I just purchased a Buick Grand National This past week and I will pick it up next week once I have the rest of the money. THis is a 1987 Buick Grand National with a 114,000 miles on the engine. I plan on rebuilding the engine in the future and adding some chrome to it. As for now it runs great.

My question is what octane gas should go into this car. Is it Regular(87 Octane),super regular(89 octane) or Premium(91 octane) I'm hoping just regular since gas has skyrocketed here.

Here's the link to see my car:

http://performance-auto-group.com/images/eBay/Stock-0031/Large/Stock-0031-b001.jpg
Thanks
John

excellent! How much did you pay for it?

I'd assume it would run best on 93(premium), simply because 93 is more knock resistant than regular, and with the added boost of the TC, it will be prone to knocking. Premium is about 1.75 or so here, what is it where you're at?

I paid $9200. Gas is pretty expensive over here as of late. Regular gas cost on average $1.89 with Premium going for a wopping $2.09 ouch!!

man, I remember when you could get a gallon of premium for 75 cents!

i paid 5,900 for mine but it the motor was toredown.

Anyway soes this car have ADJ. boost controll?? if not i would reccomend runn at lest 92 octane. you can run 89 octane and get away with it (the computer will pull like 4-7 deg. of timing out) but with that many miles on the car i would run 92 or higher

Theres been lots of discussion happening here in the regal forum about GN's, I wanted all GN stuff to be in the regal forum, since it's essentially the same car. I am going to request a Grand National/GNX forum.

if it's worth anything you might wanna make it something like a tubo v-6 forum because they put thoes motors in alot of regals. they had everyting from plane jane regal's to the GNX. therer are alot of thoes motors out there and with the exception of the GNX there is no difference between them (GNX had diffrent turbo,chip,intercooler,and suspension stuff :smokin: )

AF doesn't have any forums for any engine in particular, I'm still only going to request a gn forum

Run the highest octane you can get, regardless of price. The money you spend on gas will be cheap insurance for your head gaskets. I run 91-92 mixed with xylene in mine. Went from 91-92 octane and 13-15 lbs of boost to 18-19 with the xylene. Better yet would be 110-112 race gas.

Why don't you just drive to the airport and get some 140 octane gas and watch all 6 pistons go flying through the hood! :iceslolan:grinno:

Why don't you just drive to the airport and get some 140 octane gas and watch all 6 pistons go flying through the hood! :iceslolan:grinno:
I've run 118 race gas in mine. Doesn't knock, but the headgaskets blew out at 120, tho. ;^(
Jeff

I've run 118 race gas in mine. Doesn't knock, but the headgaskets blew out at 120, tho. ;^(
Jeff


blew out at 120??? I don't understand, 120 what??. Anyway that sux man My uncles TTA uses 118 and he run 30 PSI on stock internals and heads. Hes been doing it for about 3 years now. not one thing wrong withit.



tman 140 octane!! That would be cool. Watching the pistons fly out of the block is not cool. Is 140 Jet fuel?? I have a few hours of flying cessnas and the most they have is 110 Low Lead content.



*HyPsI87 goes on a hunt for 140 octane* Must have. Must have!!

blew out at 120??? I don't understand, 120 what??. Anyway that sux man My uncles TTA uses 118 and he run 30 PSI on stock internals and heads. Hes been doing it for about 3 years now. not one thing wrong withit.



tman 140 octane!! That would be cool. Watching the pistons fly out of the block is not cool. Is 140 Jet fuel?? I have a few hours of flying cessnas and the most they have is 110 Low Lead content.



*HyPsI87 goes on a hunt for 140 octane* Must have. Must have!!
120 miles per hour (big end of a 11.10 second quarter). It was a problem with the relationship of the fuel injectors and the fuel pressure. I've got the parts to fix it.
Jeff

Aviation gas isn't a good idea, because it has other additives to prevent icing at altitude, and a host of other things you don't need in a car. For this reason, the specific heat available from Aviation gas is less than Automotive gas and you will make less horsepower. You can run big boost and more ignition advance with the 140 octane, but it still isn't a good idea.

add alcohol injection (lots of good kits-- i bought a SMC kit) then you can use the lower octane gas (actually burns better than higher octane gas because of the additives added to the higher stuff) I also upped the boost as the alcohol cools the mixture. I have the boost set at around 22 and the alcohol starts to spray at about 10-12 lbs of boost.

keith

Okay, one more time. Jet fuel is kerosene: don't ever put it in a car!

