Removing the air box cover....
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Joined: Jun 2001
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From: West Mids.
I don't think there are any arguments here. There are no power gains with removing the lid, but almost certainly a slight loss due to the fact that the open lid allows the filter to draw hot air from under the bonnet, by-passing the stock intake. Having said of all of that it does sound awesome 
I ran mine with the lid off for a few days but found the noise a little too raucous for my tastes. There's also a high pitched whistling sound on tick over which I didn't like but which is harmless and common to all cars when you remove the lid.
The stock intake really sucks IMHO as it draws air from right over the top of the hot rad. I am still looking at various CAIs which I think is the real answer. Any power gains are likely to be very marginal, but I'm coming to the conclusion that a lot of the ''bogging' idling problems people have in stop start traffic are due in large part to the stock intake. The Spoon version is a thing of beauty IMHO but rather expensive!
I ran mine with the lid off for a few days but found the noise a little too raucous for my tastes. There's also a high pitched whistling sound on tick over which I didn't like but which is harmless and common to all cars when you remove the lid.The stock intake really sucks IMHO as it draws air from right over the top of the hot rad. I am still looking at various CAIs which I think is the real answer. Any power gains are likely to be very marginal, but I'm coming to the conclusion that a lot of the ''bogging' idling problems people have in stop start traffic are due in large part to the stock intake. The Spoon version is a thing of beauty IMHO but rather expensive!
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Joined: Jun 2001
Posts: 7,446
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From: West Mids.
That's in effect what The Spoon one and others do. I've actually thought about doing something like this. A minor cautionary note. The Spoon intake actually faces forward at the intake end behind the grill. The cold ram air benefits are obvious. I have a minor concern that the forward facing intake could suck water into the engine in heavy rain particularly when VTEC ing. There are water traps in the stock air box, so I'm probably being over cautious, but we may well be talking void warranty and a new engine! Mingsters CAI is similar to the Spoon one but is in effect a simple extension from the stock intake which makes a 90 deg bend over the top of the rad and draws air from behind the grill. The intake does not face forward but points downward. Far less risky.? The dangers of running into any depth of standing water with either system would be obvious!!
Biker 1 and others have made their own CAIs. Why don't some of you engineering types apply a little thought to this it can't be that difficult?
Mingsters CAI is similar to the Spoon one but is in effect a simple extension from the stock intake which makes a 90 deg bend over the top of the rad and draws air from behind the grill. The intake does not face forward but points downward. Far less risky.? The dangers of running into any depth of standing water with either system would be obvious!! Biker 1 and others have made their own CAIs. Why don't some of you engineering types apply a little thought to this it can't be that difficult?
Joined: Sep 2001
Posts: 6,524
Likes: 88
From: Soham Cambridgeshire
Cedric
I see what you mean regarding water ingress , a problem with earlier Astra's I seem to remember thier first apperance on the RAC rally ended on the first stage
But for the weekend and high fine days drivers this could be the solution , and if the actual air intake was at the top of the aperture it would need some pretty careless driving to attempt to take a stook through that much standing water ! , unless of course it was unseen !!
When number one son comes back from uni for a while, will get him on the Auto Cad to firm up some of my fag packet sketches , have also designed a front turret brace got to spec aluminium and check with brother as to ease of machining ect . Intend to manufacture from 30mmx30mm bar and machine to improve weight and looks . How about colour coded anodising to match car oo er .
But if interested will let you know any further developments , I think cost will be less than those advertised eslewhere hopefully !
Have other ideas but often get carried away , depleated uranium to to improve 50/50 weight distribution as used by Boeing
I see what you mean regarding water ingress , a problem with earlier Astra's I seem to remember thier first apperance on the RAC rally ended on the first stage
But for the weekend and high fine days drivers this could be the solution , and if the actual air intake was at the top of the aperture it would need some pretty careless driving to attempt to take a stook through that much standing water ! , unless of course it was unseen !!
When number one son comes back from uni for a while, will get him on the Auto Cad to firm up some of my fag packet sketches , have also designed a front turret brace got to spec aluminium and check with brother as to ease of machining ect . Intend to manufacture from 30mmx30mm bar and machine to improve weight and looks . How about colour coded anodising to match car oo er .
But if interested will let you know any further developments , I think cost will be less than those advertised eslewhere hopefully !
