Cone air filters

[gazzab]

I have the cone air filters on my 4.5. The F1 style ones.
I still have the front section of the air induction system (not the front mouth bit) attached on mine ie no hoses and no paper air filter. Prev owner refitted this bit as he felt the air pressure under the bonnet increased etc...
Anyone ever removed this bit?

[ridds]

I'd leave it there Gary, the more cold air you get to your filters the better.

Hot air gathering under the bonnet when in traffic etc will do nothing for low engine speed, high intake temp combustion detonation (which these suffer from very badly).

Got any pics of these filters? I am currently looking at making some modded air boxes and intake pipes with some guys from work.

[gazzab]

They are just the BMC F1 ones?

[ridds]

Found 'em. Just wan't sure if they were enclosed.

Really need a direct cold air feed for these engines. The position of the rad etc does nothing for charge air temps.

[gazzab]

Joolz has experimented with filters and under bonnet temps and reckons the cone filters are ok temp wise compared to the standard set up.
Carbon al does a set up for enclosing the cone type and giving them a direct feed.

[trackcar]

yeah, the slightly higher air temps are insignificant compared to the restrictive dirt build up on the std filter... ie a pair of cones in the engine bay gives you good hp for longer than the std air filter which clogs quickly and can easily cost you 20bhp towards the 12k service!

[ridds]

Even when sitting in traffic etc?

Dyno work I do on other engines show charge air temp to be critical if you are running anywhere near to the engines Det limit. I know mine was det-ing quite badly over the weekend on pullaway when heat soaked for a while.

[trackcar]

ridds said:

Even when sitting in traffic etc? Dyno work I do on other engines show charge air temp to be critical if you are running anywhere near to the engines Det limit. I know mine was det-ing quite badly over the weekend on pullaway when heat soaked for a while.

you don't often need full power whilst sat in traffic, and the air temp is inflated by the heat soak from the hot exhaust manifolds radiating and convecting to the large plenums where the air is slow moving. The effect of the inboard air filters is surprisingly small compared to the obvious shortcomings in the rest of the system.

[ridds]

Wasn't so much the full power but more the high load that the engine is under during pullaway, high load at say 1500 revs/min. Saying that those manifolds radiate so much heat that it probably doesn't matter what you do with the intake air as it'll be toasty once in the airboxes.