Re-map, air intake, ITG filter

[Bill]

Hey guys. So as some of you may be aware I firstly fitted an after market air-scoop and removed the lip from the internals of the original intake.\


Next up was a remap done by Surrey Smart Centre in Croydon, which made a huge difference to power in the turbo range. Still gave great mpg and was as smooth as stock in the lower rev ranges.

Today I fitted an ITG performance air filter before I set off on my commute into London from Brighton.

The air filter has altered the car a lot!!! It hasn't increased performance more in any shape or form. On the original filter it felt free spinning and very nippy with the only gripe being the very initial pick up from stand still being a touch sluggish compared to once moving.

The new filter has taken away some of the free/nippyness it had and given it a more broad acceleration so not as quick but more even. I'm not sure if fuel consumption has changed for the worse until the tank is empty but have a feeling its used more fuel than before.

I know I fitted a performance filter on an old BMW 535 I had which made it worse, and know its often the case that it ruins a cars performance.

Am going to give it till the end of this tank of fuel then swap back and feel the difference again.

I guess I was just hoping it would be appreciated by the engine because of what I've already done but am thinking not lol.

Any comments much appreciated

[RacingSnake]

I'm a great fan of ITG stuff - I've used their filter in all of our smarts, and had a custom one for the roadster.

[tolsen]

Interesting post Bill. Supports my conclusion after lots of tests and analysis that free flowing air filters have and adverse effect on performance: 450 Inlet Duct Losses.

[cougar7609]

Have you tested this on the petrol version? Im wondering if it is the inherent properties of the diesel engine that causes your results. It would be interesting to find out if it applies to the petrol as well. Could you do a test on one?

[Bill]

Having thought about today and how it has made the car feel worse I'm putting the original filter back in tomorrow (look out for a cheap ITG filter on the bay).

[Ocracoke]

I tried a ITG Filter, K&N filter and a standard air filter on my 600cc. While both the ITG filter and the K&N filter sound as if they are better than the standard filter, I would probably stick with a K&N filter. The ITG filter fits in the airbox but only just so I guess only 90% of the area is being used to filter the air. The K&N filter fits better so I would probably go back to that.

[tolsen]

Have you tested this on the petrol version?

I have no petrol Smart that I can test but one can do a fairly accurate estimate: 0.7 litre petrol 450. 4500 rpm, 0.8 bar turbo boost, ambient air temperature 14 C. Assume petrol engine is just slightly lower on volumetric efficiency than the diesel, i.e. 70% as opposed to 75%. Free air flow becomes 30 litres per second. Air intakes on the petrol and diesel are essentially identical, hence one can estimate vacuum in TIK pipe just in front of turbo by extrapolation and arrive at 225 mm H2O. Total inlet duct loss between air intake at side to turbo compressor becomes thus 0.0030 [m3] x 2250 [Pa] = 68 Watt or 0.092 Hp. Again only a very modest energy loss also for the petrol Smart hence no scope for improvement by fitting free flowing air filters or de-lipping your air intake etc.

[Kapt. Q]

I have no petrol Smart that I can test but one can do a fairly accurate estimate: 0.7 litre petrol 450. 4500 rpm, 0.8 bar turbo boost, ambient air temperature 14 C. Assume petrol engine is just slightly lower on volumetric efficiency than the diesel, i.e. 70% as opposed to 75%. Free air flow becomes 30 litres per second. Air intakes on the petrol and diesel are essentially identical, hence one can estimate vacuum in TIK pipe just in front of turbo by extrapolation and arrive at 225 mm H2O. Total inlet duct loss between air intake at side to turbo compressor becomes thus 0.0030 [m3] x 2250 [Pa] = 68 Watt or 0.092 Hp. Again only a very modest energy loss also for the petrol Smart hence no scope for improvement by fitting free flowing air filters or de-lipping your air intake etc.

Interesting figures, but a mapped smart can have boost of 1.5 bar, volumetric efficiency is at times over 100% on boost and redline is 6000+rpm.

Cheers!

[Bill]

I popped the stock filter back in, ran the engine till warm, checked the oil and then took her out and happy to say (my wallets not though) that its far far better on the stock air filter.

As new ITG filter for sale!!

[Thrumbleux]

Assume petrol engine is just slightly lower on volumetric efficiency than the diesel, i.e. 70% as opposed to 75%.

