XRI vs EFI

[Glastron1987]

From what I can tell there are three versions of the fuel injected 2.4/2.5s... XRI , EFI much like the XRI, and EFI with an air handler.

Is there any practical difference among them in terms of:
performance
fuel efficiency
maintainability
complexity
weight
reliability?

Also, what is the purpose of that air handler that older version didn't seem to need?

[David]

By EFI with air handler, do you mean the Optimax motors? The Optimax motors are far more fuel efficient and complex. They use an air pump to mix compressed air with the fuel, which results in a smaller fuel droplets that are already mixed with air when they enter the cylinder. Also, the injection is timed to enter the cylinder after the exhaust ports are closed. With conventional XRI, EFI, the gasoline is injected into the 'normal' air flow into the engine.

[25two.stroke]

Dont know what you mean xri vs efi. Xri was like a model name mercury pulled out their a** to make fuel injection sound fancy. That is technically "throttle body injection." It is electronic fuel injection and the injectors are inside the throttle body and are controlled in batches (batch injection).

During that same time period mercury's high performance engines were also "efi" but the injectors in those engines were in the crankcase. Kinda like the multiport injection of 2-strokes...but not entirely cause they injectors were still controlled with batch injection. But the crankcase is as close as you can get to the port on a 2stroke and still lubricate what is necessary; thats why I say its kinda like the concept of multiport injection (MFI) on cars.

In the 2000s mercury came out with the air plenum you are talking about on their efi (tbi) consumer motors. The injection concept was the same (in the throttle body) the only real difference was the air plenum was re-designed to help even out the air flow to all 6 cylinders. During this re-design mercury also switched over to CDM ignition and started using Motorola computers that reliably handled a lot more data. So rather than controlling the engine on a mechanical+theoretical basis (mechanical throttle advancing and ignition timing, with a theoretical advance in fuelling using the manifold pressure and rpm to "guess" the engine load) they could use real-time digital monitors like crank position, throttle position etc. With these additional monitors the engines idled better, started better and were arguably more "reliable." That being said they were also more tamper-resistant. You cant make more hp than stock easily cause all mercury's stuff is encrypted.

This is the easiest way for me to understand it. I know some people will disagree with my terminology.

Dfi came out later and is a totally different animal. Still used the same motorola electrics and sensors on the dfi engines.

[Glastron1987]

By EFI with air handler, do you mean the Optimax motors? The Optimax motors are far more fuel efficient and complex. They use an air pump to mix compressed air with the fuel, which results in a smaller fuel droplets that are already mixed with air when they enter the cylinder. Also, the injection is timed to enter the cylinder after the exhaust ports are closed. With conventional XRI, EFI, the gasoline is injected into the 'normal' air flow into the engine.

No, by EFI with air handler I mean the late model EFIs based on the parts sites. The parts sites list the DFI separately, which I take those to be the Optimaxes.

[Glastron1987]

Dont know what you mean xri vs efi. Xri was like a model name mercury pulled out their a** to make fuel injection sound fancy. That is technically "throttle body injection." It is electronic fuel injection and the injectors are inside the throttle body and are controlled in batches (batch injection).

During that same time period mercury's high performance engines were also "efi" but the injectors in those engines were in the crankcase. Kinda like the multiport injection of 2-strokes...but not entirely cause they injectors were still controlled with batch injection. But the crankcase is as close as you can get to the port on a 2stroke and still lubricate what is necessary; thats why I say its kinda like the concept of multiport injection (MFI) on cars.

In the 2000s mercury came out with the air plenum you are talking about on their efi (tbi) consumer motors. The injection concept was the same (in the throttle body) the only real difference was the air plenum was re-designed to help even out the air flow to all 6 cylinders. During this re-design mercury also switched over to CDM ignition and started using Motorola computers that reliably handled a lot more data. So rather than controlling the engine on a mechanical+theoretical basis (mechanical throttle advancing and ignition timing, with a theoretical advance in fuelling using the manifold pressure and rpm to "guess" the engine load) they could use real-time digital monitors like crank position, throttle position etc. With these additional monitors the engines idled better, started better and were arguably more "reliable." That being said they were also more tamper-resistant. You cant make more hp than stock easily cause all mercury's stuff is encrypted.

This is the easiest way for me to understand it. I know some people will disagree with my terminology.

Dfi came out later and is a totally different animal. Still used the same motorola electrics and sensors on the dfi engines.

Actually, I think this pretty directly answers my question. Thank you.

[tlwjkw]

ta put it simply... XRI was justa "marketing" badge...........................

[David - WI]

I have one of the opti-style downdraft air handlers but with the injectors in the reed plate. Looks like it ran a belt-driven alternator (judging from the flywheel cover/airbox?)

[Mrzip]

Sorry to jump in. I have a lot of Nice XRI Parts. Minus the Crank which was ruined. Thanks

[Glastron1987]

Carb, pre-reed EFI (older design and XRI), crankcase EFI (newer design), and Optimax (DFI)... I read a lot that the fuel efficiency is much better on the Optimax/DFI, but didn't either of the EFIs, especially the newer EFI design improve fuel efficiency too?

[25two.stroke]

No. Dfi was the only "fuel efficient" 2 stroke. Arguably as fuel efficient as a 4s...depending on the application.

[berdes]

Sorry to jump in. I have a lot of Nice XRI Parts. Minus the Crank which was ruined. Thanks

You have these listed on marketplace? What happened to the crank? I ask because I may need that engine, depending on if/when I get my sportjet boat back from the shop.

[Mrzip]

No I Don't. Actually forgot about it. Crank was ruined.. I have to go threw it. See what all is there.

[Glastron1987]

For the EFI (tbi), was Mercury able to do away with the bleed system entirely?

[25two.stroke]

For the EFI (tbi), was Mercury able to do away with the bleed system entirely?

No.