Sunny Truck: Engine Swap

Last week we offered an analysis of the tough little Sunny Truck. Following suit, this week we'll talk about the possible engine swaps a Sunny Truck can receive (easily and affordably, of course).

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What Engine Is Best For My Sunny Truck?

     Since there are probably fewer than 1000 of these little trucks in America, you just have to keep searching, but say you find one, and it does not have an engine- what would be a good fit both from performance and cost perspectives?  You may have read on some forum that almost any four cylinder engine will fit, or can be made to fit, which is true, but have you thought of the weight of “almost any” other four cylinder engine?

     The biggest problem with engine swaps on Sunny trucks is weight; Sunny trucks are not very well balanced, even in stock trim, since it is basically a car that was turned into a pick-up truck without incorporating any of the design considerations that goes into the making of a pick-up truck. Nor was it built for comfort, so if the engine transplant requires modification of the transmission tunnel or firewall, an already cramped interior is going to get a whole lot smaller, so it comes down to a trade off between comfort and weight distribution. 

     By moving an engine backwards, you might improve balance and weight distribution, but there are other things to consider- such as the facts that the rear suspension, (as opposed to the rear axle) cannot handle massive power increases without extensive modification, and that the chassis itself is susceptible to deformation under high torque loads. 

     Unfortunately, these two facts preclude LS1’s and other crazy, high performance engines but then a Sunny truck is so light that you hardly need anything of that size, so if you have your heart set on not using a stock engine, not even the upgraded 1400 cc engine in all its variations,  there are a few possible candidate engines for fitment, so read on and we will look at some of them, albeit briefly. 

     Nonetheless, all of these possible choices involve modifications to the brakes, suspensions, rear axle, fuel systems, and possibly the steering mechanism of a stock Sunny, so be prepared to spend as much, (or more) on these issues as on the engine and transmission.

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Nissan A15.

     Although you will need to fabricate engine mount adapters, you can use the stock A12 mount on the right hand side of the engine, and a stock A15 mount on the left, since these mountings require the least amount of fabrication. 

     No modification is required to fit the A12 flywheel to the A15. However, since the alternator on the A15 is on the opposite side from its location on the A12, you need to slightly modify the stock A12 alternator bracket, but even so, it might be necessary to move the battery to the trunk to allow for full alternator belt adjustment. Other modifications include fitting a more efficient radiator, such as one from a Chrysler Le Baron, installing a 20 amp circuit to manage the fuel cut-off solenoid on the A15 engine, and a longer throttle cable.

Nissan CA18.

     Although relatively easy to fit by modifying the engine mounts, this engine requires some modification of the intake for the small engine bay to accommodate the air filter and mass airflow meter, plus the battery has to be moved to the trunk since there will be no room for it in the engine bay.

     You will also need to install the CA18’s entire fuel system, plus the radiator from a Corolla to handle the heat effectively. Several transmissions can be mated to the CA18, but a stubby 5-speed transmission from a Skyline mated with a series 3 Bluebird bell-housing requires the least amount of modification, although you may need to fabricate a transmission cross member and mount. Monaro V8 tail shafts are the easiest to modify for this application. 

Toyota  4AGZE 

     This is probably the easiest engine to fit, since it only requires the removal of the stock engine mounts from the cross member, and the fabrication of suitable mounts. By mating a transmission from a rear wheel drive Toyota Sprinter, which bolts straight on, the engine set fits into the Sunny with no modification to the transmission tunnel required, although you will have to have a driveshaft made up to suit, as well as fit a custom made radiator and electric fans. 

     Moreover, by tilting the engine towards the exhaust side, it is even possible to fit a supercharger, as has been done a few times!  

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Cost Factors.

     Although the above engine swaps have all been done for $2000 to $3000, these amounts generally do not include items such as wheels, extensive brake and suspension modifications, turbos, superchargers, and after market engine management systems.  

     However, stock  A12 engines are notoriously expensive to develop to the point where they will deliver the same horsepower as any of the above engines even in stock trim, which makes an engine transplant in to a Sunny truck an attractive option. Nevertheless, all of the above engines are significantly heavier than an A12, which could add to the cost of a transplant in a major way, since the added weight seriously upsets the little Sunny’s dynamics and handling. 

     Also bear in mind that there are no known development kits for Sunny trucks- everything you may want or need to improve handling and braking must either be made, or developed on a trial and error basis, depending on the desired end result. There are simply not enough modified Sunny trucks anywhere in the world from which to extract lessons and methods, which means that for the most part you are on your own but where there is a will, there is always a way, so don’t let any of this stop you!

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