KAROBUS 734

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

I got pretty close to the specs of the LIAZ ML 635 NA engine, depiste getting more torque. I think in that case we could think of a wear out engine with less power, to maybe match better the torque.

LIAZ ML 635
148 kW / 2 100 rpm
742.6 Nm / 1,300 - 1,400 rpm

In low LOD, the bus turns into a shiny white brick.

Quote from PedroXDBR :

I got pretty close to the specs of the LIAZ ML 635 NA engine, depiste getting more torque. I think in that case we could think of a wear out engine with less power, to maybe match better the torque.

LIAZ ML 635
148 kW / 2 100 rpm
742.6 Nm / 1,300 - 1,400 rpm

That is pretty good! Thanks

I think I will actually go for the original NA variant because the turbocharged one had the exhaust pipe tip in the rear bumper, which the model doesn't have. I think it should be better off going uphill now with more torque in the engine that you provided.

Quote from Flame CZE :

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

turbo diesel engines usually run crazy high pressure, 2-3 bar on big rigs easily, however diesel engines and their operational characteristics are extremely different from gasoline engines and so far, our editor is too simple for these differences.

For example, a factory 2022 Ford F350 6.7 Turbo diesel here in the US runs roughly 40 psi of boost which is almost 3 bars. Horsepower is 450, torque is 1280 nm... something you can't do in the editor unless you set the pressure at 0.3 bar lol.

The good part about having to run super low boost when recreating a diesel engine in the editor is that the turbo will spool super-fast which is another characteristic of a diesel engine. Those fords will build 3 bar of boost in a blink of an eye. Turbo lag is nonexistent in large diesel engines, it's too small to be noticed.

Changed engine specs to get closer to the the original LIAZ ML 635 engine (thanks to PedroXDBR!):
- Power: 146 kW @ 2111 RPM
- Torque: 781 Nm @ 1330 RPM
- removed turbo

- Added proper skin textures to LOD3 mesh
- Reduced LOD2 mesh triangle count (still to be completed)

Things to do:

- Try to fix bad visibility in right side mirror
- Fix bad looking vertices on sides
- Make interior tubes colourable
- Try to fix collision box issues
- Add more details (front grille, engine side vent)
- Add 3D "bars" on the sides and rear
- Add a "dirty" configuration

First of all, awesome work on imo the best bus in LFS history
Since LFS still has not been able to add virtual side mirrors in 18 years and indie developers make a game in a month with working side mirrors (motortown) I was hoping maby you could add or move right side mirror closer to center so you can drive the bus and be able to see your sides in turns. This would be really helpful and for big vehicles like this, sidemirrors are very important. Also this mirror mod could be a configuration in case some people dont want. but i think if you could add this, alot of people would be really happy with an even better bus see my attatched image for ideas, thanks

I'm glad you like it!

Unfortunately, having a side mirror inside the bus doesn't work - the mirrors come out black.

I'm adding some details to the side panels - progress so far:



Credits for the original details: https://blendswap.com/blend/16380

Hi Flame!

Do you think you could do rear view mirror on glass? (like OMSI mod Karosa C954E LUX shown below)
Also, are you gonna do something like textured destination plates to make use of the non used space on skin template? I know we talked about this, but not sure if you remember, or progressed. Either way, the Karobus looks cool now with the sidepanels you added!

Hi, I haven’t worked on this mod for quite some time… I’m glad you like the side panel details. I’d like to get back to it at some point.

I can try the different mirror placement and see how it will look.

I like the idea of having skinnable destination plates! I haven’t worked on that but it’s something I’d like to add as well.

Some progress, also using the new test patch features. I'll publish a new version once the patch is official.

Driver swap possible
Different front and rear wheels
Working fog lights
Working side lights
Interior lights as "extra" lights
Adjusted right side mirror for better visibility alongside the bus (still needs manual adjustment in view options)
Rubber-metal trim around the sides and rear
Changed class to 'bus'

BUG: side mapping is flipped when driver on right, not sure why