Turbo Boost and FE

[AlainB7]

My wife have a Hyundai Sonata 1992 with a 4g63(mitsubishi 2.0l) and 3 speed automatic FWD 3 speed + overdrive + lock-up.

My Galant VR4 also have a 4G63 but Turbo and 3 speed automatic AWD + overdrive witout lock-up.

Both car have similar FE but The Galant made a bit better with about 5MPG more. But It is Turbo without lockup and it's AWD. So if the galant was FWD with a lock-up, it will do better FE. Both car weight almost the same.

But if I dont run at low trottle FE will rise up, full trottle @ 25 psi of boost, i'm about 375HP at the wheel! Not good for FE

In 4g63, the compression ration of turbo and non-turbo engine is different.

[GasSavers_Dust]

One thing that is being missed here I think, but was covered on the ecomodder site, is fueling.When in boost, the fuel pressure will rise. The effective compression ratio will also rise.

As as anecdotal aside, several turbo mustang guys have noted increased MPG from their turbo bolt-ons.

I think a 9.0 CR with a low compresion turbo, or a turbo with some meth or water added would be the best of both worlds.

[AlainB7]

Originally Posted by Dust

One thing that is being missed here I think, but was covered on the ecomodder site, is fueling.When in boost, the fuel pressure will rise. The effective compression ratio will also rise.

As as anecdotal aside, several turbo mustang guys have noted increased MPG from their turbo bolt-ons.

I think a 9.0 CR with a low compresion turbo, or a turbo with some meth or water added would be the best of both worlds.

For me. 43 psi base pressure and 68 psi of fuel @ 25 psi of boost.

For shure compression ratio is different from a NT vs Turbo 4G63.

1G 4G63 NT: 9.0:1 (192 psi compression)
1G 4G63 T: 7.8:1 (164 psi compression)
2G 4G63 T:8.5:1 (168 psi compression)
Galant 92+ 4G63 NT: 9.8:1 (220 psi compression)

[GasSavers_BEEF]

I'd love a 1 liter turbo 3 cyl.

talk about the best of both worlds. gas mileage without boost and enough tail to get out of the way with boost.

[DRW]

Originally Posted by BEEF

I'd love a 1 liter turbo 3 cyl.

talk about the best of both worlds. gas mileage without boost and enough tail to get out of the way with boost.

That's the rub, how much fun vs. how much FE?
Certainly a turbocharged engine is the right way to push both ends of the envelope. But there's still a limit to how much power you can get and still keep good FE. I'd like to see what a 3 cylinder 1 liter engine could do with direct injection and compound turbocharging. Maybe add an electric motor to make it a hybrid, and setup the engine so it can run as a generator when needed.
What would you guess? Maybe 75mpg and 250HP?

[AlainB7]

DRW, explain me how you get 46 to 53 mpg with your big Laser?

You almost make the FE of my VX with the set-up of my Galant that make 19 mpg...

[Dalez0r]

Originally Posted by AlainB7

DRW, explain me how you get 46 to 53 mpg with your big Laser?

You almost make the FE of my VX with the set-up of my Galant that make 19 mpg...

No offense, but your galant's aero looks like this:




It's also an automatic, does that torque converter lock up at cruise? Or does your high stall converter slip constantly? That would annihilate your fuel economy.

[AlainB7]

Originally Posted by Dalez0r

No offense, but your galant's aero looks like this:




It's also an automatic, does that torque converter lock up at cruise? Or does your high stall converter slip constantly? That would annihilate your fuel economy.

This car is modify to drag, fnot for FE.
For shure I know that my AWD, Automatic, High stall and no lock-up don't help my FE, but I am not at my first DSM.

I had a 92 NT, 90T, 91T, 95T, Elantra swap 4g63T.
Even the Elantra(1000 pound less than the DSM) can't do best than 35mpg and it was MT FWD.

[DRW]

Originally Posted by AlainB7

DRW, explain me how you get 46 to 53 mpg with your big Laser?

You almost make the FE of my VX with the set-up of my Galant that make 19 mpg...

Haha, it's magic!
It's all in my gaslog. Essentially I have a long boring commute, which gives me plenty of time to think of new ways to squeeze more mpg out of the car. The car is fwd with a taller 5th gear and an eprom ecu with extensive mods. I've been on the dsm-ecu list for several years, and they released a full commented disassembly which makes it easier to mod almost everything in the ecu. Not to rain on anyone's parade, but even the famous AEM EMS would be a step backwards compared to the level of control I have with this ecu.
I also drive really slow.

[suspendedhatch]

There is no reason why a turbo car can't have the same compression ratio as a stock non-turbo car if you tune it carefully.

I'm willing to bet that you could add a turbo to a N/A engine, keep the stock compression ratio, and tune it with a standalone for a pretty significant gain in both FE and HP.