LRP Nitro Engine ZR.28 Spec.4 Pullstart

Due to modifications of the already great predecessor, the LRP ZR.28 Spec.4 Pullstart has been significantly improved in the carburettor vernier adjustment as well as in the cooling of the cylinder head. The Heavy-Duty CoolDownMax cylinder head that has already successfully been introduced with its bigger brother, now also serves in the ZR.30.

A completely new carburettor has been build-in for an even better adjustability especially when in at idle speed. The performance, especially when stationary, has been improved with this move. All in all, the ZR.28 Spec.4 offers more torque with better adjustability and improved responsiveness.

Otherwise being a giant, it is a true midget in its dimensions. Due to its compact construction the engine can be used as a direct replacement to the .21 engines. The ZR.28 Spec.4 fits into all common .21 engine mounts.


Soon available again.

RRP: 149,99 EUR
(Recommended retail price)

Shop-price: 149,99 EUR
(Price incl. VAT, excl. shipping costs)

Pictures and videos



  • MASSIVE Big Block size - You cannot replace displacement with anything… but even more displacement!
  • New CoolDownMax cylinder head - Improved cooling and higher efficiency through new cooling fin arrangement
  • XTEC PowerCarb3 15S-2 carburettor - Flow optimised carburettor with 9.0mm inlet for maximum power and easy adjustability at the same time
  • Universal fit - Fits all major .21 engine mounts
  • FREE PLUG - FREE LRP Platinum / Iridium R5 glow plug included
  • Standard burn room - Guarantees easy adjustment of the engine in all conditions
  • XTEC T6 engine housing - Especially reinforced heavy duty engine housing for toughest offroad action
  • Massive con rod - Extra reinforced con rod. Specially adjusted for .28 engines
  • Ultra strong pullstart - Pullstart specifically developed for big block engines
  • Power Start capable - Prepared for the use of the LRP Power Start for starting the engine at the push of one button
  • Torque you can barely handle

Technical data

Cubic capacity .28 (4.57 ccm)
Bore 18.50mm
Hub 17.00mm
Power 3.93 HP*
RPM 33.900 RPM*
Number of ports 8 + 1
Glow Plug LRP Standard R5 (No. 35051)
Carburetor XTEC PowerCarb3 15S-2 with 9mm Venturi
Weight 420g
Class 1/8th Offroad Buggys/Truggys
* Figures may vary depending on used fuel, muffler and tuning

Spare parts
Tuning parts