SDP wz 66 Grom

Last updated on 14 September, 2025.

SDP wz 66 Grom is a tier 8 Polish TD. It features a 162mm gun with high damage and great DPM. It has good mobility, but a limited top speed; and it has reliable frontal armour.

1. Armour
2. Gun
3. Mobility
4. Equipment, Consumables, & Provisions
5. Gameplay advice
6. Overall
7. Is it worth getting?
8. Legendary Camos:

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Armour

(The SDP wz 66 Grom in the images is using Improved Assembly)

Drag slider right -> to view 225mm AP
Drag slider <- left to view 265mm APCR

Armour when facing head on:
Upper plate (under gun) 425mm
Main superstructure 280-295mm
Upper plate shoulders 400-425mm

Lower plate 170mm
Cupola & viewport 130-290mm

Side armour:
The hull side is 60mm thick behind the tracks, the side of the main superstructure is 66mm.

Armour vs tier 7 enemies:
Facing against tier 7 tanks, no enemy has enough penetration to penetrate anywhere on the upper superstructure.
The only weakpoints against a tier 7 tank are the lower plate and the cupola.

Armour vs tier 8 enemies:
Facing tier 8 its a very similar situation, most tanks can’t penetrate the upper plate even with premium ammo, and the main weakpoints are the lower plate & cupola.

The tanks that this doesn’t apply to are tanks with exceptional premium penetration (over 285mm), or tank destroyers.

Armour vs tier 9 enemies:
Against tier 9 enemies the upper superstructure is still very strong, a few TDs with very high penetration can penetrate with standard ammo, but all other tanks will need to use premium ammo.

Without angling, most tier 9 MT & HT  can go through the front. Angling the hull can help to premium ammo, but only up to the ~300mm penetration mark. Any more than this will require you to use gun depression to bounce.

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Gun

The Grom mounts a 162mm gun that shoots 100mm shells. It has Assault Shells mechanic, where damage gets less the further away from enemies you are.

Damage:

Range	0-50m	51-120m	121-200m	201-720m
DPM	3378	2896	2413	1930
Standard Alpha	518	444	370	296
Premium Alpha	448	384	320	256
HE Alpha	630	630	630	630

Firepower:
-Ammo: APCR/APCR/HE.
-Penetration: 243/305/63mm.
-Reload time is 9.2s.

Handling:
–Estimated aim time is 4.0/4.3s
–Base aim time is 2.52s, but it can get down to 2.02s.
-Dispersion is 0.353/0.300
–Gun handling is 0.15/0.18/0.08, or 0.13/0.16/0.07 with Vertical Stabilizer.

Usability:
-Shell velocities are 900/1200/750 m/s.
-Gun depression is -7 degrees.
-Gun arc left/right is +10/-10 degrees.

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Overall this is a good gun, given that you are using it correctly for the majority of the battle. Standard penetration is mediocre by TD standards, but good on premium. The gun is mounted quite low on the tank, combined with -7 gun depression and good gun arc make it quite flexible.

Effective range:
-Up to 50m your DPM & alpha are insane and completely unmatched, accuracy & aim time don’t matter at this range.
-Up to 120m you still have very competitive alpha & DPM, still more than most TDs at tier 8. Accuracy & aim time still don’t matter too much, but occasionally you will have to take some time to aim, however for 444 alpha, its accuracy isn’t too bad.
-Up to 200m your alpha & DPM are not competitive against TDs, but still good compared to HT. 370 damage means many HT will out-trade you, and the accuracy & slow aim time at this range make it easier to miss or bounce.

Ineffective range:
-Past 200m its not ideal to use the gun. Damage is terrible, accuracy is horrendous for that damage, and DPM is abysmal. Its not worth shooting enemies at this range unless its the only thing you can do.

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Mobility

Raw stats:
-Forward speed is 35km/h.
-Reverse speed is -13km/h.
-Raw acceleration rate is 16.2 hp/t.
-Engine power is 776 horsepower for its 48 ton weight.

Hard terrain mobility:
-Actual acceleration is 16.2 hp/t.
-Traverse speed is 42.1 deg/s.

Medium terrain mobility:
-Actual acceleration is 13.5 hp/t.
-Traverse speed is 35.1 deg/s.

Terrain resistance stats:
–Terrain resistances are 1/1.2/1.75

Overall this is great mobility. Consider that the Grom has armour like a heavy tank, or even better than a heavy tank. Its top speed isn’t crazy but its decent, but reverse speed is quite slow. Acceleration is great, making it very easy to maintain that 35km top speed throughout the battle. Traverse speed is decent, but the tank can still be circled by faster tanks

(The most important part of the mobility here is the 1.2 medium terrain resistance, it gives Grom a significant advantage in mobility compared to all Polish tech tree TDs.)

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Equipment, Consumables, & Provisions

SDP wz 66 Grom has no special consumables or provisions.

Gun Rammer:
Use gun rammer, there is no point or reason to use calibrated shells, as the entire point of the Polish TDs is to have great damage & DPM at close range. Gun rammer focusses on this aspect, improving the reload time from 9.7s to 9.2s, and max DPM from 3207 to 3378.

Enhanced Armour:
While the armour of this tank is good enough to not need enhancing, using enhanced armour just makes it much more reliable, especially against high penetration tier 8 tanks.

Using enhanced armour will improve the frontal superstructure by 8-10mm of effective thickness, going from 280mm at its weakest, to 288mm.
Grom already has respectable HP at 1320 base, which is perfectly decent for a TD.

Improved Control:
Due to its good acceleration and limited top speed, Grom can get away with losing a bit of acceleration. The traverse speed of the tank can sometimes be a bit awkward, since its decent for a TD, but definitely not very quick. Since you don’t have a turret, the hull traverse speed is more important than on most tanks.

