1G-GTE into Ra23 Celica
Installation Guide
Abstract:
The following guide is designed to assist in the installation of a 1g-gte twin turbo six cylinder motor into the 1976 RA23 Celica. This guide deals only with the dropping in of the motor, fabricating engine mounts and/or cross member mounts and the alteration of a gearbox cross member. This guide aims not to touch on fuel system, braking system or suspension setup. This should be only taken as a guide, it aims to be as accurate as possible, however no responsibility can be taken for incorrect information.
Contents:
The 1G-GTE primarily comes in two types. An earlier version, 185hp, typically with water to air intercooler, and a later version, 210hp, typically with air to air intercooler. There is a third version, however this is just a variant on the 210hp version, between which there are no physical differences.
1G-GTE 185HP 1G-GTE 210HP
Water to Air Intercooler Air to Air Intercooler
The main obvious difference between the two motors is the intercooler piping. You’ll notice on the 210hp version, the intercooler piping travels across the turbo side of the motor to the front, and then on the intake side from the front to the throttle body. These pipes do not exist on the 185hp version.
Either motor is suitable for installation in the Ra23.
1.1 Turbo Positioning
Both motors have the same twin ct12 turbos on the same side in roughly the same position. These are the first point of confliction when installing either of these motors. As will be covered later, the twin turbos will touch the steering box if they are installed with the motor. Either they need to be removed and replaced with a larger single turbo, or precautions need to be taken to ensure that they do not knock on the steering box. I would recommend removing them and installing a single turbo. How to do this is not covered in this article.
1.2 Sump Types
There are a few sump types available on the 1G-GTE, depending on what type of car the motor came from. Typically speaking, the 1G-GTE will come with a mid-rear position sump, because typically the 1G-GTE came out of either a soarer or a supra, however a front position sump or a mid position sump are also available on other versions of the motor. It is recommended that a mid-rear position sump is used in this installation, as a front position sump will simply not fit and a mid position sump requires severe modification.
1.3 Engine Mounts
There are two types of engine mounts available for the 1G-GTE. A cast alloy mount and a steel fabricated mount. It is common that a 1G-GTE will come with the cast alloy mount, which is useless for this installation. A steel fabricated mount will either need to be sourced, or made.
The 1G-GTE originally came with either a 4 speed electronic automatic gearbox or a 5 speed manual gearbox. Both will be suitable for this installation, however it is recommended that the manual be used, as wiring the automatic gearbox to get it to work is not an easy task. The manual gearbox in question is what is commonly referred to as a supra 5 speed. The actual model name of the gearbox is a w56, w57 or w58. A gearbox of this type can be sourced separately, however the bell housing required by the 1G-GTE is very specific, as a result, it must also be sourced for use in this installation.
By this stage, the motor should be assembled along with the gearbox, and the engine bay should be free of everything except minimal wiring looms, brake lines, steering and cross-member.
2.1 Mounts
On the 1G-GTE there are two mounting positions for the engine mounts. A rearward position that fits the cast alloy mounts and the front position that fits the steel fabricated mounts. Seeing as the steel fabricated mounts are to be used, the mounts must be bolted on to the front (red) position.
The steel fabricated mounts are very similar to the original 18rc mounts, and as a result they bolt onto the same rubber mounts. Having said this, it is possible to use the old 18rc rubber mounts however it is suggested that new mounts be purchased, given the sudden power increase that will be experienced.
At this point, it is possible to bolt the motor directly onto the cross-member and it will fit. However, two problems arise from doing this. 1) The motor will sit too high, and 2) if using the twin turbos, the turbos will foul the steering box. To avoid these problems, the mounts need to be cut from the cross-member and shortened.
In the case of using twin turbos, the motor does need to be installed on an angle to clear the steering box. This can be done by either using a spacer in between the engine mount and the rubber mount, or by cutting the engine mounts to accommodate an angle.
It is also suggested, despite the fact that the motor does fit in well without moving it either backwards or forwards, that you relocate the engine mounts either backwards or forwards to make the engine sit either further back or further forward to suit your requirements. However, be careful in doing this, because there is commonly difficulties in the front crank pulley clearing the radiator.
2.2 Gearbox cross-member
The supra gearbox, whilst being the same overall length as the original 18rc gearbox, both the cross-member rubber mount bolt holes, and the shifter hole, sit further back than the original. The original cross-member will bolt onto the gearbox, however given the above, the boltholes on the cross-member that meet the base of the car, don’t line up any more. The front boltholes on the car no longer line up with the cross-member, and the rear boltholes on the car line up with the front boltholes on the cross-member. The diagram(s) below illustrate this.
Standard bolt holes W58 bolt holes
As a result, the cross-member will need to be modified in the following fashion. The standard cross-member’s bolt holes will need to be removed from the cross-member and welded further forward to line up with the bolt holes under the car.
Depending on the type of gearbox, the center of the cross-member may need to be cut out and lowered, in order to accommodate the gearbox.
As previously mentioned, the sump required for this installation, is the mid-rear sump pictured above. There is a protrusion at the rear of the sump that will hit on the steering drag link. It is possible to remove the hump with a hammer, however it is suggested that cutting and welding the protrusion into a different position is by far a better method.
The sump needs to look like this once finished:
Before:
After:
If the engine mounts have been cut correctly, there should be no need to modify the radiator. In the event that the engine has not been moved far enough back, the crank pulley can be removed and the front disc of the pulley machined off. There should be no need to move the radiator forward, however it is suggested that the radiator be triple cored to ensure it’s capable of cooling the turbo-charged six.
Provided the gearbox is not too far back, the tail shaft will still fit and bolt up.
References