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Adding a turbo to N/A 4JG2

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Adding a turbo to N/A 4JG2

Postby Kevin85 » Sun Jun 07, 2020 7:16 am

I have a '96 Jap import ELF/N series motorhome, chassis code NHS69 with an n/a 4JG2.

Long story short: can I get all the turbo bits required from a bighorn for example and bolt them on? Are the cr's the same, are there any variations I should be aware of?
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Re: Adding a turbo to N/A 4JG2

Postby isuzurob » Sun Jun 07, 2020 7:53 am

It will all bolt on off a bighorn, but you run into issues with the turbo hitting the underside of the seats and cross over pipe etc, also you might have to put a oil drain into the sump for the turbo
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Re: Adding a turbo to N/A 4JG2

Postby Kevin85 » Mon Jun 08, 2020 4:37 am

yeah, I'm thinking clearance will be a big issue, but I should be able to make things fit and work. Oil return isn't an issue.

My main concern was getting enough fuel in and the compression not being different between the big horn and elf 4jg2's.

How do these injector pumps regulate the amount of fuel going in, or would it be a case of using the big horn's pump and be done with it?
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Re: Adding a turbo to N/A 4JG2

Postby Kevin85 » Sat Jun 20, 2020 4:22 pm

Anyone have any more info on this? Surely there's a 4JG2 brain out there.
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Re: Adding a turbo to N/A 4JG2

Postby isuzurob » Sat Jun 20, 2020 6:19 pm

Can run the na pump and just wind the fuel screw in, or fit a compensator to your pump or fit a complete bighorn pump if you can find one
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Re: Adding a turbo to N/A 4JG2

Postby Kevin85 » Sat Jun 20, 2020 10:55 pm

Do you know if the NA pumps are the same? The ELF is very low mileage so would prefer to keep as many of it's components as possible.
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Re: Adding a turbo to N/A 4JG2

Postby geeves » Sun Jun 21, 2020 7:11 am

turbo motors have a boost compensator which adds fuel under boost
Sanding your knuckles before starting work can help. That way you cant skin them
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Re: Adding a turbo to N/A 4JG2

Postby Kevin85 » Sun Jun 21, 2020 7:37 pm

I see.

Do you know if that's the only difference between NA and boost pumps? Hopefully I can fit the compensator onto the existing pump.
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Re: Adding a turbo to N/A 4JG2

Postby paulthepilot5 » Sun Jun 21, 2020 7:40 pm

A non compensated pump can still be run it just means fuel will not be reduced during low or no boost situations. It will be Smokey and running richer AFRs during those situations but this can be completely controlled by your right foot. Fueling can be increased on the fuel screw. Would not be worried about the minor differences in compression ratio.
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Re: Adding a turbo to N/A 4JG2

Postby Kevin85 » Sun Jun 21, 2020 10:31 pm

I understand that now, but it's not ideal having it run rich on idle/lower rpm as it's a motorhome and might be sat stationary with the engine running.

Plus, the mrs who actually owns it isn't going to want black diesel smoke pouring out of her beloved motorhome haha
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Re: Adding a turbo to N/A 4JG2

Postby geeves » Mon Jun 22, 2020 7:00 am

Or leave the fuel at a compromise where it is still smoke free at low power settings but you dont get all the benefit of the turbo
Sanding your knuckles before starting work can help. That way you cant skin them
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Re: Adding a turbo to N/A 4JG2

Postby Kevin85 » Sun Jun 28, 2020 7:30 pm

That would mean it ran lean up top?

Surely the best way to do it is to fit the boost compensator to the na pump?

If it's just a case of using a boost compensator, it makes no sense guessing the afr and running rich or lean. Rich is a waste of fuel and smokey, lean potentially makes too much heat which will be especially bad if the na motor is a higher CR. It spends a lot of it's life high up the rpm as the gearing is quite short. It will be even more important to have the fuelling right once I start towing the racecar. It definitely needs some boost before it start towing anything though!

To know where I'm at with the compensator, I need to know if there are any other differences to the pumps, or if it's even possible to bolt the compensator to the na pump.
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Re: Adding a turbo to N/A 4JG2

Postby geeves » Mon Jun 29, 2020 7:41 am

Within limitations a diesel doesnt care about air fuel ratio. It does not regulate airflow so once you have the optimum air for the fuel adding more air does not make any difference. Likewise if you add more fuel it just ends up as smoke
Sanding your knuckles before starting work can help. That way you cant skin them
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Re: Adding a turbo to N/A 4JG2

Postby Kevin85 » Tue Jun 30, 2020 1:01 am

That's a good point.. I'm used to working with petrol engines.

Are the differences between screw tuning and boost compensator so minor it makes the job not worth doing?
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Re: Adding a turbo to N/A 4JG2

Postby geeves » Tue Jun 30, 2020 7:59 am

Fuel screw adjusts total fuel. You could set it rich and remember not to put foot on floor until you have good boost but that is a crude answer. Boost compensator increases fuel with boost so its always the maximum you can burn
Sanding your knuckles before starting work can help. That way you cant skin them
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