Turbocharging for FE
 

it may sound strange but a light pressure turbo system may provide a fuel savings. I am currently researching a LPT system for my wagon. My research has shown that a low (2-5 psi) boost turbo system will keep the transmission in lock up on hills resulting in a small improvement in FE. If I end up with the same FE and a touch better freeway performance I'll be fine with that. Having the car downshift to 3rd and even 2nd to make hills is ridiculous.

You aren't alone in thinking that turbos can improve FE. Lots of auto manufacturers are going in that direction as well.

A quick tip though, is that if you can manage (ie, if traffic allows) it, you should try to coast up the hill as much as possible. Get going fast on flat ground, and then coast up the hill as far as possible. If absolutely necessary, you can downshift, but your momentum might be able to tackle some of the smaller "bumps in the road."

A properly matched turbocharger (meaning one designed to provide boost at LOW rpm) will usually provide better efficiency. It usually also helps to change the gear ratios to a taller gear with a low rpm turbo.

Unfortunately, most guys want power and they size the turbo for high rpms and high power. This will drain your gas tank faster too.

turbo's definately are handy to improve FE, the main advantage is that they can get more power out of a much smaller engine block.

Fiat for example is currently developeing a 2 cylinder 0.9L turbo engine that should output between 90 and 110 hp... i'd love to put that in my car... less weight more power...

I can't help but notice you're trying to keep the auto trans from downshifting too early. Perhaps the problem isn't a lack of power, since most auto trannies will shift to an easier gear around 2/3 throttle, which means there's more throttle and slightly more power already there.

I'm getting good FE out of my turbo car by staying out of boost. I'm very familiar with the operation of my car, and it will begin to run rich even when making low boost. I tried leaning it out at the onset of boost, but it just knocks at that point. So I tried reducing ignition timing at that point to reduce knock and power dropped noticeably. Timing has more of an effect on power than A/F ratios, and running a richer A/F ratio lets me use more timing.

Have you thought about using adjustable cam gears to improve low end power? MetroMPG has a good thread about swapping the cam in his metro.

the problem with this car is that it is heavy and has a smallish 4-cyl (3400lb and a 2.2l) with just 135hp. it really needs a bunch more torque to move the car effectively. on the freeway I come to a slight rise and I am down on two or even three gears to get over it, this is at 65-70mph. If a low pressure turbo system will make enough differenc that I only need one lower gear than I will see some improvement. Trust me 6500 at 65mph is NOISY!!!

3400lbs is indeed quite hefty for an engine with as little power as that de-tuned Ecotec... Have you looked into a transmission controller? You may just want to control the gears yourself, this may alleviate some of your downshifting problem (stay in higher gears at the expense of "performance" maybe?)

Look here at the transmission controller: https://awshifting.com/index.html

It may be a good first step for you and you should definitely be able to improve your fuel economy using it. A turbo is going to be an expensive and complicated endeavor, just remember that.

turbo is easy on this engine trans control isn't and the site you posted doesn't cover any gm transmissions. But thanks anyway.

Oh wow, I didn't realise your power to weight ratio was that bad. OTOH it's nice to see someone actually opt for the base engine instead of the ultra gashog option. Since you're climbing hills, weight reduction will make a bigger difference on your car.

How about a small shot of nitrous for the hills?
If the guys at Mythbusters can come up with a JATO for their car I don't see why you couldn't use one, too!

I have a feeling you might get a good bump in FE with a slight adjustment to your speed. Would the trans hold a higher gear if you kept the speed around 55-60mph on the uphills? WOT at high rpm is will really suck down the gas.

Can those ecotecs do the Saab parts shuffle?

You win the prize the 2.0 LPT saab 9-3 is where I'm getting all my bits. They make just 175hp out of 2 litres at a mere 4-6 psi. I have a slightly larger 2.2 litre engine.

Unfortunately even at lower speed it drops gears to climb even the slightest of hills.

I've been a fan of this since day one. You can bet on seeing many more vehicles using forced induction and smaller motors in the future.

Why? The recently passed energy bill.

I also think forced induction will be used to deal with alternative fuels in order to change compression on demand. We most likely won't see water injection from the factory because people are so lazy, but that's a method that can be used in conjunction with FI for increased FE. WI + FI allows for a leaner mixture without the adverse effects.

FI relies on the tactic of using power when you need it and using less fuel when you don't (cruising, idle, etc).

The most important aspect of a turbo setup is the tuning.

VW came up with a setup I thought was interesting. It used something like a 1.4L motor with a super charger for low end and turbo for high. IIRC it put out well over 200hp and I think FE was around 40mpg.

DRIVENBYNOTHING, it's a 2.0L here in Japan, and it's called FSI

I think it sounds like a great idea to add a small turbo to your Saturn, but I've heard some bad stories about turbo'd automatic Hondas. Hondas are notorious for their auto trannies, and if Saturns have not the strongest autos, I would have an extra tranny ready if you do add a turbo.