Using improved control would improve your traverse speed from 42.1 to 44.7 deg/s on hard terrain, or from 35.1 to 37.3 deg/s on medium terrain.

Vertical Stabilizer/Refined Gun:
This will be down to personal choice, as the Grom has both mediocre dispersion and aim time.

Vertical stabilizer will help to improve your effective aim time (from 4.3s to 4.0s), however it leaves your dispersion at an unimpressive level (especially noticeable when you get fully aimed).
Refined gun improves your dispersion (0.353 to 0.300), making the gun more accurate at all ranges but with slower aim time.

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Gameplay advice

The Grom plays just like the Kilana, Gonkiewicza, or Błyskawica (Polish TDs tier 8-10).

It has better mobility & gun depression, and compared to the Błyskawica better effective armour, tier-for-tier than these tanks. However its characteristics and gameplay remain largely the same due to its gun mechanic, good armour, and good mobility.

General gameplay:
General gameplay is relatively simple. When loading into battle, note the map and which side you spawn on.

Go to the side of the map that has the shortest engagement distances (closest range fights). On many maps it will be the HT flank, but on some it will be the MT side, especially maps where HT often camp across from each other at distance to trade shots (such as Faust, Castilla, or Canal).

From there, try to take hulldown positions where you can hide the lower plate, and use some gun depression to hide the cupola. Prioritize shooting the closest enemy to maximize damage & DPM.

Try to play aggressively and on the frontlines, its where the tank works well. It has reliable armour & gun depression to use positions, and its gun lets it trade damage effectively in brawls.

Account for range:
When playing, and in general when taking shots, make sure to pay attention to the range indicator on your screen.

Using the rangefinder & your range/damage indicator will help you know how much damage you will do to an enemy, or how easy it would be to move closer for higher alpha.

Drive towards enemies:
In the right situations, you should drive towards enemies before shooting. This increases your alpha damage of a single shot. Generally only do this in close range fights where you have an isolated enemy you can push towards (such as at 70m, you can drive an extra 20m to increase your damage).

Don’t do this if you are far from the enemy, as most of the time, performing this maneuverer isn’t worth it due to your limited top speed.
Your damage drops off by 74 per range increment, so unless you are already quite close to the enemy, the time it takes to drive to the enemy usually makes this not worth doing.
In that case, take the shot, drive forward, and by your next reload your alpha damage will be higher.

Long range shots:
Only take long range shots if there’s nothing else you can do.

For example:
If you aren’t spotted by any enemy or in danger of taking damage, you have time to aim fully, and the enemy you are shooting at is the only one available, then you can take that shot at long range.

-If you are spotted and not hulldown, just retreat. Most enemies will out-trade you at 296 alpha.
-If there’s a different enemy at closer range, switch targets and shoot them. You’ll do more damage and be less likely to miss your shot.

Using premium ammo & HE:
Note that premium ammo also loses damage at longer ranges, but HE does not.

Use HE on any tank that you can penetrate, especially at longer ranges, since if it does penetrate it will always do more damage than your standard or premium ammo.

HE can also be very useful for doing splash damage over further ranges as it won’t bounce, and a good HE roll even when not penetrating (150-250 damage), isn’t too far off your premium APCR at long range (which is 256 damage at 200m).

Facehugging:
Facehugging can be done in this tank quite effectively. Enemies can shoot down on the upper plate and penetrate with premium ammo, but you can angle the tank and put the large gun mantlet in the way of their gun.

Enemies which don’t load premium ammo won’t be able to penetrate the upper plate.

Angling armour:
Despite having angled “shoulders” on the superstructure, the hull of the Grom can be angled (unlike the tier 10 NC-70 Błyskawica).

The armour of the entire front is the same thickness, at 210mm base. Wiggling/angling the front of the tank helps a lot to bounce higher penetration rounds, such as from tier 9 tanks or from high penetration tier 8 heavies.

Trades:
When trading damage, make note of the range your tank is at. At the furthest range, you 296 alpha generally won’t out-trade many tanks, and even if it does, those tanks will have much faster reload than you.

In medium range where you do 370 alpha, you can out-trade many tanks, but there are still many other tanks with 380-420 alpha that will out-damage you.

In the closer ranges (less than 120m) where you do either 444 or 518 alpha, you’ll easily out-trade or out-reload enemies at the same tier, and even most tier 9 enemies.

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Overall gameplay of the Grom is quite similar to its tech tree counterparts. Playing aggressively, in close range, and using hulldown whenever possible.

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Overall

Armour – 8/10
Gun – 7/10
Mobility – 6/10
Speed – 5/10

SDP wz 66 Grom is overall a great tank.

Armour is very reliable and easy to use, with the only weakpoints being the cupola & lower plate.
Gun is great considering its used right. Mediocre accuracy & aim time only become issues at longer ranges, & at close range the DPM & alpha damage are unmatched. Standard penetration is below average, but premium is good. -7 gun depression & low gun make it fairly flexible.
Mobility is good, with good acceleration rate on both terrain types, and decent traverse speeds.
Speed is average (considering HT levels of armour) at 35km/h.

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Is it worth getting?

The Grom is worth getting if you like the mechanic or gameplay of the Polish TDs. Grom is essentially an improved version of the Polish TD tech tree, with tier-for-tier better armour than the tier 10, and significantly better mobility than all other Polish TDs.

The SDP wz 66 Grom is worth 9,000 gold. Its a great tank, and due to its mechanic it has interesting and different gameplay compared to other premium/collector tanks.

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Legendary Camos:

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