Hi is anyone fa with converting a standard 152-115HP To 125HP The STC is available ,My questions are What is involved I know that changing pistons to increase compressionis one , I have heard that the prop also is changed? I am trying to look at how much it will cost ,and what are some of possible drawbacks, one person told me the 125 HP was more prone to cracking the Cylinder Heads? Anyone have eany experience with this Conversion?
William, I flew a 152 with the Sparrowhawk conversion during the first part of my primary training. It was a fast plane during cruise, as fast if not faster than the 172G that I own now, but I think it hurt the climb rate some. I flew a 150H the latter part of training, and it would climb much better than the 152. If I'm not mistaken, I think the TBO goes from 2400 hrs. to 2000 hrs. Based on my experience, I think it is a good conversion if you are not planning on using it for a lot of short field work. Just my $.02.
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SPARROWHAWK CONVERSION
Author: Bob
Date: 2/19/2003 5:43:33 PM
I owned a 1980 152 with "half" the Sparrowhawk conversion--the Sensenich cruise prop. The climb rate was terrible--and I have a feeling with the additional 10-15 HP you get with the oversized pistons in the conversion, it would probably just bring it back up to the climb rate of an un-converted 152. The cruise would probably be a few knots better though. It is a pretty expensive conversion for what you get, and probably not an efficient spend unless you plan on keeping it a long time. It adds NO value in resale. A few people I spoke with who had knowledge of some converted planes didn't think the "claimed" benefits were very realistic. If I wanted a hot 152, I would look at a 150HP engine conversion instead--they are pocket rockets, but again you are not going to get it back at resale. Good luck!
I spoke to Ken Blackman of AirMods yesterday. Regarding the TBO, it goes something like this: The FAA has no stance on the altered TBO. Years ago, Lycoming built a powerplant that put out 125 hp. These engines had a 2000 TBO. The higher compression shortened the life of the pistons. The pistons were later improved and TBO was back up to 2400. The Sparrow Hawk conversion is essentially the same engine, using the durable piston. So, TBO is assumed to be unchanged (2400), even though TBO has not actually been established for the Sparrow Hawk mod.
As far as performance goes, the website tells you that it increases climb and cruise. I have no first-hand experience flying a Sparrow Hawk, but maybe I will in a year. I'm looking to buy an Aerobat with a high-time, first-run engine. After all is said and done, the engine overhaul with Sparrow Hawk mod will cost $20-25k. (Phew!)
Ken will answer most FAQs. Very informative fella. He's had the STC since 1980. He stands by his product.
Look up these STCs on the FAA website:
SA1008NM --Installation of Sensenich prop on Lycoming 0-235-L2C (Sparrow Hawk prop mod only. This increases the output of the O-235-L2C to 115 hp @ 2700 rpm)
SE792NW --Modification of a Lycoming0-235-L2C engine to increase HP rating from 115-HP at 2700 rpm to a continuous 125 HP at 2800 rpm (Full Sparrow Hawk conversion, engine mod after Sensenich prop installation)
SA1000NW --Installation of Lycoming O-235-L2C(modified) (SE792NW) engine, McCauley 1A103/TCM 6958 propeller (Sparrow Hawk conversion, engine only).
I have flown in other 152's with the Sparrowhawk conversion, and have done one on mine. Performance is affected STRONGLY by the condition of the engine compressions. A weak engine just can not handle the additional 'bite' of the Sensenich prop, and the plane becomes a dog.
My engine is high time (~3,000 hrs smoh) but has great compressions still. I could not be more pleased with the results that I have gotten. I routinely fly between Montrose, Colorado and Jeffco/Boulder, Colorado at 15,000 to 17,000 msl.
If anyone would like to discuss this, or other 152 mods/stc's, feel free to contact me.
Re: 150 HP engine conversion for a 152??? Anyone?? STC??
I have put the Sensenich prop on my 152 and wanting to finish the Sparrowhawk conversion. My question is can I just do a top end,replacing cylinders and pistons or should I do a complete overhaul. The engine is at TBO and #3 cylinder compression is the lowest at 66 cold. I am also getting alot of lead fowling on two cylinders.
For the Sparrowhawk conversion are the cylinders standard cylinders from lycoming with higher compression pistons? Can I have the higher compression pistons installed into the cylinder from Lycoming? Or should I order the pistons from Airmods NW.and install them into the cylinders?
Re: 150 HP engine conversion for a 152??? Anyone?? STC??
I did the full sparrowhawk conversion on my C-152 in 1982 with good results. My engine was at TBO and lesed to a flying club at TTD-Flying Adventures(757FY). My menory is that only the top end change is req. for new pistons. The rebafelling is a must. i choose the standard prop--you can choose from a climb, standard, or cruise. My experiance was performance that matched closely to a C-172. ATC called me "cessna 172" all the time. On a standard day with me-165lbs-and full fuel it was common to get 1100-1200 fpm climb rates. For my personal flying, I would choose the cruise prop, as I wasnt flying in and out of short strips or high in mts a lot. But for training, the standard prop was great and had only praises told about it. Sorry I ever sold the plane.
The 150 O-320 is a good choice as I currently have a friend with one and it performs great--a hot rod!
Re: 150 HP engine conversion for a 152??? Anyone?? STC??
I for got to add that the plug fouling will disapear because the RPM limit goes to 2800 continueous. I had my engine balanced-pistons and rods weighed on a gram scale and matched to opposing pistons and filed the skirt of the heavier one to match them. This includes the rods compared seperatley and matched. I then had the prop dynamicly balanced at Western Propeller there at TTD. What a difference that made in the smoothness of the engine and entire aircraft. I have done it on all engines I have overhauled--cars included--since then. It's cheap and makes it a joy to opperate. Well worth it while its in pieces.