The main problem I see with a turbo on a nonfactory-turbo'd auto is that when the tranny is between gears, the car will continue to make power due to the turbo spooling. I just don't see this as a good thing for the auto tranny that's not designed for this type of abuse. I might be all wrong, it's just something I through wouldnt be good for the tranny.

Fortunately GM equipped this car with the same transmission they use in the MonteCarlo SS with the 305hp LS1. it's plenty strong

I think adding a turbo to an existing engine is a great way to increase the power. I can't see how it will improve fuel economy.

In fact you can look up the turbo vs. non turbo versions of Volvo's legendary long-lived 2.3 liter engine, sold between from about 1981 through 1995. 240's offered turbo 'till '85, then the 740 and 940 offered it through the end of the 940 run. Turbo always got less mpg even though it's the same basic block.

If you use a SMALLER engine and turbo it to get more power then the overall FE might be better than a bigger engine without turbo. Partially because you're not dragging around the weight of a bigger block. The Europeans figured that out decades ago because they tax cars based on displacement.

Well, a smaller engine generally means less in pumping losses too. If you've got a V8, that engine has to keep 8 pistons moving regardless of power requirements. Most V8s will be injecting fuel into those cylinders at all times as well. If your four cylinder with a turbo can put out the same power as the V8 when it's needed, only 4 pistons are moving and only 4 injectors are spitting fuel into the motor.

Again, if you use water injection you can also lean out the fuel.

You have to remember that most every car turbocharged from the factory was done so for power purposes.

this car had a V6 option and from the posts I've read on the saturn fan sites they are not too reliable and drink fuel like water. If I can get similar performance to the v6 and no loss in milage I will think of the project as a sucess.

Turbo's are still untapped.
 

I have been a turbo lover for years, I have been fortunate to drive a number of them. The 930 Porsche, Pontiac Sunfire turbo, Sprint turbo GT, and the one I owned for years was a Volvo 240 turbo. Dig up stuff online about Smokey Yunich and his Hot Air Engine.

Smokey in 1978 took a low pressure turbo (1 to 4 pounds of boost) and ran it through a 4 cylinder, the 2.5 litre Iron Duke GM four. The air was pre heated before the turbo and after the turbo, through water and exhaust heat exchangers. The car was feed through a conventional carburator and the intake charge was at a temperature of 460 degrees before it entered the engine. The engine produced 200 plus horse power and gave 50 mpg.

The engine was carburated and was said to be terribly cold blooded until the intake charge was hot enough, but this was back in the late 70's early 80's. Now with fuel injection and onboard computers I think it should be much more manageable to run such a "On the Edge" engine.

A basic turbo does a number of beneficial things. It gives the engine back pressure so the fuel charge isnt blown out of engine. It lightly reduces mechanical vacuum pumping due to pressurization of the intake. It also heats the incoming air temp to around 175 degrees, improving vaporization, this is why people add intercoolers for performance and to reduce detonation.

My turbo Volvo was 3000 pounds, had the aerodynamics of a refridgerator, and gave me 24 to 26 average mpg commuting in San Francisco. Mine had the 2.1 four, the non turbo got the 2.3 litre four. Now just in a performance related spectrum, I could keep up with a V8 Mustang and a 300Z, I would say side by side performance if we were on a track.

Now lets take all this fire and speed and put it in a 750 four or 1 litre, maybe a max of a 1.3 litre four. I envision 55 to 70 mpg with all the power of todays 2 litre engines and meeting all the smog requirments.

I think the future will involve turbo's in every aspect of engine developement. When I get my next car I definetly want to put together a turbo package for it. Engineering efficiency into what was considered a performance only application of technology.

You should read this:

The Story of Turbo'ing a Hybrid Prius, Part 1
https://autospeed.com/cms/A_2658/article.html
part 2
https://autospeed.com/cms/A_2659/article.html
part 3
https://autospeed.com/cms/A_2660/article.html
part 4
https://autospeed.com/cms/A_2661/article.html
part 5
https://autospeed.com/cms/A_2664/article.html

They actually improved fuel economy by reducing the RPM at high load.

Nissan also made a superturbo. I think that is among one of the best ideas!
https://en.wikipedia.org/wiki/Nissan_MA_MA09ERT

Saab has been adding low-pressure turbos for years. I have a the 2.3L LPT engine, 185hp in a ~3700lb wagon. EPA rating is 21/30. I usually average 25mpg in suburban driving, and 40mpg very carefully on the highway.

as I slowly creep toward the 30mpg mark the turbo Idea looks better and better. I want ideally to see 40 mpg in this car I really don't need much more power, just enough to make hills less stressful.

I believe my wife's car (ladybug Maxx on my garage) has the same tranny as well - and even with her driving style we get easily over 30, can get 38-39 highway. We got 38+ MPG across Nebraska at an average of 85 MPH some time back - ALL highway miles, and let me tell you with the tank full to the top of the fuel neck with over 17 gallons in it, it's just awesome to get over 650 miles on a tank.

