Gas for a turbo engine.

well...
1) I have no personal experience with the modern turbo's
2) I do not know how far the electronics/anti-knock will actually retard the timing
3) I do not know what level of psi these turbos are gated

But, outside of any specifics, just general rule....given I do have experience being a turbo builder in the 70/80's...

A turbo, like any positive displacement blower, effectively raises compression ratio.
Generically, the higher any given compression ratio, the higher the octane required.
Therefore, in low to moderate boosted conditions, you can very easily risk using lower than recommended octane as you are effectively keeping yourself in the lower compression range.
If however you are using your engine in a high load condition, where your turbo will be operating at max output, the question becomes how far retarded will the timing go to safegaurd your engine from knocking? But for which you will then risk overheating conditions from the high load/retarded timing condition, as well as loss of power, negating the benefits of having the turbo in the first place. The requirement for premium gas is NOT relevant to low boost conditions, but it DOES become relevant once under high boost.

So, as with any choice, there ARE relative risk trade offs that you will face. Saving some $$ will carry some potential risk depending on how you use your engine.

When it comes to any boosted motors I simply feel that the extra few bucks per fill is cheap insurance. A few years back a bunch of us were running road course and drags in Vegas. A friend of mine from Tenn running 700+ rwhp in his GT500 was detonating a bit on the back straight. I suggested he drop $50-60 on some race fuel to balance out the 91 octane crap he was running. He says, "it's not too bad"

Couple hours later halfway down the strip KABOOM and he windows the block. He was stranded in Vegas, had to fly home, Car had to be shipped home, $15,000 motor job..... and when he walked by me that night he says......."guess I should've put some race fuel in it huh?" Didn't have the heart to say anything but "Sorry Bro."

I realize we're comparing apples to oranges on the boost levels but boosted is boosted.

I'm not particularly caring for the move towards boosted engines. I don't see the point. Sure you can have V-8 power from a small block V-6. But only if you push down on the throttle and work the engine. If you are working the engine, it's burning more fuel. If you are burning more fuel, you are not getting your V-6 fuel economy. Are you?
Same applies to a small I-4. It can make V-6 power, but you have to push it, even a little wastes your fuel savings.
Don't get me wrong. If you seldom call on the boost, there is no loss. Just economy. That kinda defeats the point, doesn't it?
Then you add in premium fuel, at a higher cost all the time. I'm thinking the economy thing is a bit of a wash at best case scenario.
Buy the regular while you are pedalling lightly, you can make a case. Occassional use of boost should be no issue to engine longevity. I can't imagine an Edge doing laps at Vegas.... You don't drive and Edge, do you Paul? y2:

BMarsh said:

I am thinking of buying a 2013 Ford Fusion with the 2.0 ltr. turbo engine. The "recommended" fuel is premium but in my area premium fuel is 40 to 50 cents more per gallon. I have looked at various web sites to find out if I will damage the engine if I use regular gas and it seems that as long as the manufacturer says recommended and not required, the engine will not be hurt, mostly because of the anti-knock sensor, which will de-tune the engine somewhat. I can live with a little less performance to save 50 cents a gallon. Any opinions out there? Thanks.

Click to expand...

I see from your Profile you are 69 yrs. old.

We are of the same age group so I think I can give you an honest "Matter-of-Fact" reply here.

Don't buy a Turbo Engined Car/Truck etc. if Gas Cost is that much of a concern.
I know a few Guys that actually purchased Corvettes that cost like $70,000.00 Dollars and (Refuse) to run Premium gas.
I speak here with you the truth on this.
My Brother is one of those Vette guys.

Seriously if there are options for engines like a 4-Cylinder or certainly a 6 cylinder buy one of those.

I could type here for awhile on why not to burn cheaper fuel in the Turbo Engined one but here is the bottom line.
You will NOT get the Gas Mileage or the Performance from that car burning cheaper fuel.
It will use more gas as the Turbo Cannot do what it was Designed to do.
The electronics are going to back off the Timing and I would certainly think the Boost-Pressure.
You would be paying for something that you would not be getting the Benefit of.

Note* I'm not in anyway an Expert on this subject I am giving you my Honest (Opinion).

And before I Hit the Button to Post this one last comment to another Adult.
I don"t Post to others to come across as a No-it-All or to belittle another person.
This Post and my comments are meant as information and hopefully to Help you in your final decision.

Good-Luck,
Terry

Premium is my choice for all boosted engines. I have had several boosted gas engines and have always used premium for performance and detonation reasons. Then again all of my cars have had boost controllers and have been tuned for 93 oct. The edge and fusions alike have been tuned and programmed to run on any grade of gas. Ford KNOWS that people are stupid... and when I say stupid i mean not informed about turbo gas engines. They have safe guarded against poor fuel choices but not other forms of turbo abuse such as boosting and turning the car off without letting the car idle and the turbo spool down. Also against poor oil choices. Going with the boosted 2.0 vs the n/a motors in the fusion is way more fun. The mileage is not there as soon as you get over 65mph on the freeway. We drove to illinois from texas in the ecoboost 2.0. The car would get around 38mpg at 65 but 22 at 75. So there you go.

Personnally in any of my vehicles that the manufacture bulit with need for 91 or higher octane or I have been modifed to be required to run higher octane... I suck it up and pay the higher fuel bill... I really worry about cracked rings or other internal engine failures that was caused by running cheaper gas and it can happen, besides the money I would save would not pay the repair bill for a new engine.... I carry a bottle of octane boost in each car that requires higher octane just in case I get in position where there isn't any 91 or higher octane.... I am of a dir=fferant oinion from David about boosted enegines... My Lighning would be just another F150 with out the supercharger... and My Brothers Ecoboost F150 got great mileage when I drove it (almost 25MPG on high way on a 4X4 extended cab truck).... Then when pulling my little car trailer with car on it it pulled almost as well as my old F250 super duty..... and then there is the performance!! it rocks!! Compaired to the 5.0 F150 I drove... when you hit passing gear it just keeps pulling and pulling... I am of the opinion that the this isn't late 70's early eighties the manufactures have really got this new stuff figured out.... I wish you good luck in your purchase....

I agree with David about the 3.5L V-6 as I actually prefer a N/A engine over a turbo. Unfortunately, the fusion offers engine choices of a N/A 2.5 ltr. I-4 rated at 175 h.p., 175 lb. ft. of torque at 4,500 r.p.m.; a 1.6 ltr. turbo rated at 178 h.p. and 184 lb. ft. of torque although the torque peak is low at 2,500 r.p.m. and the 2.0 ltr. turbo rated at 240 h.p. and 270 lb. ft. of torque at 3,000 r.p.m. The 2.5 engine just doesn't cut it with the torque peak being way up at 4,500 r.p.m. For what it's worth I had a 1989 Dodge Daytona 2.5 ltr. turbo that I only used regular gas in. I don't recall what gas Dodge recommended but I never had a problem with that engine and remember, it was a Dodge, not a highly recommended car at that time.
I am very easy on cars....I've never had the Bullitt over 3,500 r.p.m. as that's fast enough for me.