Ford to Add Turbos to increase fuel economy?
06-29-2007, 06:13 PM
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Ford to Add Turbos to increase fuel economy?
http://www.thetorquereport.com/2007/06/for...lans_to_ad.html
Add turbos for fuel economy??? Didnt work well on my Sti!
Add turbos for fuel economy??? Didnt work well on my Sti!
06-30-2007, 08:30 AM
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Uh, you guys saw losses because you were adding turbos for performance, not fuel economy. I would think that would be pretty damn obvious.
Ford is trying a similar tactic as VW's chosen route of super-turbo'ing small engines. Of course, we don't know which specific engines they'll be doing this to, so who knows how small "small" is in Ford's case.
Twin turbos on every turbo'd engine sounds a bit complicated though. Ya they can mass produce it quickly and easily, and it's a cheap technology to put on an engine, but they better make sure they're very low maintenance. To me it sounds like there's going to be a LOT of extra plumbing under the hood.
My 1.8T GTI I think is a perfect example of how turbo'ing can save fuel economy. The VR6 GTI certainly won't get the mileage I do, and aside from the on/off nature of my engine, both the VR6 and 1.8T are very similar in power and capability performance-wise. The 2.0Ts in the new VWs are also plenty capable that VW doesn't need to have a VR6 option anymore.
Ford is trying a similar tactic as VW's chosen route of super-turbo'ing small engines. Of course, we don't know which specific engines they'll be doing this to, so who knows how small "small" is in Ford's case.
Twin turbos on every turbo'd engine sounds a bit complicated though. Ya they can mass produce it quickly and easily, and it's a cheap technology to put on an engine, but they better make sure they're very low maintenance. To me it sounds like there's going to be a LOT of extra plumbing under the hood.
My 1.8T GTI I think is a perfect example of how turbo'ing can save fuel economy. The VR6 GTI certainly won't get the mileage I do, and aside from the on/off nature of my engine, both the VR6 and 1.8T are very similar in power and capability performance-wise. The 2.0Ts in the new VWs are also plenty capable that VW doesn't need to have a VR6 option anymore.
06-30-2007, 11:42 AM
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Well, it could work but not sure about "diesel" level fuel economy. Turbos are kind of a way of recycling some of the lost energy in the heat of exhaust fumes... it's used to drive the impeller.
Engines make more power with a higher compression ratio but obviously they can only raise CR so high before you worry about detonation. Direct fuel injection lets an engine run a higher CR than regular manifold injection (which is why the 335i motor runs >10:1 CR) because of a cooling effect of the gas being sprayed directly into the combustion chamber. This helps make more power in a smaller engine, and smaller engines have less friction/pumping losses. I think direct injection is here to stay.
BMW has their Valvetronic system that lowers the valve lift on the intake valves to the point where there's no throttle necessary and little to no vacuum in the intake manifold. This reduces pumping losses and helps save gas. The 335i turbo motor doesn't have Valvetronic, however. They have a white paper somewhere that says it's not necessary because of the turbos. Perhaps the energy extracted from the exhaust helps counteract these losses. Obviously if you hammer it all the time you'll burn lots of gas, but for just putting around town, the 335 is pretty good on gas for what it is. I get 20-21 average in mine in the same driving conditions my S2000 gets 20-21, which is pretty remarkable considering how much heavier and more powerful the 335 is.
Another thing to think about is Ethanol (E85). Even though E85 contains less energy than gasoline, it has an octane rating of about 105 which means you can run a really high CR and/or more boost than on gas. So although the fuel contains less energy the engine can be tuned to extract a higher percentage of it over gas... or something like that. I'm an EE, not an engine designer, but it seems to make sense
Engines make more power with a higher compression ratio but obviously they can only raise CR so high before you worry about detonation. Direct fuel injection lets an engine run a higher CR than regular manifold injection (which is why the 335i motor runs >10:1 CR) because of a cooling effect of the gas being sprayed directly into the combustion chamber. This helps make more power in a smaller engine, and smaller engines have less friction/pumping losses. I think direct injection is here to stay.
