REDS 521 Sport .21 Off-Road Competition Buggy Engine Combo w/2143 Tuned Pipe & M Manifold (Broken In)

Read Reviews
Write a Review
REDS 521 Sport .21 Off-Road Competition Buggy Engine Combo
Back Order Now
You may back order this item and it will ship when it arrives.
FREE Shipping Eligible! Learn More
Price: $419.99

Please Log in to receive a notification when this item arrives in stock.

Save In List
This item earns up to 420 VIP Reward Points Learn More

The REDS 521 Sport .21 Broken In Off-Road Competition Buggy Engine Combo with 2143 tuned pipe and M manifold (REDKM210011), delivers a high end balance of innovation, quality and performance - at a mid range street price. The 521 Sport features technical changes in the 5 port sleeve, combined with updated materials to offer users high reliability, tuning stability and fuel mileage. The 521 Sport guarantees excellent performance at a reasonable price.

This combo has been broken in using a specific blend of oil for breaking-in nitro engines using the Oil Bath Lapping Machines. The pre-break-in process saves time, fuel and increases the performance over the traditional break-in process. Only a quick, post oil bath, break in process is keeping you from experiencing quality and performance.


  • ALUMINUM CARBURETOR: 521 Sport engine includes the same aluminum carburetor as 721 engines to guarantee reliability and tuning stability. The insulator bushing has been improved with aerospace grade ultra high strength polymer. Furthermore, the GEN2 carburetor features a double grub screw joint link to allow positioning and fitting with the any servo linkage system.
  • STATE OF THE ART DIE CASTING: The unique high stiffness crankcase design is produced with a high quality pressure die casting process and special aluminum alloy developed by REDS Racing engineers to guarantee higher stiffness and strength.
  • 5 PORT TECHNOLOGY: The piston and sleeve features updated materials. Thanks to updated 5 port technology, this engine provides really good fuel mileage and a smooth power band.
  • HANDMADE, TUNED AND ASSEMBLED: Every single engine is hand inspected and compression checked inside REDS Racing headquarters by Mario Rossi to achieve the highest quality standards.
Category: 1/8 Buggy and Truggy
Displacement: 3.5cc
Bore: 16.2mm
Stroke: 16.9mm
Intake ports: 5
Exhaust ports: 1
Front Bearing: 7x19x6mm rubber seal
Rear Bearing: 14x25.4x6mm Swiss made steel
Carburetor Venturi: 7.0mm (6.0, 6.5, 7.5, 8.0 optional)
Carburetor: VCX2-A Aluminum Short needle
Weight: 345g
Fuel consumption: > 9:00 min
Engine temperature: 110-130°C
Recommended Glow plug: REDS TS3
Recommended pipe: REDS 2143 + M or XONE Torque
Recommended fuel: 25-30% nitro, 8-10% oil
Break-in fuel: 12% oil

This product was added to our catalog on June 24, 2022

Daniel Caines
Verified Owner
Sunday, Dec 18 2022 (12 months ago)
REDS 521 Sport .21 Off-Road Competition Buggy Engine Combo
I have 1 gallon of racing on it now and it has as much power or more than the $500 plus Japanese engines smooth and easy to drive I just one pitted a 20 minute main so great fuel mileage also.The best engine out there for the money
Joey Erwin
Verified Owner
Wednesday, Mar 29 2023 (8 months ago)
REDS 521 Sport .21 Off-Road Competition Buggy Engine Combo
Got the engine super fast shipping and no delay. Looks wise this thing is all business and very clean. Craftsman ship top notch engine was beautiful upon inspection. Ran a few more tanks easy to further break in. Ran it in front of the house in the street did a small tune. Took it to Hot Rod track in so cal and did the final touch up tune. LOVE this thing ran incredible, no issues tons of bottom end was getting over all the triples with ease and ripping the straight as well. My tune temp was about 229. Buying another one. Top notch!!