Nope! Why should it be so that the volumetric efficiency of a SI is lower than a CI's? No reason that I can see.

[tolsen]

Nope! Why should it be so that the volumetric efficiency of a SI is lower than a CI's? No reason that I can see.

You are right but do you remember we corrected the calculations to allow for the higher volumetric efficiencies earlier this year.

See post 13 of below thread:

http://smartmaniacs.co.uk/forum/the-cars/roadster/62468-tik-pipe-kit-roadster-82cv

There was only a very modest increase in power losses. Increasing volumetric efficiency from 75% to 205% resulted in a power loss increase from 60 Watts to 84 Watts.

[Thrumbleux]

I am, after my recent experience of driving with my air inlet plugged pretty tightly with a Tesco carrier bag at a loss to understand the induction system on 450s. The above should have strangled the engine into submission but I drove 75 miles with only a mild loss of top end power (admittedly I didn't attempt Nmax - shortshifting instead) and the odd strange noise.
Just as there is no explanation of why the steering on a 450 lightens with increasingly wider front tyres, the induction system too is unfathomable.

[Kapt. Q]

A partial obstruction of the intake will increase velocity of the air past it without effecting performance much until required airflow is too great, this effect is used elsewhere (intake runners, throttle, etc) to increase throttle response (at the expense of high rpm performance). Interestingly the OP complains that response is affected but torque is more even (I have my doubts that just changing filter type by itself has any really noticeable difference without using a dyno). It all goes to show how little people understand what is going on when it comes to the induction, what is good for response may not be good for total hp and visa versa. The dynamics within the different parts are mind boggling in complexity and any gains in one dept usually have costs in another. for instance you can gain a few hp just by increasing the size of the plenum part of the intake manifold (with other mods) but at a cost to response. A very free flowing induction throughout will undoubtedly damage turbo response but can also vastly improve high rpm and off turbo performance. You can never have your cake and eat it. Modders should always have a definitive idea of what they are trying to achieve and what they are willing to pay for it elsewhere.

Cheers!

[Thrumbleux]

A partial obstruction

Partial?!!!! Go take a Tesco carrier bag and stuff it down the neck of delipped 450 intake (as I do to prevent water ingress while washing car). Now tell me just how partial an obstruction that is?! Also surprising was that it was still where I placed it and not dragged into the air box. (I suspect the air box let air in via another route, eg drain holes).

of the intake will increase velocity of the air past it without effecting performance much until required airflow is too great, this effect is used elsewhere (intake runners, throttle, etc) to increase throttle response (at the expense of high rpm performance). Interestingly the OP complains that response is affected but torque is more even (I have my doubts that just changing filter type by itself has any really noticeable difference without using a dyno). It all goes to show how little people understand what is going on when it comes to the induction, what is good for response may not be good for total hp and visa versa. The dynamics within the different parts are mind boggling in complexity and any gains in one dept usually have costs in another. for instance you can gain a few hp just by increasing the size of the plenum part of the intake manifold (with other mods) but at a cost to response. A very free flowing induction throughout will undoubtedly damage turbo response but can also vastly improve high rpm and off turbo performance. You can never have your cake and eat it. Modders should always have a definitive idea of what they are trying to achieve and what they are willing to pay for it elsewhere.

Cheers!

Some good points there. Diagram below shows some of the complexity.

[Kapt. Q]

Partial?!!!! Go take a Tesco carrier bag and stuff it down the neck of delipped 450 intake (as I do to prevent water ingress while washing car). Now tell me just how partial an obstruction that is?! Also surprising was that it was still where I placed it and not dragged into the air box. (I suspect the air box let air in via another route, eg drain holes).

It is also possible that air could have entered where the inlet joins the pipe to the airbox as it's a loose fit.

Yes, the complexities of all the factors involved are awesome and super computers are often used for modelling potential designs.

One of the biggest restrictions in getting even bigger hp figures from a heavily modded suprex is the intake manifold, but if you were to address this then drive-ability would be seriously impaired, not to mention that it would also take a huge amount of development using a flowbench and engine dynometer with more than a few rejected design.

Some free flowing experiments of my own have resulted in an engine that will comfortably travel at a constant 42mph in 6th gear at about 2000rpm (700cc with a 600cc gearbox). However throttle response is compromised and the exhaust is too loud!

Cheers!