Lubrizol says SN PLUS and GF-6 not enough for LSPI protection in TGDI engines

[dblshock]

In the county I live in is so rural they don't have a single electric traffic light, the sheriff radar policy is always on, redline goes off miles ahead...the perfect environment for the TGDI Civic, great fuel mileage and some decent HP pop brakes and suspension for the money it's a marvel.

 

[novadude]

Originally Posted by pitzel

DI does little to nothing to improve inherent combustion efficiency. It changes the thermodynamic efficiency of an engine not one iota.

I was thinking about that a bit too. I would think that spraying finely atomized fuel into the vacuum above the valve (port injector or carburetor venturi) would also give a bit more time for liquid to flash to vapor. Maybe the DI nozzle design, chamber design and pressures can efficiently atomize, but I would think that putting the fuel into the air stream and over the intake valve would provide a more homogeneous mixture and allow more time for vaporization. I am probably wrong though. If GDI engines had inefficient burn they likely would have a hard time meeting emissions standards.

 

[demarpaint]

Originally Posted by Bryanccfshr

This is an issue that crankcase oil will not solve. It is an engineering problem and requires an engineering solution.

I agree. It seems like they engineer something problematic, flood the market with, it and then pass the buck to the oil companies to solve it. The problem should have been solved prior to releasing the technology to the public.

 

[BMWTurboDzl]

I find it interesting that the German makes don't have this issue. The BMW N53 is a NA/ DI engine had better fuel economy and also matched the output of its NA/PI predecessor the N52. Both are the same I6 engines except for the fuel delivery. Companies whose engines have LSPI could easily design an engine without it by just reducing power output but it's the consumer which is driving that demand for more power. They're caught between a rock and a hard place. Fulfill the market demand for power while meeting FE/emissions requirements. What we're watching is the demise of the ICE. Bittersweet.

 

[StevieC]

Could it be related to gearing between the German makes and North American makes causing the conditions right for LSPI?

 

[SubieRubyRoo]

Originally Posted by BMWTurboDzl

I find it interesting that the German makes don't have this issue.

It's more likely to do with the TCU programming- the lowest speed that will shift into the next higher gear is likely higher, and downshifts are set to occur at lower throttle openings, removing a lot of the low-speed, high load situations. It can really just come down to "we program our vehicles to feel more responsive" and that should eliminate most of the conditions that make LSPI possible...

 

[BMWTurboDzl]

Originally Posted by SubieRubyRoo

Originally Posted by BMWTurboDzl

I find it interesting that the German makes don't have this issue.

It's more likely to do with the TCU programming- the lowest speed that will shift into the next higher gear is likely higher, and downshifts are set to occur at lower throttle openings, removing a lot of the low-speed, high load situations. It can really just come down to "we program our vehicles to feel more responsive" and that should eliminate most of the conditions that make LSPI possible...

Perhaps, but I would imagine that the germans would've noticed it when they were testing the "eco pro" *** driving modes. ***Driver select mode which among other things lowers the shift points. I kid you not the vehicle drives like an big turd with it engaged although the sailing feature is kinda cool (Sailing: TQ converter completely disengages when coasting, imagine dropping a manual into neutral on the hwy).

 

[PimTac]

Originally Posted by SubieRubyRoo

Originally Posted by BMWTurboDzl

I find it interesting that the German makes don't have this issue.

It's more likely to do with the TCU programming- the lowest speed that will shift into the next higher gear is likely higher, and downshifts are set to occur at lower throttle openings, removing a lot of the low-speed, high load situations. It can really just come down to "we program our vehicles to feel more responsive" and that should eliminate most of the conditions that make LSPI possible...

I think this comment is the key. Automatic transmissions are programmed to shift up early and fast. I find that I can start off at a intersection and be in third gear before I completely cross. One scenario I run into is driving in a low speed limit residential area that is hilly. The engine is lugging going uphill. I get around that by selecting sport mode on the transmission which keeps engine revs up.

 

[bfleeman]

Didn't AMSOIL fix this problem with their oil? I know they claim a 100% fix to this problem.

 

[Danh]

This could explain why automakers other than GM haven't jumped on the SN Plus/D1G2 bandwagon. Honda, for example, has a real, and becoming more publicized, issue with fuel dilution in its 1.5T engines. One could suppose part of this is due to LSPI-prevention fuel richening logic that automakers seem to use. If SN Plus was an absolute solution it would have made sense to see 2019 Hondas with revised programming and an SN Plus requirement, but this didn't happen. Maybe a change will occur when GF-6 oils are introduced. (And maybe Honda is smarter than they're getting credit for...)

 

[StevieC]

Originally Posted by bfleeman

Didn't AMSOIL fix this problem with their oil? I know they claim a 100% fix to this problem.

No, Only as it pertains to this test. They call this out...

Quote

Amsoil achieved 100 percent protection against LSPI in the engine test required by the GM dexos1® Gen 2 specification."

Also this is their definition of LSPI just to add to the thread...

