30 replies to this topic

[Pugley]

Had some time over the bank holiday to modify my NA airbox having searched threads back over the last few years. Hopefully, this crystalises the experiments and experience gleaned from many contributors. I know it is possible to purchase various inlet tract tuning parts but I genuinely believe that the dimensions of the existing filter and airbox are more than capable of delivering more air than the 2.2 engine requires. The surface area of a normal paper panel filter is enormous and it offers very little air resistance - plus they are easy and cheap to replace and ensure the engine only eats clean air. I wanted to hear some of the induction roar but not drown out the exhaust note or make the car too loud when on an even throttle when cruising. I discounted drilling large holes on the airbox and have tried the ensure that as much cool air from the side vent found it's way into engine whilst trying to avoid warm air from within the engine bay being drawn in. The original piece fibre of pipe was removed along with the 2 half collets fitted to hold it in. These collets were reused to secure the new inlet. I then fitted 2 Floplast drian pipe connectors into the lower section and solvent welded them in place with rings of drain pipe on the inside [attachment=19296:airbox4.jpg] 2 sections of drain pipe were cut to fit behind the side vent and "catch" maximum cool air [attachment=19297:airbox5.jpg] The "trumpet" in the upper cover was removed [attachment=19298:airbox3.jpg] And finally the airbox was installed [attachment=19299:wheelarch2.jpg] In all honesty I would say that any performance improvement is only marginal but when added to a pre-cat removal there is a very noticeable improvement across the rev range. Removal of the trumpet in the top cover simply removes a little sound damping and allows you to hear a nice induction roar at about 3000 rpm. Overall the mods make the system sound better without being noisey. I am trying to prepare the engine for the installation of the eagerly awaited 2.4 manifold so any streamlining of air in or exhaust out can only improve the situation.

[Anarchy]

Had some time over the bank holiday to modify my NA airbox having searched threads back over the last few years.

Hopefully, this crystalises the experiments and experience gleaned from many contributors.

I know it is possible to purchase various inlet tract tuning parts but I genuinely believe that the dimensions of the existing filter and airbox are more than capable of delivering more air than the 2.2 engine requires. The surface area of a normal paper panel filter is enormous and it offers very little air resistance - plus they are easy and cheap to replace and ensure the engine only eats clean air.

I wanted to hear some of the induction roar but not drown out the exhaust note or make the car too loud when on an even throttle when cruising.

I discounted drilling large holes on the airbox and have tried the ensure that as much cool air from the side vent found it's way into engine whilst trying to avoid warm air from within the engine bay being drawn in.

The original piece fibre of pipe was removed along with the 2 half collets fitted to hold it in. These collets were reused to secure the new inlet.
I then fitted 2 Floplast drian pipe connectors into the lower section and solvent welded them in place with rings of drain pipe on the inside


2 sections of drain pipe were cut to fit behind the side vent and "catch" maximum cool air


The "trumpet" in the upper cover was removed


And finally the airbox was installed


In all honesty I would say that any performance improvement is only marginal but when added to a pre-cat removal there is a very noticeable improvement across the rev range. Removal of the trumpet in the top cover simply removes a little sound damping and allows you to hear a nice induction roar at about 3000 rpm. Overall the mods make the system sound better without being noisey. I am trying to prepare the engine for the installation of the eagerly awaited 2.4 manifold so any streamlining of air in or exhaust out can only improve the situation.

That is pretty much what I have done, originally just removed the collets and fitted a bigger pipe cut at an angle. Recently I put another big hole next to it and another similar pipe and removed the trumpet.

To be honest I thought maybe there was a little less power low down but much better noise all round, in the last few days I have done the fuel pressure pipe swap which I am hoping will restore the low down torque, not sure yet

I am also considering fitting a Vectra C intake pipe, which is round not flat like the VX one, it may or may not fit but they are only £20 from Vauxhall.

Then the 2.4 manifold.

Are you on standard exhaust?

Edited by Anarchy, 25 March 2008 - 08:31 PM.

[Pugley]

Let me know how you get on with the Vectra intake

Apart from removing the pre-cat Im not sure how many horses will be freed up by the fiitting of any other system without fitting a race cat. The pipework on the standard stainless vauxall system is of the same diameter as most aftermarket systems and not particularly restrictive. A cat free system will probably give the best increase but I dont really want to re map the engine untill the there is a rock solid solution that includes the 2.4 inlet manifold and possibly an improved exhaust manifold (4into2into1)?

This link to the useful threads section on NA back boxes seems to support the evidence that exhaust systems alone dont make a lot of difference to power output - Although some of them really do sound good!

http://www.vx220.org...a...kbox&st=120

I'm happy to review this in the light of new evidence?

[jimmymac]

2 sections of drain pipe were cut to fit behind the side vent and "catch" maximum cool air

Just an observation, but would putting the scoop ends of your modified intake pipes forward facing immediately behind the side vent cause water to be sucked in to the airbox on wet days?

