Installing the Škoda Felicia engine in the LUAZ-967

Sometimes, sanctions pressure, lack of spare parts and documentation force us to look for non-standard solutions to keep critical equipment in working order… And sometimes you just have a LoIS-967 — and you really need to cram a Škoda Felicia engine into it. Just need to. The situations seem to be different, but the approaches and technologies used are the same.

Okay, not "just necessary" — there is also a technical justification. A carburetor engine from Zaporozhets was installed from the factory in the LuAZ-967: not the most efficient, powerful, lightweight or reliable choice for a floating transporter vehicle.
The Škoda Felicia engine is an injection engine: more compact, lighter, and even more powerful, more economical, and more reliable. The replacement is reasonable and logical.

But with approaches and technologies, everything is serious and without irony. Yes, in this article we will talk about the car of the 1970s, which you need to fit the engine of the 1990s. But in their place, they could just as well be, say, a Swedish-made screw compressor from the 2020s and a Rogachev electric motor from the same decade. The point is not the age of the units and mechanisms, but how to accurately and quickly connect what was not designed to work together.

The task for the ScanPro 3D specialist sounded extremely simple: to ensure the installation of the Škoda Felicia engine in the LuAZ-967. Only the engine must be replaced — the gearbox remains native, from the LuAZ.

Extremely simple, but! The LuAZ in which the new motor needs to be installed is not yet available. Only the second engine from LuAZ (without gearbox), the engine and the Skoda gearbox are available.

In fact, the specialist had several tasks at once:
— to develop a 3D model of the transition plate for docking the new engine with the native gearbox;
— perform a virtual fitting of the motor and gearbox in the engine compartment and find their optimal relative position;
— design new engine brackets and landing elements on the power elements of the body.

The original design of the LuAZ in places, to put it mildly, does not shine with thoughtfulness: the motor is attached exclusively to the gearbox and, according to the factory designers, simply "hangs" on it. This is a controversial decision that will also need to be dealt with.

First of all, the key surfaces were scanned.
The Felicia gearbox was scanned to determine the location of the starter on the adapter ring and to determine the location of the crankshaft sensor.

The Skoda flywheel was scanned to determine the desired thickness of the transition disc (looking ahead, the location of the slots for the crankshaft sensor was taken from it, but more on that below), the flange and mounting zones of the Škoda engine and similar sections of the native V—shaped Zaporozhets to combine all the mating parts.

Without all this data, there is no virtual assembly, no precise alignment of the axes, no gap calculation.

A RangeVision Helix handheld 3D scanner with a resolution of up to 0.15 mm was used to collect the geometry. However, in this project, most surfaces were scanned with a resolution of 0.3−0.4 mm: there were simply no small threads, grooves, or complex profiles requiring maximum detail. In this project, excessive point density is not needed: it will only slow down processing without increasing accuracy in solving the task.

After receiving all the scans, the most crucial part began — the virtual docking. A scan of the gearbox from Škoda was taken as the starting point. The goal is to align the engine, flywheel and gearbox strictly on the same axis, precisely align the mounting holes and choose a mutual position in which the starter will stand perfectly.

The area on the cylinder block turned out to be particularly delicate: to make room for the starter, it was necessary to carefully "chew out" part of the aluminum housing, but at the same time in no case touch the oil channels and preserve the threaded holes for the studs.

It was working with accurate 3D models that allowed us to analyze the relative position of all components in advance, select the optimal geometry, simulate a CAD model for production and avoid mistakes — even before the first cutter touches the metal.

Based on the approved virtual assembly, an adapter ring was designed — it will connect the Skoda motor to the LuAZ checkpoint. The structure is made of three parts: two of 5 mm steel and one of 4 mm, welded with subsequent welding of pins.

This is an experimental sample, the purpose of which is to verify the correctness of the 3D model in reality.

By fitting the ring, it was possible to determine exactly where to saw the Skoda motor for the new starter location: now it will look the other way relative to the native configuration.

It also became clear that the installation of the crankshaft sensor according to the factory scheme is not possible. The solution?

Transfer the reference disc from the flywheel to the front pulley. Everything has already been scanned, and designing the reference disk did not take much time. The test sample was cut from two halves of 5 mm steel and sent to assembly.

The final assembly is underway, and an experimental launch will take place in the near future. If the engine "comes to life", ScanPro 3D will begin the next stage: scanning the engine compartment and designing new brackets for attaching the motor to theLuAZ spars. After all, hanging on a checkpoint is, of course, brave … but not reliable.

We will talk about this stage of work in a separate article.

The material is provided by ScanPro 3D