Thread: fuel economy

Just to bump this I'm seeing 11L/100km out of my 4BD1T. Not bad for an engine that's nearly 4 litres and has such much torque.

After reading this thread I am reading that a 4BD1 is generally a tad more economical than a 4BD1T, lets say by may 2L/100kms. Does this appear correct to you all out there. Is this a fare assumption, does the difference decrease with a loaded up vericle say? Am interested to know beacause I always thought turbos made engines more efficient by utilising wasted heat. So I am a tad confused can a turbo motor get better economy than a NA motor? Yes I have driven a few turbo motor landys and they are great but the economy question has head me stumped.
Is it all down to how heavy the right foot is not sure?

regards
Garry

Originally Posted by garryseries3

After reading this thread I am reading that a 4BD1 is generally a tad more economical than a 4BD1T, lets say by may 2L/100kms. Does this appear correct to you all out there. Is this a fare assumption, does the difference decrease with a loaded up vericle say? Am interested to know beacause I always thought turbos made engines more efficient by utilising wasted heat. So I am a tad confused can a turbo motor get better economy than a NA motor? Yes I have driven a few turbo motor landys and they are great but the economy question has head me stumped.
Is it all down to how heavy the right foot is not sure?

regards
Garry

Often stated but just not true.

How much fuel ver your foot you shove in is how much you use. Since the NA is a bit lacking at times it is easy to understand that with the extra O available ver the turbo that the foot shoves in a bit more fuel.

Hence the difference

I have been playing around with my rack averaging about 9.6 as a daily to work city drive 3 X 126ltr tanks so far

Originally Posted by 85 county

Often stated but just not true.

How much fuel ver your foot you shove in is how much you use. Since the NA is a bit lacking at times it is easy to understand that with the extra O available ver the turbo that the foot shoves in a bit more fuel.

Hence the difference

I have been playing around with my rack averaging about 9.6 as a daily to work city drive 3 X 126ltr tanks so far

The reason I ask is because I am considering putting a turbo on my 120 primarily for economy not for extra torque that it will deliver and would like to know the best way to go about this. In addition I have a sequential 2 LPG system to fit off to the motor. If it delivers extra efficiency for the engine I would think this will translate into increase economy. I have read that the same amount of fuel (diesel & LPG combined) is a result. I have wondered if the burning of what is unburnt fuel in a NA isuzu motor (approx 20%) post combustion will lead to a higher EGT's which in turn may drive a turbo a bit more, pumping in more oxygen. Wondering if this is a realaistic concept, or am I off the track. My 120 get around 9.7 -10.5L/100L which is I think is good, so you have a turbo engine and from what I am understanding its the driving style that results economy gains no matter if the engine has a turbo or not?

regards
Garry

Full tank is gone in about 350-400kms

Originally Posted by garryseries3

The reason I ask is because I am considering putting a turbo on my 120 primarily for economy not for extra torque that it will deliver and would like to know the best way to go about this. In addition I have a sequential 2 LPG system to fit off to the motor. If it delivers extra efficiency for the engine I would think this will translate into increase economy. I have read that the same amount of fuel (diesel & LPG combined) is a result. I have wondered if the burning of what is unburnt fuel in a NA isuzu motor (approx 20%) post combustion will lead to a higher EGT's which in turn may drive a turbo a bit more, pumping in more oxygen. Wondering if this is a realaistic concept, or am I off the track. My 120 get around 9.7 -10.5L/100L which is I think is good, so you have a turbo engine and from what I am understanding its the driving style that results economy gains no matter if the engine has a turbo or not?

regards
Garry

wow way off base.
I have LPG fumigation. 28 ltrs that lasts for about 10 hours driving. but I have a NA Isuzu so I use it for a bit more power, taking off at the lights or heading up a hill when i don’t want to change down IE 60klms in 4th ( lt95)

so for me LPG is not an economy thing.

LPG fumigation lowers EGT without lowering boost. It is not heat that spins the fan but gas flow or volume. temp drops but volume increases = net effect about the same.

rule of thumb if your not driving with the boot in all the time. + 2Ltrs LPG = less 1 ltr diesel.

your economy is good, check valve clearances filters. Crack pressure on the top fuel filter and timing for an NA i think about 11 BTDC is good

If you add a turbo to an NA motor, you are making use of heat that would otherwise be lost - but you are using it to increase the amount of air that is taken into the motor. This will make virtually no difference to the efficiency of the motor, until you add more fuel than could be burnt without the turbo, when efficiency will be improved because the mechanical work that would be needed to induct and compress the extra air has been replaced by work converted from exhaust heat.

This should make it clear (I hope) that fitting a turbo is unlikely to make any improvement to your fuel economy except by the very indirect effect of not needing to change down - which will rarely have a noticeable effect. What fitting the turbo will do, is provide some extra oomph, available by simply pushing your right foot down. And this, which few can resist doing, will increase you fuel consumption, despite the fact that efficiency may be a little higher; you are using the engine to do more work to propel the vehicle faster.

John

Originally Posted by JDNSW

If you add a turbo to an NA motor, you are making use of heat that would otherwise be lost - but you are using it to increase the amount of air that is taken into the motor. This will make virtually no difference to the efficiency of the motor, until you add more fuel than could be burnt without the turbo, when efficiency will be improved because the mechanical work that would be needed to induct and compress the extra air has been replaced by work converted from exhaust heat.

cool, so if I put a turbo in my oven it will spool up? Mass X volume velocity, less backpressure and lack of scavenging.