Ultimate MK4 TDI build for MPG

[oil pan 4]

I barrowed my friends stock 2003 jetta and while changing the oil on it (part of the deal) noticed the size of the intercooler is a joke and the intake air piping is pathetic.
At one point where the intake pipe squeezes between the tire and the body on the passanger side, I bet the cross section of that pipe is maybe 2 inches tall and an inch to 3/4 inches wide. Diesel intakes and exhausts need to be big and free flowing, to improve both power and fuel economy.

Now you could put too much intercooler on and over cool the air going into the engine during winter if it gets real cold, but that can easily be fixed with duct tape or cardboard.

I was assuming you were going to replace the intercooler and intake piping? But then I didn't see it listed any where on your planed mods.

[PremierSprinter]

Originally Posted by oil pan 4

I barrowed my friends stock 2003 jetta and while changing the oil on it (part of the deal) noticed the size of the intercooler is a joke and the intake air piping is pathetic.
At one point where the intake pipe squeezes between the tire and the body on the passanger side, I bet the cross section of that pipe is maybe 2 inches tall and an inch to 3/4 inches wide. Diesel intakes and exhausts need to be big and free flowing, to improve both power and fuel economy.

Now you could put too much intercooler on and over cool the air going into the engine during winter if it gets real cold, but that can easily be fixed with duct tape or cardboard.

I was assuming you were going to replace the intercooler and intake piping? But then I didn't see it listed any where on your planed mods.

Yes and no. I'm not going to replace the charge pipes and intercooler, just remove them. Instead, I am favoring a water-cooled intake manifold with a 5"x10"x4" core and a separate cooling reservoir. One of the downfalls of the ALH motor is that the intake and exhaust ports are both on the rear of the cylinder head, meaning charge pipes, the intake and the down pipe all have to come from that area and it gets cramped. By running a water-cooled intake manifold, the outlet of the turbo can go straight into the intake manifold with no restriction and the level of cooling can be controlled by the coolant circulation pump.

[oil pan 4]

An aftercooler, yeah that would fix it pretty good.

Had you considered heating the after cooler tank with external power for cold starts?

[PremierSprinter]

Originally Posted by oil pan 4

An aftercooler, yeah that would fix it pretty good.

Had you considered heating the after cooler tank with external power for cold starts?

That wasn't something that I had ever thought of. If I were ever to build a lower compression motor for power it would probably be a good idea. The modern vw diesel start pretty well in the cold with a working glow system though and I have never had any cold starting problems in the past. I'll keep the idea on hand if it ever arrises.

[oil pan 4]

Intake heaters are not stock for my diesel but am very glad I added them.