Have other ideas but often get carried away , depleated uranium to to improve 50/50 weight distribution as used by Boeing
Joined: Apr 2001
Posts: 7,653
Likes: 4
From: The Beautiful South
Originally posted by CHIPPO
It was interesting to note that my standard air filter was dirty after only 3100 miles from new , can a better filter to fit in place of the standard be obtained ie K&N ? and maybe with a less restricted air flow and more BHP
It was interesting to note that my standard air filter was dirty after only 3100 miles from new , can a better filter to fit in place of the standard be obtained ie K&N ? and maybe with a less restricted air flow and more BHP
Joined: May 2001
Posts: 3,332
Likes: 2
From: On a fencepost
I was actually avoiding this thread... I understand about liking the noise, but my mind knows it's not the best thing for the engine. Anyway, I've decided to do quite a long post, detail what I've learned and my opinion on all this.
What are the effects of removing the cover?
- Noise
You'll get much more pronounced induction noise when with the cover removed, which is why most people remove it.
- Power loss when you're car's warm. You're intake air temperature can easily rise beyond 50 degrees C with the cover off. That's enough to lost quite a bit of power. You lose something like 1% air density (and therefore potential power) for every 3 degrees of temperature. So even in the current weather you could be losing ~10% peak power. Whether this is something you notice, and whether it bothers you is up to you.
What's the airbox there for anyway?
- For reducing induction noise.
- To protect the air filter, both from excess particulates, and water.
- The partition is there for a few reasons as well. It stops water intake - that's why there's the drain whole in the first section. It also has a quite an impact on induction noise. Removing the partition increases induction noise at a slight increase of water ingestion. I have had both some water, and all sorts of crap in this section. The biggest was actually a crushed flat empty 10 pack of Lambert and Butlers. I'm serious on that one - I have no idea how it got past the air guide etc and in there...
I personally, don't plan on running without the cover as the power is more important to me than the induction noise. What I would like people who run without the cover to consider is uprating their filters. I run a JR filter. Either the K&N or the JR filter are more likely to save the engine that the stock paper one should the worse happen. They also increase induction noise as well, and last the life of the car with cleaning/reoiling. The JR has dynoed a little better (it has a pronounced bellmouth which is a little better for airflow), but the power difference from either is minor.
What's the business with cold air intakes?
- As Cedric's posted, the 'bill' on the stock air box isn't really long enough. The airbox takes some of it's air from the radiator exhaust, while some cold air gets in past the air guide, and through the slots in it.
- There are 2 main current design approaches to CAI's what I'd call short and long ducts. (I'm ignoring the new Comptech CAI, as I'm not sure it will fit RHD cars.)
:- Short ducts, are designed to come out in, or around the main bumper. I'd include the Mugen CAI (both versions), Spoon duct and Mingsters blatant Spoon clone, erm tribute
:- Long ducts. These replace the stock intake tube with there own tubing, and have a longer duct to place the inlet either underneath the car, or down in front of one of the front wheels.
So what's the difference/benefits of the two approaches?
- Short ducts
:- These don't change the length of the inlet duct to the throttle body. The length effects the tuning inlet side of the engine. Varying this length, is like tuning the length of throttle bodies but to a lesser extent. Short ducts leave the tuning as Honda developed it. This effect is due to wave effects as the different cylinders draw air through the inlet manifold.
:- On some types, small amount of positive pressure at speed. It's been noted that both the earlier Mugen CAI, and the Spoon (and it's -ahem- tributes), create a small amount of positive pressure at speed. So above ~60mph you get a small power advantage.
:- On the later Mugen CAI, the intake appears to be inside the front bumper duct, but not visible from the front. I say appears, because I've not seen pictures of a new style Mugen CAI installed. From what I read about the new design, it creates as much power as the old Mugen CAI did when the front number plate was there. Since we pretty much have to run with a front plate in the UK, this isn't a big deal. The big benefit was the chance of water ingestion was greatly reduced.
- Long ducts.
:- These do change the length of the inlet duct to the throttle body. Hang on you, say, he's just cited not changing this as an advantage for the short ducts. Well, it's a tuning issue as I said. If you look at the dyno's for the AEM CAI, then you'll see an interesting 'bump'. This is due to waves in the air intake combining due to a function of the length of the tubing, and the engine rpm. One possible negative effect is that generally the gains from these intakes are dropping off at higher rpms. So you don't get as big an advantage over stock. This can give a psychological feeling of the engine losing power, or feeling breathless at high rpm. You might like this effect, you might not.
