Sunoco 260GT 100 Octane Fuel

[Rodney Dangerfield]

Uhh the health benefits for your engine from using premium is superior to regular lol.. continuously using top tier like shell v power nitro will extend the life of your engine and keep it very clean.. but you seem like the type of guy that'll just buy any brand gas for the cheapest price from any station.. sooo

The compression for my engine is 10.4:1 and the manual states it’s fine to run on 87 octane. I don’t hear pinging and it doesn’t gain anything appreciable so I’m not wasting my money. I’m also not wasting my money trying to modify an engine that quite frankly has little to no performance parts. Thanks btw for trying to shame me for using regular instead of shell v nitro power (there’s actually no Shell stations in my normal range of travel). This is my daily driver with 98% of the travel being highway.

 

[Cali Gen]

I agree mostly. 11.5:1 compression engines or similar compression used to run only on high octane race fuel not pump gas. I was only giving my opinion that the stock ECU parameters would not allow the 5.0 TAU engine to run at it best while using 100+ octane unless Hyundai has some secret aggressive fuel trim maps for 100+ octane locked into the ECU, however I am sure that the engine may run strong with 100+ octane but not at its full potential.

Worst case is that the stock ECU does not adjust the timing enough to properly burn the 100+ octane fuel and actually cause the engine to lose power by running too rich due to unburnt fuel.

My bet is that the stock engine would run great with about a 95 octane blend(91or 93 mixed with 100 octane). However, this all speculative.

Orrr soon hopefully the 5.0s will have tuning capabilities like the 3.8s now do. Mtmotorsports along with alphaspeed have just picked up a long block 5.0 tau(as of 2 days ago) and they will be working on cracking it. Then you can be tuned for the higher octane race fuels. Or e85 or meth injection.

 

[Cali Gen]

The compression for my engine is 10.4:1 and the manual states it’s fine to run on 87 octane. I don’t hear pinging and it doesn’t gain anything appreciable so I’m not wasting my money. I’m also not wasting my money trying to modify an engine that quite frankly has little to no performance parts. Thanks btw for trying to shame me for using regular instead of shell v nitro power (there’s actually no Shell stations in my normal range of travel). This is my daily driver with 98% of the travel being highway.

I dont care if you use regular it's your car and even if you use regular it's still better to use the top tiers like shell chevron Texaco etc.. But.. to say having a cleaner engine throughout its life from using premium gas which has more detergents/cleaning properties isn't appreciable is just funny to me. I mean at least before you suggest people "save" their money on cheap stuff try to explain the benefits that you have opted out of. Just because you dont see or feel anything happeneing doesnt actually translate to nothing happening. And I understand you dont have a shell but for instance I have a fuel rewards card through shell. It's free I'm a gold member I save 10 to 15c per gal on fill ups normally around 15gal at a time (you have to fill up 6 times in 3 months to maintain gold otherwise your silver and it's still 5c/gal discount) but it translates to me filling my car up with premium for just 0-5c more than the price of regular but with all the additional benefits. And sorry if If you took major offense to my comment It was just sarcasm(albeit hard to tell in text I shouldve added a winky face) there are people that like to pave paths( aka modding engines that have never previously been modded)and others who like reading the signs and following those before them. (Using regular 87 octane because the manual says it can be done)

 

[TinsleyC]

Using a higher octane fuel than your car requires is wasting money, as there's no gain or value in doing so. Sure, some cars can benefit slightly in performance or MPG from higher octanes, but it's marginal at best. Top Tier fuels have better additives for better cleaning and do have a benefit.

Better fuel "economy" means a better combination of mileage and costs. Gaining 2 miles per gallon is great, but if gaining that costs you 25% more in fuel costs, it's hardly "more economical".

 

[Cali Gen]

Using a higher octane fuel than your car requires is wasting money, as there's no gain or value in doing so. Sure, some cars can benefit slightly in performance or MPG from higher octanes, but it's marginal at best. Top Tier fuels have better additives for better cleaning and do have a benefit.

Better fuel "economy" means a better combination of mileage and costs. Gaining 2 miles per gallon is great, but if gaining that costs you 25% more in fuel costs, it's hardly "more economical".

If anyone is looking for performance benefits from using higher octane fuel whether its 89 91 93 95 100 meth injection etc you have to be tuned for it. Period. Even with VVT like you said marginal results at best otherwise.

 

[Suburbazine]

I'll chip in a few cents here:

Static compression ratio (SCR) was more important "in the olden days" of people thinking camshafts (haha 3/4 cams) and fuel injection were some sort of hocus pocus. Nowadays with modern VVT and DI, the rage is all about dynamic compression ratio (DCR). You can have your SCR for gauging the peak octane required (11.5:1 is perfectly happy with 91 octane naturally aspirated), but with VVT your DCR can be lower than your SCR. With lower DCR, you can run lower octane numbers with no issue...well, except you make less power by rule of less volume. On the flipside, you can get slightly higher DCR than SCR with carefully engineered timing giving you a pseudo-boost effect from the air ripple in the intake runner.

 

[TinsleyC]

...On the flipside, you can get slightly higher DCR than SCR with carefully engineered timing giving you a pseudo-boost effect from the air ripple in the intake runner.

Good stuff there. So, for a 3.8 to get any more power out of, say, 91 octane, you would need a slightly different tune?

 

[Suburbazine]

Good stuff there. So, for a 3.8 to get any more power out of, say, 91 octane, you would need a slightly different tune?

You could get a tiny amount of power out of a tune. The issue with the Lambda and Tau engines is that they're already highly optimized peak-power-wise. The bigger benefits would be in changing the powerband using the spark and cam adjustments. You might be able to squeeze 10HP more out of a tune and octane change.

To see real improvements you need to make sweeping design changes, to the intake/exhaust, hard parts or boost.

 

[Cali Gen]

Good stuff there. So, for a 3.8 to get any more power out of, say, 91 octane, you would need a slightly different tune?

Yes