Just a thought, my mechanical knowledge is limited but in theory, would a turbo car travelling at a constant speed and load be better in fuel economy than a non turbo'd equivalent! Because, the turbo brings in more air into the cylinder, which means more power which means less load on the engine.! correct me if Im wrong.
meathead_timaru,
Apr 24, 4:20am
The only real factors are total weight (only for rolling resistance - weight doesn't affect top speed nor energy required to maintain a speed on a flat road other than for rolling resistance), aerodynamics and engine efficiency @ the rpm for that road speed. The power required to maintain a specific speed of a specific vehicle of a specific weight does not vary with engine configuration.
morrisman1,
Apr 24, 4:30am
turbos do increase engine efficiency but I dont think the amount is significant.
jsbike,
Apr 24, 7:43am
I was led to belive turbo diesels can get far better fuel economy than the na version of the same diesel. true!
r15,
Apr 24, 7:53am
i had a 2.8 non turbo hiace my mate had a 3.0 super custom turbo hiace
his van would typically use less fuel to travel across the counrty than my one would- didnt matter who was driving or what size load we had, his would always be the cheaper and faster way
unfair comaprison though as the technology in the 2 engines was totally different
mrcat1,
Apr 24, 8:16am
All a turbo does is forced induction, so more air means more fuel which in turn means more horsepower, it doesn't matter what the engine is or it's configuration, it just matters how much air/fuel mixture ( at the correct ratio) it can get thru the engine to give it horsepower. But in saying that as technology gets better the engines increase in horsepower but also in fuel effenciary.
tnt423,
Apr 24, 10:06am
Turbo Nissan Silvias use less gas than the same car that is non turbo. 160kw vs 100kw
eronacax,
Apr 24, 10:15am
a guy i was speaking to at a conference said that a turbo can increase efficency in diesel engines, don't quote me on it i think he said something about making the air mix slightly more with the diesel and having a better burn! (he was the designer of some turbo company)
jsbike,
Apr 24, 10:17am
only if the non turbo is auto and the turbo is manual.
Off the line, up to 50MPH, the 2.4Turbo was as fast as the 202, after that, it ran away from it.
The 2.4NA was a gutless slug.
carkitter,
Apr 24, 10:59pm
My experience of driving non-turbo Hiace vans is that they are so slow they can't get out of there OWN way and need to be driven with the foot to the floor, hence the poor economy figures. Adding a turbo to a petrol or diesel engines adds significantly more torque which means a manufacturer can run higher gearing which then aids fuel economy. I had an '86 Mitsi Sigma GSR turbo which was geared for a top speed of 250km/h, not that it could reach it. Second gear would reach 100km/h though and cruising at 120km/h = 3000rpm and minimal fuel usage.
1ollie,
Apr 24, 11:49pm
Its so funny when you see turbo haters spouting off that a turbo will allways give bad fuel ecconomy blah blah even despite all the common knowlege and evidence out there that proves them wrong! From my experience having a turbo will ALLWAYS give better economy if you drive it in a respectful way as you dont have to load the engine right up to go up hills or get upto your desired speed etc but if you flat foot it everywhere and race to get up to speed then of course it will use more. Now im not saying every single vehicle is like that as there are way to many variables but speaking generly that is the case
carkitter,
Apr 25, 1:01am
Even funnier when people forget an engine is not directly connected to the wheels and uses a gearbox. A 2L turbo Sigma GSR has high gearing but a 2L WRX does not. Add in the extra weight of 4WD and you have a thirsty turbo car. It is horses for courses and if you throw VTEC into the mix then you find even greater efficiency when a non-turbo high-revving engine is matched to a lightweight body. Audi recently dropped the 4.2L V8 from some of their performance models in favour of a twin turbo V6. The V6 makes the same hp with better economy was their argument.
dave653,
Apr 25, 1:22am
It cracks me up how metric measurements make a difference. In the 'old' days a 4.2ltr V8 was the 253! Doesn't sound so great anymore does it!
johnf_456,
Apr 25, 1:54am
It does for most people , guess the older generation it doesn't. My grandad still goes on about miles.
moosie_21,
Apr 25, 7:58am
+1, amen.
fordcrzy,
Apr 25, 9:08am
after adding a turbo to my car my average fuel consumption stayed the same. whati lost when flooring it i gained in cruise.
vtecnet,
Apr 25, 11:07am
My CRX still uses 7L/100k(on the open road at 100km) with the turbo fitted set at 9.4psi max boost, without turbo the result was about the same, the car is only 890kg, the gear ratios don't really suit Turbo though, as its almost 3500rpm at 100km in 5th gear, but this results in more then enough overtaking power without needing to change gear at all, even on an uphill passing lane :) This is due to the use of a small turbo, this gives alot of low down torque, in non honda fashion I don't even have to rev the engine high at all. as now at 3500 it has more torque then it had at 6000rpm stock standard
movnon,
Apr 25, 9:12pm
why bother with turbos if they achieve insignificant efficiency gains- any energy exiting the exhaust is wasted!I have a 2.2 turbo diesel estima, include the RUc's & it costs less than my 2l corona na to run $ per km. The estima is way heavier & less aerodynamic than the corona - surely that says something for the efficiency of turbos. (the estima is no slug either but it is a manual & 4wd )
peejeles,
Apr 25, 9:26pm
i thought that too. particularly with large truck engines
peejeles,
Apr 25, 9:29pm
lol. got me a 253 audi v8
peejeles,
Apr 25, 9:31pm
the xr6 turbo falcon is quite a bit hungrier than its n/a equivalent.
morrisman1,
Apr 25, 9:38pm
I don't think you quite get it, efficiency is related to specific fuel consumption. engine power is a completely different matter but is why turbos are added in most cases.
movnon,
Apr 26, 8:54am
Crap.efficiency gains can be utilised to gain more power or give better fuel consumption by utilising the energy disappearing out of the exhaust but usually it is a combination of both factors to givebetter engine efficiency. Do you get that!
hijacka,
Apr 26, 9:11am
Giving your talking about a injected petrol engine then no it wouldn't be, because if your traveling at a constant speed and load then the manifold pressure will be reading the same kpa value as the non turbo equivalent.(vac) as you wont be creating boost so there for will be using the same amount of fuel giving the weight,\and injector size and cycle are the same. Also the more air it brings in the more fuel it needs, The faster you go the more gas you need, theres no other way around it
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