Random question

"HammerheadFistpunch" (hammerheadfistpunch) 03/14/2014 at 12:20 • Filed to: None

0

35

I'll make it short and sweet. What engines can you think of that make more power with Premium than regular, but are approved to and run fine on regular?

The question brought up by osiris reminds me how often people ask if putting premium in their car or truck is a good idea...the answer is almost always "no, not unless it requires it" but there are some engines out there that DO benefit from premium and will produce more power with premium fuel but will run just dandy on regular.

The Toyota GR engines used in the Tacoma, 4runner and others is a good example, it makes more horse power and more torque with premium(+3 hp and 12 ft-lbs on the Tacoma, +31 hp +19 ft-lbs on the 4runner), , but the timing width is sufficient that its approved to run on regular 100% of the time. So, what other engines is the answer to the question: should I use premium? actually a maybe.

jariten1781 > HammerheadFistpunch 03/14/2014 at 12:25

0

A lot of the small turbo engines do it. Fiesta ST off the top of my head.

dogisbadob > HammerheadFistpunch 03/14/2014 at 12:26

0

03+ Accord V6 manual

Hyundai's higher engines (the V6 and turbo 4 from the Genesis come to mind, and Hyundai actually publishes separate figures for both grades)

You can tell a Finn but you can't tell him much > jariten1781 03/14/2014 at 12:26

0

I think all the Ford EB's do. The 3.5 is the same.

Nibbles > HammerheadFistpunch 03/14/2014 at 12:30

0

Saab engines, pretty much their entire line since the late 70s (with APC). The early ones were rudimentary, but included mapping for different octane levels. They would run on regular but limit boost to 7.5 PSI. That's also why many Volvo guys like to adapt the APC system for their turbo bricks - for being rudimentary, it was a pretty robust system

HammerheadFistpunch > You can tell a Finn but you can't tell him much 03/14/2014 at 12:31

0

Do they actually advertise a power increase? I just assumed that they calibrated it for regular and left it alone.

oldirtybootz > HammerheadFistpunch 03/14/2014 at 12:32

0

I'm not sure how much power I lose, but my car makes its 160hp on premium though I can use regular in it.

McLarry > HammerheadFistpunch 03/14/2014 at 12:32

0

My impression has always been that the problem with putting premium fuel into a car that expects regular fuel is that it'll throw off the timing due to the change in flash point...seems to me any car with an ecu that can adjust ignition timings and such on the fly should be able to benefit from premium fuel.

Tom McParland > HammerheadFistpunch 03/14/2014 at 12:32

0

I don't know about more power but the 3.5 V6 in our Sienna is optimized for premium but can run on regular. I always but the good stuff in.

crowmolly > HammerheadFistpunch 03/14/2014 at 12:33

0

The GR is an exception to the rule. Lexus rates it as needing 91 to hit their numbers.

You can tell a Finn but you can't tell him much > HammerheadFistpunch 03/14/2014 at 12:36

0

I'm about 99% that they advertise MOAR POWAH if you run premium.

HammerheadFistpunch > McLarry 03/14/2014 at 12:36

0

that's only true if the compression ratio, combustion chamber design and a few other factors are such that the engine is tuning down for regular. Most cars are built with regular in mind and don't have the ability to tune up. i.e. if your compression ratio with optimal valve timing would require premium but you can adjust timing such that you don't knock if regular is used then you will see a gain using premium but if your compression ratio is such that with optimal valve timing you don't require premium, you will see no gain and even some loss using premium (harder to ignite for no benefit= wasted energy)

McLarry > HammerheadFistpunch 03/14/2014 at 12:38

0

Gotcha, thanks for the clarification

HammerheadFistpunch > Tom McParland 03/14/2014 at 12:38

0

The Sienna is a GR engine as in the example above. Given its a Dual VVT-i motor, I would suspect you get about 15 hp and 10 ft-lbs using the good stuff, but it will run like a champ on the cheap stuff.

HammerheadFistpunch > crowmolly 03/14/2014 at 12:39

0

yes, its requires 91 to hit their numbers, but it does run fine on regular.

Zoom > HammerheadFistpunch 03/14/2014 at 12:40

0

Since the combustion event is much more unpredictable in any forced air configuration, that is one of the obvious answers.

Secondly, I would think anything above about 10.0/1 CR, ping is monitored closely. Any detonation would require immediate timing action. Correct me if I'm wrong, but hp took a sizeable jump in the last ten years, after engineers found ways to use a decent cr, along with agressive control of detonation (cooling aluminum heads, and immediate timing corrections) So, I would think any engine built in the last ten years or so that has decent hp, also would benefit from octane.

Party-vi > HammerheadFistpunch 03/14/2014 at 12:41

0

The V8 engine in the Hyundai Genesis. It was apparently rated at 385HP on premium and 378HP on regular.

I think we're looking at this the wrong way. It's not that premium gas increases the output of an engine, it's that regular gas decreases output. There is not more explosive force in a gallon of 93 octane gas than there is in a gallon of 87 octane gas.

Tom McParland > HammerheadFistpunch 03/14/2014 at 12:41

0

I did not know that was the engine code...cool! I will stick with the extra horse power. :)

HammerheadFistpunch > Zoom 03/14/2014 at 12:43

0

The bump in power due to cooling and higher CR's is mainly due to the increased cooling charge effect of direct injection. Direct injected, high CR dual variable vale timing engines are pretty flexible, but It would depend on how the engine and ECU mapping was set up as to whether or not it would see gains, or just run fine on either octane.

