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vitz

Direct/Port/Direct+Port Gasoline Engines

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Posted (edited)

Guys,

As far as the Direct (GDI) and Port injection (MPI) engines are considered, it is often said that the port injection engines are better in terms of the durability, ex- less bulding up of sludge on intake/exhaust valves, low cost of replacements. Problems related to GDI could become severe when mated with a turbo unit (in case of oil leaks etc).

Due to combined benefits,  many manufacturers nowadays are going for GDI and MPI combined engines....e.g. Mitsubishi Eclipse Cross 4B40 engine!!!!.

However, it seems the C-HR (8NR-FTS) still uses a GDI engine.

Why Toyota still relying on GDI? and is that indicate potential problems in C-HR in the future......

Edited by vitz

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Well the GDI+MPI combination should give you the best of both worlds, about potential issues only the time will tell I guess

 

Manufacturers doesn't give that much thought about reliability nowadays anyway, passenger safety, fuel economy and affordability seems to be the driving factors of Toyota mass production cars nowadays

 

 

 

 

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Mitsubishi 4B40 employs Direct + Multipoint injection system.  Any difference between Multipoint and Port Injection?

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Just now, Jason Bourne said:

AFAIK MPI is just another form of what we call "Port Injection"

Yeah agreed...

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Yeah agreed...
Purely on a technological standpoint though, GDI+MPI combination should trump traditional GDI systems when it comes to reliability.

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Posted (edited)

The MP injectors of GDI+MPI engines have no significant benefits for power or durability, they are just a trick to optimize the emissions and avoid having to add otherwise a costly gasoline particles filter(disadvantage if pure GDI).

Edited by ajm

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Posted (edited)
58 minutes ago, ajm said:

The MP injectors of GDI+MPI engines have no significant benefits for power or durability, they are just a trick to optimize the emissions and avoid having to add otherwise a costly gasoline particles filter(disadvantage if pure GDI).

But, MPI system adds a cleaning effect for valves avoiding carbon/sludge build up on intake valves. Of course in Pure GDI the chances of building up of carbon on intake valves are higher, if not properly tuned. 

 

Note this is a conference abstract: "A Study of GDI+MPI Engine Operation Strategy Focusing on Fuel Economy and Full Load Performance using DOE,DOI: 10.7467/KSAE.2014.22.3.042.

The gasoline direct injection (GDI) system is considerably spreading in automotive market due to its advantages. Nevertheless, since GDI system emit higher particle matter (PM) due to its combustion characteristics, it is difficult to meet strengthened emission regulation in near future. For this reason, a combined GDI with MPI system, so-called, dual injection (DUI) system is being investigated as a supplemental measure for the GDI system. This paper focused on power and fuel consumption effect by injection mode strategy of DUI system in part load and idle engine operating condition. In this study, port fuel injectors are installed on 2.4 liters GDI production engine in order to realize DUI system. And, at each injection mode, DOE (design of experiment) method is used to optimize engine control parameters such as dual injection ratio, start of injection timing, end of injection timing, CAM position and so on. As a consequence, DUI mode shows slightly better or equivalent fuel efficiency compared to conventional GDI engine on 9 points fuel economy mode as well as MPI mode shows less fuel consumption than GDI mode during idle operation. Furthermore, DUI system shows improvement potential of maximum 2.0% fuel consumption and 1.1% performance compared to GDI system in WOT operating condition.

Another One: The dual-port fuel injection system for fuel economy improvement in an automotive spark-ignition gasoline engine "https://doi.org/10.1016/j.applthermaleng.2018.04.027"

Abstract
The purpose of the present study was to investigate the performance of the dual-port injection (DPI) system in an automotive spark-ignition engine. The DPI system utilizes two port fuel injection (PFI) injectors per cylinder, i.e., one injector at each intake port. An original 4-cylinder PFI engine head was modified to accommodate total 8 PFI injectors. In the present study, three spray angles and two install configurations were investigated in the intake port visualization, steady-state part-load experiments, and cold-start experiment. The intake port spray visualization experiment showed that the wider fuel spray provided better fuel distribution, but also more wall wetting. The steady-state engine experiment at the several critical part-load conditions showed that the DPI system in combination with the open-valve-injection strategy achieved the most brake specific fuel consumption (BSFC) reduction of 4.6%. The average BSFC reduction of the 9-point experiment was 2.8%. The cold-start experiment also showed a fuel economy gain by the DPI system. In the cold-start experiment the wider spray angle exhibited higher total hydrocarbon emission likely due to the greater wall wetting observed in the intake port spray images.

Edited by vitz

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LOL, didn't AJM explain the same thing using 10 times less words? Or someone trying to prove his smart because he reads "papers"😆

 

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As far as I know manufacturers are coming up with better designs to avoid issues like carbon build-up of Direct Injection engines. Such as: better head designs, improved PCV systems, variable valve timing programming to heat-up intake valves, etc...

Perhaps Toyota has made such improvements and decided that a costly dual injection system is not justifiable for a relatively low cost car.

Also, manufactures tend to be extremely careful to avoid reputation damage to their bread-and-butter products (i.e. Toyota Corolla) but could be lenient when it comes to not so common niche products (i.e. CH-R)

 

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