This is what I was looking for earlier and put up the V6 instead. This is on a GM website. Is it just a mistake?

http://www.gmbuypower.com/pages/submodelPerformance/2008_Pontiac_G8+Sedan.jsp;jsessionid=6143E285A28BF 32A96B560FF705B90C6?userType=GMSUPPLR&partnerId=510023#pa_2

Engine: 6.0L V8 aluminum, with Active Fuel Management, 355-hp and 395 lb.-ft. of torque (standard on GT Sedan models)

Actually, the important thing is with a little tuning and a couple of bolt-ons, the G8 will be well north of 400HP. :driving:

SAE = 361 hp. All the others were guesses until the official numbers came out.

Yeah, I noticed that earlier. It's 6hp too low and 10lb-ft too high.

Yeah, I noticed that earlier. It's 6hp too low and 10lb-ft too high.

Did not notice that the torque is higher. I will take mine that way, more torque, little less hp would be fine!

I just wonder if SAE testing revealed these new #s.

I'd like to know if the 361 is on regular or premium fuel, too. From what I'm hearing about stomping the R/Ts, these might be 361 on regular and more on premium. If the car is sold as a regular fuel car, don't the EPA and stated engine stats have to be with the advertised fuel?

I'd like to know if the 361 is on regular or premium fuel, too. From what I'm hearing about stomping the R/Ts, these might be 361 on regular and more on premium. If the car is sold as a regular fuel car, don't the EPA and stated engine stats have to be with the advertised fuel?


I believe the first member to get his here says the manual says regular.

I'd like to know if the 361 is on regular or premium fuel, too. From what I'm hearing about stomping the R/Ts, these might be 361 on regular and more on premium. If the car is sold as a regular fuel car, don't the EPA and stated engine stats have to be with the advertised fuel?

With a tune you will gain more than 361 hp with premium. Other wise 361 hp is max with any grade.

With a tune you will gain more than 361 hp with premium. Other wise 361 hp is max with any grade.

I'm not sure I agree with that. When the engine uses lower grade fuel, there is a tendency to pre-ignite. The knock sensors hear that pre-ignition and retard timing to compensate and protect the engine. If power output is identical with regular or premium, then you're saying, in effect, that retarded timing has no adverse effect on power output. What is the compression ratio of this engine? If it is low, then premium would not help. If it is 10.5 or 11:1 then premium should improve performance. Didn't I recall somewhere that Pontiac said the use of premium would improve performance?

The engine is tuned for regular. It will not knock unless like is was stated earlier "towing a trailer up a hill in 100 degree heat". It will not retard the timing using regular unless you get bad gas. Putting in super will not advance the timing.

I'm not sure I agree with that. When the engine uses lower grade fuel, there is a tendency to pre-ignite. The knock sensors hear that pre-ignition and retard timing to compensate and protect the engine. If power output is identical with regular or premium, then you're saying, in effect, that retarded timing has no adverse effect on power output. What is the compression ratio of this engine? If it is low, then premium would not help. If it is 10.5 or 11:1 then premium should improve performance. Didn't I recall somewhere that Pontiac said the use of premium would improve performance?

I think GM has been a very fine point on the rating. They can achieve 361HP for the SAE test on regular gas. According to Chris White (Chris correct me if I'm wrong), the premium timing table is not different than the regular grade timing table. During the summer or under heavy load, we might not always achieve 361HP on regular. However, spring and fall we might. If we run premium, we will have 361HP accessable to us most of the time. This leads me to believe that the stock tune is on the edge or maxxed out for regular gas tuning, more so than normal GM factory. That also means that if we get a tune for 93 octane, there is alot of potential in conjunction with CAI and exhaust.

Chip

IIRC, the snippet from the owners manual said the V6 would benefit from premium in towing situations. However, it made no mention of anything but regular for the V8, other than if knock occurs.

The engine is tuned for regular. It will not knock unless like is was stated earlier "towing a trailer up a hill in 100 degree heat". It will not retard the timing using regular unless you get bad gas. Putting in super will not advance the timing.

Not disputing you here. It all depends on the compression ratio of the engine, cam timing, plugs and heat dissipation. It was not clear, either, if this was using "straight" unleaded regular or the new low percentage ethanol blends (not E85). I'll see if I can find the comment I thought I saw from Pontiac. Since Pontiac concedes that engine knock is a possibility, it would therefore suggest that unleaded regular is on the bleeding edge of the envelope, and that higher octane might help, especially in performance situations and summer driving.

There was a test a while back for cars designed to run on 87 and cars designed to run on Premium. Cars designed for 87 saw no gain and even a loss when filled with premium. Cars designed to run on premium saw major performance losses. (I think the BMW M3 had major issues on regular)

There was a test a while back for cars designed to run on 87 and cars designed to run on Premium. Cars designed for 87 saw no gain and even a loss when filled with premium. Cars designed to run on premium saw major performance losses. (I think the BMW M3 had major issues on regular)

It would be interesting to see the G8 in that test under some differing conditions. I believe this is probably a fairly unique car. I think this car is tuned to produce its power rating with 87 octane under ideal "normal" conditions. Unlike a typical 87 octane car that is tuned conservatively (unlikely to knock unless under very extreme conditions), this car will most likely pull timing under less than ideal conditions even though things are not extreme. It would most likely act like a car requiring premium under these less than ideal conditions. It is more aggressive tune than what we normally see for an 87 octane tune.

Chip