pumping losses compared to a throttled engine); they are really the ideal match.
For a gasoline engine, the RPM of the engine dominates the fuel requirement for the engine. Pressing the throttle down further at lower RPM actually increases the efficiency of the gasoline engine to an extent (because of reduced pumping losses against the more open throttle). The extra fuel added to enrich the mixture at higher throttle inputs is small compared to the fuel required to run the motor at a higher RPM.
-David
I had a mustang 5.0 for a while, then changed to an import 2.0 turbo AWD. The 5.0 might have been a hair faster. Driving the same route to work of ~20 miles each way I would short shift the V8 as low as 1500, the turbo would not pull the car under 2500 but V8 would at 1000rpm. And the 2.0 was geared fair amount lower both were 5 speeds. I got 21-22 all the time with the V8 and 1-2mpg better with the 2.0. I stood on them once in a while but drove pretty normal to work, was about 2/3 expressway 70-80mph and rest was town. Now I have a 2.0 auto in a little sedan. It gets mid 20s mixed and have pulled 34 on highway trips with the A/C on at 95F. Once got 17 hammering/spinning around town in the snow, pretty much worst case I was in a hurry. In summer mostly town/rural driving it often shows 24mpg, 28-30 with some highway added in. Its still not good enough.
Another thing I do with most of my cars is run water wetter in the coolant, it can help with detonation so the ecu will run more timing advance. Learned that with turbo cars. Also put a trans cooler on this 2.0 auto, it runs cooler all the time now I'm sure it helped for <$40. Synthetics can help too as well as new air filters when needed, they can be easy to forget.
Another thing I do with most of my cars is run water wetter in the coolant, it can help with detonation so the ecu will run more timing advance. Learned that with turbo cars. Also put a trans cooler on this 2.0 auto, it runs cooler all the time now I'm sure it helped for <$40. Synthetics can help too as well as new air filters when needed, they can be easy to forget.
Car is broken
If you are getting 20 MPG the car is broken. I don't know if your car has one but on my old Dodge, I got crappy mileage and it turns out there was a thing called a fuel pressure regulator and it allowed the fuel pressure to be too high. When I replaced it, my mileage jumped by 30%. I went from 300KM to almost 400KM between fill ups.
See if there is one on your car and have the fuel pressure checked out if there is one.
Because the way you are driving you should be getting closer to 30 MPG.
If you are getting 20 MPG the car is broken. I don't know if your car has one but on my old Dodge, I got crappy mileage and it turns out there was a thing called a fuel pressure regulator and it allowed the fuel pressure to be too high. When I replaced it, my mileage jumped by 30%. I went from 300KM to almost 400KM between fill ups.
See if there is one on your car and have the fuel pressure checked out if there is one.
Because the way you are driving you should be getting closer to 30 MPG.
I would expect low 20's in town for that model, being the 2.0 gasoline turbocharged. Maybe 26 hwy. Its difficult to keep off the pedal with turbo'ed gasoline vehicle. It's not a civic 1.6 na.
Oh yes, boost gauges sure are intoxicating.🙂 Before I stopped driving mine I wanted to install an exhaust valve. I had the converter plug and the turbo comes on much lower rpm with a restriction, would have been nice for sedate driving. I even wondered about one of those spring loaded flapper valves like they use on boats or an rpm/boost sensing valve.
Use a vacuum actuator for your wastegate and connect it to the intake, under vacuum the gate will be open, no vacuum the gate is closed.....no tuning required.
This will give you max boost during cruising speeds and no boost to accelerate.
While I have never heard of this being done it should, in theory, give you better MPG based on reducing pumping losses by returning otherwise wasted potential energy back to the motor.
Higher FP could give you bad MPG.....but any car with an O2 should cause a code to throw and let you know that your fuel air ratio is out of range.
As a rule detonation is caused from turbos because the air charge is so hot, or the fuel octane is too low. I would caution you from thinking the motor is OK because you are using water wetter. Even if the block may be a few degrees cooler the events that cause detonation still exist (detonation can happen on a motor running well below its standard opperating temp.. Running your engine cooler below its optimum temperature will get worse MPG. *Also, the temp of the motor is governed by the thermostat, only if the cooling system is not adaquate to cool the engine (way more HP on a stock cooling system for instance) would water wetter give you any cooler engine temps....but never lower than what the termostat will allow.
