Fuel Economy, Hypermiling, EcoModding News and Forum - EcoModder.com - View Single Post - More efficient air intake (1.6HDi)

Piwoslaw · 12-14-2010, 09:40 AM

My car's intake is a little messed up. The route that air must go before it gets to the manifold is very long and full of kinks and bends. The air filter is buried deep behind the engine, so by the time intake air hits the turbo it's had more than enough time to warm up - good if you have a gasser and want a WAI, but bad if you have a turbo diesel which prefers cold air.

Here is a diagram of the pre-turbo part:

and picture of how it's all crammed in there:

Fresh air gets scooped up by the intake (1) and goes into a "box" (2) which in many official documents is called an air filter. It has no filter inside, in fact it's not even an air tight box - only one wall (with in and out ducts) and a cover. My guess is that once inside, air must slow down and make a U-turn inside, and that removes debris and water. But when the car is not moving and no air is being forced through the intake (1), then a large protion of the air sucked from box (2) actually comes from inside the engine bay. Next the air goes around the battery to the real air filter (3) way back behind the engine, from which it comes back forward to the turbine (6). From there it passes through the intercooler (7), pressure sensor (8) and finally hits the intake manifold.

So why is the filter behind the engine, while the same car with the larger 2.0 liter turbodiesel has the filter box up front? My guess is that having to take apart half the engine bay just to change the filter will send more customers to the authorized service station... ($$$)

Well, I don't want my air box snuggled back there between the engine block and the EGR pipe, soaking up the heat. Putting an air filter box up front would allow air to take a much shorter and direct route to the turbo, reducing both pumping losses and air temperature. But any new ductwork would have to account for the air flow and temperature sensor (nr 4 on the photo), and maybe for a mysterious pipe connecting the air duct with the header cover (nr 5 in the photo), the purpose of which I have no idea.

Any ideas on what to change? Is redoing the whole intake ducting worth the results?

12-14-2010, 09:40 AM	#1 (permalink)
Piwoslaw aero guerrilla Join Date: Oct 2008 Location: Warsaw, Poland Posts: 3,705 Svietlana II - '13 Peugeot 308SW e-HDI 6sp 90 day: 58.1 mpg (US) Thanks: 1,278 Thanked 731 Times in 464 Posts	More efficient air intake (1.6HDi) - ideas My car's intake is a little messed up. The route that air must go before it gets to the manifold is very long and full of kinks and bends. The air filter is buried deep behind the engine, so by the time intake air hits the turbo it's had more than enough time to warm up - good if you have a gasser and want a WAI, but bad if you have a turbo diesel which prefers cold air. Here is a diagram of the pre-turbo part: and picture of how it's all crammed in there: Fresh air gets scooped up by the intake (1) and goes into a "box" (2) which in many official documents is called an air filter. It has no filter inside, in fact it's not even an air tight box - only one wall (with in and out ducts) and a cover. My guess is that once inside, air must slow down and make a U-turn inside, and that removes debris and water. But when the car is not moving and no air is being forced through the intake (1), then a large protion of the air sucked from box (2) actually comes from inside the engine bay. Next the air goes around the battery to the real air filter (3) way back behind the engine, from which it comes back forward to the turbine (6). From there it passes through the intercooler (7), pressure sensor (8) and finally hits the intake manifold. So why is the filter behind the engine, while the same car with the larger 2.0 liter turbodiesel has the filter box up front? My guess is that having to take apart half the engine bay just to change the filter will send more customers to the authorized service station... ($$$) Well, I don't want my air box snuggled back there between the engine block and the EGR pipe, soaking up the heat. Putting an air filter box up front would allow air to take a much shorter and direct route to the turbo, reducing both pumping losses and air temperature. But any new ductwork would have to account for the air flow and temperature sensor (nr 4 on the photo), and maybe for a mysterious pipe connecting the air duct with the header cover (nr 5 in the photo), the purpose of which I have no idea. Any ideas on what to change? Is redoing the whole intake ducting worth the results? Attached Thumbnails __________________ e·co·mod·ding: the art of turning vehicles into what they should be What matters is where you're going, not how fast. "... we humans tend to screw up everything that's good enough as it is...or everything that we're attracted to, we love to go and defile it." - Chris Cornell [Old] Piwoslaw's Peugeot 307sw modding thread Last edited by Piwoslaw; 12-15-2010 at 02:32 PM..