Chase Bays - Tucked Aluminum Radiator BMW E30 / E36 / E46

Chase Bays - Tucked Aluminum Radiator BMW E30 / E36 / E46

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The all new Chase Bays Tucked Radiator for BMW is finally here! This product is designed for those wanting to open up space in their crowded engine bays, improve cooling performance, and get a better look aesthetically. This radiator is a cooling upgrade, it offers more fluid capacity than stock, more direct airflow, and dual pass design. It is mounted under the core support to open up to 6" inches of space. This radiator has been rigorously track tested on our Chase Bays E36 drift car and our other applications are on countless show winning engine bays.

We've designed this all aluminum radiator to fill every bit of space under the core support while still being able to run one powerful 16" electric fan. This radiator requires some light cutting of the front core support. We wanted to make the radiator as large as possible while staying under the core support. To accomplish this we had to cut into the chassis. More modification info on the bottom of this page.

We've integrated a lot of features that no other competitor is offering. From fan sizing to modularity. We'll start at the...


Although there are many factors in keeping a car properly cooled, we'll assume you have all your bases covered (good water pump, no leaks, sufficient wiring, etc). It is important that the fan is on its own relay with proper sized wiring and that the fill point is actually the highest point in the system. These 2 things are the most commonly overlooked. For this reason we make a Dual Fan Relay Harness with 180º F Thermoswitch that greatly simplifies the wiring (couldn't be easier). We do not currently have a single fan relay harness with thermoswitch for this single fan application but we will soon.

WARNING: DO NOT ATTACH FAN DIRECTLY TO THE RADIATOR VIA FAN ZIP TIES. Over time this can wear through the core and will eventually puncture through. The aluminum on radiator cores is very thin and this mounting method is not secure to eliminate movement. Especially with our powerful fans. This will immediately void your warranty on your radiator.

We include threaded holes on the top and bottom header cover (see photos), if you do not use a shroud, utilize those for fan mounting brackets. 

Fill Point

Since the top of our radiator sits about 6" lower than stock, we have to make a new fill point. The first step is getting an inline filler neck, luckily you can get that through us... Click here for a link to the Chase Bays Raised Modular Filler Neck.

The way you setup the filler neck will make your hose selection easier. Our personal favorite is on the radiator itself using our Raised Inline Filler Neck. We've attached a photo of this below. To do this just select -20AN for one side of the Chase Bays Filler Neck when selecting options. The other side will be whatever hoses you choose to go with. So if you were using OE Push-On style Silicone Hoses, you would select "1.5mm Normal Hose" for one option and "-20AN" for the other. The -20AN side will thread right into the radiator then you will twist the filler neck onto that. With the thick O-Ring Seal on both side, getting the filler neck 0º vertical is easy with the adjustment of both sides:

The other option is putting it on the upper water neck which will require some fabrication work. 

Modular Inlet/Outlet and Reversible Orientation

We have designed the radiator to be completely reversible with interchangeable inlet/outlet types. The radiator inlet and outlet have to be on the same side since it is a dual pass design. Formerly when you purchased a radiator through us you would have to select driver or passenger side. With our new design the radiator orientation is completely reversible. It looks the same on top and bottom and the brackets are centered.

The inlet and outlet are -20AN female threads. So we just install whichever adapters you need. If you change your mind down the road, there is no cutting and welding. Just threading on new adapters. We offer OE style in 1.38", -16AN, and -20AN. We recommend you put the radiator inlet/outlet closer to the upper water neck since that hose will more visible.

We do NOT recommend -16AN for high power setups! (400hp and up) The stock inner diameter of hose for BMW is usually 1.5" / 38mm. -16AN is 1" inch and -20AN is 1.25" inch. By going with -16AN, you are creating a restriction that is normally not there and reducing the flow by 34%.


Factory hoses do not work since the radiator is mounted farther forward. We piece together silicone hoses bends with small joining couplers and use gates heat shrink clamps for a seamless install. We have been drifting our E36 non stop with these clamps with no issues.

We will be offering all of the above in the coming weeks! (typed April 9th)

BMW engines with expansion tanks can eliminate the expansion tank with this radiator if you place the fill point on the radiator as shown above. Just use a sufficient plug on the side inlet under the intake manifold and the fill point is on the radiator. This applies to M50, M52, S50, S52, S54, M60, M62, S62, etc. The below photos shows a version of this. 

Dual Pass Design

This simply means the coolant passes through TWO times instead of ONE. Which, even more simply put means TWICE the cooling and half the size. Both inlets are on the same side of the radiator and a plate is welded inside between the two inlets. The radiator has two L brackets on each side that you bolt to your core support. This radiator doesn't use any of the OEM radiator mounting points, and it's easier to install and un-install.

Pressure Tested

Each radiator is water pressure tested to 40psi. Your radiator shouldn’t see more than 16-19psi before the radiator cap spring does its job and expands into the overflow.

Chassis Modification

E30 requires the most cutting. The lower bar has to be cut (see photos) and the hood latch has to be completely removed plus the surrounding hood latch metal trimmed. The lower bar is not structural and you won't miss it. You cannot run AC with this radiator since it takes its place. You could custom fabricate a forward mounted condenser and extended lines. An intercooler can work with some trimming of the metal valence.

E36 requires a slight trim to the upper grille valence on left and right side and the E46 requires no trimming at all. 
You cannot run AC with this radiator since it takes its place. You could custom fabricate a forward mounted condenser and extended lines. An intercooler can work with light bumper trimming (bumper trimming is required either way).


NO FAN OR SHROUD INCLUDED - Please visit link for more information -