Engines w/ knock sensors & octane rating

[DonR]

Not sure where this belongs, move if necessary.

I have a question about engines with knock sensors & gasoline octane rating.

Has anyone experimented with different octane ratings on engines with knock sensors? Would the higher octane rating stave off knock, thus allowing more advanced ignition timing?

The Wife's Hot Rod has an engine with equipped with knock sensors that will change the ignition timing if a knock is detected. It also has Displacement on Demand, I haven't got a clue as to what parameters are used to turn it on & off. It seems to run fine on 87, but I'm not sure I would notice a difference due to the electronics.

What are your thoughts?

Don

[rmay635703]

Originally Posted by DonR

Not sure where this belongs, move if necessary.

I have a question about engines with knock sensors & gasoline octane rating.

Has anyone experimented with different octane ratings on engines with knock sensors? Would the higher octane rating stave off knock, thus allowing more advanced ignition timing?

Don

Yes but on my cobalt which is over 10:1 it still swings out to 50 degrees anyway. I do seem to get better FE on higher octane.

[oil pan 4]

To track this I say you need some instrumentation. Something that will show ignition timing while you are on the road. Set a base line and try to test different octane gas under the base line conditions.

The 09 G8 has the base engine I want to use in my next build. A 12:1 compression LS3 stroked to 6.7L. I am trying to learn as much as I can about its DOD, VVT systems before I start the build.
I will use VVT, have a couple different plans on how to control it.
Not sure about DoD yet. I would like to use it but not sure how.

[99LeCouch]

I'm going to find out in a few tanks. My Cruze has a turbo engine that's okay to run on 87. Reports say that it does best on 91 octane or higher. All the stations around me have 93 octane, so I'll use that for a few tanks to track my FE average. This engine is dependent on its knock sensors to keep from grenading, so it'll see less knock on 93 than 87. Whether that impacts FE enough to be detectable is up in the air for now.

My SGII will show timing and knock. Good enough for the tuna.

[DonR]

Originally Posted by oil pan 4

To track this I say you need some instrumentation. Something that will show ignition timing while you are on the road. Set a base line and try to test different octane gas under the base line conditions.

The 09 G8 has the base engine I want to use in my next build. A 12:1 compression LS3 stroked to 6.7L. I am trying to learn as much as I can about its DOD, VVT systems before I start the build.
I will use VVT, have a couple different plans on how to control it.
Not sure about DoD yet. I would like to use it but not sure how.

The LS3 doesn't have the DoD. The L76 does. Basically it is an LS3 with a different cam that won't break the DoD lifters.

[oil pan 4]

The stock LS3 or L76 doesn't have what I want, that is why I am building my own.
I like the stock LS3 heads, stock LS3 intake manifold, stock block and truck VVT; thats about it. I am looking at using mostly factory parts.
So its pretty much a high compression LS3 with VVT and more cubic inches.


Today I was looking at some stuff and figure DoD wont work very well with what I would like to do.