Hi All

Ive come across couple of guys with fairly standard red 308s who have run a hose from the standard air cleaner to the front grille to benefit from a cooler air feed.
Question is, in a fairly standard motor, would this alone really make a difference that you would notice?

If you're running a larger opening on the aircleaner (like the VH/VK Brock type) and a suitably large cold air intake duct, then it can make a dramatic difference during slow moving, stop/start traffic, and general around town type driving, where heat soak under the bonnet becomes an issue for the air going into the carby, and there's not enough air speed to cool the engine bay.

At high speed on the open road, there's usually enough airflow within the engine bay to almost negate the need for it. The "ram air" effect of it facing the front also makes negligible difference at legal speeds, and it would be unlikely that you'd detect any difference there.

But overall, anything you can do to improve the flow of cooler air into the engine will make an improvement, with the only exception being the warm-up cycle, where warm air is desirable to aid combustion (via better atomisation) in a cold motor.

I went into more detail with my Commodore 308 experience here: http://www.fastlane.com....--torque.aspx#post170890

I was talking to Chiptorque about a V6 Hilux they dynoed. Some idiot put a snorkel on it - and it lost over 5rwkW with the addition of the snorkel (it was done before and after).

Note that these already have a cold air intake, but it is reasonably small. They suffer from heat soak in the air cleaner housing as it is attached to the top of the engine. TRD make a separate air box that sits behind the headlight (like a Commodore), and the opening in the inner guard is opened up. This mod is good for near to 8kW over the standard setup, even more when the engine is hot. I have noticed it with mine - how much more responsive it is in the morning before the whole engine bay heats up.

For a HQ I'd get hold of a VC-VK HDT style air cleaner with the bigger inlet (or just modify an original to have a bigger inlet which would give you the option of pointing the inlet where you like) and run a pipe to where you can suck cooler air. You could even try a Corvette style with twin inlets which will fit on a Quadrajet, and run pipes to both corners of the engine bay.

I would love the WB one!

The NACA scoop on the bonnet feeds in via the bonnet's plastic grille (on all VL bonnets) into the plenum, directly above where that rectangular section of duct is in the plenum.

So at speed, there would be more air coming in via that path, than what would enter from the front.
This setup was only fitted to the VL Group A as standard, but it could be ordered on any VL V8 HDT.

You can go further than that, with a "race tray" that fits under the air cleaner (sealing it up against the bonnet) and it is matched up (but not connected firmly) to a duct in the plenum to direct air down into it. The earlier race trays ran to the front - over the top of the radiator, and there was a gap between the bonnet & grille that allowed enough air in to feed the tray. With the new front design on the VL, this was no longer possible (flush-fitting bonnet) so that was the alternative.

There is another version of the "factory" VL Group A CAI that only has the front half - the rear section of the T on the end of the air cleaner is capped off - cars like the Calais Sport & the like only had the front half of the full Group A system, unless optioned up.

I did put one of those on a VC 3.3L in the early 90s. It also has a plastic duct that runs down the LH chassis rail to pick up cold air (and inspired the VL HDT one).
Didn't make much of a difference in outright power, but in slow moving traffic on hot days you could feel the difference.

Yes, it's a WB Magnum (in response to wbute's question).

HSV had an early VN cold air duct that ran through the bottom of the airbox & into the wheel-well area, in front of the passenger front wheel.
It was revised soon after when problems arose with engines taking in water - just from large puddles & the like during heavy rain.

After that all VN-VS (and most of the later ones too) Holden & HSV air box inlets were either aimed at the area behind the LH headlight (a surprising amount of air comes in around the lights) or over the top of the radiator - taking advantage of the air that comes in between the top of the grille/bumper, and the bonnet.