Thread: isuzu air filter

Originally Posted by mattmac

Been thinking of removing the inner air filter as imagine only really needed if doing extended travel on dirt/dusty roads.

That's what I've done. Actually I think I forgot to put it in on the last trip.

The inner filter is to guard against failure of the main filter, for example, if it comes loose (as has happened once to me). Hence it normally does not need replacing. It makes an insignificant restriction compared to the intake piping and main filter.

I cannot imagine any reason why anyone would want to remove this protection that the designers thought was necessary.

John

I agree with John, it probably doesn't make a difference for a NA 4BD1. It is noticeable on a turboed 4BD1 as it pulls through a lot more air.

Thanks for the reply-thought it might cause unnecessary restriction if not on dusty roads.

Originally Posted by rar110

I agree with John, it probably doesn't make a difference for a NA 4BD1. It is noticeable on a turboed 4BD1 as it pulls through a lot more air.

"A lot more air"? The power output of a typical turbo installation is probably less than 50% greater than the n/a version, and this is a measure of how much more air is passed through.

I would be interested in seeing any dynamometer results to confirm that the guard filter makes a measurable difference. Should be very easy to do if the turbo installation is dynamometer tuned.

And even if the difference is measurable, is it worth the risk, remembering that the guard element is just that - to provide filtration if the main element fails.

I also suspect the assumption that you are in a non-dusty environment anywhere in Australia is a bit suspect - even if you live in the few places that are never dusty, it is likely you occasionally drive out of them - or encounter dust from industry, demolition etc.

John

Yes. The filter service/restriction indicator triggers even after a new main element and no safety element, and after swapping the indicator.

I ended up making a bigger inlet to the filter canister which helped.

Originally Posted by JDNSW

"A lot more air"? The power output of a typical turbo installation is probably less than 50% greater than the n/a version, and this is a measure of how much more air is passed through.

Need to be cautious as power while related to airflow it can not be correlated directly. Donaldson recommend 1.5 to 3 times the cfm on a turbo diesel. This is 174cfm for NA and 290cfm to 578cfm for a Isuzu turbo diesel. This calculated at 2800 rpm. It's significantly more airflow when going to a turbo especially when you up the boost which the Isuzu handles with ease.

Had a quick look at taking the air filter out last weekend, is there an easy way to do this, or a trick to it? Turbo piping etc seems to have it wedged in there.