ASP 180 FS gas conversion
08-09-2014, 04:27 AM
#26
Senior Member
Join Date: Nov 2007
Location: newark, UNITED KINGDOM
Posts: 525
Likes: 0
Received 0 Likes
on
0 Posts
One thing I can suggest is what size prop are you running and perhaps too much load? 16*8 on petrol with spark ignition is max. 18*8 on glow and methanol. That is with a well run-in engine.
The other question if the engine wasn't new, perhaps it was already worn before it was converted?
I guess you ran in a couple minutes at a time then cooling and not too chugging away at full throttle for an hour!
The other question if the engine wasn't new, perhaps it was already worn before it was converted?
I guess you ran in a couple minutes at a time then cooling and not too chugging away at full throttle for an hour!
08-09-2014, 05:34 AM
#27
Member
Join Date: Apr 2014
Posts: 63
Likes: 0
Received 0 Likes
on
0 Posts
The engine is new, the spark was advanced ok and it was not petrol, was ethylic alcool.
The hole at that position, pointing up to piston, was in a position where the oil film must be the strongest possible.
besides oil scaping the presence of a hole itself in that position generates heavy turbulence that brakes the film.
I posted my problem couse I judge an 'engineering absurdity' a hole in that position.
The prop used was apc 17x8.
The hole at that position, pointing up to piston, was in a position where the oil film must be the strongest possible.
besides oil scaping the presence of a hole itself in that position generates heavy turbulence that brakes the film.
I posted my problem couse I judge an 'engineering absurdity' a hole in that position.
The prop used was apc 17x8.
Last edited by PARDAL; 08-09-2014 at 05:41 AM.
08-09-2014, 09:14 AM
#28
Senior Member
Join Date: Nov 2007
Location: newark, UNITED KINGDOM
Posts: 525
Likes: 0
Received 0 Likes
on
0 Posts
So prop load was not the problem.
I think the idea is that the oils runs down the rod and into the bearing via that hole. Maybe not the best idea, since that is where maximum pressure is. Perhaps there was a burr on that hole which is why it picked-up and marked.
I have 2 of these engines, both have had many flights on Methanol and several on petrol with no big end issues. Your bronze bush will be a better item than the original I am sure.
I think the idea is that the oils runs down the rod and into the bearing via that hole. Maybe not the best idea, since that is where maximum pressure is. Perhaps there was a burr on that hole which is why it picked-up and marked.
I have 2 of these engines, both have had many flights on Methanol and several on petrol with no big end issues. Your bronze bush will be a better item than the original I am sure.
Last edited by dogshome; 08-09-2014 at 09:17 AM.
08-09-2014, 03:38 PM
#29
Member
Join Date: Apr 2014
Posts: 63
Likes: 0
Received 0 Likes
on
0 Posts
dogshome, I'm really curious about this bearing (or bush).
If, i designed such a bearing, my Machine Elements professor would reprove me and whip me to death. Ugh.
The next opportunity You get, please check if that low end bearing have 3 holes drilled in Your engines.
I've never seen such think in 40 years dealing with machines.
Theoretically, these engines have maximun 'burning' pressure at-2000rpm, slow-running, say, 20 Bar and at 6000 or 8000 rpm, 50 bar at maximun torke.
Such bearing with capacity of 20 bar at 2000 rpm would be able to support 20x3x3 = 180 bar at 6000, then, theoretically, the size of the propeller would be a problem in extreme cases only.
Tks
If, i designed such a bearing, my Machine Elements professor would reprove me and whip me to death. Ugh.
The next opportunity You get, please check if that low end bearing have 3 holes drilled in Your engines.
I've never seen such think in 40 years dealing with machines.
Theoretically, these engines have maximun 'burning' pressure at-2000rpm, slow-running, say, 20 Bar and at 6000 or 8000 rpm, 50 bar at maximun torke.
Such bearing with capacity of 20 bar at 2000 rpm would be able to support 20x3x3 = 180 bar at 6000, then, theoretically, the size of the propeller would be a problem in extreme cases only.
Tks
Last edited by PARDAL; 08-10-2014 at 12:41 PM.
08-10-2014, 12:50 PM
#30
Member
Join Date: Apr 2014
Posts: 63
Likes: 0
Received 0 Likes
on
0 Posts
I got the point.
Searching Just Engines I found a review "A.S.P. 'Series 3' 1.80fs - RCM&E" of which I took an extract.
Quote.
The single ring piston is a permanent die casting from alloy, is of the slipper type and fully finished by machining. Internally it has two large webs to support the fully floating gudgeon pin. This has been fully bored, for lightness and is retained at the front by a semi blind hole in the piston. It is fitted with a PTFE wear pad at the rear, to ensure no damage is done to the liner when the engine is running.
This leaves us with the heavy-duty con rod. CNC machined from high tensile alloy. Bronze bushed at both ends, with a single oil hole centrally at the top for the small end, and two oil holes for the big end. Now it?s time to remove the crankshaft.
Unquote.
dogshome, if Your engines ara running fine they must have only two holes oil holes in the big end of con rod.
Searching Just Engines I found a review "A.S.P. 'Series 3' 1.80fs - RCM&E" of which I took an extract.
Quote.
The single ring piston is a permanent die casting from alloy, is of the slipper type and fully finished by machining. Internally it has two large webs to support the fully floating gudgeon pin. This has been fully bored, for lightness and is retained at the front by a semi blind hole in the piston. It is fitted with a PTFE wear pad at the rear, to ensure no damage is done to the liner when the engine is running.
This leaves us with the heavy-duty con rod. CNC machined from high tensile alloy. Bronze bushed at both ends, with a single oil hole centrally at the top for the small end, and two oil holes for the big end. Now it?s time to remove the crankshaft.
Unquote.
dogshome, if Your engines ara running fine they must have only two holes oil holes in the big end of con rod.