:- Bigger chance of water ingestion. Still a very small chance, unless you're driving through big puddles, fords etc.
What's the big idea behind CAI's anyway?
- Warm air is less dense than cooler air. Less dense means less oxygen. Less oxygen means you can burn less fuel. Less fuel burning means a smaller bang. Smaller bang means less power.
- When the air/fuel mix for the engine is warmer, it increases the chance of detonation. This forces the ECU to retard the ignition to avoid this. This also reduces power.
So I just need to get cold air to the filter and that's it isn't it?
- Erm... no. It's not quite so simple. Cold air will help keep consistent high power from your engine, but won't by itself keep a consistent air/fuel charge temperature.
- The inlet manifold and throttle body run hot. They are heated by engine coolant to prevent icing in extreme cold weather. Normally airflow cools them somewhat, but they are still pretty hot. Worst, is that when you sit in traffic, or idling they heat up to close to engine coolant temperature - around 100 degrees. It takes a while for increase airflow when you open the throttle to cool things down again. Note that the ECU's air temperature sensor is in the inlet manifold. The heating here, is one thing that contributes to the sluggish feel in traffic. Warm air intake is a bigger factor, but the inlet manifold, inlet tube and air box temperatures all have an effect as well. You can help this - Hondata Intake Manifold Gasket, Coolant channel bypasses etc, but it's more involved. The cooler running thermostat/thermoswitch/rad cap packages from Spoon/Mugen and others help a bit as well.
Of course, you could just make an XViper style radiator mat. You can buy the proper Motorsport mat material for about
What are the effects of removing the cover?
- Noise
You'll get much more pronounced induction noise when with the cover removed, which is why most people remove it.- Power loss when you're car's warm. You're intake air temperature can easily rise beyond 50 degrees C with the cover off. That's enough to lost quite a bit of power. You lose something like 1% air density (and therefore potential power) for every 3 degrees of temperature. So even in the current weather you could be losing ~10% peak power. Whether this is something you notice, and whether it bothers you is up to you.
What's the airbox there for anyway?
- For reducing induction noise.
- To protect the air filter, both from excess particulates, and water.
- The partition is there for a few reasons as well. It stops water intake - that's why there's the drain whole in the first section. It also has a quite an impact on induction noise. Removing the partition increases induction noise at a slight increase of water ingestion. I have had both some water, and all sorts of crap in this section. The biggest was actually a crushed flat empty 10 pack of Lambert and Butlers. I'm serious on that one - I have no idea how it got past the air guide etc and in there...
I personally, don't plan on running without the cover as the power is more important to me than the induction noise. What I would like people who run without the cover to consider is uprating their filters. I run a JR filter. Either the K&N or the JR filter are more likely to save the engine that the stock paper one should the worse happen. They also increase induction noise as well, and last the life of the car with cleaning/reoiling. The JR has dynoed a little better (it has a pronounced bellmouth which is a little better for airflow), but the power difference from either is minor.
What's the business with cold air intakes?
- As Cedric's posted, the 'bill' on the stock air box isn't really long enough. The airbox takes some of it's air from the radiator exhaust, while some cold air gets in past the air guide, and through the slots in it.
- There are 2 main current design approaches to CAI's what I'd call short and long ducts. (I'm ignoring the new Comptech CAI, as I'm not sure it will fit RHD cars.)
:- Short ducts, are designed to come out in, or around the main bumper. I'd include the Mugen CAI (both versions), Spoon duct and Mingsters blatant Spoon clone, erm tribute
:- Long ducts. These replace the stock intake tube with there own tubing, and have a longer duct to place the inlet either underneath the car, or down in front of one of the front wheels.
So what's the difference/benefits of the two approaches?
- Short ducts
:- These don't change the length of the inlet duct to the throttle body. The length effects the tuning inlet side of the engine. Varying this length, is like tuning the length of throttle bodies but to a lesser extent. Short ducts leave the tuning as Honda developed it. This effect is due to wave effects as the different cylinders draw air through the inlet manifold.
