Premimum Fuel

[Aftershock_024]

In the GTP with the 3800 supercharged engine do you need premium fuel? My bro has a 2000 bonne with the 3800 supercharged engine and he for a couple months used just the regular fuel and has been fine. So what do you use in your GTP?

[BNaylor]

Yes, premium only. 91 octane or better.

[xeroinfinity]

You get to low octane and it'll knock & ping.

[bmwgolfguy]

You are wasting your money unless your engine pings or you have a noticable difference in perfomance. You will know if you do.

[BNaylor]

Originally Posted by bmwgolfguy

You are wasting your money unless your engine pings or you have a noticable difference in perfomance. You will know if you do.

Timeout.

GM specifies premium on any L67 GM car for a reason. When boost kicks in on a L67 you may not hear any pinging but the knock retard (KR) is definitely in. I've tested using Autotap and the KR will get as high as 10 degrees on regular unleaded.

Plus 1/4 mile times are terrible running on regular.

Good way to destroy your engine over a period of time.

[mike561]

I just run on the premium stuff, ive had WAYYY too many other problems with this car then to risk running into many more problems in the future. BUT correct me if im wrong, i herd if you remove the supercharger belt you can put in lower octane, but of course will notice a huge difference in pickup.

[04GTP-WhatLAG?]

with the L32s you don't HAVE to run 91 or higher(even the manual says you can run 87 with the s/c, but it "recommendnes" 91 or higher) and if you have a performance oriented mind, well, you'll want too... now once you get a reprogrammed PCM, 91 or higher only, though I believe the L67s are supposed to run 91 or higher from the factory...

[Aftershock_024]

Alright Thanks for the replies. When I get my GTP I'm not to worried about the preformance cause I won't be racing. I still want to have some fun with it but I'm sure even with running regular fuel it will be better than my little cavi with a 2.2. The reason I want the GTP the most is the HUD and heated leather seats. And I wanted the supercharger to but I'm not to worried bout like 1/4 times and all that. Also, I guess we have a 1000 barrel of gas on our property. We usually put 89 octane in it. Will that work ok with out a significant preformance difference?

[richtazz]

My 99 GT has all that, leather, hud, moonroof, etc... so you don't have to get a GTP for those options. I would advise strongly against running low octane, as you'll be tempted to goose it, and knock can do evil things to a motor over time as bnaylor stated earlier.

[BNaylor]

For the '97 - '03 L67 GTPs the owner's manual states:

If you have the 3800 supercharged V6 engine Vin Code "1", use premium unleaded gasoline rated at 91 octane or higher.

With the 3800 supercharged engine, in an emergency, you may be able to use a lower octane --as low as 87 --if heavy knocking does not occur.

Lets get our facts straight.

[JonJon68]

97 GPGT Non-supercharged. To add to Rich's comment, I have a GT with heated seat, hud. These options just don't come with GTP's

[mike561]

Originally Posted by JonJon68

97 GPGT Non-supercharged. To add to Rich's comment, I have a GT with heated seat, hud. These options just don't come with GTP's

really? i did not know that

[Aftershock_024]

Ok, I guess I ahve never seen a GT with HUD. Hope I come across one ! Anyways I do know quite a bit about cars and combustion engines ..... Dont know much about disels.... But waht exactually is *knocking*?

[BNaylor]

Originally Posted by Aftershock_024

But waht exactually is *knocking*?

Knocking (also called pinging). Technically detonation. In internal combustion engines occurs when fuel/air mixture in the cylinder has been ignited by the spark plug and the smooth burning is interrupted by the unburned mixture in the combustion chamber exploding before the flame front can reach it. Combusting stops suddenly, because of the explosion, before the optimum moment of the four-stroke cycle. The resulting shockwave reverberates in the combustion chamber and pressures increase catastrophically, creating a characteristic metallic "pinging" or "knocking" sound.

Typically caused by low grade/quality fuel or even a mechanical malfunction.


Detonation
The fuel/air mixture is normally ignited slightly before the point of maximum compression to allow a small time for the flame-front of the burning fuel to expand throughout the mixture so that maximum pressure occurs at the optimum point. The flame-front moves at roughly 33.5 m/second (110 feet/second) during normal combustion. It is only when the remaining unburned mixture is heated and pressurized by the advancing flame front for a certain length of time that the detonation occurs. It is caused by an instantaneous ignition of the remaining fuel/air mixture in the form of an explosion. The cylinder pressure rises dramatically beyond design limits. If allowed to persist detonation will damage or destroy engine parts.

[phaelax]

I put nothing less than 93 in my gtp, and preferably only from shell or sunoco. I tried BP 92 once, car kept stalling under hard acceleration. My friend put BP gas in his 73 Duster once, that was fun trying to start.