Engine downsizing comes with downside

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Downsized turbocharged engines continue to grow in popularity because they offer impressive fuel efficiency and squeeze out the power. But there’s a downside.

Their high-compression nature in certain circumstances can damage engine parts, sometimes catastrophically, says Joachim Wagenblast, director of R&D-engine systems and components for engine supplier Mahle USA.

He cites broken piston rings, cracked off tops of pistons and bent connecting rods.

The culprit is called low-speed pre-ignition, or LSPI. It is an abnormal combustion phenomenon that occurs before the normal spark-plug ignition and is not widely known.


I've heard of LSPI here but not a lot of it. This article makes it sound like it's more widespread than I thought.

Quote:
Mahle says the need to address the issue is dire, especially because of the increasing popularity of downsized turbocharged engines that can be 30% smaller than their naturally aspirated equivalents.
 
One way to help avoid LSPI in a DIT engine is to use oil that doesn't promote it.
dexos1 Gen 2 includes an LSPI test in a GM DIT engine and I will sure be looking for that license when it goes live in September. Interestingly enough, it looks like M1 5W30 AP already has a Gen 2 license number.
Here is a good thread that wemay started discussing LSPI and oil, there are more in the "Interesting Articles" forum.

Oronite on LSPI

dexos1 Gen 2 Licenses

BTW, I am interested in LSPI because my car was recalled for it...
 
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Whats the difference between LSPI and engine knock?
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oil squirters, sodium valves---- get the heat out.... and DI can all help here.

turbocharging is not new--- I wonder what the mfrs are missing.
 
Sounds like a Tier 1 parts supplier is crying over warranty claim issues. No news flash here that turbo charged engines are higher stressed.

That his name is Wagenblast; now that's ironic!
 
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Originally Posted By: meep

turbocharging is not new---


Just think - the 1987 Buick GNX (underrated at 276 hp from 231 cubes) was 30 YEARS ago!!!
 
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Originally Posted By: Bamaro
Whats the difference between LSPI and engine knock?
21.gif


I don't remember the details, but LSPI is much more destructive. You can have low-level knocking for a while without completely destroying your engine, but as I understand it, on LSPI event often destroys a piston/ring/rod.
 
Originally Posted By: Linctex
Originally Posted By: meep

turbocharging is not new---


Just think - the Buick GN-X was 30 YEARS ago!!!


Chevy Corvair Monza was even older.
 
Originally Posted By: KGMtech

Chevy Corvair Monza was even older.


But it was a little too early and under-engineered for the technology.

Modern turbocharged engines really need to have a computer involved in the management of fuel & ignition to make turbo work in everyday passenger cars. (racing is altogether a different scenario)
 
It's not like LSPI is news to engine makers. After a few, early missteps (e.g. Subaru), they seem to have the issue under control. Now the methods they've used to mitigate LSPI may have other consequences like fuel dilution and slightly decreased fuel economy, but we don't hear many horror stories about TGDI engine failures these days. For example, has anyone here heard of a serious mechanical problem with a Ford EcoBoost?
 
I think the 2.0L in the Cadillac ATS was prone to this, as it seemed to break pistons kind of irregularly, not related to how hard it was driven.
 
Originally Posted By: Danh
It's not like LSPI is news to engine makers. After a few, early missteps (e.g. Subaru), they seem to have the issue under control. Now the methods they've used to mitigate LSPI may have other consequences like fuel dilution and slightly decreased fuel economy, but we don't hear many horror stories about TGDI engine failures these days. For example, has anyone here heard of a serious mechanical problem with a Ford EcoBoost?


The Ecoboosts seem to have done quite well, but GM had a recall fairly recently for 1.5l DITs in Malibus. Note the very specific oil recommendations...

Malibu SPI Recall
 
Originally Posted By: Lolvoguy
"there's no replacement for displacement"
smirk.gif


And small displacement may require frequent replacement.
smile.gif
 
Originally Posted By: Lolvoguy
"there's no replacement for displacement"
smirk.gif

The only substitute for cubic inches is cubic money --- Smokey
 
Originally Posted By: Linctex
Originally Posted By: meep

turbocharging is not new---


Just think - the 1987 Buick GNX (underrated at 276 hp from 231 cubes) was 30 YEARS ago!!!


My FXT makes 250HP (probably accurately reported) from 122 cubes and has the benefit of water cooling for the turbo...one of the advances made in the last 30 years. The supposed 420 lb-ft that the GNX made is much closer to the FXT per cube, though.
I actually made a rash decision to go find myself a new Grand National when I was a young punk, but this was around 1988 and their last model year was '87...probably lucky for me, would have been "fun" dealing with that RWD power in snow and ice when I moved back North. Actually, I probably would have crashed and died right away in Dallas...
 
Not really a huge fan where a turbo on a tiny engine makes most of it's power. I doubt morons who drive these things will keep it out of boost to reap the fuel economy benefits.
 
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