Instead of water wetter, I suggest an intercooler or water injection to cool the intake charge (the temps out of a turbo can be 300+ degrees!)
Good luck
This will give you max boost during cruising speeds and no boost to accelerate.
While I have never heard of this being done it should, in theory, give you better MPG based on reducing pumping losses by returning otherwise wasted potential energy back to the motor.
Higher FP could give you bad MPG.....but any car with an O2 should cause a code to throw and let you know that your fuel air ratio is out of range.
As a rule detonation is caused from turbos because the air charge is so hot, or the fuel octane is too low. I would caution you from thinking the motor is OK because you are using water wetter. Even if the block may be a few degrees cooler the events that cause detonation still exist (detonation can happen on a motor running well below its standard opperating temp.. Running your engine cooler below its optimum temperature will get worse MPG. *Also, the temp of the motor is governed by the thermostat, only if the cooling system is not adaquate to cool the engine (way more HP on a stock cooling system for instance) would water wetter give you any cooler engine temps....but never lower than what the termostat will allow.
Instead of water wetter, I suggest an intercooler or water injection to cool the intake charge (the temps out of a turbo can be 300+ degrees!)
Good luck
that is not bad for that motor , that is not much lower than the 240's ( silvia's) get and they have a lot less weight.
I would be glad to get 20 mpg in town ,my Dodge Srt-4 only gets about 16 to 18 in town and 25 to 27 highway.
I would be glad to get 20 mpg in town ,my Dodge Srt-4 only gets about 16 to 18 in town and 25 to 27 highway.
This 2.0 has an intercooler on the turbo. I put a head on it and then set the timing, well later set it higher because the ecu cuts it back at any sign of detonation anyway. In below freezing temps it had way more power for example though sure intercooler did some of that.
However I could tell it ran with more timing with water wetter in hot temps say 90F or more for sure, the ecu was far slower to cut timing. I could hammer on it some and before it would cut soon as it had full boost for maybe 4 seconds. Even its fuel requirements went by temps, roughly under about 50F I could run midgrade and regular at/under freezing.
I was told water wetter can reduce hot spots in the head, and that is what can cause more detonation than just high temps (say high coolant temps) in general. Was told I could not drop thermostat much or ecu would think something was wrong. I did change the hose on the wastegate for more initial boost as well as some intake mods and this and that. Ran syntheic oil only in engine/trans. The additional timing also made more power with no boost, I'm sure it helped economy a little. I did drive it off boost at times, lol. What a fun car. I suppose other cars may react differently. I did set the timing stock and higher a few times to compare. I had to do this because it would cut timing bad when it was over 90F here, and I did a few things including reworking the ducting to the intercooler for more flow.
A guy around here has a nice SRT4, he never steps on it going by here. The car I had was an eclipse with awd, it would often get 20mpg around town as well. I think the low gearing and awd kept the highway mpg from going higher than the 24 or so I got. I ran it hard at one job I had out of town, used to run 90mph on the highway at times and some city and still averaged 22. If I stayed under 70mph I hit 25mpg a few times.
However I could tell it ran with more timing with water wetter in hot temps say 90F or more for sure, the ecu was far slower to cut timing. I could hammer on it some and before it would cut soon as it had full boost for maybe 4 seconds. Even its fuel requirements went by temps, roughly under about 50F I could run midgrade and regular at/under freezing.
I was told water wetter can reduce hot spots in the head, and that is what can cause more detonation than just high temps (say high coolant temps) in general. Was told I could not drop thermostat much or ecu would think something was wrong. I did change the hose on the wastegate for more initial boost as well as some intake mods and this and that. Ran syntheic oil only in engine/trans. The additional timing also made more power with no boost, I'm sure it helped economy a little. I did drive it off boost at times, lol. What a fun car. I suppose other cars may react differently. I did set the timing stock and higher a few times to compare. I had to do this because it would cut timing bad when it was over 90F here, and I did a few things including reworking the ducting to the intercooler for more flow.
A guy around here has a nice SRT4, he never steps on it going by here. The car I had was an eclipse with awd, it would often get 20mpg around town as well. I think the low gearing and awd kept the highway mpg from going higher than the 24 or so I got. I ran it hard at one job I had out of town, used to run 90mph on the highway at times and some city and still averaged 22. If I stayed under 70mph I hit 25mpg a few times.