[Pugley]

I dont think the air scoops collect any more water than the front intake pipe behind the grille on many front engined cars. There is always the chance of some moisture entering the air filter on most cars. That is probably why there is a drain hole in the bottom of the filter box and paper filters are usually treated with a water repellant coating. I drove the car on the motorway in heavy rain for about 2 hours with absolutely no adverse effect. In fact roll-on acceleration from 80 in 5th seemed to be very crisp. Water vapour, in moderation, also actually improves the performance of most engines as the air charge is more dense. Not a design factor in this case!

[MartinS]

Can you tell me what you meant by 'in the last few days I have done the fuel pressure pipe swap which I am hoping will restore the low down torque'

I have had a lot of work done lately and it hasnt been as succesful as hoped (2.4 inlet, 4-1 manifold, bigger injectors, ITG remaps to make all work, then just 180 bhp and lowered torque, so any ideas welcome.

Martin s

Had some time over the bank holiday to modify my NA airbox having searched threads back over the last few years.

Hopefully, this crystalises the experiments and experience gleaned from many contributors.

I know it is possible to purchase various inlet tract tuning parts but I genuinely believe that the dimensions of the existing filter and airbox are more than capable of delivering more air than the 2.2 engine requires. The surface area of a normal paper panel filter is enormous and it offers very little air resistance - plus they are easy and cheap to replace and ensure the engine only eats clean air.

I wanted to hear some of the induction roar but not drown out the exhaust note or make the car too loud when on an even throttle when cruising.

I discounted drilling large holes on the airbox and have tried the ensure that as much cool air from the side vent found it's way into engine whilst trying to avoid warm air from within the engine bay being drawn in.

The original piece fibre of pipe was removed along with the 2 half collets fitted to hold it in. These collets were reused to secure the new inlet.
I then fitted 2 Floplast drian pipe connectors into the lower section and solvent welded them in place with rings of drain pipe on the inside


2 sections of drain pipe were cut to fit behind the side vent and "catch" maximum cool air


The "trumpet" in the upper cover was removed


And finally the airbox was installed


In all honesty I would say that any performance improvement is only marginal but when added to a pre-cat removal there is a very noticeable improvement across the rev range. Removal of the trumpet in the top cover simply removes a little sound damping and allows you to hear a nice induction roar at about 3000 rpm. Overall the mods make the system sound better without being noisey. I am trying to prepare the engine for the installation of the eagerly awaited 2.4 manifold so any streamlining of air in or exhaust out can only improve the situation.

That is pretty much what I have done, originally just removed the collets and fitted a bigger pipe cut at an angle. Recently I put another big hole next to it and another similar pipe and removed the trumpet.

To be honest I thought maybe there was a little less power low down but much better noise all round, in the last few days I have done the fuel pressure pipe swap which I am hoping will restore the low down torque, not sure yet

I am also considering fitting a Vectra C intake pipe, which is round not flat like the VX one, it may or may not fit but they are only £20 from Vauxhall.

Then the 2.4 manifold.

Are you on standard exhaust?

[oakmere]

[quote name='MartinS' date='Apr 23 2008, 06:53 ' post='720739']
Can you tell me what you meant by 'in the last few days I have done the fuel pressure pipe swap which I am hoping will restore the low down torque'

I have had a lot of work done lately and it hasnt been as succesful as hoped (2.4 inlet, 4-1 manifold, bigger injectors, ITG remaps to make all work, then just 180 bhp and lowered torque, so any ideas welcome.

Martin s




Do you have any graphs of your torque and power? So the injectors make little difference up to 180BHP as you had 177BHP without?

Looks like the TMS manifold is not improving the torque much when fitted with the 2.4 manifold. Roll on a 4-2-1 manifold!

Cheers Oakmere

[Winstar]

Can you tell me what you meant by 'in the last few days I have done the fuel pressure pipe swap which I am hoping will restore the low down torque'

I have had a lot of work done lately and it hasnt been as succesful as hoped (2.4 inlet, 4-1 manifold, bigger injectors, ITG remaps to make all work, then just 180 bhp and lowered torque, so any ideas welcome.

Martin s

Martin the details of the fuel pressure mod are in this thread clicky, in summary the fuel pressure is regulated by the depresson in the intake system, so if you've fitted a low pressure loss induction system then the fuel pressure will be reduce.

[oakmere]

Can you tell me what you meant by 'in the last few days I have done the fuel pressure pipe swap which I am hoping will restore the low down torque'

I have had a lot of work done lately and it hasnt been as succesful as hoped (2.4 inlet, 4-1 manifold, bigger injectors, ITG remaps to make all work, then just 180 bhp and lowered torque, so any ideas welcome.

