Compression ratio?
 

What is the compression ratio for the Bosch 4.6 V8 (04 Discovery 2)?
I am curious about the supposed need for premium gas. Why?
I would think a slow revving, low oil pressure engine would not have high compression. That detonation from lower octane (87) would not be an issue?
Do these engines run poorly with anything below 91-93 octane?
Can anyone explain?
Thank you

After much searching, I found nothing.
As soon as I posted this question, multiple threads popped up explaining it.
No EGR valve.
Makes sense.
Sorry for a repetative question.

I believe it also has to do with how the computer is programmed regarding the fuel to air mix etc.

Be sure to use Top Tier premium as well, the cheap gas without additives will gunk up your injectors and you will lose performance and spend more money via less efficiency anyway.

This may help you understand the differences. IMO you should be running RON 98 minimum or 93 PON. IMO 87 PON is for parts cleaning or lawn mowers ;):)

https://www.etuners.gr/fuel/

Hey, Don't diss the lawn mower!! I only use 92 octane non ethanol in mine!!!

Thank you sir

I wouldn't put that 87 in anything I owned. I ran it the first few year I had my D2, because I was totally ignorant. I had issues with O2 sensors, coil packs, and since I have changed to premium I haven't had any issues with combustion. My cats went bad, but they were overdue anyway.

Static Compression ratio is only one variable that determines the octane requirements

the combustion chamber and piston shape is unaltered from 1960. Modern designs have shapes that turn more of the combustion to power rather than heat. Since these engines are less thermally efficient hot spots are more likely and high octane is required. It's also why a 3.9 has a giant 3 core brass radiator

According to Rave, its 9.35:1

I have never used 87, but mine is noticeably smoother and gets 1-2 additional MPG running 93 vs. 89

1-2 mpg is worth an extra .40 cents a gallon!
I've only put gas in this one 3 times, and only 93 octane.
Quality wise, the engines on these seem like junk compared to Japanese or U.S. vehicles. And part prices...
Someone please explain to me why I still like this thing so much!?