Prius owners- fuel grade?

I am contemplating buying a Prius, and stopped by the dealer yesterday to pick up a brochure. The brochure says the engine compression ratio is a whopping 13:1. That seems a bit high to run well on regular, even with a knock sensor. The brochure does not mention what grade of fuel is required. What DOES the Prius take?

Reply to
Don Stauffer
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  1. Do I need to use special gasoline? No. Prius can be fueled with regular 87-octane gasoline, saving you money at the pump.

Even though Toyota explicitly says 87 octane is OK, the octane-lovers will be coming out of the woodwork to say they know better. It's your car and your wallet, do whatever you want.

BTW compression ratio is not a universal figure of merit in figuring out what octane is required. It really is best to read and follow the owner's manual recommendations.

Reply to
Mark Olson

The Prius engine gets away with running regular fuel because its a fixed-RPM engine (well, it operates at several discrete but fixed RPMs actually). TAt any rate, it doesn't have to operate over a range of RPMs and randomly varying load so it can run a very high static CR. It also uses a modified cycle where the expansion and compression strokes are not the same length (the crankshaft is offset relative to the cylinder bore).

In short- check your suppositions at the door where octane is concerned.

Reply to
Steve

Look on the web for, Toyota Prius fuel requirment

I think I saw an article which said regular 87 octane or higher. cuhulin

Reply to
cuhulin

Or, you could go directly to Toyota's web site and trust that their answer to the octane question (87) was the correct one...

Reply to
Mark Olson

Toyota is building a new Prius factory nearTupelo, Elvis the Pelvis old home town.Don't get all shook up.Email Elvis, he can tell you what kind of gas to use.

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cuhulin

Reply to
cuhulin

Yup. Every other fill-up I vary between 89 and 93, maintaining 91 octane. I have no fuel problems at all, even in three 20 year old cars.

Reply to
Hachiroku $B%O%A%m%/(B

Boy, I missed that. I looked for it and didn't find it. Proves I am really getting old.

Reply to
Don Stauffer

How does that work,Steve.. Doesnt that generate some undesirable side forces?

Reply to
HLS

Actually the hybrid engines operate under similar conditions to the test engines that are used to measure octane. The test engine are also designed to maintain very constant rpm and engine load. Pretty much any gasoline engine can be made to operate more efficiently by increasing compression if you also have a way to hold engine loads and RPM to within certain limits.

-jim

Reply to
jim

I'm not really up on exactly how it works, although I understand that its an approximation of the Atkinson cycle where the compression and expansion strokes are different. Its different than the Miller cycle where forced induction is used to manage a deliberate reversion of compression back into the intake manifold. It surely does change cylinder wall forces, and probably doesn't do the inherent balance any good either. However from what I've read, it actually *reduces* the most damaging frictional force, which is the side-thrust on the cylinder wall during the expansion phase of the cycle. It does that by likely increasing the side thrust during the compression phase, but the magnitude of that force is always lower than the expansion phase force so its a net friction reduction.

You can do a lot of things when you only have to have the engine survive at a couple of fixed speeds and loadings, rather than everything from idle to redline at every possible loading.

Reply to
Steve

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