Atkinson cycle and low octane fuels

if premium makes more power than regular, you would not be able to feel the difference. placebo

 

I really liked this video and part 2 on the Atkinson Cycle engine. Not sure if its a repeat, if so im sorry.

 

Hmmm - I think my '17 has MUCH more power than my '08 did!

 

same here (2011)

 

Good thread folks and interesting videos re: Atkinson Engine. So with a "self-cleaning engine" I can skip going to Chevron gas and just buy the cheap COSTCO stuff? Ran COSTCO gas through my 2002 3.4L and had to replace #3 & #6 injectors due to clogs at around 100K miles and a catalytic converter (maybe due to alcohol?). Switched over to Chevron and ran that engine over 250K without revisiting the issues. Another question, with our PNW winter blend (read alcohol) my mileage has gone down a couple of MPGs. Thinking about going to alcohol free unleaded which I run in my four stroke Honda OB and lawn mower. Thoughts on alcohol laden gas, i.e., issues with shortening the life of exhaust systems due to condensation and lower MPGs?

 

Just a curious question, but if they gained 42 more hp with half a litre less displacement compared to the previous engine, what would the hp and torque specs look like if they stayed with a 4 litre displacement?

 

Costco is a 'top tier' fuel.

http://www.toptiergas.com/licensedbrands/

 

My wife's Prius has had a few drinks of premium.....never an issue

 

Extrapolate.

What is the new HP/litre?

Assuming you could stay linear with additional displacement, then add 1/2 that for the extra 1/2 L to get you to 4.0.

 

The dual VVT-i 1GR

 

Here is my take. Turbo and specialty engines need premium. My GTI runs perfect on 91, 87 meh and can't use 85. The Taco does 85 fine but does better by brand. Shell gas reg unleaded 85 truck kicks arse. Averaging 23 mpg combined.

 

I feel the same with my 2017 Off road MT.
Did you notice increase in power in the lower RPM range (less than 3,500)?

 

to sum it up, what he is saying they took a 3.5 V6 and de-tuned it. if this video would have been playing in the dealer showroom when i bought my truck i would have walked. saving grace is the ECT button which i never have to push because i did the ECT mod.

 

New fuel emissions standards are great, it's a race to the bottom for auto manufacturers.

 

anyone who runs higher octane fuel than the engine is speced out to run is throwing away money. Octane is basically the fuels resistance to ignition during compression. If your engine is designed to run lower octane it will not get any benefit from a high octane fuel because it doesn't have the compression ratio needed to harness that additional energy, no added power, no boost in milage. Forced induction vehicles need it because the added air from a turbo or supercharger increase the compression ratio. If you run low octane fuel in a vehicle that requires high octane you will get pre-ignition/knocking and could cause serious permanent damage because the fuel is burning uncontrolled and at the incorrect time during the cycle. Atkins engines are even lower compression ratio but have a high expansion ratio and that's where they get some of their power back.

 

I noticed a knock in my 2017 sport TRD going up the hill to my house, non ect mode, running 87 octane, used 89 octane no knock, so is this good or bad for my engine ?

 

You might get a slight knock when accelerating or going up a hill with these engines. Check your owner's manual, it says that this behavior is normal and is nothing to worry about. Go back to 87 and see if it does it every single time you go up that hill. My guess is it won't.

 

I got 317hp/307ft-lbs torque with 4 litres displacement.

I know those probably aren't real world numbers if this were a 4L Atkinson, but makes you wonder if that would have helped sell the truck from a marketing standpoint (not that they need help selling it).

 

I can't argue with anything you're saying. However, the one possible advantage that premium may have over regular fuel are the additives. While all fuels are required to have a minimum requirement of detergents, most Top Tier premium fuels have detergent additives that go way beyond what you'll find in "Acme" brand regular fuel.

So, over the life of the engine, the fuel system, intake and valves may stay cleaner. For some people that's a plus and is not necessarily "throwing away money".

That said....I burn either Shell or BP 87 in my rig

 

And I'd like to add....the 2GR mill in the Taco is certainly designed to burn 87 just fine. But towing 5000 lbs on a 110' day....it certainly could hurt to have a tank of premium for a situation like that.

Will it net you more power? Probably not. But it will most likely keep the ECM from having to pull timing. So at least you won't be losing any power