Shipping Estimate
USA
- USA
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- USA
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Ships within 48 hours · Estimated delivery Jul 11 - Jul 16
Promo Codes Available:
For Your Every Summer RSVP, with Code: SUMMER15
Description
O.S. Speed 91HZ-R 3D Helicopter EngineFollowing the popularity of the 91HZ R with On Demand Regulator, O. S. has now taken high performance, high speed helicopter engines to the next stage of evolution. Introducing the 91HZ R Speed Engines based on the 91HZ R, factory tuned at the O. S. Japan facilities and guaranteed to blow you away! Features: Lightweight, machined heat sink head Big bore carburettors best suited for the intended use (F3C or 3D) Best precision advanced exhaust cylinder
Following the popularity of the 91HZ-R with On-Demand Regulator, O.S. has now taken high-performance, high-speed helicopter engines to the next stage of evolution. Introducing the 91HZ-R Speed Engines - based on the 91HZ-R, factory-tuned at the O.S./Japan facilities and guaranteed to blow you away!
Features:
- Lightweight, machined heat sink head
- Big-bore carburettors best-suited for the intended use (F3C or 3D)
- Best precision advanced exhaust cylinder timing (for F3C or 3D)
- Newly designed combustion chambers, shaped to match the big bore carburettors and advanced exhaust cylinder timing
- Lightweight, forged steel crankshaft counter weight to lower vibration for higher speeds
- Improved back plate shape, to accommodate Futaba's BPS-1 RPM Sensor and increase primary pressure for greater stability
- The cover plate has a cell to accept a sensor designed to install in the cover plate from Futaba GY701 / CGY750 Governor
Technical Specifications
- Displacement: 14.95cc
- Bore: 27.7mm
- Stroke: 24.8mm
- Output: 3.6ps/15,500RPM
- Practical RPM Range: 2,000-16,500
- Weight: 603g
Package Included:
- Engine Pack O.S. Speed Tuned .91HZ-R Helicopter Engine with Pump, 61G Carb
- #8 Glow Plug
- Check Valve
- Head Gasket 0.2mm
- OS Speed Decal and English Instruction Manual
Pipe: O.S. Powerboost Pipe 105
Shipping Notes
- Free Standard Shipping on $100+ Orders to the USA.
- Except Preorder products are shipped in 48 hours.
- Delivery to the USA:
- Standard Shipping : 3-10 business days
- If time is of the essence, please consider selecting expedited delivery for faster service.
Exchange/Return Notes
- We offer a 30-day return/exchange service after receiving.
- Final sale items are not eligible for returns or exchanges.
- To process your return/exchange, please contact us at [email protected]
- Please click here for more details>>> Return & Exchange Policy
4.1 ★★★★★
Based on 782 reviews
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Product Reviews
★★★★★ 1
Fit
Size: XX-Large, Color: Black
These shirts are very soft and comfortable but the mock fits very lose and sloppy
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Reviewed in the United States on March 15, 2026
★★★★★ 5
Great quality!
Color: Beige, Size: Large
Perfect for my husband for maternity photos. Large was the perfect size, it was long enough, and thick enough for the chilly weather! Would purchase again.
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Reviewed in the United States on May 2, 2026
★★★★★ 5
Will be buying more for the hubby for summer time.
Color: Beige, Size: Large
I was a little nervous buying this shirt as an anniversary gift for my husband but its actually really nice quality and the color wwas pretty accurate and he wants more!! Hes about 5'9" 190lbs and I ordered a Large and it fits him very nice. The material is very lightweight and so soft. Its definitely on the dressy side. I feel that the wrinkle quality is pretty good to because when. It came out of the package there wasn't much wrinkling and when it was folded there wasn't much either.
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Reviewed in the United States on March 2, 2026
★★★★★ 4
Looks great, however had size issue
Color: Blue, Size: Small
I ordered the small, however the sleeves were too long and will return it. The shirt looked great and seemed to be of very good quality. Certainly would have kept it if not for the sleeves.
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Reviewed in the United States on January 22, 2026
★★★★★ 5
Excellent!!
Color: Beige, Size: Large
Really loved these shirts for my hubby. They were pretty good quality shirts. Love the linen material. Also love the buttons on the collar which my husband prefers to wear with his jackets. They are very comfortable. As far as size, I ordered according to the size chart. He typically wears a size Large. According to the size chart an XL would best so that’s what I ordered. But I truly believe that a size L would’ve been better. So I would say they are true to size. My husband weighs 205, and has muscles and a size L would’ve been just fine. I ordered 3 because I loved them. I’ll stay with the XL. But if I were to order more I’ll preorder a Large. Very happy with this purchase. They are not slim fit either. Just for an FYI.
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Reviewed in the United States on February 22, 2026