Yea jet fuel is bad. I knew about the additaves in avaiton fuel to keep it from deiceing and such but, I did not really put 2 and 2 together. Thanks for the info. In all I have to agree with gnfreak. SMC alcohol is the way to go to run big boost on pump gas. I run 18* timing and 24 PSI on pump gas (93 octane.) the SMC dual nozzle kit starts spraying at about 11 PSI.

I work at the factory where the engine was manufactured and about 5 years ago a few of us were selected to go down to engineering for a week long engine repair class where this topic came up.

If the vechicle is stock, use whatever the owner's manual calls for unless the engine knocks, if it does, go up in octane until it stops. Computers are set-up for the recommended octane and can't utilize any more than what's recommended, so by running a higher octane you would just be wasting your money. We were told this by a GM Factory Master Mechanic that specialized in building our 3800's into engines only imagined by the buying public.

Not too long ago, at our plant's "family day," we had on display one of these engines in a heavily modified brand new Regal that carried the GNX logo.
This car was "full tilt!" So much so in fact, that they had a security guard posted by it all day. At first they were'nt even going to display it with the hood open but myself and another guy "lobbied" hard and they finally relented, grudgingly. It was worth the effort!!

There has been talk about coming up with something along the lines of the car that was on display, one can only hope. Just to be on the safe side I'm holding off on replacing our 98 Regal GS, which I wanted to do to take advantage of the extra hp put out by the Eaton SC but that's getting harder all the time. I walk past hundred's of these newer type "blowers" every day at work so I'm reminded of it constantly.
I'll eventually cave in and get a new one, probably before the Regal is discontinued, which will be happening real soon.

Jack

I work at the factory where the engine was manufactured and about 5 years ago a few of us were selected to go down to engineering for a week long engine repair class where this topic came up.

If the vechicle is stock, use whatever the owner's manual calls for unless the engine knocks, if it does, go up in octane until it stops. Computers are set-up for the recommended octane and can't utilize any more than what's recommended, so by running a higher octane you would just be wasting your money. We were told this by a GM Factory Master Mechanic that specialized in building our 3800's into engines only imagined by the buying public.

Not too long ago, at our plant's "family day," we had on display one of these engines in a heavily modified brand new Regal that carried the GNX logo.
This car was "full tilt!" So much so in fact, that they had a security guard posted by it all day. At first they were'nt even going to display it with the hood open but myself and another guy "lobbied" hard and they finally relented, grudgingly. It was worth the effort!!

There has been talk about coming up with something along the lines of the car that was on display, one can only hope. Just to be on the safe side I'm holding off on replacing our 98 Regal GS, which I wanted to do to take advantage of the extra hp put out by the Eaton SC but that's getting harder all the time. I walk past hundred's of these newer type "blowers" every day at work so I'm reminded of it constantly.
I'll eventually cave in and get a new one, probably before the Regal is discontinued, which will be happening real soon.

Jack


That is true about the computer being programed for a certian octane. But all of us who race a turbo buick, We usually have a chip to be able to run that certian octane.

That's why the first few words of my advice about the octane rating were "If the vechicle is stock."

At the factory we hear about a lot of the tricks that are used to get more hp out of our engine, the chip being the easiest & most common.

Jack

That's why the first few words of my advice about the octane rating were "If the vechicle is stock."

At the factory we hear about a lot of the tricks that are used to get more hp out of our engine, the chip being the easiest & most common.

Jack


Sorry I just need to learn how to read :icon16: .

if it's worth anything you might wanna make it something like a tubo v-6 forum because they put thoes motors in alot of regals. they had everyting from plane jane regal's to the GNX. therer are alot of thoes motors out there and with the exception of the GNX there is no difference between them (GNX had diffrent turbo,chip,intercooler,and suspension stuff :smokin: )

Ok guys, Don't mean to be too picky, but the "X" Had the exact same intercooler as the gn.. Sorry-pet peeve...