I know with a TDI if you increase the intake temp the ECU will retard the timing to account for the warmer air and thus reduce you mileage. Unless you can trick the ECU in to thinking it is still cold this would be a problem with a TDI. Unless maybe you advance the timing manually to account for the heating?

My 4JA1 Diesel engine is Naturally Aspirated engine without ECU so I have no idea how to set the timing on TDI engine. Maybe anyone know to help us on this? Thanks :)

webasto warms up the air before you start the car.. check it out in google..

Odd, the only one I have seen was just in line with the coolant, nothing in line with the air intake on a TDI anyway. It is about the size of a can of soda, but about 1.5 times as long.

are you saying that warm air causes a rich mix?? I find In the summer my cummins is more powerful and less a pig on diesel.

I thought Helmholtz resonance was only used after the throttle plate?

I can see the similarity to the original Helmholtz chamber though. How does it reduce noise? For example, simply blowing out air makes little noise. Blowing across the mouth of a bottle causes a whistle.

Also, what impact do these types of intake resonators (I them on my Camrys) have on FE? If one were willing to live with louder intakes, could one save gas?

Hold up, some of those resonators are worth torque, the principle is to get a sort of sonic charging effect by managing pressure waves. If it's in front of the TB it's probably a silencer, if it's after the TB, it's probably useful. On 2nd gen escort GTs, there's one that's been dyno tested to be worth about 5-10 ft/lb below 3000 rpm, that's a leaver-inner, but on the regular escort 1.9, there's one in the airbox that's just a "silencer" and that's been dynoed as being worth 2-3HP across the rev range for removal, that's a taker-outer.

In general, the more volume in the intake tract after the TB and in the case of a diesel, I guess it's everything after the air filter, the better the low end torque is. Thinking of trying to design a resonator for Marvin that works at about 2500 rpm. Not so easy to figure for 6 cyl though as for 4 or 8.

Warm air in a diesel allows ignition to occur earlier with less air density. Most diesels have no throttle restriction and rely on the volume of fuel injected to control power output (not the case in earlier times Mercedes changed over in 1982 I think). Warm air contributes to better fuel atomization as well as providing the same compression pressure with less air and fuel combined.

Air density at 200 degrees F is 75% of density at 32 F (close to the same as 0 and 100 C).

The engine will not produce the same maximum power as it would with cold air intake, but under all circumstances it will burn less fuel for the same cruising speed, because less fuel and air will be necessary for the same effective compression. In essence you have higher effective compression with less air and fuel, so the 20% inprovement makes perfect sense to me.

Most diesel injection pumps are thermally compensated, but of course the older ones may not be that way. In that case if you go wide open throttle the mixture would be too rich, if the intake air was high.

Everyone knows diesels dont like cold air, obviously they should love hot air.

Remember we are not talking about gobs of power and a cloud of black smoke.

regards
gary

Yeah, I know about the variable intake stuff, it can increase torque at lower RPMs while sacrificing less top end. Feel free to read the wikipedia article on Helmholtz resonance, I have been researching it for a while now.

But I never knew that Helmholtz resonance was used before the TB, since I thought Helmholtz resonance creates noise, whereas the resonance chambers before the TB are used to quiet the inrushing air (at least as far as I know).

In other news, I just noticed that the pre-TB resonator in my V6 camry is exactly opposite the breather tube for the PCV system....makes sense!

Oh yeah and in my V6, the way the variable intake system works is that in normal use, there is a divider between where the ports/runners for each bank branch out of the airbox. At ~4500 RPM, a butterfly valve in the divider opens, effectively making one big airbox. Maybe that will spark an idea for yours?

I know on the VW TDI diesel's as the air intake warms up the engine retards the timing to keep emissions as clean as they can be. This causes reduced mpg's. Some fanatic TDI'ers are putting a resistor in line with the temperature sensor to trick the ECU to think it is 20-30 degrees colder then it is all the time, keeping their timing more advance, and increasing their overall mpg's.