Hmmm. But wouldn't poor boost-less acceleration encourage a more open throttle during the severe turbo-lag, negating a repectable portion of the increased efficiency?
Would it make sense if compression was increased to a more normal ratio with a mild turbo boost coming on as above?
And the difference between pre-compression and combustion temperatures limits the energy to be released. Colder in, hotter burn = more efficient burn.
The real problem with turbos is off boost low compression. Variable valve systems may help. Saab was once working on a variable compression engine that would tilt the whole top end, was quite interesting but I think about that time GM bought them or something. That is why they don't get great highway mpg, though you can use less displacement to partly make up for that since you have increased maximum power. If off boost, its off and you get no help from the turbo. To get just a little boost I would be above speed limits here and out of good mpg speeds. The heat is an issue at high boost.
Take a look at the new VW engine with a turbo and supercharger, it is impressive for a 1.6L as I recall. They say it is even with a normal 2.0L but better economy.
Take a look at the new VW engine with a turbo and supercharger, it is impressive for a 1.6L as I recall. They say it is even with a normal 2.0L but better economy.
Hey this is still on topic....maybe if we can increase his turbo's mpg he can once again run a sub box....LOL!😀
This is possible.....but in my way of thinking there would be a grey area crossover, where the car would accelerate much better if you were giving it a "pinch" more gas then WOT. This would mean the engine would still have boost to accelerate if you had a small amount of gas pressed (just over the ablility to maintain RPM) but if you hammered it...poof it goes away. It would train the person driving to just apply enough gas to get the car to pull good without pushing the peddle to the floor.
Remember this is not to get a performance advantage or to emulate a turbo motor; it is just to use a turbo to gain MPG.
In truth the performance would be no better than a NA motor of like displacement....only that in my head it would get a good bit better MPG.
This is un tested.
I challenge anyone to do this concept.....but remember where you heard of it!
-JH
jh:
That makes sense. It'd be like driving a 1980 Toranado Diesel, which almost went 80mph once on I-10. Downhill, of course.
Defensive driving would be a must, since you'd lose power if you
hammered it to avoid a dangerous situation.
jh:
So it should be named in your honor now before someone else steals it. Certainly we can help with that.
How about The Hotnuts Blower?
That makes sense. It'd be like driving a 1980 Toranado Diesel, which almost went 80mph once on I-10. Downhill, of course.
Defensive driving would be a must, since you'd lose power if you
hammered it to avoid a dangerous situation.
jh:
So it should be named in your honor now before someone else steals it. Certainly we can help with that.
How about The Hotnuts Blower?
you could always lean out your afr to 12 to 12.5 and use water injection and have more power to.
Lots of subie guys boost their n/a 2.5 boxers and get awesome boost response, usually only maxing at about 7psi. They can keep decent mileage until boost is needed. I'm about to swap in an ej20k (low compression + 19.5psi @ boost = crappy mileage 🙁 )
Motors have a sweet spot AFR that is best for your motor; there is no perfect AFR # that works best on all motors. Funny thing is that two of the same motors with the same mods can require different AFRs to make the equal HP.
I will agree that a dyno tune to make the most HP by locating the best AFR # is important to safely find the engines peak efficiency without detonation or making the exit gas too hot.
Depending on your boost PSI, intercooler efficiency, CR, fuel quality-octaine, water/meth injection, ambient temps and timing, increasing your AFR even .5 could cause a piston to melt.
Proceed with caution with messing with AFR.
-JH
Thought this tthread was dead
Hello, hold up guys, thats not my engine. Just someone gave me wrong info. It doesn't have a turbo, I know that much. Also, just found the Thermastat is missing. Its cold here and its not heating up, I've had to shove cardboard down it at the mo. My local supplier is waiting delivery of a new stat.
So thats the problem, me hopes.
Yeah, the info is usualy good here, richie00boy.
Thanks as ever guys.
Now, wheres me sub?😀
Mike
Hello, hold up guys, thats not my engine. Just someone gave me wrong info. It doesn't have a turbo, I know that much. Also, just found the Thermastat is missing. Its cold here and its not heating up, I've had to shove cardboard down it at the mo. My local supplier is waiting delivery of a new stat.
So thats the problem, me hopes.
Yeah, the info is usualy good here, richie00boy.
Thanks as ever guys.
Now, wheres me sub?😀
Mike
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