Friday, October 8, 2010

Air Intake Manifold and Throttle Body

Here is a top look at the air intake manifold and throttle body (taped up). As it sits in stock position, the manifold has the throttle body facing toward the transmission. Fine in a Subaru, but in a Bus it won't work.

If you notice how close the throttle body extends in relation to the engine mating surface for the transmission, and if you think about the alignment of the VW transmission bellhouse almost inline with the firewall above, you can see that there is going to be a conflict. There is no way to attach an air intake pipe/filter to the throttle body without interfering with the firewall and gas tank.

The most common remedy for this is to flip the throttle body 180* and then flip the wiring harness 180* again so the fuel injectors still fire in the correct order. The problem with this solution is that the throttle body then intrudes into the space that the alternator normally sits, requiring a custom fabricated bracket system to reposition the alternator where the a/c compressor normally sits.

My dilemma is that I am not sure I want to screw around with fabricating a bracket, and there are none to purchase aftermarket right now. Richard at RJES is potentially going to sell an off the shelf alternator bracket to help this problem, but it is not available currently. An added problem is that this solution eliminates the possibility of an A/C compressor since the alternator has to be be repositioned to the spot the A/C compressor us ally sits. I kind of like the idea of retaining the A/C compressor so we can have air conditioning. Windows down with a two year old and a 10 month old is not always a good thing.

However, the alternative to reversing the manifold is to modify the firewall or potentially run without the firewall (may not be a smart choice without a fire repression system installed). AND, I don't know of the air intake pipe will even fit without the firewall due to the gas tank. I have to mock the engine up in place to see what type of, if any at all, clearance I have.

In the meantime, I pulled the intake manifold off.

The coolant heater manifold sit underneath the intake manifold.

A lot of people doing this conversion on Vanagon VW have the coolant manifold reversed to better fit and locate with the original Vanagaon coolant lines, which sit on the top passenger side of the engine compartment. Since I don't have stock radiator or lines to mate up, I don't have to reverse the coolant manifold. However, I am considering doing so since most/all radiator coolant schematics are based on this manifold being reversed. It is an added cost but it would make routing and plumbing against common schematics very easy. Tom Shiels has quite a bit of excellent info on coolant and radiator set ups on his Website although it is all for Vanagon conversions not Bays like mine.
The decision to reverse the manifold or modify the firewall/fuel tank will have to wait until I can roll the engine under the bus and jack it up into rough position. Before I do that, I have to finish the tank restore project and replace the timing belt on the Subaru motor.

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