Quote

WHAT IS LSPI? Piston Damage LSPI is another version of engine knock, which has been around since engines were invented. In this case, it occurs under low-speed, high-torque conditions in turbocharged gasoline direct-injected engines and is more destructive than typical engine knock. Under normal operation, spark-triggered ignition is timed to work in tandem with downward piston momentum. LSPI occurs when an oil/fuel droplet hiding in the piston crevice launches into the combustion chamber and ignites the fuel/air mixture too early. The resulting force clashes with the upward moving piston and can cause damage like that on the piston shown.

 

[webfors]

Originally Posted by Bryanccfshr

Originally Posted by Gokhan

LSPI happens in TGDI engines but it's caused by the oil. Therefore, it's possible to prevent it by changing the oil chemistry.

Altering the boost at low speed, or allowing the transmission to downshift and the engine to rev would remedy the issue regardless of oil formulation. This may cost a couple of MPG on the epA sequence test though.

An aftermarket tune would do exactly that, and provide an additional 40-50 hp/tq. Not that I would do, or recommend, such a thing Another suggestion is to change the oil more often. I do that.

 

[parshisa]

finally, somebody said it!!!! .

 

[Patman]

Originally Posted by Brigadier

Is it the DI that helps with the fuel economy, or the higher number of gears?

The gearing change does help a bit, but also keep in mind that between 2013 and 2014 the Corvette had the same 6 speed automatic transmission with the same rear end ratio too, but yet people still see an improvement in MPG with those A6 2014s as well. DI also accounts for a good part of the 55hp increase in 2014 as well.

 

[Patman]

Originally Posted by pitzel

On the Corvettes -- the gearing went from 0.50 in 6th to 0.45 in 7th between the 2005 and the 2019 models, ie: they were able to add another gear because DI augmented the torque and power of the engine at the extremities of power and torque required during transients that were reasonably expected to be experienced with such higher gearing. Given that the Corvette's fuel (in)efficiency is dominated by pumping and mechanical losses due to it being grossly oversized for the application, reducing operating RPMs by 10% logically improved efficiency by nearly the inverse, ie: +10%.

That's not a logical assumption actually. It doesn't work that way. You can't just change the gearing by 10% and get 10% better gas mileage. Conversely, if you change the gear ratio by 10% the other way you won't lose 10% gas mileage. I have done rear end gear swaps in 3 different cars (2.73s to 3.55s in a Mustang, 2.73s to 3.42s in a Trans Am and 3.42s to 4.10s in a Firebird Formula) and I didn't lose as much MPG as the % of the gear swap. For instance, the change from 3.42 to 4.10 is a 20% difference. I did not lose anywhere near 20% in MPG, I lost maybe 5% tops. I'm not sure where you're coming up with these little nuggets of "knowledge" lately

 

[Brigadier]

Originally Posted by Patman

Originally Posted by pitzel

On the Corvettes -- the gearing went from 0.50 in 6th to 0.45 in 7th between the 2005 and the 2019 models, ie: they were able to add another gear because DI augmented the torque and power of the engine at the extremities of power and torque required during transients that were reasonably expected to be experienced with such higher gearing. Given that the Corvette's fuel (in)efficiency is dominated by pumping and mechanical losses due to it being grossly oversized for the application, reducing operating RPMs by 10% logically improved efficiency by nearly the inverse, ie: +10%.

That's not a logical assumption actually. It doesn't work that way. You can't just change the gearing by 10% and get 10% better gas mileage. Conversely, if you change the gear ratio by 10% the other way you won't lose 10% gas mileage. I have done rear end gear swaps in 3 different cars (2.73s to 3.55s in a Mustang, 2.73s to 3.42s in a Trans Am and 3.42s to 4.10s in a Firebird Formula) and I didn't lose as much MPG as the % of the gear swap. For instance, the change from 3.42 to 4.10 is a 20% difference. I did not lose anywhere near 20% in MPG, I lost maybe 5% tops. I'm not sure where you're coming up with these little nuggets of "knowledge" lately

I believe he was referring to the gearing in the transmission. The more gears you have, you can make the top gear really low for MPG.

 

[Patman]

Yes, and he said a 10% difference equals 10% better efficiency. Not true.

 

[dailydriver]

Originally Posted by Virtus_Probi

I am going to go look for "Formulation 1" brand oil at Walmart! Do you think it has a rebate? ;^) Although the definition of "Aged" is not given, I'm feeling good about changing oil at 5kmiles now.

Yeah, this kind of runs counter to all of those claiming harm from too frequent OCIs even with D1G2 oils, although they are referencing intake valve deposit formation, and not LSPI. I have a close ratio geared manual, so I just downshift, and let the little EcoBoost sing (as long as everything is up to operating temp).

 

[wemay]

According to Infineum's latest... https://www.infineuminsight.com/articles/passenger-cars/lspi-and-lubricant-auto-ignition/ What i also find interesting is that Conventional Grp II is more resistant than the commonly available and bought Grp III and even Grp IV Synthetics (see chart)

 

[dblshock]

what a mess.