The infamous Czech boxy bus from the 80-90's is coming to LFS So this is the intercity bus Karosa C 734.

Sources

I got a permission to use this 3D model for VBus and textures from the version for OMSI. The author of the OMSI mod sent me his original model too, which was more detailed, but sadly it has too many polygons and I couldn't reduce it enough to be useable. But I think even the less detailed version that I'm using looks decent.

Specs

Engine: 11.9 litre turbocharged inline 6 / RWD
Power: 148 kW (199 hp) @ 2868 RPM
Torque: 675 Nm (498 lbft) @ 968 RPM
Mass: 9600 kg
Weight distribution: 35.8 F / 64.5 R
Transmission: H-pattern
Suspension front: double wishbone
Suspension rear: trailing arm (closest to solid axle I guess)

I found original user manuals in PDF which had more than enough of technical specification of the drivetrain, suspension, gearbox etc. so I could implement it in the editor.

It was difficult to get the power/torque ratio right - in reality it should have about 742 Nm.
Regarding the front supension - one of the original authors sent me a great reference photo so I could align it in the editor as close as possible.

Progress

The engine and suspension should be pretty much done. I also updated the driver animation so it's aligned with the steering wheel. Now I've started texturing the exterior as well as the interior, which will take some time. The body is fully skinnable.

Added some more interior textures.

There are two configs:
- reglar numberplates
- numberplates behind windshield to act as a line name

Only good looking bus for now. Thumbs up mate!

Wow really high quality! Looking forward to drive it!

Some time ago we had buses almost like this in my town! I hated them (probably because they were in very bad shape).
Good job on the mod! Looks like fun.

Edit: they were Ikarus, not Karosa.

nice, goodluck

Nice project, good luck!

Well done, it's looking good

Aaaand it's published!



There are still parts that need texturing, especially in the interior, but it should be drveable. Enjoy!

Nice mod!

- fixed some gaps in car body
- increased maximum lock to 40° to replicate the real turning circle diameter of 22 metres

Perfect!

Nice! I remember taking these buses from school to home, but ours had a standing area in the back. I liked standing there and jumping when it rode over bumps. Also articulated Ikaruses were fun to ride in the joint, watching everything move.

Seems that there's no collision box, or it's very small: you can turn around a pillar and have the pillar between front and back wheels.

That brings back some memories

Quote from detail :

Seems that there's no collision box, or it's very small: you can turn around a pillar and have the pillar between front and back wheels.

This is a quirk of the way the box works, I think - detection is done between the centre of the vehicle and the nodes of the crash box. If there's no node in that side, stuff can 'get in' there undetected.

It happens with long vehicles as you turn a corner and the side comes in and hits something at the apex of the turn - nothing registers as a hit until the rear wheels touch it, and by then it's a big overlap with a lot of energy instead of a smaller scrape.

It's on my list to tinker with all this, but, well... it's a long list

Torque should be coming in a bit lower in a 11.9L engine, and shouldn't rev more than 2500 rpms, i don't know the exact specs of this specific bus and the engine it's using, but i drive trucks IRL and that's usually the characteristics of engines this size.


I love the mod, and you did a great job!

Quote from Racon :

This is a quirk of the way the box works, I think - detection is done between the centre of the vehicle and the nodes of the crash box. If there's no node in that side, stuff can 'get in' there undetected.

It happens with long vehicles as you turn a corner and the side comes in and hits something at the apex of the turn - nothing registers as a hit until the rear wheels touch it, and by then it's a big overlap with a lot of energy instead of a smaller scrape.

It's on my list to tinker with all this, but, well... it's a long list

It's strange indeed. I've tried to tackle this by splitting the side collision box into multiple sections. It helps a bit in some situations.




But there are still some odd collisions, especially in the South City chicanes. It seems to happen with other buses too.

Quote from [OD :

Jardim;1985630"]Torque should be coming in a bit lower in a 11.9L engine, and shouldn't rev more than 2500 rpms, i don't know the exact specs of this specific bus and the engine it's using, but i drive trucks IRL and that's usually the characteristics of engines this size.

You're right about the max RPM. The real bus has max RPM at 2300 RPM.

I couldn't get the power & torque just right, that's true, but this is the closest we could get If someone could help me out with getting the curves right, feel free to contact me

Realistic target values:

Power: 148 kW @ 2100 RPM
Torque: 742 Nm @ 1300-1400 RPM
Redline: 2300 RPM

Quote from Flame CZE :

But there are still some odd collisions, especially in the South City chicanes. It seems to happen with other buses too.

I've had that last one happen to me in the Racha too.

in rus wiki this bus hade some engines with power from 210 hp (LIAZ ML63*) but in game 199 hp

in game we have torque 675Hm but LIAZ ML63* had 920 Hm

the current engine values cannot move the bus on a slight slope.


please use Renault MIHR 62045 A/3 with 253hp and 1000Hm torque

I want to keep the LIAZ engine. The Reanult engine seems to have been on the C734.1345 variant which is not what my model is.

But I will consider upgrading it to the LIAZ ML 636N engine with 155 kW / 2000 RPM and 920 Nm / 1400 RPM.

Edit: I just tested it and it seems too powerful I might go with the LIAZ ML 636 - 152 kW / 2000 RPM and 845 Nm / 1100-1200 RPM.

i recorded video with torque test. bus can start driving only if i push and release clutch manually

Quote from Flame CZE :

You're right about the max RPM. The real bus has max RPM at 2300 RPM.

I couldn't get the power & torque just right, that's true, but this is the closest we could get If someone could help me out with getting the curves right, feel free to contact me

Realistic target values:

Power: 148 kW @ 2100 RPM
Torque: 742 Nm @ 1300-1400 RPM
Redline: 2300 RPM

https://barringtondieselclub.co.za/scania/scania-ds11.html

I based this loosely off this 11 liter engine, with less power for this application since the one here is more recent (90's) If the specs you provided are realistic, that means this engine was originally naturally aspirated because the max torque @ rpm is way too high for a turbo 11.9 liter engine. I made one based on the specs you provided as well. Try them, tweak them to your liking.


EDIT:

http://www.kamim.sk/doprava/technika/karosa/700.php

Based on what i've read, the original 1982 bus used a N/A LIAZ ML 635 engine (which explains why i couldn't get the power figures close with turbo) and that a turbocharged variant didn't come out until 1987.

You are right, my original target specs were wrong - indeed it is from the NA variant, which didn't fit the LFS implementation which had turbo in mind So I will have to change them.

Quote from OD Jardim :

http://www.kamim.sk/doprava/technika/karosa/700.php

Based on what i've read, the original 1982 bus used a N/A LIAZ ML 635 engine (which explains why i couldn't get the power figures close with turbo) and that a turbocharged variant didn't come out until 1987.

I'm using the table at the bottom of the page as a reference now. I would like to go with the turbocharged variant, which could be this:

LIAZ ML 636
152 kW / 2000 RPM
845 Nm / 1100-1200 RPM

But to get those values, the turbo boost is too low So I got this so far:

155 kW / 2093 RPM
846 Nm / 1303 RPM

I don't know what the real turbo pressure should be but surely more than that