Head Swapping

[Rajkumar]

To ALL who read this. I found this article on line on some Austrailian website. So everything posted here may not apply to all.


SUZUKI
Conversion:
Twin cam G13B head onto G16A block.


Replaces the narrow angle 16 valve SOHC design fitted with throttle-body injection for a 16 valve DOHC equipped with multi-point EFI.

Mods Required:
Firstly (in case you're thinking of another way), the 1600 engine's crank is slightly too long to fit in the 1300 twin cam block, which is why this head conversion is the only viable option for a big cube Swift.

A 16 valve 1600 bottom end is the best platform, as it already has valve recesses in each piston. Stud patterns, bolt sizes and galleries all match perfectly. The block should be then equipped with a 1.8mm Vitara head gasket (Part No 1114171C00) to lower the CR to a more manageable level. Compression ratio with this head gasket will work out to just over 10:1.

A cam belt sourced from a belt supplier (such as Gates), is also needed to compensate for the 1600's 30mm taller block. The belt must be connected to the GTi's crank pulley (Part No 12631 53B00) while a smaller diameter tensioner (Part No 12810 53B01000) may give more flexibility when choosing the belt. In addition, custom cam belt covers will need to be fabricated.

The safest and most effective method of controlling fuel and ignition is to use an aftermarket ECU suitably programmed.


NISSAN
Conversion:
DOHC 24 valve RB25/RB26 head onto RB30 block


The head from this:
...onto this blockBenefits:
Replaces the narrow angle 2 valve SOHC head with a DOHC 4 valve head with larger valves, ports and intake runners. The RB26 uses six throttle body induction also.

Please note: this is NOT an easy conversion and only the RB25DE or RB26DE head gives worthwhile power gains over standard. The RB20DE head CAN be fitted to the RB30 block, but if you're chasing more power from an already modified engine, the 2 litre engine's small ports and valves impose a gas restriction over around 4000rpm. It also requires enlargement of combustion chambers, and the welding-up of water galleries which are then required to be moved 5mm outward from the bore.

Mods Required:
First up, an RB25 belt cannot be used in this swap. A Gates belt or one from a belt supplier needs to be sourced. The readily available RB30 head gasket is able to be used.

The RB25 twin cam head's variable inlet cam timing can be retained on the RB30 block by teeing off the oil pressure galley on the head and feeding the standard RB25 piston mechanism. This pushes the camshaft through a full 10 degree advance. All oil and coolant galleries mate up perfectly, with the exception of this cam advance unit.

Programmable fuel and ignition control is needed to run the multiple coils of the RB25/26 as well as supplying to the different fuel requirements of the new hybrid engine.

The RB26 also requires modification of car's existing throttle linkages to mate to the engine's six throttle body induction system.



Conversion:
Z18 twin plug EFI onto L20 block.



Replaces non cross-flow head and carb with cross-flow, multi-point injection and small T3 turbo.

Mods Required:
Luckily, the Nissan L and Z series engines are very closely related. All studs, bolts and galleries line up correctly for this swap.

The conversion requires a complete Z20 timing case to go onto the L20 block, but the timing chain from the L series is too long. A Z20 chain and head gasket must be used (Part nos 13028N8400 and 11044W4002).

All Z series heads are the same combustion volume with the only variations in CR being through pistons. The L20 engines have two different CRs - 8.5 in the 200B and 9:1 in the Bluebird. When mated to the Z18 turbo head, the 200B engine will give 8.1:1 and the Bluebird 8.6:1 static CR.

An oil feed for the turbo should be tee'd from the oil pressure sensor, and a custom sump return pipe can be run back into the top of the pan.

Because the Z series head uses 2 spark plugs per pot, one socket can be blocked off on each cylinder which will allow the L series ignition (bolted into the Z series timing case Part no 13501W8402) to be used. A better alternative is to use the Z series distributor drive and 8-plug dizzy which has its own module, allowing it to be used as a standalone system. In both cases, a programmable fuel-only computer is required.

An accelerator cable from Series 1 or 2 Bluebird is ideal.



DAIHATSU
Conversion:
EF12 valve turbo TRX-X EFI head onto ED850 cc block.


Replaces 6 valve SOHC head and carb with single cam 12 valve multi-point EFI and RHB31 turbo.

Mods Required:
To place the hi-po head onto the 'big block', an L80 660cc head gasket is needed. Also, an 850 belt is necessary as the 850 has a slightly taller block. (Belt part no 1351487211, gasket no 1111587211).

All bolts and galleries line up. The naturally aspirated 660's CR is 10:1, while the 850 has a slightly lower compression ratio. An oil return line from the turbo is required to be tapped into the top of the sump.

For best results, an aftermarket engine management system will be needed. But since overall this is such a cheap conversion, perhaps the stock (import-only) Mira TR-XX computer that came with the 12 valve turbo could be adapted to suit.



MITSUBISHI
Conversion:
Twin cam VR4 turbo head onto 2Litre 4G63 turbo block


Replaces 8 valve SOHC head with 16 valve DOHC.

Mods Required:
The longer VR4 cam belt is needed to accommodate the journey around the two cam sprockets. All stud patterns, bolts and galleries align perfectly to make things easier. A VR4 head gasket and bottom front sprocket need to be bought from Mitsubishi (Part nos MD183808 and MD141953) and depending on the type of car the engine will be going into, there might be enough room to keep the standard turbo and exhaust manifold. The turbo's oil drain pipe could then feed into the original return fitting on the sump.

Because the VR4 head uses direct fire ignition, an aftermarket computer is definitely needed to run the engine.

TOYOTA
Conversion:
20 Valve 4A-E head onto 4A-GZE block



Replaces the DOHC 16 valve with the DOHC 20 valve head. Expect a whopping specific power output from this one!

Mods Required:
The 20 valver will bolt atop of the blown bottom end without drama and the static CR will remain about the same since the variation in CRs comes about by using 'turbo' spec cast pistons. Incidentally, the conrods in the 20 Valve are much skinnier than the ZE's. Unfortunately, the 20 valve's quad throttle body induction can't easily be retained, however, the great factory extractors fitted to the 20 valve can stay.

Problems making the variable cam timing operate under supercharged conditions mean the system has been disconnected in the engines we've seen, as there is a too much valve advance under boost. A programmable EFI computer must be used to control fuel and ignition requirements of the new hybrid engine.

Unlike a turbo, the supercharger unit has a self contained oil supply which negates the need for oil feed and return pipes. A problem DIYers have experienced is connecting the complex water cooling system, but perseverance will eventually prevail - or alternatively contact Tony Rigoli.

The approximate cost of this conversion is A$10,000 on a drive-in, drive-out basis. This includes the purchase of complete 4A-E and 4A-GZE engines and the fitment of Microtech Digi 2 injection.


Readers' Response
Regarding the Suzuki head conversion: yes the head fits on easily enough. However to get the block to fit into the Suzuki GTi's engine bay, the gear box must be removed, the block alloy welded, and new holes drilled to match the existing holes on the gearbox. When this is done, shavings will enter the cylinders and the heat from the welding may distort the block. Also, new engine mounts must be fabricated to mount the new block. The engine will sit a lot higher, so cooling is an issue. In many cases, the oil pump will need rebuilding to provide enough oil pressure to operate the buckets properly. These are just a few extra things to consider if you wish to under take this conversion.
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