Classic Army DT4 HPA DIY Kit

This is a DIY HPA Kit for the DT4. I've built quite a few of these, using this exact kit with almost every engine on the market.

Engines
The DT4 has an abnormal engine mounting. It does not have a peg like most other gearboxes. Wolverine and Pulsar engines completely drop in, no modifications needed. Polarstar engines do need modified to fit by sanding or cutting a groove in the engine itself (see photos of the Jack engines). Due to wiring, F2s will not work.

The new Gate Pulsar S (not the Dual Solenoid) will drop right in, but I have not tested the Titan II board. Pulsars will work perfectly with Polarstar Electronics.

Electronics
Wolverine Reaper EM is the easiest to install, but will be limited to semi only. You can use the stock trigger board and micro switch for this, although the lifespan of the microswitch may be decreased with the extra power going through it.

Wolverine Gen 2 Premium electronics will NOT work. They have a build in short detection that will be triggered if you split the wiring to two engines. Finding the Gen 1 Premium electronics may be difficult.

Wolverine Spartan board can be made to work, but is not a complete drop in and may require major modifications.

Gen 1 Premium electronics will drop in using my kit, but will require using the included splitter.

Polarstar Trigger boards drop in without a problem and you can use the second solenoid adapter typically used for the F2 engine. I want to note that both engines will never be able to fire at the exact same time, but changing the dwell settings can make them virtually identical, or you can purposefully have each barrel alternate. The left solenoid connector will need to be unsoldered and wires will need to be directly soldered to the board to clear the DT4 trigger. This can be tricky to remove, so be careful when doing so (I unsoldered both in the photo).

If your Polarstar V2 board does not have two solenoids, you can use a splitter like the Wolverine engines, although I have never done this personally.

You can use a Polarstar FCU with Wolverine engines, but performance may vary.

Printed Parts
With the trigger board adapter, you can drop in most an V2 trigger board and use the stock DT4 Trigger. Aftermarket triggers will not work in the DT4 without major modifications.

Selector switch adapter allows for the stock selector switch to work with a V2 trigger board full auto switch. The only requirement is a small hole threaded into the stock selector plate. Be careful when doing this as to not strip it and to insure the screw does not interfere with anything.

I should note that some of the photos reflect the airline going out the grip, but I have found that it is easier to run it out the rear of the gearbox under the buffer tube. This puts less stress on the airline and makes install much easier, but will require some drilling/cutting. This is pictured with the Jacks where I cut the whole rear of the gearbox out.

Barrel/Bucking
I have yet to find an aftermarket hopup that fits well in the DT4, and unfortunately the stock blue hopups are prone to breaking the C clip, so be careful. When it does break, the outer barrel will hold it in place. The stock 363mm barrels are fine, but you can upgrade them with any AEG barrel. Buckings are recommended to be upgraded and I would highly recommend Madbull Redsharks because they are awesome buckings and come in a two pack with nubs.

Materials Required
x2 Wolverine, Polarstar, Pulsar, or Protech engines
V2 trigger board and FCU
Saw, File, sanding etc if you use Polarstar or Protech engines

(Included) M2x4mm for the selector switch, plus spares
(Included) Micro Mini JST Connectors 
(Included) Air line splitter

Professional tech installation recommended, some minor modifications or sanding may be needed for fitment

Some photos may be from older builds and may not reflect the finalized product. The second photo shows the most up to date version of the kit.