Re: Subaru fuel economy - Saab General Bulletin Board - Saabnet.com
NG900 & OG93 |
Vintage Models |
Clubs & SOC |
Other Cars |
Member Photo Galleries |
Member Directory |
*Buddy Registry |
*Mileage Registry |
What's New |
Photo of the Month |
[Main General Bulletin Board | Post Followup | BBFAQ ]
[ Prev by Date ] [ Next by Date ] Member Login / Signup [Latest Member Gallery Photos]
Re: Subaru fuel economy
Posted by Dean (more from Dean) on Thu, 5 May 2016 08:02:05
In Reply to: Subaru fuel economy, Erik919kt, Tue, 3 May 2016 19:06:46
When driving a turbocharged engine, it is rarely on boost. But to accommodate boost the compression needs to be lower. That decreases efficiency. Saab engineers were doing research on variable compression engines to try to get the best of both worlds, but the methods tested seemed to be impossible to realize. So you are mostly driving around in a lower compression engine that reduces MPGs and have to spend more money on premium fuel to support the brief moments that you are on boost. Premium fuel has less combustion energy than lower octane fuels. Economy is more than MPGs. The Saab turbo engines did have great weight and MPG advantages over larger displacement naturally aspirated engines of equivalent performance.
Many advances have occurred in engine technology in the last few years with modified Atkins cycles, variable separate intake and exhaust camshaft timing and direct injection [DI]. Unfortunately, DI engines get some soot backflow in the intake ports and they get carbon fouled and air flow can be restricted. Fort injection keeps that area clean, something that was happening that was not recognized at the time. These technologies were once restricted to expensive vehicles, but are now very mainstream.
posted by 108.207.118...
Posts in this Thread:
- Subaru fuel economy, Erik919kt, Tue, 3 May 2016 19:06:46
- Re: Subaru fuel economy, Dean, Thu, 5 May 2016 08:02:05 <-- Viewing This Message
- Re: Subaru fuel economy, Ed, Wed, 4 May 2016 09:43:35
- Driving style ?, GFW3pedals , Wed, 4 May 2016 06:19:081
- Re: Subaru fuel economy, cheaptech , Wed, 4 May 2016 04:01:15
- Re: Subaru fuel economy, AdamSAAB2kAero , Tue, 3 May 2016 19:40:22
Post a Followup
No Site Registration is Required to Post - Site Membership is optional (Member Features List), but helps to keep the site online
for all Saabers. If the site helps you, please consider helping the site by becoming a member.
This is a moderated bulletin board - Posting is a privilege, not a right.
Unsolicited commercial postings are not allowed (no spam). Please, no For Sale or Wanted postings, SERIOUSLY.
Classifieds are to be listed in The Saab Network Classifieds pages.
This is a problem solving forum for over 250,000 Saab owners, so expect to see
problems discussed here even though our cars are generally very reliable. This is not an anything goes
type of forum. Saabnet.com has been a moderated forum since 1988. For usage guidelines, see the
Saabnet.com Mission and Purpose Page. Please remember that you are
not anonymous. Site Contact | Site Donations | Other Sites by SP -
Your address is: 220.127.116.11 - Using CCBot/2.0 (https://commoncrawl.org/faq/) - Logged.
Site Members do not see red text instructions, bottom of the page anchor ads, or box ads.
Click here to see all
the Site Membership Benefits!