HammerheadFistpunch > Tom McParland 03/14/2014 at 12:45

0

Depending on the conditions, it may or may not be worth it. In the cold for example, running regular would probably net you the same gains as premium but as a rule for more horsepower generally...I knew I could count on you.

crowmolly > HammerheadFistpunch 03/14/2014 at 12:47

0

I think it may be kind of a loaded question, though. There are premium-only cars that will adjust to regular fuel by pulling a lot of timing and have no ill effects other than cut power. Just nobody dyno'd them to see how much.

Zoom > HammerheadFistpunch 03/14/2014 at 12:48

0

Agreed. I was thinking Vortec II and the early new Hemi. These engines suddenly jumped 100 hp, the result of higher cr from cooler cylinder heads, and more accurate timing control.

DI will also allow lower octane fuel with decent cr, but you can bet there still is agressive detonation monitoring....

Rico > HammerheadFistpunch 03/14/2014 at 12:48

0

Not more power but my family's CRV gets better gas mileage with premium than regular. I don't have any other data to back it up other than less frequent fill ups.

Tom McParland > HammerheadFistpunch 03/14/2014 at 12:48

0

In terms of longevity do you think it matters much? If the engine is optimized for Premium do you think it will effect the wear?

HammerheadFistpunch > crowmolly 03/14/2014 at 12:49

0

perhaps. I guess the question was to find engines that are dual rated like the Toyota that show a measurable reason to use premium.

Also, A great many engines rated for 91 simply WONT run regular, so its not like you can say in a blanket statement that if you have a modern engine that asks for premium, running regular is probably fine too.

HammerheadFistpunch > Rico 03/14/2014 at 12:51

1

I've heard of that as well. Not sure i can explain it, but as long as the increase cost of fuel still plays out in the cost per mile equation, then go for it.

HammerheadFistpunch > Tom McParland 03/14/2014 at 12:53

0

nope. They are rated for both octanes, Toyota recommends using premium in GR in "demanding applications; such as heavy loads, towing or high elevations". But if you are just cruisin around town, there will be no ill effects. There really wont be any ill effects in "demanding applications" either, but you will definitely be down on power.

HammerheadFistpunch > Rico 03/14/2014 at 12:58

1

I will add that using name brand gasoline versus discount gas is a proven way to increase mileage as well, as long as you aren't cheaping out on gas. As another word of caution on cheap gas...don't do it, modern injectors are sensitive to clogging and I've had numerous problems with cheap gas and injectors from previous owners of the cars I've bought. The up front savings aren't worth new injectors in the long run.

Rico > HammerheadFistpunch 03/14/2014 at 13:04

0

Yeah I try to stick with the big brands. Someday I'll purchase a BT OBD dongle and really see what the mileage difference is on the CRV, but I recall when the car had a tune up with new sparkplugs, tire rotations etc, we were using regular still and didn't think twice.

When a family friend who has a similar model told us they use premium and it got them better fuel economy we switched. It took about 3 fill ups or so before we started to really see the difference. Where we'd typically be at 1/4 of a tank after 2 weeks we were instead at 1/2 and it's been consistent ever since.

HammerheadFistpunch > Rico 03/14/2014 at 13:08

1

There are some that say the additional detergents in the premium fuels matter, others say its the lower amount of ethanol, and others still have different ideas all together. Either way, as long as its paying dividends in the cost per mile, keep it up.

crowmolly > HammerheadFistpunch 03/14/2014 at 13:19

0

Yeah, I understand your question, I'm just wondering if "adjust the tune up" is just stemming from the way they are presenting the data. It's either a Toyota engine that can tune up vs a Lexus engine that can tune down. I know some of the Caddy engines that required premium can run just fine on regular as an example- just with less power. Rated at 300hp or so on premium. I couldn't tell you the actual change though.

There are plenty of engines that run like flat shit on regular or won't run at all without pinging, no argument there.

jariten1781 > HammerheadFistpunch 03/14/2014 at 13:21

0

Depends where you look. In the US the advertised power figure on the 1.6 ecoboost in the FiST is 197 HP. That is with overboost (21 psi for 10 seconds in 3rd gear and above) AND 91 AKI. In Europe the advertised 178 HP which is without overboost (16 psi in gears 1 and 2 or if you are WOT for more than 10 seconds in higher gears) on 91 RON.

It's underrated in either case though.

HammerheadFistpunch > crowmolly 03/14/2014 at 13:22

0

"It's either a Toyota engine that can tune up vs a Lexus engine that can tune down."

its both, just depends on if you are Lexus buyer dumb, or Toyota buyer dumb.

Its the EXACT same engine in both vehicles (most of the time), just with different badges

HammerheadFistpunch > jariten1781 03/14/2014 at 13:24

0

Great explanation, and I think you are dead right on the 178 vs 197, I think most of the time you are getting ~180, the overboost is the only place you are getting the rated power and only with 91 r+m/2 (we don't use AKI in the US)

jariten1781 > HammerheadFistpunch 03/14/2014 at 15:06

0

AKI is r+m/2, no?

Anyhow, there's a data stream you can pull with a Cobb Accessport that gives you a general idea of what power map you're getting. I don't recall exactly what it's called, but its value ranges from -1 to 1. -1 is the full power map and is generally gotten with 91 though some folks on winter blend 91 were getting -.8 to -.5 meaning they were having power pulled. Folks on 93 were sitting comfortable at -1 all winter. On 87 it was right around 0 with a few reports of it hitting .1 to .2. Supposedly if the value reaches 1 the car goes to limp mode, but I haven't heard of that happening to anyone yet.

The engine management on these cars is getting quite involved.

NaturallyAspirated > HammerheadFistpunch 03/14/2014 at 15:58

0

The 3.0l and 3.2l Yamaha v6 engines used in the '89-'95 Ford Taurus SHOs run fine on regular, but get better mileage on high octane. No extra power, because once the secondaries open, the ECU can't properly read the knock sensor, so it goes to the safe fuel map.