Patrick G

iTrader: (14)

I just got done tuning another G8. This one is my own personal vehicle. You may recall a 2008 G8 from last year that had big gains on the dyno:

https://ls1tech.com/forums/dynamomet...tane-only.html

That particular 2008 G8 made 279rwhp/299 rwtq with the bone stock baseline. The owner wanted to run 87 octane so I made him a killer regular unleaded tune and the results were 313 rwhp, 328 rwtq.

For my particular G8, it's a 2009. Comparing the factory calibrations, GM did a much better job on the 2009s than the 2008s and there wasn't as much power to be gained with just a tune.

My new 2009 G8 put down 307rwhp/333rwtq bone stock with 87 octane in the tank. With my slick 87 octane tune, we still picked up 18rwhp and 2 rwtq. The car can now cruise 75-80 mph in 4 cylinder mode. Fuel economy is up nicely. I like tuning these cars with 87 octane. We get them on the fringe of the knock sensors kicking in and lock it down. Then if we ever want to go racing, a splash of 93 octane keeps it happy. While I might have been able to get a few more ponies on 93 octane, the tune on 87 octane is really good and leave very little power on the table.

Just a small explanation about the low rpm torque difference: On my baseline dyno pull, we stabbed the throttle 100% later in the rpm range. While we did gain nicely at lower rpm, it was not quite that dramatic. For those who think you can only get strong performance on 93 octane, think again.

cam75w/ls1

iTrader: (2)

Looks good Pat. Is this the new daily driver?

SS02

Good stuff bud

Patrick G

iTrader: (14)

Yes, this is the new long distance cruiser for me. This is one of the reasons why I need it to knock down big MPGs on the highway. AFM will be used to its advantage. Stay tuned for more mods down the road. Right now, the G8 is bone stock down to the paper air filter. The only mod is the tune.

Suaveat69

Did you get a baseline MPG before your tune? Interested in seeing what you gain in MPG by the tune.

Nitroused383

iTrader: (10)

I am curious on how much compression these cars come with. Also how much timing can you actually run on 87 octane, I was tuning my brothers 2000 4wd 5.3 silverado and they only have 17-18 degrees of timing at WOT.

ScreaminRedZ

iTrader: (3)

Big gains! Definitely curious as to the mpg you get with it now. I understand the fact that it looks like you gained more from when you put your foot down, but are the actual gains down low due to reduced torque management? (My G8 is the first car I've owned that has it and I'm not quite sure how it works).

Thanks!

allngn_c5

iTrader: (3)

Pretty damn amazing on 87 octane.

allngn_c5

iTrader: (3)

So you have the cylinder shut down? Ok, what kind of speed could you cruise at with 4 of the cylinders shutdown before the tune ? When you said cruise at 75-80 in 4 cylinder mode is that an improvement over the stock tunes capability ? What kind of gas mileage did this car get pretune, and what do you guess post tune ??

Good job Pat, and looking fwd to the gas mileage results. So many people believe that just because you gain power you must lose mileage. Not always true.

Subscribed for your updates !!!

Patrick G

iTrader: (14)

The MPG difference between running in 4 cylinder mode and 8 cylinder mode is around 2 mpg. With the ability to cruise on level ground at 75mph in 4 cylinder mode (could not with factory tune), my mpg has risen approximately 1.5 mpg compared to stock (city and highway mpg have both increased around the same). Maybe not a big gain for some, but it was a free mod as far as I was concerned.

Considerable time was spent logging and tweaking the AFM. Not just engagement and disengagement tables, but lots of time on the AFM timing tables (which are way too aggressive from the factory).

maddboost

iTrader: (11)

What type of MPG where you getting before the tune?

Patrick G

iTrader: (14)

23-24 mpg on the highway with stock tune. Now it's 25-26mpg. Around town went from 16 to 17 mpg after the tune. My G8 is still bone stock down to the paper filter. The only mod is a tune.

allngn_c5

iTrader: (3)

Thanks for the inciteful write up Pat. Looks like you put some time into this one. What mods if any are you considering ?

RJB01camaross

Great results for just a tune

slowride

iTrader: (3)

How much more could you get with say 92-93 octane? I'd guess it runs so well on the 87 due to lower compression than say a LS2, etc.

Patrick G

iTrader: (14)

I ran the car on the dyno yesterday with 93 octane in the tank and it dynoed exactly the same rwhp and rwtq. Guess the tables are pretty nicely optimized.