Thread: Britpart/Wolf RAI on 4BD1-T

Originally Posted by Lotz-A-Landies

Today Ben suggested that a disco snorkel would be too small on a 4BD1-T.

Out of interest, I have a Britpart raised air intake of the type that are used on the British Army Defender Wolf that I bought to use on a Rover 6 cyl in a Series.



Would it also be too small to use on a Defender with a 4BD1-T?

nope you'll be fine, so long as the intake diameter is larger than the throat on the turbo or any restriction after the airfilter its not going to be the choke point.

Originally Posted by Lotz-A-Landies

Today Ben suggested that a disco snorkel would be too small on a 4BD1-T.

Out of interest, I have a Britpart raised air intake of the type that are used on the British Army Defender Wolf that I bought to use on a Rover 6 cyl in a Series.



Would it also be too small to use on a Defender with a 4BD1-T?

The Wolfs are TD5s aren't they???

TD5s flow a lot of air - similar to a 4BD1T, so if designed correctly it will be OK, however I have never liked the look of those snorkels from a fluid dynmics perspective. It also looks like the design is the same as the 300?

Pressure drop in a pipe (turbulent regime) is proportional to V^2/D (*Length, with additional losses for each bend and change in diameter). V= velocity, D= diameter.

If a snorkel is not large enough then it will impede highway performance. As you can see from the above relationship, increasing diameter makes a big difference - as it changes both V and D for the better.

Some info here too

http://www.donaldson.com/en/engine/s...ary/034973.pdf

If there was an "ugly" variable in the pressure drop formula it would definitely be too restrictive. It looks a lot like the sewer pipe that runs down the wall of my house

I've got a mandrel bent stainless snorkel with a standard type Donaldson snorkel head on it, connected to my air filter housing with approx 60cm of that wire reinforced corrugated ducting. Snorkel, ducting, and inlet into the air filter are all 75mm diam.

I ran without the snorkel for a few months, and never had the filter restriction indicator pop on me, but since I fitted the snorkel it pops as soon as it gets a decent run, so the snorkel and ducting are definitely creating a restriction. Hopefully in my case its the ducting that's causing most of it, since that would be easy to improve.

I guess the question is how much restriction is too much? Is there a guideline for recommended maximum pressure drop that we can measure and compare to?

Steve

Originally Posted by steveG

...
I guess the question is how much restriction is too much? Is there a guideline for recommended maximum pressure drop that we can measure and compare to?

Steve

Any intake restriction on a diesel will result in less power and increased fuel consumption.

How much you are willing to live with to ensure clean air (and no water) getting to your engine is another matter. Personally I would not run the snorkel in Diana's pic. I suspect they have not been designed by anyone who understands fluid dynamics (and/or were designed for the na2.5, and have not been upgraded).

OK, Ben has set a home work assignment, so I'm guessing I need to check the airflow inputs.

Going by rolling radius X 3.54 diffs X 2.11 transfer and 5th gear @100KPH I'm calculating approx 4.4K litres/min on a NA 4BD1 engine. Are those parameters O.K.?

What is the difference (increase) in airflow with an OEM turbo?

Originally Posted by Lotz-A-Landies

OK, Ben has set a home work assignment, so I'm guessing I need to check the airflow inputs.

Going by rolling radius X 3.54 diffs X 2.11 transfer and 5th gear @100KPH I'm calculating approx 4.4K litres/min on a NA 4BD1 engine. Are those parameters O.K.?

What is the difference (increase) in airflow with an OEM turbo?

Some good info from Donaldson here on airflow requirements (on the first page): http://www.donaldson.com/en/engine/s...ary/056798.pdf

Basically double the NA airflow for turbo/intercooled.

Steve

Originally Posted by Lotz-A-Landies

OK, Ben has set a home work assignment, so I'm guessing I need to check the airflow inputs.

Going by rolling radius X 3.54 diffs X 2.11 transfer and 5th gear @100KPH I'm calculating approx 4.4K litres/min on a NA 4BD1 engine. Are those parameters O.K.?

What is the difference (increase) in airflow with an OEM turbo?

Intake Airflow (CFM) = (engine size (CID)*rpm/3456)*VE

VE for a properly set up 4BD1T = ~2

So that gives you almost 500 CFM at 3500 rpm.