Okay, first post, first design. I'll be continually adding stuff to the factsheet to incorporate criticism and/or additional ideas I came up with.
Don't be to harsh on me, kay? :P

Designation
M8A1 Tiamat MBT



Dimensions
Hull length: 7.76 m
Length (gun forward): 11.29 m
Height (to turret roof): 2.62 m
Height (to CITV top): 3.02 m
Height (to RCWS top): 3.1 m
Width: 3.9 m
Mass: 78.5 t
Ground Clearance: Variable, 0.5 m default

Key Data
Crew: 3
Fuel Capacity: 1250 liters

Drivetrain
Power Pack: TBD (To Be Determined)
Engine: TBD
Power: 2000hp
Displacement: 30 liters (total)
Layout: 90° V16
Turbocharger: twin-stage
Transmission: Electrically Variable Transmission
Fuel Consumption: 2.5l per km

Running Gear
Suspension: In-Arm Active Hydropneumatic Suspension
Road Wheels: Seven Per Side, Rubber-Tired
Length of Track on Ground: 6 m
Width of Track: 0.5 m

Performance
Maximum Speed: 60-70 km/h
Power to wate Ratio: 25.5 hp/ton
Range: 500km max.
Ground Pressure: 1.308 kg/cm²

Armament
Main Armament: Allied Armament Inc. 140 mm L44 smoothbore gun (36 rounds)
Coaxial: Browning M2HB 12.7 mm machine gun (1,500 rounds)
Additional weapon: Browning M2HB 12.7 mm machine gun in RCWS (500 rounds)

Armor, Protection, and Countermeasures
Armor Composition: TBD
Armor Materials: TBD
NBC Protection: TBD
APS: „Lightning Curtain“ soft-kill system (IR and laser jammers)
Countermeasures: 20 76mm smoke dischargers

Sensors
360° CCTV system with Image Intensifiers instead of vision blocks
CITV with Image Intensifier and Thermal Imager, Laser Rangefinder, continuous zoom up to x5
GSS (Gunner's Sight System) with Image Intensifier and Thermal Imager, Laser Rangefinder, continuous zoom up to x15
MGBS (Main Gun Backup Sight) with Image Intensifier, stadiametric rangefinder

Electronics
3 digitally encrypted radio sets
AVCS (Allied Vehicular Command System)
Tank-Infantry phone at the rear of the tank

argh why does it seem like there's >9000 tanx with some sort of "M8" designation

Anyways, this is largely a visual thing since I don't have time to look through the statblock, but looking at the picture it doesn't seem like there is much room for a significant amount of turret armor.

Regarding the designation... Well, I just selected a number. *shrugs*

About the room for the turret armor:
- The whole turret is 3.04m (top) to 3.30m (bottom) wide.
- The hatches are both 0.70m wide and 0.70m apart.
- From the outer edge of the hatches to the upper edge of the main turret body (not the small "step"), it is 0.47m
- From the front edge of the hatches to the frontmost part of the turret, it is 1.47m

This should be enough, I guess?

use kkkounterslope

You don't limit your engine in peacetime, it won't save you much fuel, or anything else really. Losses are affected by your maximum design rating, not artificial limit. And then 1350L won't last a 2500hp engine with 80t long (450km) either way. And 2000hp is enough for a heavy tank, which this is.

Your 12.7 ammo loads are too high. 10,000 rounds, in belts and mags, would weigh 2.2 tons. Even if you don't care about weight, that's a whole lot more boxes than pictured.

You are cutting great big holes in the armor from the commander's and gunner's sight , which is what I was referring to.

2500hp from just 30 litres is a big ask. It's going to mean either an extremely high compression ratio or ridiculously high boost.

Okay, I get your point.
Both the CITV and the gunner's sight are on top of the armor, the only holes in the armor are those for the wiring, since both systems use digital cameras instead of a traditional optical system.

Nice. :D I already saw it before on the "Your Nation's MBT" thread.

Is this made in Google Sketchup?

Yes, I started with SU and I kinda like it.

@Vault X and Forza:
I updated the factsheet according to your criticism.

I'm kind of doubtful that you have enough room for any sort of serious sensor and optics setup in the amount of space you have there. Modern tank sighting systems aren't exactly small, and it's not because they need to have a human looking through them. Your best bet really would be to move them back to just forward of the hatches.

Nice picture mate.

You want direct optical backups too though.

Advice for the best armour/sight set up is to loom at the Challenger 2, it is hands down the best. The digital (TOGS) system is above the main gun, outside of the mantlet, and wiring passes around the mantlet instead of through it. And the gunner's backup optical sight is actually right above his head. So there are no protrusions through the front armour. Chally 1 does it the same way (As does Chieftain), for a reason (different placement of TOGS though).