The Maxx comes with a 3.9L SS option but I can tell you that her V6 has zero problem on the hills, and this is an automatic car.

I think GM intentionally sabotaged the 4 cyl so that people wanted the V6. this thing has a 4.39:1 diff and tall gears in 2nd 3rd and 4th the final drive ratio in this is 3.91 so it's a huge jump from 1:1 and with a little more power that jump probably won't matter.

From what I was told, which makes sense, is that a small turbo which hits full boost at 2500-3000k will give you better mileage, cause of the air forced into the motor with the turbocharger. It was explained to me, but can't remeber it exactly. I don't want to say something that isn't ture

But what I've noticed, since I have a turbo on my car. Is that a lot of things cancel out the effecientcy of the turbo to not even having one.

Extra weight: of the turbo, intercooler, charge pipes, etc.
Premium gas: I don't use it cause I don't even rev my car up enough to actually build booost.
Sythentic oil: is better, cause it has a higher boiling, which makes it less susceptable to coking the the turbos center cartridge. I don't run synthetic though....
not really having the ability to do EOC'ing. which get me to another thing. having the leave the car running for a minute or so before tuning off the engine. synthetic oil and water cooling the turbo help this, but at what cost.
though water cooling could eliminate the need to "turbo time" the turbo before you shut off the car and still allow you to EOC. plus a synthetic is more costly, but it supposedly gives your better mileage anyway.
Plus the cost to put in a turbo and tune it is probably somewhere in the range of 6 months( actually way more then that) gas, at least. then troubleshooting it and tuning it.


sorry, I'm rambling. I've been into mileage for awhile now and site is really motiving me,

I agree on all your points. I must add I don't EOC due to the power steering basically making it impossible to turn. I have two or three turbos to choose from: T25 off of a dsm, an IHI from a Tbird, or a T3 off of a Chrysler. I am leaning toward the Tbird turbo due to the availibility of T3 flanged manifolds and the small size of the turbine housing. on the 8 valve 2.3l Tbird it is at full boost by 2000 rpm so I figure on my 16 valve 2.2l it should spool in similar time.

wow, I wrote that post bad, I'll go back and clean it up.

but a t3 is way bigger then a 14b or IHI. I have an IHI on my civic and that things tiny. I don't what rpm it hits full boost, cause I've yet to fully tune and diagnose all my problems with hitting full boost.

Not all T3's are big. The biggest T3 is the Super60, which flows about 35lbs/min. The smallest is the 40trim which flows about 20lbs/min. See
www.64.225.76.178/main.htm
Turbo Tbirds came with T3 turbos, not the T3/T4 hybrids that are popular in the import tuner scene, which can put out over 500hp. I used to have a T3/T4 50 trim on my other car- it was big.

A Mitsu 14b from the 1990-1994 DSM is rated at 28lbs/min. A T25 from the 1995-1999 DSM is rated at about 25lbs/min. I upgraded the turbo on my Laser from the stock 14b to a 16G, which is rated at about 38lbs/min. I think the bigger exhaust side of the 16g lets the motor breath better even when not making boost.

VFAQ.com is a great site for turbo DSM's, here's some related info:

"What is the maximum output from the various turbos?

Max output from various turbos
TD05-14B (stock 1st gen) 275-300hp @ 21 psi
TD05-16G (small) 345-365hp @ 22 psi
TD06-16G (large) 365-385hp @ 22 psi
TD06-20G 430-450hp @ 22 psi
T25 (stock 2nd gen) 235-250hp @ ?? psi
T3 (super 60)/T2.5 hybrid 265-280hp @ ?? psi
T3 (super 60)/T2.8 hybrid 270-320hp @ ?? psi"

and more info about some popular DSM turbo upgrades: www.vfaq.com/mods/Turbo-compare.html


Water cooled turbos don't need to a turbo timer unless you like to shut the motor off right after a hard run at WOT. Mitsu turbos are water (engine coolant) cooled. I've been EOCing off the freeway for over a year. I'll see EGT's around 820*C while cruising on the freeway, ECT around 206-209*F, everything is hot, and I'll shut the motor off and coast, sometimes stopping at a red light before restarting the car. Yes, synthetic oil is needed, plus my car came with an oil cooler, so the turbo has protection from heat damage. I'm glad I have a OEM reliable turbo system.

The IHI is a VC32ax also known as the RHB52 it came off of a Thunderbird Turbo Coupe Your IHI probably was a VJ11 and yes they are tiny. My T3 is a .42/48 the DSM is a 14b. I figure any of these will work for what I want.

Autospeed just released this article called Turbo'd for Fuel Economy... The answer to your question is yes!

the key in that article is turbo matched to the engine. people put way bigger turbos in cars that aren't effecient as fas as fuel econmy goes.