Nissan aims for "more complete burn" with new injectors

[MetroMPG]

Nissan is modding its gas engines for 2010 with dual, "regular" pressure injectors (one per port) instead of a single injector.

This reduces the diameter of the fuel droplets by about 60%, resulting in smoother, more stable combustion.

(Left: One port of the Dual Injector Right: Conventional system injecting to both ports)

Source: NISSAN | Nissan Introduces New Dual Injector System for Improved Fuel Efficiency in Gasoline Engines

How much better?

They don't quantify gains for the change in the fuel injectors alone, but in combination with variable exhaust timing, say it's worth a ~4% improvement compared to similar Nissan gas engines without the mods.

This is in line with what Tony has reported at fuelsaving.info on research into optimized fuel vaporization, where "the saving is a couple of percent at best."

Source: Fuel saving gadgets - a professional engineer's view

Interesting side effect: that couple of percent improvement in the burn will permit Nissan to reduce the amount of rare (ie expensive) metals in the catalyst while maintaining its effectiveness.

[Daox]

Makes sense. Many manufacturers have been doing the exact same thing with each consecutive model they bring out. Smaller droplets of fuel vaporize quicker due to more surface area. This leads to faster combustion which is more efficient.

[MetroMPG]

Another example of the longer ladders coming out. It's not exactly low hanging fruit.

To me, the most interesting bit was that it supports what Tony had reported about the magnitude of the gains to be had.

Some more hard facts to point when someone claims to have come up with a scheme for getting huge gains through "more complete combustion".

[ConnClark]

Variable exhaust timing is more likely responsible for most of the gains. There isn't much room to improve on burning more fuel on a modern engine.

EDIT: one more technology that has been proven to work is electrostatic fuel injectors http://www.sae.org/technical/papers/2000-01-2041

If 2 to 3 percent improvement in mileage were possible from better atomization alone they would be doing already.

[gone-ot]

...the "new" Toyota 2ZR-FE 1.8L engine is Spark-Ignition Direct Injection (SIDI) which is combination of diesel-like injection directly into the cylinder but using normal spark ignition, rather than compression-ignition. One side benefit is that slightly higher compression ratio is possible (better economy and power) because (a) only AIR travels through intake manifold and past the values, and (b) fuel vaporization occures inside the cylinder and cools the charge mass.

...Toyota has an Japan-SAE paper out on development of this engine.

...GM implemented same thing on the 260 HP 2.2L turbo engines in HHR, Cobalt and Solstice.

[tjts1]

The dual angle injectors have been around for at least 10 years now. I assume most cars on the road already had them. A lot of people driving older bmws are switching their single pintle style EFI injectors to disk type 4 hole injectors. For cars with Bosch components, its a drop in replacement.

Left EV6 20# injector from a 2000 GM/Opel vs right EV1 injector from a 1991 bmw


The 4 holes in the injector nozzle are cut with a lazer which can be set at any angle the manufacturer requires. The injector can be optimized for the specific port design my the angle the laser is set for each of the 4 holes. Most people converting to these injectors report a very slight reduction in fuel consumption. The only trick is to find a donor that has the same size injectors and similar port design to your vehicle. A lot of these injectors are starting to show up in the JYs.

More info on specific Bosch injector nozzle spray patterns.
Bosch Motorsport - Injection Valves

[beatr911]

Sport motorcycles have been using the dual injectors for some time. I think this was to achieve better driveability at lower speeds and maintain the awesome top-end power they now make. A single injector is used under say 6000 rpm and above that the second is added.

Our 2002 Honda Odyssey has air-assist injectors from the factory. I can only imagine that other Honda products have this same injector technology. It is interesting to note that the air assist is only used during warm-up, presumably to reduce emissions. I've been wondering what would happen if I rigged the air assist to work 100% of the time. I'm guessing Honda has already tried that with no improvement.