BMW has their Valvetronic system that lowers the valve lift on the intake valves to the point where there's no throttle necessary and little to no vacuum in the intake manifold. This reduces pumping losses and helps save gas. The 335i turbo motor doesn't have Valvetronic, however. They have a white paper somewhere that says it's not necessary because of the turbos. Perhaps the energy extracted from the exhaust helps counteract these losses. Obviously if you hammer it all the time you'll burn lots of gas, but for just putting around town, the 335 is pretty good on gas for what it is. I get 20-21 average in mine in the same driving conditions my S2000 gets 20-21, which is pretty remarkable considering how much heavier and more powerful the 335 is.
Another thing to think about is Ethanol (E85). Even though E85 contains less energy than gasoline, it has an octane rating of about 105 which means you can run a really high CR and/or more boost than on gas. So although the fuel contains less energy the engine can be tuned to extract a higher percentage of it over gas... or something like that. I'm an EE, not an engine designer, but it seems to make sense
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06-30-2007, 04:52 PM
#8
Acura tried it on the RDX. Really doesn't work for them, either...
06-30-2007, 06:01 PM
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In my experience (Volvo and SAAB) turbos usually can help mileage because they let you run a small displacement engine at lower RPM most of the time. At lower RPM you can run the throttle plate closer to WOT which helps mileage. Keep in mind that part of the mileage advantage of a Diesel motor is the ability to run at WOT at all times (no throttle plate).
The Volvo 850 got the same highway mileage (based on first hand experience) as the 850T-R. The TR basically had a longer top gear. So while the motor was not more fuel efficient at any given RPM, the car was more efficient because it had a longer top gear. It still had good passing power because the turbo can help the engine produce great midrange torque when needed.
Now as for the mileage. We could be seeing one of two things. The Acura RDX clearly didn't see any mileage advantage over a V6 with it's turbo 4. It's possible that Acura could play some tricks with shift points and the like so the car could do well on the EPA test but didn't do as well with real world heavy foot drivers. It certainly wouldn't be the first time a manufacture designed the car to get good mileage on the tests while the real owner sees nothing special. It's also possible the RDX really will get good mileage but for all the lead footed testers. I've found that turbos don't seem to get good mileage at all if you are actually working the turbo all the time. At least that was my experience with SAABs.
It
The Volvo 850 got the same highway mileage (based on first hand experience) as the 850T-R. The TR basically had a longer top gear. So while the motor was not more fuel efficient at any given RPM, the car was more efficient because it had a longer top gear. It still had good passing power because the turbo can help the engine produce great midrange torque when needed.
Now as for the mileage. We could be seeing one of two things. The Acura RDX clearly didn't see any mileage advantage over a V6 with it's turbo 4. It's possible that Acura could play some tricks with shift points and the like so the car could do well on the EPA test but didn't do as well with real world heavy foot drivers. It certainly wouldn't be the first time a manufacture designed the car to get good mileage on the tests while the real owner sees nothing special. It's also possible the RDX really will get good mileage but for all the lead footed testers. I've found that turbos don't seem to get good mileage at all if you are actually working the turbo all the time. At least that was my experience with SAABs.
It
07-01-2007, 01:06 AM
#10
Sounds like BS. Turbos can boost fuel economy but "diesel" like fuel economy? They can't even get four-cylinder fuel economy in their four-cylinder cars!
As for VW's twincharged (or "superturbo") motors? It claims to push 170 hp and get 40 mpg? FI gets more power by putting more oxygen into the engine. More oxygen means more gas can get burned... gas cars already run lean (hence, some things such as exhaust gas recirculation were made) so its hard to imagine how you can improve the oxygen:gasoline ratio. We'll have to wait and see.
As for VW's twincharged (or "superturbo") motors? It claims to push 170 hp and get 40 mpg? FI gets more power by putting more oxygen into the engine. More oxygen means more gas can get burned... gas cars already run lean (hence, some things such as exhaust gas recirculation were made) so its hard to imagine how you can improve the oxygen:gasoline ratio. We'll have to wait and see.