Automotive Forums .com - the leading automotive community online! Automotive Forums .com - the leading automotive community online!
Automotive Forums .com - the leading automotive community online!
Become a fan of Igor Sushko - Racecar Driver
-
Latest | 0 Rplys
Go Back   Automotive Forums .com Car Chat > Buick > Grand National/GNX
Reply Show Printable Version Show Printable Version | Email this Page Email this Page | Subscription Subscribe to this Thread
 
Thread Tools Search this Thread
Old 05-30-2011, 11:28 AM   #1
MrCreosote
AF Regular
 
Join Date: May 2006
Location: jeannette, Pennsylvania
Posts: 212
Thanks: 0
Thanked 0 Times in 0 Posts
The Mysterious Ultra High MPG 3.8 and GN too.

The last version of the "3.8," before the engine was called a "3800," came in at least 2 flavors: Ordinary and Legendary.

There was a 3.8 variant that got unspeakably high gas mileage. These cars were coveted by taxi companies. My friend who owns a taxi company bought his first one unknowing of any of this. The first day they put it in service, at the end of the day, the driver says, "It runs good but the gas gauge is broke." It barely moved after about 1/2 days use as a taxi. They got over 25-28 mpg in city use.

I even remember a road test of a GN or GNX where they were driving to the strip with the 5th wheel on and running and they were getting 44 mpg on the highway. I suspect this Mystery 3.8 might even appear in the turbo cars too. (Or will all turbo Buicks get 44 mpg on a level highway?)

We never figured out which 3.8's got the mileage. It was probably something like has to have the "brown" injectors instead of the "blue." And maybe a few more things.

Does anyone remember this or has identified that amazing variant?

Thanks
Tom

Last edited by MrCreosote; 05-31-2011 at 01:24 PM.
MrCreosote is offline   Reply With Quote
Old 08-22-2011, 07:08 AM   #2
Blue Bowtie
Registered Offender
 
Blue Bowtie's Avatar
 
Join Date: Mar 2006
Location: Rural
Posts: 4,964
Thanks: 2
Thanked 51 Times in 51 Posts
Re: The Mysterios Ultra High MPG 3.8 and GN too.

It may be legend, or it may be that the ECM was programmed a bit differently. From late 1985 on through at least 1994 the GM ECMs almost all had coding for Highway Fuel Mode and Highway Spark Mode operation. Even though the coding existed, it was turned off in the programming because the operation at 17:1 mixtures and 48 timing advance at light load values and low throttle angle would not allow the engines to control NOX emissions enough to meet EPA standards. Some of us who have played with the Highway Mode settings have been able to achieve more than 30 MPG highway on L98 V-8s and slightly better on LB9 V-8s in F-cars which were rated for 22 MPG.

GM pretty much had a method to increase mileage but at a cost of higher emissions of nitrides of oxygen. The result is that we burned 30% more fuel on the highway because Uncle Sam was more concerned about what it thought might be damaging the stratospheric ozone layer.
__________________
Permanent seat assignment on the Group W bench...
Automotive Forums Survival Guide
Blue Bowtie is offline   Reply With Quote
 
Similar Threads
Thread Thread Starter Forum Replies Last Post
3.8 head changes. help? thunderbirdcoupe89 Thunderbird 2 12-10-2009 12:43 PM
Amazing MPG :D jarl Trans Sport 1 08-16-2009 12:16 PM

Reply

POST REPLY TO THIS THREAD


Bookmarks
Go Back   Automotive Forums .com Car Chat > Buick > Grand National/GNX

Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off



All times are GMT -5. The time now is 09:25 PM.

Community Participation Guidelines | How to use your User Control Panel
Automotive Forums .com - Car Forums - Privacy Statement - Top

Powered by: vBulletin | Copyright Jelsoft Enterprises Ltd.
Powered by Searchlight © 2014 Axivo Inc.
 
no new posts