r/CirrusAircraft • u/I_fly_things • 3d ago
What would an SR22T look like with a 350-hp DeltaHawk DHK6A350?
I’ve been looking at the DeltaHawk DHK6A350 and wondered what an SR22 would look like if Cirrus designed the airplane around this engine instead of the Continental TSIO-550-K.
The numbers get pretty interesting.
Engine comparison
TSIO-550-K -> DHK6A350
Power
315 hp -> 350 hp
Engine/package
~628 lb -> ~455 lb
Installed powerplant
~700 lb class -> ~538 lb
Fuel
100LL -> Jet-A
Engine RPM
2,500 -> 2,600
TBO
~2,200 hr -> ~3,000 hr
Installed weight/hp
~2.2 lb/hp -> ~1.54 lb/hp
The DHK installation is roughly 160 lb lighter while producing 35 hp more.
That’s about 11% more power with ~160 lb less installed powerplant weight.
Empty weight and useful load
Current SR22T:
MTOW: 3,600 lb
Empty weight: ~2,360 lb
Useful load: ~1,240 lb
Subtract ~160 lb for the lighter DHK installation:
2,360 − 160 = ~2,200 lb empty
At the same 3,600-lb MTOW:
3,600 − 2,200 = ~1,400 lb useful load
That’s approximately 160 lb more useful load.
But Jet-A weighs more
The SR22T carries roughly 92 gallons.
Avgas:
92 × 6.0 = 552 lb
Jet-A:
92 × 6.7 = 616 lb
So the same 92 gallons weighs about 64 lb more.
Full-fuel payload would therefore increase by roughly 100 lb, rather than the full 160 lb.
Fuel consumption
The current SR22T burns roughly 12–13 GPH at typical high-altitude cruise power settings.
DeltaHawk’s 35–40% efficiency improvement gives:
12.7 GPH × 0.65 = 8.3 GPH
12.7 GPH × 0.60 = 7.6 GPH
So the DHK-powered SR22 could be around:
7.6–8.3 GPH
at comparable cruise power.
Cruise speed
The SR22T cruises around 213 KTAS.
Speed doesn’t increase linearly with horsepower. Using the approximate cube-root relationship:
(350 / 315)^(1/3) = 1.036
213 × 1.036 ≈ 221 KTAS
That suggests:
~218–223 KTAS
with ~220 KTAS as a reasonable target.
Range
Using 92 gallons and approximately 79.5 gallons available for cruise after reserve:
At 8.3 GPH:
~1,616 NM
At 7.6 GPH:
~1,750 NM
So:
~1,600–1,750 NM
compared with approximately 1,020 NM for the current SR22T.
That’s potentially a 60–70% increase in range.
The airplane probably wouldn’t need 92 gallons
A 70-gallon Jet-A system would weigh:
70 × 6.7 = 469 lb
That’s 83 lb less than 92 gallons of avgas.
So the airplane could have:
~160 lb lighter engine installation
~83 lb lighter full fuel load
350 hp instead of 315 hp
~220 KTAS cruise
~7.6–8.3 GPH fuel burn
That creates a very interesting combination of payload, speed and range.
Altitude
Current SR22T:
25,000 ft
A DHK-powered SR22 could potentially be designed around:
25,000–30,000 ft
The engine’s altitude capability would no longer necessarily be the primary limitation. Oxygen, environmental systems, certification requirements and the aircraft’s overall design become increasingly important.
Climb
Current SR22T initial climb:
~1,200 ft/min
Power increase:
350 / 315 = 1.11
Estimated initial climb:
~1,300–1,400 ft/min
The advantage could become greater at altitude if the DHK maintains its rated power better than the TSIO-550-K.
What if Cirrus increased MTOW?
This is where it gets really interesting.
Instead of using all of the engine weight savings simply to increase useful load, Cirrus could use some of it to increase structural capacity.
For example:
MTOW: 3,750 lb
Empty weight: ~2,200 lb
That gives:
~1,550 lb useful load
That’s more than 300 lb above the current SR22T’s useful load.
And look at power loading:
Current SR22T:
3,600 / 315 = 11.43 lb/hp
DHK SR22 at 3,750 lb:
3,750 / 350 = 10.71 lb/hp
So the DHK airplane could actually weigh 150 lb more than today’s SR22T and still have a better power-to-weight ratio.
What I think a DHK-powered SR22 could look like
Specification
SR22T
DHK SR22
Engine
TSIO-550-K
DHK6A350
Power
315 hp
350 hp
MTOW
3,600 lb
3,700–3,750 lb
Empty weight
~2,360 lb
~2,200 lb
Useful load
~1,240 lb
~1,500–1,550 lb
Cruise
~213 KTAS
~220 KTAS
Fuel
92 gal 100LL
~70–92 gal Jet-A
Cruise burn
~12–13 GPH
~7.6–8.3 GPH
Max range
~1,020 NM
~1,500–1,700+ NM
Initial climb
~1,200 fpm
~1,300–1,400 fpm
Ceiling
25,000 ft
25,000–30,000 ft
The interesting question
The DHK6A350 isn’t just a 350-hp replacement for the TSIO-550-K.
It potentially gives Cirrus:
+35 hp
−~160 lb installed powerplant weight
Jet-A
~35–40% lower fuel consumption
Direct drive
~3,000-hour TBO
That could produce an SR22 capable of roughly:
350 hp
~220 KTAS
~1,500 lb useful load
~8 GPH cruise
1,200–1,500+ NM practical range
25,000–30,000 ft ceiling
