Volumetric efficiency's effect on brake specific fuel consumption (BSFC)

[Daox]

Assuming all variables stayed the same (yes, I know thats impossible), can we say that if an engine has greater volumetric efficiency or torque that it is also more efficient? I would tend to think yes.

I'd really like to hear some theoretical conversation on that idea, but I'll also share my situation as an example. I bring this up as I will be working on getting my 1993 Tercel back on the road fairly soon. The engine is going to need work in to the not too distant future (217k and burns oil), and I'm thinking about updating to a newer engine (5E-FE or 1NZ-FE). The newer engines are the same displacement, but put out more torque and at lower rpm, and thus I would imagine they're more efficient. Obviously (if you know Toyota engines), the 1NZ-FE is quite a few years newer technology than the stock 3E-E and would be the optimal choice. That also means it will be the most work to put in too...

[aerohead]

Originally Posted by Daox

Assuming all variables stayed the same (yes, I know thats impossible), can we say that if an engine has greater volumetric efficiency or torque that it is also more efficient? I would tend to think yes.

I'd really like to hear some theoretical conversation on that idea, but I'll also share my situation as an example. I bring this up as I will be working on getting my 1993 Tercel back on the road fairly soon. The engine is going to need work in to the not too distant future (217k and burns oil), and I'm thinking about updating to a newer engine (5E-FE or 1NZ-FE). The newer engines are the same displacement, but put out more torque and at lower rpm, and thus I would imagine they're more efficient. Obviously (if you know Toyota engines), the 1NZ-FE is quite a few years newer technology than the stock 3E-E and would be the optimal choice. That also means it will be the most work to put in too...

I would lean towards volumetric efficiency.Toyota's most advanced engine is a gasoline direct-injection type,(no throttle),which takes the 'parachute valve' out of the intake tract completely.All rpm control is done with EFI.
These engines match the mechanical efficiency (43%), of a turbo diesel,lacking only the additional Btu content of the diesel fuel itself.
Some of the proprietary pent-roof cylinder heads designed for SAE Eco Marathon competition stressed easy-breathing for both intake and exhaust as a strategy for 7,000 + mpg racers.
What would be helpful,is a set of 'charts' for available engines,developed on dynamometers,illustrating :indicated power,friction power,net power,pumping losses with and without the head,mean effective pressure,torque,BSFC,and such across the rpm band.
It would give us really valuable insight into any particular power plant.

[mechman600]

Ahem....EV conversion....ahem.
Seriously though, it's awesome to see all your latest projects and I look forward to seeing whatever you decide to do with the Tercel.

I would go old school. Modify what you already have. Do a proper two cylinder delete (like what has been discussed a bunch in this forum but rarely actually attempted). A 41 HP 750cc Tercel, anyone? Then I would maybe find an small turbo to gain back some WOT oomph for "those moments", when a wild pass is necessary. Maybe. Probably a nightmare to get boost to work properly with a de-nutted Tercel engine, but hey, adventures like this are what most of us dream of, right?

Arduino based management system?
DIY TerEcoBoost?

Just sayin.

[serialk11r]

If one of your controlled variables is the valve timing, then I would guess yes, but not by much. BSFC charts are hard to find but there was one from Eaton's TVS marketing materials and the turbo engine appeared to have very high efficiency at a specific torque output slightly higher than the usual NA engine.

[Daox]

I really like the idea of working with what you got. The problem is, the engine is quite old and there have been substantial efficiency upgrades over the years. The weight issue alone is quite important as the 3E-E (current engine) has a cast iron block vs the 1NZ-FE's aluminum block. I could probably drop a good amount of weight right there. The 1NZ-FE only weighs in at 183 lbs. I'm not sure about the 3E-E. The 1NZ-FEs can also be had for less than $300 around these parts. Its hard to rebuild the 3E-E for too much less than that price.

I guess I'm curious what the benefit would be if I changed nothing, but dropped a 1NZ-FE in the Tercel. I realize that the question really isn't answerable. I'm sure it would be a heck of a lot more fun with 107hp vs 82hp, and I bet it would get better mileage too.

Anyway, its mostly a theoretical discussion as I still have to get the car running before I do anything with it.

[abently]

Short answer is yes...

This gives you an idea of what Toyota Engineers were doing pre 2000.

http://www.mr2roc.org/misc/reference...edesigndoc.pdf

I would try and go with the 1.3L, to maximise the potential fuel savings by minimising pumping losses.

[Daox]

Dropping a 1.3L would be a great idea, but it would have to be an imported engine, and I'd rather stay with something I can get parts for.

[Superfuelgero]

Depends on gearing (has to be within the peak at your normal operating speed). This project can start to spiral...

[Daox]

Eh, I'm okay with it spiraling a bit. I want to try different more wild things with this car anyways. Its not a daily driver at this point, so I have time to do what I really want with it.