turbo for better mpg

[jm283611]

so I've been searching around and haven't come up with a good answer and would like to try it, but I'm looking for some input, I have read that turbos have the potential to increase mpg, I have a 1996 civic ex 5 speed 2 door, I get 34mpg with the ac on, 37mpg with it off, running usually 60-65 but up to 70-75 (32 mpg with the ac on) I would like to try to hit 40+ on a regular basis, the car is bone stock as it sits. My thought is to add a turbo, without an intercooler, run less than 6lbs of boost (7 is max on stock internals) and maybe keep it on the lean side (adding a wide band O2?) also I have a thow out bearing that's gonna go out soon, so when I tear that apart maybe swap the trans for an hx or something, any thoughts? ideas? anyone done this? I'm back and forth west Virginia quite a bit in the summer and that's the reason for the 70mph, right now I drive to Athens for school (OU oh yeah) so 55-60 is the speed limit for my winter drives, right now at 55 my car spins 2500 rpm. and I also know I will have to use premium fuel, I ran a tank through before and so no improvement so I'm still running 87

[cRiPpLe_rOoStEr]

I'd rather get an intercooler.

[jm283611]

educate me please, one of the biggest things I see is warming up the intake air. I figure the turbo would do a good job of that, is there such thing as too warm?

[ksa8907]

Originally Posted by jm283611

educate me please, one of the biggest things I see is warming up the intake air. I figure the turbo would do a good job of that, is there such thing as too warm?

warmer temperatures will allow the fuel to evaporate into the air better causing faster combustion and flame front propagation. however, you can have an air charge that is too warm, the ecu will freak if it senses high intake charge temps and retard the timing to slow the combustion process. some cars can tolerate higher temps than others.

[jm283611]

I know the old turbo coupes didn't have intercoolers but I guess they were fine cause they had an 8:1 compression ration, as opposed to my 9.4:1, thanks on the clarification on that before I tear my motor up too badly lol

[redpoint5]

Unless you get the turbo for free, you will never recoup the cost. Plus you have the added cost of having to run premium, and the extra wear on the engine that will necessitate rebuilding it sooner (or scrapping it).

If you want a fun project and a car that goes faster, get the turbo. If you think the project can be considered "green" while saving some green in the long run, think again.

I've thought about a turbo for my TSX, but the relative lack of aftermarket support and scarce examples of successful builds has all but killed my enthusiasm. If I had a car that has lots of support for turbo builds, such as a Civic, I would be tempted to build it just to see if I can realize fuel savings and quantify those savings for communities such as this. I'd never recoup the cost, but then again, hobbies rarely ever do.

If 40mpg is the goal, you need to spin your engine slower at 55mph. 2,500 RPM is quite high. Start thinking final gear change, etc.

[jm283611]

final gear change is the reasoning behind the hx tranny swap the ex has the lowest gears to make it "sportier" I do understand prob not paying for itself, on the other hand I did find a kit locally for $200 it has a t4, manifold, bunch of other stuff, the guy said all I have left to get is a tune, intercooler, piping, bov, and exhaust. don't quote me, but i think the ex trans is 4.2x final drive? and the hx is is 3.7x final drive, or maybe its ring and pinion. the thinking behind this is after reading about a guy that has a turbo civic that gets 55mpg, I do have an ihi turbo

[jm283611]

here is the link, I have to separate the posts cause i don't have enough

[jm283611]

http://ecomodder.com/forum/showthrea...rbo-11881.html
here is the basis of my idea

[Frank Lee]

The reason "they" say turbos can increase fuel economy is for those situations when a much smaller displacement turbocharged engine is fitted instead of a bigger naturally aspirated lump. Sticking a turbo onto whatever is already in there will not result in fuel savings.