[bigbigboy88]

i've got a 3.0 omega, the air filter need replacing soon, i can get a performance filter either K&N or green or around £40 just a panel filter, is it worth spending the extra money and di you think it will make a difference in performance as it is doing 210bhp already? cheers mat

 

[trebor]

Hi. All these Omega owners coming out of the woodwork!!

I have 2.5CDX and use a K&N Cone Filter. Which I proved (on a rolling road) to make more power all through the rev range.

No doubt there will be others who disagree and will recommend a panel filter. I can only tell you my own experience with this engine.

ALso get rid of the complete "MUlti Ram intake" system and replace with a single pipe... WHAT A DIFFERENCE this makes to throttle response and power

 

[Stuart]

I give the K&N element the thumbs up as well, although avoid the pipercross induction kit. Bad move

Removing the dual ram would be interesting, have you done it? if so whats your replacement like?

 

[trebor]

I actually use a K&N CONE Filter basically making it a K&N induction kit...

Yes, indeed I have taken the multiram pipes off and it makes a BIG difference, though it could do with setting up properly with more fuel.

The MultiRam pipes are just a gimmick by Vauxhall, and I have noticed no loss in low down performance, general running, or fuel economy.

In fact I use most of original pipes along with some drainpipe!!! from B&Q. The cone filter thus sits right in the bottom left hand corner of the engine bay, where the original cold air pipe comes into the airbox, and is above a hole in the wing (under where the original airbox is)

 

[Stuart]

any pictures?

 

[tomstickland]

Ram induction is a waste of time. Even at 100mph the pressure gain is a fraction of a percent!

Anything that gets cold air in is good, the bigger the better up to a point. I calculated that about 2.5" diameter was as large as you needed for virtaully zero pressure loss on the the air flow for about 150BHP, going on up to 3" for 200BHP and so on. But it will rise to the 1/4th power of the engine power, so about 3" would do any car on this bboard.

 

[Stuart]

There must be a fine line between breathing easily and having too much of an airflow. I've played about with cone filters, elements, no elements and performance varies between great and pathetic, pathetic is always when something changes to increase airflow dramatically.

Either that or is air temperature more of an important factor? I know the colder the better, but what will hinder performance more, hot air or too much air?

 

[trebor]

Increasing the airflow is only the half the story, the other half is to get the fuel in to match the increase in air. You can't have too much airflow, except when it makes the engine too lean...


(Check your accelator linkage, 'cause when garages change the plugs, they remove it to gain easier access to plug. Get someone put their foot on the pedal whislt you make sure that the linkage is fully against the "stop".)

Can try to get you a picture of shortened pipes, prob is that it is a bit of a bodge job!!!

 

[tomstickland]

As Trebor says, you only have "too much air flow" if the ECU can't cope with it and makes the engine run lean. Not a likely occurence with just filter / box mods. The the standard air flow meter should sense the extra air flow and increase the fuelling to match. I mean there must be a 3-4% variation between "identical" engines.

I wouldn't expect to increase air flow by more than 4-5% by doing filter swaps and ducting etc. Depends on the particular engine since some have more restrictive air filter systems than others.

But a trip to the rolling road with a probe shoved up the pipe would prove all of that out.

Cold air is defintely what's required, heat lowers the density so you're getting less mass flow.

 

[trebor]

That's what I did, standard engine pushed out 168BHP (bang on the money) but fuelling was weak, tracked prob to accelator not fully open - once corrected 171BHP.

K&N cone filter instead of standard airbox = 175BHP but still running slightly weak. I know I will get a gain in BHP if I increase the fuelling - probably by uprating the Fuel Regulator or maybe Unichiping it???