Basil, if you cover the intake with tape it will not run

I was assuming the i/c was already at equilibrium, and describing what happens when a pulse of hot air from an acceleration event goes through it. At that point, the extra energy is absorbed by the metal first, then dissipated to the atmosphere over a period of time. A larger mass of metal is better able to smooth out this peak than a small mass.

This is definitely the case, however a larger mass also cools less quickly, so the benefit is moot. Generally, manufacturers design ICs to have the smallest mass of metal for their area possible. This means they have the lowest thermal inertia.

Still does not alter the fact that improving airflow over the IC if it is less than optimal will improve the performance of the IC.

Chris

yes it should work basil but it isn't cheap, i bought some and installed it on ym mazda

i am planning buying a shed load and doing all the intake pipes on the skoda :eek: not going to be cheap!

This is definitely the case, however a larger mass also cools less quickly, so the benefit is moot. Generally, manufacturers design ICs to have the smallest mass of metal for their area possible. This means they have the lowest thermal inertia.

Still does not alter the fact that improving airflow over the IC if it is less than optimal will improve the performance of the IC.

Chris

All the Vag-Com logs I took when I was playing with i/c sprays indicated that the equilibrium state wasn't a problem on the Fabia vRS with the small i/c - IAT was elevated but not excessively (e.g. about 45

was idly thinking of covering PD160 intake with reflective insulation to see if that makes any difference. Suppose it could be done proper with logged air intake temps before and after but cant be bothered....

Trouble is, the air goes through the turbo immediatly after the intake, pressurising it and heating it up hence the need to then pass it through the IC prior to it reaching the intake manifold.

I'm sure cooling the air even more before it reaches the blower would be a good thing but not quite as beneficial as proper post boost cooling.

From what I've read, manufacturers seem to be trying to strike a compromise on their IC's. TMIC's reduce lag due to the shorter lengths of piping required between intake and turbo etc, but due to their location they don't get as much air flow as their front mounted counterparts, even with a bonnet chomper fitted.

SMIC's don't restrict air flow to the radiator and A/C condensor etc like the FMIC's do, but due to their location may require more piping and they have limited air flow.

As above FMIC's are first in line for getting the cool bumper air, but this air then has to pass over the rad and the A/C condensor afterwards meaning they wont benefit as much as without the IC in the way. Means less effective A/C and a hotter running rad which in the worst case may result in overheating.

IMO a FMIC is best fitted to an efficient diesel as these produce the least heat from combustion (hence why the PD take 3 months to warm up on a morning) and so they don't rely on the radiator as much for their cooling. I think on the PD130's they struck a compromise by using the SMIC. Less piping (less lag) and more air flow over the radiator etc but placed in a non ideal location in the wheel arch as air flow is limited.

This is not discussing IC size and shape by the way in terms of the best thermoconductor, purely location.

My other question is, how does the engine benefit performance wise from greater air cooling post MAF? The engine senses the volume and warmth (and thus the density) of the air immediatly after it passes through the airbox using the MAF. It uses this reading to determine injector pulse width and the amount of fuel its slapping in. Cool the air more after this point.....surely the engine has no way of telling? Would it still affect fuel delivery? Is there a sensor for air temp post intercooling?

I think the thermal mass idea about i/cs is wrong. The material separating the cooling air from the charge air needs to be as thin as possible to allow most interaction. Kind of like a condom.... :eek:

The i/c needs to be strong enough to deal with the boost and wear and tear, without unduly affecting the thermal transfer from the charge air to the cooling air.

Insulating any cold pipes, or even the factory airbox should have a beneficial effect. So the inlet from the bumper to the turbo and from the intercooler, back to the inlet manifold should be insulated from the higher under bonnet temps.

J.

Is there a sensor for air temp post intercooling?

Yes there is, and that's one of the things Vag-Com logs.

I really do recommend hooking up Vag-Com to your car and seeing what happens to a real car in actual practice. You might be surprised.

Yes there is, and that's one of the things Vag-Com logs.

I really do recommend hooking up Vag-Com to your car and seeing what happens to a real car in actual practice. You might be surprised.

I see, so the ECU is aware of the IC's effectiveness. This should again mean then that the fuelling should be cut as boost temps increase resulting in no smoke and also a power reduction.

Might have to buy a VAG-COM cable and download the freebie read only copy.

On the inlet temperatures, the hotter the air, the less volumetric efficiency the engine has, the less effective the diesel combustion, so the more smoke. The mixture will remain correct, but the lower volumetric efficiency will increase the soot output.

On the subject of lagging pipes, two things. If the pipes are plastic, they will have minimal thermal conductivity anyway, so I would be very surprised if any detectable benefit could be measured. If the pipes are boost pipes, at higher speeds, where underbonnet temps tend to be quite low, you may be holding heat in the intake air.

Chris

On the inlet temperatures, the hotter the air, the less volumetric efficiency the engine has, the less effective the diesel combustion, so the more smoke. The mixture will remain correct, but the lower volumetric efficiency will increase the soot output.

But surely the engine measures the density of the air which is what volumetric efficiency is all about....the 'amount' of air in the cylinder, based on volume and density. Hot air is less dense and this is why the engine measures both volume and temperatures not just volume, therefore it is aware of the reduced air density due to the higher temp and thus reduces fuelling according and therefore means less smoke?

Hotter cylinder temps on the other hand help reduce smoke as more of the excess hydrocarbons are burnt off. EGR reduces cylinder temps meaning a higher risk of smoke, so the ideal would be very cold intake temps and high cylinder temps although I don't know what the engine longevity would be with a situation like that.

But surely the engine measures the density of the air which is what volumetric efficiency is all about....the 'amount' of air in the cylinder, based on volume and density. Hot air is less dense and this is why the engine measures both volume and temperatures not just volume, therefore it is aware of the reduced air density due to the higher temp and thus reduces fuelling according and therefore means less smoke?

You have a less effectively filled cylinder, so during the burn, although the mixture is correct, you get a less efficient burn. Also consider that the ECU may richen up the mixture a little to compensate for the reduction in performance. Bottom line is mine smokes more when heat soaked.

Chris