Airbox sizing

[blackmav]

Just looking at a Donaldson airbox and on their site it says multiply engine horsepower by 2.5 to find out what CFM it needs.
If a Patrol TD42 turbo made 100kw=134hp x 2.5=335CFM

That would mean that this box would be too small, I am pretty sure I am missing something.

http://www.westernfilters.net.au/produc ... cts_id=966

[KiwiBacon]

Donaldson ratings are very conservative. If they say it will work then it will work in the worst conditions you'll ever encounter.

335cfm is correct for a TD42T at 4000rpm with 12psi boost and no intercooler.

[dogbreath_48]

Donaldson ratings are very conservative. If they say it will work then it will work in the worst conditions you'll ever encounter.

335cfm is correct for a TD42T at 4000rpm with 12psi boost and no intercooler.

Have you any idea of a maximum acceptable or average pressure drop, as a guide?

[KiwiBacon]

Donaldson ratings are very conservative. If they say it will work then it will work in the worst conditions you'll ever encounter.

335cfm is correct for a TD42T at 4000rpm with 12psi boost and no intercooler.

Have you any idea of a maximum acceptable or average pressure drop, as a guide?

Somewhere deep in the donaldson literature you'll find the pressure drop that their flow ratings are given at.
Unfortunately I don't have the space I need to run the donaldson filter I want, so I run a home-made casing with a LC100 filter element inside. I do run a donaldson informer on the top which shows maximum pressure drop in your filter. Takes out all the guesswork.
This PDF for the donaldson informers has some recommended maximum pressure drops. They're quite high, up to 5kPa.
http://www.donaldson.com/en/engine/supp ... 053979.pdf" onclick="window.open(this.href);return false;

I just checked mine and it's sitting on 2kpa as the max pressure drop it's experienced, which is the first notch it reads. This is pulling 20psi boost up to the rev limit so I'm okay with that.
This pressure drop includes about 2 feet of 2.25" pipe which the intake pulls through.