Still a 4% incremental improvement from improved injector design is nothing to sneeze at. Smokey Yunicks vapor engine makes one think and Naturalextraction that visits here is doing some interesting work in fuel phase change. Intuitively, if all the fuel injected were in a truly burnable state, meaning completely mixed with air in a stochiometric ratio, catalytic converters would not be dealing with reducing HC, it would be entirely spent during combustion. Seems there is still room for improvement.

tjts1, nice photo. Some of those injectors don't look so effective. It would be interesting to know what improved injectors are available for older vehicles, like the BMW example that was mentioned. You know, like a plug and play upgrade guide for us with the old pintle style.

[tjts1]

Originally Posted by beatr911

tjts1, nice photo. Some of those injectors don't look so effective. It would be interesting to know what improved injectors are available for older vehicles, like the BMW example that was mentioned. You know, like a plug and play upgrade guide for us with the old pintle style.

The ones I'm familiar with are European cars with Bosch injectors for one kind or another. Fords from the late 90s used the 4 hole Bosch injectors and a handful of GMs as well. All Bosch injectors no matter what car they went into were one of 2 standardized physical sizes. Ignoring the spray pattern for a moment, a 20# Bosch injector from a Ford Crown Vic will work just as well in a Volvo, Saab, BMW, Mercedes etc as long as they also used 20# injectors. The spray pattern makes a minor difference in fuel economy, peak power and drivability but is not absolutely critical. Seek out injectors from a car with a similar port design and single cyl displacement as your own. So for example a 20# Bosch injector from a 4.6 liter 32 valve V8 (575cc cyl) 1999 Ford will make a good replacement for a 2.3 liter (575cc cyl) 4 cyl 16 valve 1989 Volvo that also requires a 20# injector.
The EV1 style injector with a single needle like pintle was designed in the 60s while the EV6 hit the market in the mid 90s. There is a good bit of R&D between the two yet one will swap right into the place of the other.


Injector size and aplication lists.
Stan Weiss' - Electronic Fuel Injector (EFI) Flow Data Table
WitchHunter Performance - Injector Cleaning & Flow Testing Services
ASNU Fuel Injector cleaning by post

More injector info.
ZETEC RACING CLUB › News › ZX2 Fuel Injector Guide

Most of this stuff applies to Bosch injectors but similar generational changes happened with Denso and other Japanese manufacturers. I just don't know the specifics.

[cfg83]

tjts1-

Could I get those for my 1999 Saturn SW2, with the same flow rate characteristics?

CarloSW2

[tjts1]

I'm not really familiar with most GM injectors. What you can do is remove your stock injector or find an identical one at the JY, note the part number stamped on the side, the type of nozzle (single pintle, 4 hole etc) measure the resistance across the 2 pins in the electric plug and measure the distance between the 2 rubber O rings at each end. Then you can determine if there is an upgrade available for your car. Generally speaking for cars using Bosch injectors, the cut off around 1995-1997 when pretty much all cars switched from EV1 style to EV6 style. GM didn't use bosch injectors in most of its cars but they might be compatible.

A couple more articles on injector swaps for fuel economy.
http://autospeed.com/cms/A_110767/article.html
http://autospeed.com/cms/A_0102/article.html

EDIT: I forgot to mention that the resistance across the 2 pins on the injector is VERY important because there are 2 families of injectors. Low impedence (less than 10ohm) and high impedance (10-16ohm). These 2 families of injectors should never be mixed. If you car has low impedance injectors, ONLY swap low impedence injectors. If your car has HIGH impedance injectors, ONLY swap high impedance injectors. This is VERY IMPORTANT! You can damage your ECU if you mix the two. Always check the resistance. The vast majority of cars built in the last 20 years use high impedance injectors. But you never know for sure until you check. You can move around inside each family of injectors. For example you can safely replace at 14ohm injectors with a 12ohm injector. But you can't use a 2ohm injector in a 10ohm or higher stock injector car.
More info
http://www.hondata.com/techlowohminjectors.html