:- On some types, small amount of positive pressure at speed. It's been noted that both the earlier Mugen CAI, and the Spoon (and it's -ahem- tributes), create a small amount of positive pressure at speed. So above ~60mph you get a small power advantage.
:- On the later Mugen CAI, the intake appears to be inside the front bumper duct, but not visible from the front. I say appears, because I've not seen pictures of a new style Mugen CAI installed. From what I read about the new design, it creates as much power as the old Mugen CAI did when the front number plate was there. Since we pretty much have to run with a front plate in the UK, this isn't a big deal. The big benefit was the chance of water ingestion was greatly reduced.
- Long ducts.
:- These do change the length of the inlet duct to the throttle body. Hang on you, say, he's just cited not changing this as an advantage for the short ducts. Well, it's a tuning issue as I said. If you look at the dyno's for the AEM CAI, then you'll see an interesting 'bump'. This is due to waves in the air intake combining due to a function of the length of the tubing, and the engine rpm. One possible negative effect is that generally the gains from these intakes are dropping off at higher rpms. So you don't get as big an advantage over stock. This can give a psychological feeling of the engine losing power, or feeling breathless at high rpm. You might like this effect, you might not.
:- Bigger chance of water ingestion. Still a very small chance, unless you're driving through big puddles, fords etc.
What's the big idea behind CAI's anyway?
- Warm air is less dense than cooler air. Less dense means less oxygen. Less oxygen means you can burn less fuel. Less fuel burning means a smaller bang. Smaller bang means less power.
- When the air/fuel mix for the engine is warmer, it increases the chance of detonation. This forces the ECU to retard the ignition to avoid this. This also reduces power.
So I just need to get cold air to the filter and that's it isn't it?
- Erm... no. It's not quite so simple. Cold air will help keep consistent high power from your engine, but won't by itself keep a consistent air/fuel charge temperature.
- The inlet manifold and throttle body run hot. They are heated by engine coolant to prevent icing in extreme cold weather. Normally airflow cools them somewhat, but they are still pretty hot. Worst, is that when you sit in traffic, or idling they heat up to close to engine coolant temperature - around 100 degrees. It takes a while for increase airflow when you open the throttle to cool things down again. Note that the ECU's air temperature sensor is in the inlet manifold. The heating here, is one thing that contributes to the sluggish feel in traffic. Warm air intake is a bigger factor, but the inlet manifold, inlet tube and air box temperatures all have an effect as well. You can help this - Hondata Intake Manifold Gasket, Coolant channel bypasses etc, but it's more involved. The cooler running thermostat/thermoswitch/rad cap packages from Spoon/Mugen and others help a bit as well.
Of course, you could just make an XViper style radiator mat. You can buy the proper Motorsport mat material for about
Registered User
Joined: Sep 2001
Posts: 5,373
Likes: 1
From: Lagru
[QUOTE]Originally posted by Lotusman
[B]On the topic of small mods do many S2000 owners put sports exhausts on their cars..and if so what are the best ones to buy. Is the car loud enough without the exhaust...don't want it to sound like a metro on E
[B]On the topic of small mods do many S2000 owners put sports exhausts on their cars..and if so what are the best ones to buy. Is the car loud enough without the exhaust...don't want it to sound like a metro on E
Joined: Sep 2001
Posts: 6,524
Likes: 88
From: Soham Cambridgeshire
Bmarshall ,
Thanks interesting reading , I hope you use more than my 2 fingers (sore)
Any way , it seems that you have firmed up a number of my suspicions , re power water ect and I just might now sorce a new filter .
Obviously the CA1 type you suggests needs a buck or mould and would be made in Fibre Glass or Carbon ect , but what about a fabricated aluminium one , will have to look and see exactly how much room is available , perhaps use of the old plastercine ball might come in handy for this .
Will post when I find time to look and think about it
Thanks interesting reading , I hope you use more than my 2 fingers (sore)
Any way , it seems that you have firmed up a number of my suspicions , re power water ect and I just might now sorce a new filter .
Obviously the CA1 type you suggests needs a buck or mould and would be made in Fibre Glass or Carbon ect , but what about a fabricated aluminium one , will have to look and see exactly how much room is available , perhaps use of the old plastercine ball might come in handy for this .
Will post when I find time to look and think about it
