Custom Exhaust Manifold is Finished

Yesterday I completed the build of my custom exhaust log manifold for the 4Runner. The flange is 0.50" steel and so is the flange for the turbo. The tubing is 1 1/4 schedule 40 pipe. I used 4 90 degree elbows and 2 45 degree bends, plus a few straight sections of roll bar tubing left over from my Mustang project. The roll bar tubing turned out to be the same thickness and diameter as the pipe, so that worked out great. I TIG welded the entire manifold while it was bolted down to a spare cylinder head. End result was a flat flange and good penetration on the welds. After all the welding was complete, I used a carbide burr to clean up the port inlets and outlets in hopes to remove any flow-impeding edges, etc. Not sure how much that will matter on this application, but I do know it won't hurt.

I also built a bracket to brace the manifold to the block. The turbo is pretty heavy, and the manifold will hold a lot of heat. Nearly all factory turbo setups are braced to the block, so I am hoping this will help to prevent any future issues. I only want to build this once!

The bends are lightly tacked in place just to get the project started.

It is kind of like a puzzle.. there were known angles I had to have, and then I just had to fill in the missing pieces.

I still am surprised at how this turned out! I used a sharpie and a cutoff wheel to cut the two 90 degree fittings to merge them into the collector. That was some pretty precise eyballing right there :)

All the tubes are notched and fitted reasonably well and tacked together.

Nearly all welded up.

Bolted to the spare cylinder head - keeps the manifold from warping when welded.

That is the support brace tab on the bottom of the manifold.

Support brace - it's not very pretty, but it'll definitely do the job. I did not have a long enough piece of flat steel on hand, so I had to use a portion of round pipe to make it work.

This is how it all sits in the chassis.

Everything is bolted down on the engine - even installed the gaskets! Hopefully I won't be taking this off again any time soon.

Wiring mostly done & ECM is working!

I have spent the last few weeks working on the wiring harness. It really isn't all that complicated. The level of diagram comprehension has to be high in order to properly adapt necessary circuits and remove others. Thankfully, I have the early ALH engine, which only has an 80 pin ECM instead of 121 pins!

I started by printing the diagrams so I could color code some circuits and write notes. Next, I identified battery power, switched power, ECM grounds, etc. After I throughly understood the factory setup, I was then able to draw up my own power distribution diagram & fuse block.

Today I made lots of progress with the wiring adaptation. End result is the ECM powers on with with the ignition switch, sensors are powered, and I can read codes and the datastream with an OBDII scanner! The part that surprised me is that it all worked the first time I put power to the system once it was all connected. :) The key was lots of research up front to ensure I fully understood the function of each wire.

Yesterday I jumped power to the starter solenoid with the Power Probe, and the engine turned over without any issues. Glad to see the factory Toyota starter & ACME Adapters flywheel are working well together. There's been no reports of issues, but it was nice to see mine worked properly. :)

Next big step is to fabricate the exhaust manifold. I am hoping to create a tri-y style header similar to the one found here. I think I will have enough room. The manifold will be created from schedule 40 weld els and 1/2" flanges.

Murphy's law of automotive wiring: if you make it all neat and tape up the harness before you throughly test it, it will be wrong and you'll have to untape it & start over! Now that it works, I can fully secure a few temporary connections and then clean up the harness.

I'm going to put the battery on the driver's side. The air filter needs to be on the passenger side fender well due to turbo placement. In this picture, I have the the battery charger, power probe, and multiple jumper wires attached to the battery. Most of that is for testing purposes & will be eliminated once all is more permanent. Keeping a battery charger nearby & maintaining full battery voltage is critical for proper electrical system testing & functionality.

This is the power distribution diagram I sketched out and is similar to the VW track style diagrams (which I really like!). Power comes in from the top and output & grounds are towards the bottom. Solid orange is B+ at all times. Hashed orange is switched B+. Yellow is ground. Penciled circles at the bottom tells me what wire &/or circuits this fuse is powering on the factory VW wiring harness.

Functioning fuse block and OBDII connector. Power enters the bottom of the fuse block and exits to different circuits and components at the top.