| Author |
Message |
    
paul_brooking
| | Posted on Saturday, October 19, 2002 - 06:07 pm: | 
|
I have a st p55 but I am curious about the cylinder head, could it be a p66.
The diameter of the combustion chambers in the head is slightly (about1/4 to 1/2 inch without measuring) larger than the bores. This does not seem a particularly wise design feature in terms of minimising surface area to reduce heat loss. Is this just tollerancing of the castings, as the head chambers are not machined ? Does the p66 have larger bore, longer stroke , or neither and some other feature to get more power.
I dont know for sure myne is a p55, but the cylinder capacity is 270cc per and the manual for a p55 gives this capacity. There is no engine plate |
peter ogborne
| | Posted on Tuesday, October 22, 2002 - 10:28 am: |
|
Paul.........all my data is packed ready for a move i am making . But if my memory serves me right the bore of the P55 is 2.250 inch with the same stroke . I can't remember what the bore and stroke of the P66 is but it is rated at 10 HP as against the 8HP of the P55 . Both these are at 1500 rpm .
If I can help at a latter date ........dont hesitate .
There have been some quite different types around ,some with magneto ignition ,some with battery and coil . A couple of different carburettor types are also found . |
paul_brooking
| | Posted on Tuesday, October 22, 2002 - 12:05 pm: |
|
thanks Peter , my findings agree with what you say. Understand about the move . I just wonder if my engine has a head from a larger engine.
I think Tim Mulvey may be able to give me some info as he is working on a P55
Paul |
paul_brooking
| | Posted on Wednesday, October 23, 2002 - 08:40 am: |
|
I have only just got to go to the garage and properly take the dimensions, afraid it shows me being an armchair mechanic 
cylinder dia 2 1/4 inch
head chamber dia 2 15/16 inch dia
This is a bigger difference than I thought. I dont think 2 15/16 can be the bore of P66 because even with a 2 1/4 stroke this would be around 14BHP. and such a bore/stroke ratio may cause piston heating problems.
The sketch of the p55 in the manual shows head and cylinder same diameter, though this is not a proper drawing.
I think it must have been made with these mushroom shaped combustion chambers. |
paul_brooking
| | Posted on Friday, November 01, 2002 - 08:33 am: |
|
It is difficult to find much on P6 & P66 but I've found a helpful chap Guy Cook at www.tradboatrally.com with a P6 manual who tells me that the stroke and bore are both 2.75 inch. Now we all know that the P5 is 2.25 by 2.25
This does not explain why my head chambers are 2.937 inch dia.
Another thing that I can't explain is why the capacity of a 4 HP (1500 rpm)engine is increased by 82.5% to make it a 5 HP engine. I am told this is also at 1500 RPM anyone got an idea?
Paul |
paul_brooking
| | Posted on Friday, November 01, 2002 - 08:52 am: |
|
Have just been going round in circles, could not make cylinder capacity sums make any sense !
**********
The P5 P55 are 2.75 inch by 2.75 inch (not 2.25)
so engines are same capacity.
Obvously they did somthing else such as increase compr. ratio to get more power.
so seems it must be the correct head on my engine.
would be interested to hear next time someone has one off.
Paul |
Joe Lawson
| | Posted on Monday, April 21, 2003 - 11:59 pm: |
|
Hi I think that the only difference in the p5-the p55, and the p6 -and p66 is the introduction of a different carb. giving it the increased HP .I read this in som info I got with an engin I bought.I have a p-5, and an st4 12HP four stroke Stuart's that I am Looking for a hull to put them in.I live in West virginia ,USA. I also have the operating manuals for both engins if someone needs info. Thank's ,Joe Lawson |
Alex Stewart
Visitor
| | Posted on Saturday, December 03, 2005 - 10:01 pm: |
|
I have 2 P55 - the name plate clearly states this, and also clearly states that they are 10HP.