Martin s

Martin the details of the fuel pressure mod are in this thread clicky, in summary the fuel pressure is regulated by the depresson in the intake system, so if you've fitted a low pressure loss induction system then the fuel pressure will be reduce.

]

Most people with the 2.4L Manifold have set the fuel pressure pipe back to the standard configuration because it gives a higher fuel pressure at lower revs contrary to what was originally thought!

[MartinS]

My car was done in various stages and I have to say, adding the 4-1 manifold didnt seem to reduce torque, with the 2.4 inlet added the car was as good as when it was a stage 2 until 4-4500 revs then it got better. The bigger jets and an ITG were then added and it didnt get any better at the top end and feels flat generally now. It doesnt start so well and generally feels like the fueling is wrong in some way, either to rich to to weak cant tell. The dyno show 180bhp at 6400 rpm with max torque at 170 at 4800. The two lines cross at 2200 prm. On the road my car was always exactly matched in performance to a freinds stage 3 Courtenay na, now after all the mods, it now exactly matches my freinds car still. Driving together, his would pull away until my finally got going above 5000 but even then I couldnt pull away from him and his fealt the nicer car to drive. Is it worth taking the ITG off? any suggestions welcome Martin s

[oakmere]

My car was done in various stages and I have to say, adding the 4-1 manifold didnt seem to reduce torque, with the 2.4 inlet added the car was as good as when it was a stage 2 until 4-4500 revs then it got better.
The bigger jets and an ITG were then added and it didnt get any better at the top end and feels flat generally now. It doesnt start so well and generally feels like the fueling is wrong in some way, either to rich to to weak cant tell. The dyno show 180bhp at 6400 rpm with max torque at 170 at 4800. The two lines cross at 2200 prm.
On the road my car was always exactly matched in performance to a freinds stage 3 Courtenay na, now after all the mods, it now exactly matches my freinds car still. Driving together, his would pull away until my finally got going above 5000 but even then I couldnt pull away from him and his fealt the nicer car to drive.

Is it worth taking the ITG off? any suggestions welcome

Martin s

I am surprised TMS suggested the injectors at this point of tune because the 2.4l car in the US uses the same injectors as ours and that has 177 BHP as standard?
There has been some talk that by replacing the original airbox with the top trumpet back in helps the torque curve I tried this and the car felt much soother mid-range but felt restricted top end.
It sounds to me like the map isn't correct as the ITG is on many cars with no downsides apart from to loud for some people? What did the air fuel ratio map look like? Sounds possibly like yours is running to rich.

Cheers Oakmere

[MartinS]

The injectors were changed as it was thought the car would produce over 190 bhp with the mods and the standard injectors are apparently only any good upto 185 bhp. I dont know what the fuel air mix is as I havent been given any info on that. I think it might be running rich as its certainbly drinking fuel at the moment. Martin s

[Jase_MK]

The dyno show 180bhp at 6400 rpm with max torque at 170 at 4800. The two lines cross at 2200 prm.

Aren't they supposed to cross at 5600rpm, assuming the scales on the graph are the same? Otherwise something's up with the dyno calibration?

[oakmere]

The dyno show 180bhp at 6400 rpm with max torque at 170 at 4800. The two lines cross at 2200 prm.

Aren't they supposed to cross at 5600rpm, assuming the scales on the graph are the same? Otherwise something's up with the dyno calibration?

Is the cross not due to the large dip in torque in the lower rev range?

I would get TMS to get it back on the rollers to be remaped. Are they just using the map supplied to them by superchips for Vocky?

The 2.4l TB might help if it can be sorted.

Regards
Oakmere

[Jase_MK]

The dyno show 180bhp at 6400 rpm with max torque at 170 at 4800. The two lines cross at 2200 prm.

Aren't they supposed to cross at 5600rpm, assuming the scales on the graph are the same? Otherwise something's up with the dyno calibration?

Is the cross not due to the large dip in torque in the lower rev range?

Torque and bhp are equal at 5600rpm by definition, regardless of how the engine is running. So if the two lines do not cross at that point then there is a dyno problem.

edit: It's actually 5200rpm, sorry

[Guy182]

its actually 5252 but whats 52rpm between friends. lol Torque = Horsepower x 5252 / rpm Torque = horsepower x 5252/5252 Torque = horsepower x 1 Torque = Horsepower

[simsy]

magic

Edited by simsy, 24 April 2008 - 01:43 PM.

[MartinS]

I have the rolling road dyno printout in front of me and they cross at 2200. Dont know how to post the printout. Martin s

[Winstar]

its actually 5252 but whats 52rpm between friends. lol

Torque = Horsepower x 5252 / rpm

Torque = horsepower x 5252/5252

Torque = horsepower x 1

Torque = Horsepower

for bhp and lbft

[siztenboots]

Plus there are different standards for correction factors.

To understand more ; http://www.dynamomet...ion-factors.htm