PHR Lower Waterneck Adapter (rotator) for 1993-98 Supra

PHR 01010602
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99.00 99.0 USD 99.00


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Problems In Need Of Solutions

Solutions provided by PHR

The 2JZ engine was not designed for single turbo setups, although in todays world, we all know single turbo is the king of the 2JZ world. The return inlet from the radiator was not oriented to accomodate big singe turbo setups, and therefore with it's position, we can have some real problems installing a top notch turbo manifold.

The Powerhouse Racing Lower Waterneck Rotator is a great solution for  turning you waterneck away from your turbo and manifold, and down behind the alternator away from problems.


Runner Interference

With the lower waterneck in the factory position, there are two problems. First, the waterneck gets in the way of the runners on many turbo manifolds.


Turbo Interference

Second, the waterneck is blocking the ideal routing for the compressor outlet and intercooler piping.



The PHR Lower Waterneck Rotator moves the waterneck out of this terrible position, allowing the manifold to fit properly and the compressor outlet to be free of obstruction.

Improvement In Design 

New Revision

Cooling system functionality

The thermostat has two functional parts to it: the thermostat valve itself, which opens at a certain temperature, and at the same time, a valve that closes off the radiator bypass hole when the thermostat opens.

Normal operation of the thermostat and waterflow is as follows: when the thermostat is closed, the bypass hole is open. This flows the water directly out of the head and back to the waterpump at low coolant temperatures, like during warmup and no water flows through the radiator. Once the coolant reaches the thermostat opening temperature (usually 180 degrees or 160 degrees), the thermostat opens and the bypass hole is closed off, forcing water through the radiator, and cooling it down.

The Factory Design

Take a look at the following picture to see what hole needs to be blocked off when the valve opens.


With other brand waterneck rotators, and even the earlier version of the PHR lower waterneck rotator, positioning of the thermostat has had to be moved away from it's proper location in the housing.

With these designs, the thermostat is moved away from the bypass hole to accommodate the rotator itself, and the thermostat installs in the lower waterneck boss. This position of the thermostate makes it so the bypass hole can never fully close. Even when the thermostat is open, the bypass hole is not closed and a large amount of the water is not allowed to go through the radiator and be cooled. This reduces the efficiency of the cooling system.

A Fix For The Problem

The NEW Powerhouse Racing Lower Waterneck Rotator solves this problem. The position of the thermostat remains in the factory location, allowing the thermostat to close off the bypass hole like it is supposed to and moving flow of all the water through the radiator, maximizing cooling system efficiency.

Hose Solutions

Once you've installed the waterneck rotator, you now have to address the hose routing. You CAN make the factory hose work, but it doesn't work well. It ends up way too long and routing is terrible and twisted in unapealing ways. You want a hose that is designed for a rotated waterneck, and PHR has produced one specifically for this need.


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Vehicle Fitment
Make Toyota, Lexus
Model Supra, GS300 (Aristo)
Chassis Code A80, S160, S161
Generation MKIV (Mark 4), 2nd Gen
Engine 2JZ-GTE, Non VVT-i, 2JZ-GTE, VVT-i