10kt more is probably never worth the expense for the speed alone. Let’s say you have a 120kt plane, and you’re flying 200nm. It’s going to save you only about 7 minutes on a trip that’s over 1.5 hours long.
Arguably, the only effective speed mod is one which reduces total journey times, and in that context reduced runway requirements (length and surface quality) usually yield better results than increased cruising speed. So perhaps fit larger tyres and/or a climb prop? 
Incidentally, I see that fully one third of landing slots at this year’s Project Propeller shindig are for PA28 airplanes. No other model comes close on the G-INFO database, and yet I’ve never had the slightest inclination to fly one. What am I missing? Are they really so much nicer or more useful than a C172?
For a PA 28 the logical upgrade would be an Arrow
A well rigged Archer -181 is so close in practical performance terms to an Arrow why take on the additional complication of CS prop and retractable undercarriage – on average adding several AMU every year in maintenance? Yes there are owners of complex types which have low maintenance, but on average, for the average owner, maintenance will increase significantly. If you are going to go complex the 160KTAS Mooney 201J is still the benchmark – a solid 40 knots gain, and 25 knots over the Arrow.
The taper wing Warrior/Archer has nicely harmonised controls (we are not talking de Havilland here) and provides a nice ride for passengers, including a superior safety record. However, many argue the Arrow II (slab wing) is nicer than the taper wing Arrow III which feels underpowered.
120KTAS is generally regarded as a practical touring proposition – speedy in comparison to 80 knots in the 90 HP Super Cub. At 8 gph the Warrior is getting 15nmpg.
Jacko wrote:
Are they really so much nicer or more useful than a C172?
Not really. The single door is – IMHO – it’s biggest negative point – when it’s raining, you’re on sodden ground, the guy sitting front right has to wait until everyone else is inside before he can clamber into his seat and, if the PIC has been a right bell-end, gets his trousers smeared with mud from the bottom of the shoes of said PIC
Additionally, low wing means nowhere to stand under when it’s raining / nowhere to erect your tent, protected partially from the elements. Of course, low wing means separate fuel tanks and no ‘both’ setting for the fuel selector – this is for a large number of pilots a concern – that they’ll forget to switch the tanks over, leading to either fuel exhaustion and an emergency landing (happened to an Instructor at our club, he was so proud of his ‘skill’ at landing in a cornfield – until someone pointed out to him: The left hand tank was empty, the right hand tank was full. Why didn’t you simply switch tanks? 
Jacko wrote:
Are they really so much nicer or more useful than a C172?
It’s all a matter of personal preference… I do prefer the PA28 over the C172. Apart from the much more effective flaps on the C172, there are is noticeable difference in handling.
The C172 commands a bit of a premium in the second hand market – when I bought the Warrior I had been looking for a 172M which I regard as a nice version (the late Richard Collins favoured the 172H), but a low time, reasonably priced version was hard to find. The Warrior I bought had low TT and was in good condition for a reasonable price.
Handling wise and as a club aircraft the Warrior has proved itself. I have flown both types on long (2,000 miles plus) multi day cross countries, and on a long sector the Warrior is less tiring. Am not sure if the relative light wing loading and the pendulum effect of the high wing makes the 172 slightly more tiring.
Both the PA28 161/181 and C172 have a demonstrably superior safety record, coupled with reasonable maintenance mean they are likely to be around for a while longer.
RobertL18C wrote:
Handling wise and as a club aircraft the Warrior has proved itself. I have flown both types on long (2,000 miles plus) multi day cross countries, and on a long sector the Warrior is less tiring. Am not sure if the relative light wing loading and the pendulum effect of the high wing makes the 172 slightly more tiring.
I think it’s the other way round. The 172 handles a bit nicer than the PA28, especially in cruise. Plus, despite the high wing, I happen to be able to see more out of a 172 than out of a PA28. In the end it’s a matter of personal preference and for me, the PA28 (no matter if -140, -180, -181, Arrows…) just don’t tick my “inner airplane”.
Advantages C172P over PA28-181
Advantages PA28-181 over C172P
As this has turned from how to make a PA28 go faster into how to make a Lycoming O-360 go faster I shall throw in my 10 cents worth.
10 KTS + is available if you fit a Robin DR400 to the engine, it will go further, faster and do it out of runway 30% shorter.
Thanks @mh, that’s a useful comparison – although I’d be inclined to put electrically operated flaps on the “con” side.
I owned a low-wing airplane briefly, a CAP 10B, and couldn’t get rid of it fast enough. But even that machine had a proper flap handle – albeit connected to pathetically small flaps.
mh wrote:
Advantages C172P over PA28-181
To be fair you should either compare a warrior with a skyhawk OR an archer with a Superhawk (180hp)….then I think most of the pa28 advantages would disappear… in Australia Cessnas are preferred for many reasons including having a nice umbrella to keep the sun off, better clearance from the scrub, sheep and fences…easier for the dog to get in and out…
