premium vs regular

[1dollardog]

I know these cars require premium fuel but I run regular in mine most of the time. I'm getting around 22-23 mpg around home. Car is bone stock. Will my mpg improve if I run premium fuel all the time? What will running regular fuel do to the engine?

 

[skylarkstage1]

I had a stock 97 GTP a number of years ago and used only 91 octane gas. I got as high as 30 mpg at an average speed of of 55. At 70 mph with cruise control and air on, 27-28 mpg.

 

[kshef]

Will my mpg improve if I run premium fuel all the time?

no

What will running regular fuel do to the engine?

you'll see reduced performance, as the pcm will be pulling timing to reduce detonation

if you keep your foot out of the gas then you won't notice a difference

 

[1dollardog]

no



you'll see reduced performance, as the pcm will be pulling timing to reduce detonation

if you keep your foot out of the gas then you won't notice a difference

So when the pcm pulls timing that doesn't cost me any mpg? What mpg or hp gains can I expect if I add one of the K&N cone filter set ups? Are there any drawbacks to this?

 

[kshef]

So when the pcm pulls timing that doesn't cost me any mpg?QUOTE]
i was refering to WOT..if you drive normal then there won't be a difference

a k&n will help out with gas mileage slightly....it'll give you a little more power and you'll hear the supercharger whine

it's a little noisy on cold start ups until it warms up


a tuner will help you out the most with mileage...i get 32mpg if i stay at 60-65mph, 29-30mpg at 75-80mph, and 35-36mpg at 45-55mph

 

[1dollardog]

I let the tank get almost empty and filled up with mid grade 89 octane. I'm getting over 1 mile per gallon less on 89 octane than I was getting with regular 87. Can this be? I like power but what can I do to get better milage?

 

[flyboy367]

sell it and buy a honda. these cars dont get good city milage. by using lower grade fuel you are just setting up the engine for failure. they are required the higher octane to compensate for boost. i cant imagine what your knock is like on 87 and under boost.
when i lent my gtp to my wife's uncle while we were on our honeymoon he filled my tank with 87. it was like the car fell on its face. i thought for a while he blew an injector until i found the gas recipt in the car. i dropped the tank and drained it. tossed that junk 87 into my wifes car and filled it with some 94.

 

[1dollardog]

sell it and buy a honda. these cars dont get good city milage. by using lower grade fuel you are just setting up the engine for failure. they are required the higher octane to compensate for boost. i cant imagine what your knock is like on 87 and under boost.
when i lent my gtp to my wife's uncle while we were on our honeymoon he filled my tank with 87. it was like the car fell on its face. i thought for a while he blew an injector until i found the gas recipt in the car. i dropped the tank and drained it. tossed that junk 87 into my wifes car and filled it with some 94.

Zero knock to my knowledge (although I haven't scanned) but I don't normally get on it much. I just drive it at speed limit to work and back. I like having that extra boost though when pulling out to pass someone. My car is like my woman, I don't lend either of them out...

 

[steveX]

If you go to a higher octane fuel you should see better mpg. running around town with low level octane fuel will more like cause KR detenation. If the PCM detect KR, it will reduce spark timing (lost power). the 3800 engine don`t start cooling down (fans ON) see 220F degree (WOW). so since heat is the cause of detenation and you engine is already at 220 (15 degree for boiling over) it will be wise to use a high octane fuel to surpress any KR. high level octane has be proven to reduce KR. so you have two option.

lower the coolant temp to around 170-180f degree and you will be fine running around town with low level octane fuel.why? the engine will be able to burn the mixture be on its FLASH (KR) point and see minimal kr, BECAUSE the cylinder walls and water jackets (coolant) will extract the heat right-away help surpress KR/FLASH POINT.

if you can`t reduce your coolant temp them it will be wise to stick with higher octane fuel.since the engine is already close to boiling over.

If your fuel management is a OBD1 OBDII you should see an increase in mgp. WHY? the OBD system is set to meet a predetermine A/F ratio. The O2 sensor will be able to determine which fuel the engine is buning base on how hot (burn rate) the sensor gets. the GM 3800 engine must see .780mv at the o2 sensor for a proper a/f ratio, if this mv (millivolt) is to change the ecm is adjust/correct (impedence) the injector ,so the O2 sensor maintain a .780mv (OEM setting). this is the #1 reason everyone tune from a O2,EGT, and wideband all do the samething, accuracy is the differance.

so since 87 octane burn at a lower temp than 93 octane before KR/FLASH POINT sets in.

Think of octane has BURN-RATE. lower octane (87) burn around 1400f degree when high octane (93) will burn at 1800f degree. the hotter you burn the power mixture (fuel/air) the more power you will make until flash point sets in. also remember FLASH POINT/KR can be control, by moving the heat quickly to the water jacket and interior cylinder walls.

example: a .44 mm had gun will carry it projectile alot far then a .38mm hand gun.

the gun power is your octane. the more in the more out. if you pack the gun/cylinder with the correct mixture the more power you will make sending you projectile across the sea`s.

the end.