How can a high compression Saturn motor run on regular?!?

Question

My friend's uncle recently showed us his new Saturn Vue, and he said it has a 3.6 DOHC V6 with 11.6-1 compression. But it runs on 87 octane regular! How in the world is that possible? In the muscle car days, that high of compression would require about 100 octane race gas.

Do engine computers and special cam profiles make it possible? I'm completely puzzled by this and I have no idea how that could work. It doesn't seem like there's any way to get around the fact that the fuel is improperly matched to the high compression.

Answer 1

It can't. It would knock itself to pieces.

"Muscle Car" days were the days of adding lead to raise the "octane rating" artificially. Aircraft fuels are still leaded.  

Answer 2

i believe the engine is actually 10.2 and not 11.6.

my honda s2000 with factory forged internals runs at 11.0:1 and i use 93 gas  but i can use 87 aslong as i am light on the accel.

from wiki on the engine thats in the vue's 3.6l engine:

The 3.6 L (3564 cc) LY7 version was introduced in the 2004 Cadillac CTS sedan. It has a 10.2:1 compression ratio and produces 255 hp (190 kW) at 6200 rpm and 252 lb·ft (342 N·m) at 3100 rpm. The bore is 3.70 in (94.0 mm) and the stroke is 3.37 in (85.6 mm). In some applications, including the Buick LaCrosse and Holden Commodore, the LY7 has an output of 235 to 262 hp (175 to 195 kW) and 225 to 251 ft·lbf (305 to 340 N·m) depending on the vehicle induction and exhaust system designs. Selected models also include variable intake. The engine weighs 370 lb (170 kg) as installed.

unless he has this:

The 3.6 L (3564 cc) LCS is derived from the direct-injected LLT for use in hybrids, using the two-mode system [7]. Differences from the LLT include a slightly lower compression ratio, 11.3:1, and lower power and torque peaks. It will debut in the 2009 Saturn Vue Hybrid, where it will make 262 hp (195 kW) at 6100 rpm and 250 lb·ft (339 N·m) of torque at 4800 rpm. [8]

Applications:

2009 Saturn Vue Hybrid

The 3.6 L (3564 cc) LCS is derived from the direct-injected LLT for use in hybrids, using the two-mode system [7]. Differences from the LLT include a slightly lower compression ratio, 11.3:1, and lower power and torque peaks. It will debut in the 2009 Saturn Vue Hybrid, where it will make 262 hp (195 kW) at 6100 rpm and 250 lb·ft (339 N·m) of torque at 4800 rpm. [8]

newer cars unlike the old muscle cars has advanced computer controled fuel and timing systems that will r****d or advance timing acordding to engine needs.  with lower octance the systems will r****d timing acorrdinly but will result in a lower hp at the wheel and increase the chances of detonation/ engine knocking.

so in the end it can be done just might not be as safe.

http://www.topspeed.com/cars/audi/2006-a...

The V10 in the new Audi S8 uses FSI petrol direct injection. This permits a high compression ratio of 12.5:1 and a correspondingly more effective combustion process based on a lambda value of 1.

my mom has this car.

yes a prodution car can have high compression ratio.

Answer 3

its more like 9.6 -1 compression

Answer 4

It's not that high, I think its around 10:1 on the Vue redline, depending on the year.

But the higher compression ratios are possible on new cars with pump gas because of the magic of knock sensors, they adjust the computer outputs for timing to help prevent detonation.  

Answer 5

Your friends uncle lied to you.  No mass production engine on this planet has 11.6-1 compression.  Thats unheard of!!