Where does this "8HP" idea stated on this site come from? Sofar the only differences I have found between P55 and P66 are minor construction details (e.g. magnito mount is on gearbox of P55, and is a seperate, adjustable part of the P66) Anybody out there know the real facts? |
Roger DiRuscio
Senior Member
Username: solarrog
Post Number: 189
Registered: 03-2002
| | Posted on Saturday, December 03, 2005 - 10:17 pm: |
|
I have a P55 MRE that plainly says 8 HP
I guess you have the super dupper model |
Peter Ogborne
Senior Member
Username: peterogborne
Post Number: 271
Registered: 09-2002
| | Posted on Sunday, December 04, 2005 - 07:12 am: |
|
To help on the subject ....the Stuart TurnerP55 and the P66 both have the same bore and stroke dimensions . The differance is the developed HP . The P55 develops 8 BHP at 1500 rpm. The P66 develops 10 BHP at 1650rpm.
Both engines have a standard bore of 2.75 inches and a stroke of 2.75 inches giving them a capacity of 536cc or 32.66 cubic inches.
The P6 and the P66 were later versions with very little external differance from their earlier versions . The P6 had an Amal carburetor whilst the P66 had the brass Solex unit.The earlier P55 had the brass Stuart carburetor. The differance between these two carburetor was that the Solex had an air mixture control.Ignition was differant the later P66 had a twin coil system as against the earlier HT magneto ignition.
Hope this jumble of info helps.......... |
S A M
Visitor
| | Posted on Sunday, December 04, 2005 - 10:16 am: |
|
I believe the P6/P66 was an update of the P5/P55, replacing S-T's traditional clearance seals with spring energised rubber ones and the iron piston/s with aluminium. In the process S-T found a couple of extra horses, probably with mildly revised porting. |
Steve Edwards
Visitor
| | Posted on Monday, January 12, 2009 - 01:38 pm: |
|
Hi I live in Zimbabwe and have a Stuart Turner motor - drives a small generator - I use it mainly for charging batteries. need spares - rings, oil seals etc. can anyone help ? |
John kidd
Visitor
| | Posted on Monday, March 29, 2010 - 05:55 am: |
|
I have a 19 foot clinker motor launch semi planing hull beam 6.5 foot. What sort of speed can I expect from a 10 h.p. S.T. engine in this. What dia. and pitch prop. will it drive?
I run a 1911 Scott so have no reservations about running a Stuart Turner I remember them as a quiet and sweet engine but worry that they not punch the tides round here.
thanks John |
R.L.Jones
Visitor
| | Posted on Wednesday, March 31, 2010 - 12:19 am: |
|
Hi John, re your query about the performance of the P66, I have a couple I fitted into a 16ft and 14ft respectively. The 16ft full bodied clinker does 7.4kt and the 14ft does 6.8kts according to GPS. The 14ft is way overpowered and I have since fitted a reconditioned P5 into it and it still does 6.8kts. The P66 in the 16ft is fitted with a 12 x 8 LH prop and I feel is about right at all range of speeds. Cheers, Roy |
storey
Visitor
| | Posted on Monday, August 02, 2010 - 07:24 pm: |
|
i need parts for a p55 can anybody help or know of a place where i can get parts thanks Gary |
Ken Richardson
Visitor
| | Posted on Saturday, March 05, 2011 - 09:25 am: |
|
Hello, I have a Stuart Turner P55 8hp engine which I would like to restore, does anyone have a manual they could email me as one would be very useful, I would very much appreciate it if you could help, best regards, Ken. R. |
steven john page
Advanced Member
Username: fairbanks
Post Number: 43
Registered: 12-2007
| | Posted on Saturday, March 05, 2011 - 04:40 pm: |
|
Hello ken, if you log on to the stuart and turner info exchange group on yahoo ,you will find a wealth of info on most S T ENGINES INCLUDING MANUALS. regards steve. |
Ken Richardson
Visitor
| | Posted on Friday, March 11, 2011 - 12:22 pm: |
|
Thanks for the info Steve, a most useful and helpful site, regards, Ken |
