5.3 LS max compression

[lewy-d]

this is my first LS build. it is an aluminum Gen IV (LC9) 5.3. What do you think, know , feel is maximum static compression ratio with 93octane pump gas?
thanks for any comments, they'll be more LS questions coming.
Lewy

[David Redszus]

this is my first LS build. it is an aluminum Gen IV (LC9) 5.3. What do you think, know , feel is maximum static compression ratio with 93octane pump gas?
thanks for any comments, they'll be more LS questions coming.
Lewy

The fuel octane rating of pump gas will vary by month and geographic area per EPA mandate.

[lewy-d]

I thought it was reid vapor pressure that changed in response to summer/ winter blends?
Does that change octane?

[1980RS]

I know if several people running 5.3's and 6.0's that are in the 11 to 1 compression range with no detonation on 93 oct. IMO those engines with such a wide camshaft LCA will not suffer from detonation like SBC and BBC's do plus the combustion chamber is so much better on LS engines. Now if you decide to use a cam with a 108° LCA you may run into problems with detonation.

[Lizardracing]

Typical street engine at sea level is around 10:1 with iron heads and 11 or a little less with alloy heads.
This assumes details such as quench and chamber shape as well as a proper cam profiling are adhered too.

[David Redszus]

I thought it was reid vapor pressure that changed in response to summer/ winter blends?
Does that change octane?

Octane changes from state to state based mostly on elevation.
RVP and distillation curve temps change monthly by state.

Parameters such as SpG and Stoich are not regulated by the EPA and left up to the fuel producer.

[panic]

LCA and IVC not the same thing.

[MadBill]

Octane changes from state to state based mostly on elevation.

One of the axioms of the refinery business is "Never ship gasoline downhill." I once fueled up an '82 Oldsmobile in Flagstaff AZ (el.~7,000') and 3/4 of the way back to Phoenix (el. ~1,000') it started pinging...

[David Redszus]

Octane changes from state to state based mostly on elevation.

One of the axioms of the refinery business is "Never ship gasoline downhill." I once fueled up an '82 Oldsmobile in Flagstaff AZ (el.~7,000') and 3/4 of the way back to Phoenix (el. ~1,000') it started pinging...

When working with vintage cars, we have often noticed they were intentionally fueled on the rich side. This compromised fuel economy and very often power and throttle response. So, they were tuned for best performance and throttle response.

But those older cars did not compensate for air density changes due to altitude. When they were driven into the highlands they ran sloppy rich. When they were driven down to sea level they were much too lean for comfort. Even today, some engines built near Denver have problems in Florida.

"Never ship gasoline downhill" is very good advice. I wish I had thought of that phrase when I was in the fuel blending business.