1MTNCAT Rebuild underway!

Trunk Monkey said:

Isn’t that what we affectionately call the crack pipe mod? Because the adapter is shaped like a crack pipe? 😆

Click to expand...

Are you referencing the cooling mods on the rear of the heads?

Trunk Monkey said:

Isn’t that what we affectionately call the crack pipe mod? Because the adapter is shaped like a crack pipe? 😆

Click to expand...

Nope, that mod brings water out of the back of the head to even out cooling flow, it’s not a factory design.

The DOHC cooling layout is the same in function as a SOHC only the thermostat blocks flow from the radiator outlet via an externally mounted thermostat housing, rather than to the inlet via the crossover on the engine. When you look at a DOHC the coolant crossover has a hose that drops down in the middle of it in addition to the one that goes to the radiator, that middle hose is the coolant bypass. When the thermostat is closed water can’t flow out of the crossover into the radiator because flow is blocked on the other end by it, so the bypass is used to let water recirculate back to the water pump and into the engine. Works the same way on the 2V only it’s all done internally, the hole that needs to be drilled is the equivalent of the bypass hose, letting water go around the thermostat back to the water pump.

It’s not absolutely essential, technically the constant flow through the heater core acts as a natural bypass since coolant is recirculated back to the water pump no matter what(even more if you do do the cooling mod), many 4V builders (particularly supercharged where the crossover needs to be modified or eliminated) for that reason eliminate the bypass setup and use an inline thermostat with a small hole drilled in it to allow some coolant to pass. The main purpose really is to speed up warm up time for better heater operation, reduce engine wear and reduce emissions, in australia the 5.4 DOHCs didn’t use a bypass.

not running a thermostat at all is a bad idea though

Some pics of work completed yesterday!.

Finished up some of the small items the last couple weeks and actually took it down the street a couple times. Needs some much needed tuning and the exhaust finished up. Have it loaded up on trailer to hopefully have the mid pipe from header to rear exhaust tomorrow. Maybe it will act a little better once there is some exhaust behind the 02 sensors. Waiting to put the E85 Fuel cell and the rear end mods in till after I get some tuning finished . Step by step as time allows but moving forward.