New Parra T3
09-08-2013, 06:41 PM
#51
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The cutaway's in the back and the front of the pistons skirt are for gas flow around the circular bulks of the bearing and the back plate, and to a lesser extent lightness of the piston.
The full depth of the piston skirt is kept on the thrust faces only.
09-08-2013, 11:39 PM
#52
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Hi Alan,
The cutaway's in the back and the front of the pistons skirt are for gas flow around the circular bulks of the bearing and the back plate, and to a lesser extent lightness of the piston.
The full depth of the piston skirt is kept on the thrust faces only.
The cutaway's in the back and the front of the pistons skirt are for gas flow around the circular bulks of the bearing and the back plate, and to a lesser extent lightness of the piston.
The full depth of the piston skirt is kept on the thrust faces only.
Chris -
Cutaways I could understand, but unless I'm very much mistaken, the pic shows a recess (or flat )on the front of the piston.
Which is why I wondered, why that way ?
Seems the more difficult way to make it, presumably there's some reason ?
09-08-2013, 11:57 PM
#53
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I don't think that there would be a flat on the piston wall and believe that to be an optical illusion backed up by the even dark vertical lines at the cutaway contact edges between the piston and the liner. (If the piston was indeed flattened off then the liner must be too to get such an even line.)
And if you accept the arced cutaways are as described you will notice that they also appear' to be almost straight.
Lets blame the lighting!
And if you accept the arced cutaways are as described you will notice that they also appear' to be almost straight.
Lets blame the lighting!
09-09-2013, 12:08 AM
#54
If so it looks like a dent in the piston side to me. Perhaps this sectioned engine was built up for the picture from available rejected or damaged parts,
and that Alberto thought that most of the sexagenarians and septuagenarians that make up his customer base wouldn't notice because of our failing eyesight?
Ray
Last edited by qazimoto; 09-09-2013 at 12:36 AM.
09-09-2013, 03:04 AM
#56
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Alan, do you mean the feature at the end of my arrow?
If so it looks like a dent in the piston side to me. Perhaps this sectioned engine was built up for the picture from available rejected or damaged parts,
and that Alberto thought that most of the sexagenarians and septuagenarians that make up his customer base wouldn't notice because of our failing eyesight?
Ray
If so it looks like a dent in the piston side to me. Perhaps this sectioned engine was built up for the picture from available rejected or damaged parts,
and that Alberto thought that most of the sexagenarians and septuagenarians that make up his customer base wouldn't notice because of our failing eyesight?
Ray
09-09-2013, 03:26 AM
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I just had a look at Alberto's site and found this photo of his 1.5 cc Wasp parts
now I'm really curious !
I know its a strange angle , but are there flats on these pistons too ?
Hmmm - don't suppose you feel like taking the piston out of one of your Parras for a look, Ray ?
now I'm really curious !
I know its a strange angle , but are there flats on these pistons too ?
Hmmm - don't suppose you feel like taking the piston out of one of your Parras for a look, Ray ?
Last edited by errormuddler; 09-09-2013 at 04:19 AM.
09-09-2013, 05:00 PM
#58
I just had a look at Alberto's site and found this photo of his 1.5 cc Wasp parts
now I'm really curious !
I know its a strange angle , but are there flats on these pistons too ?
Hmmm - don't suppose you feel like taking the piston out of one of your Parras for a look, Ray ?
now I'm really curious !
I know its a strange angle , but are there flats on these pistons too ?
Hmmm - don't suppose you feel like taking the piston out of one of your Parras for a look, Ray ?
I have some new Parra 15D ABC p/l assemblies put away in a safe place. I'll see if I can find them when I finish my morning chores.
Ray
09-09-2013, 06:57 PM
#59
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There is a disassembly video on the Parra site that may clear this up easily.
http://www.youtube.com/watch?v=LUSFspt2ueo
http://www.youtube.com/watch?v=LUSFspt2ueo
09-16-2013, 04:03 PM
#62
Another email from Alberto this morning.
I'm guessing that he's NOT talking about the T3 or T4.
Ray
Hello Friends:I have limited units of new Parra 2.5 cc diesel engine.
Diferences are new crankcase with internal CNC machining, new con-rod, carburetor, racing ventury, Quality BB, etc.
I have versions of ABC and SSC.
I have also wrenches, mounts, etc.
I have some units, then please tell me if you are interested.
For two or more engines and spares available discounts.
[TABLE="width: 16"]
[TR]
[TD="width: 71, bgcolor: #D9D9D9"] PA
[/TD]
[TD="width: 340, bgcolor: #D9D9D9"] PARRA MOTOR - PARRA ENGINES
[/TD]
[TD="width: 43, bgcolor: #D9D9D9"] [/TD]
[/TR]
[TR]
[TD="width: 71"] PA25-1
[/TD]
[TD="width: 340"] 2,5 SSC-Special
[/TD]
[TD="width: 43"] [/TD]
[/TR]
[TR]
[TD="width: 71"] PA25-1RC
[/TD]
[TD="width: 340"] 2,5 SSC- Special RC
[/TD]
[TD="width: 43"] [/TD]
[/TR]
[TR]
[TD="width: 71"] PA25-2
[/TD]
[TD="width: 340"] 2,5 ABC -Special
[/TD]
[TD="width: 43"] [/TD]
[/TR]
[TR]
[TD="width: 71"] PA25-2RC
[/TD]
[TD="width: 340"] 2,5 ABC-Special RC
[/TD]
[TD="width: 43"] [/TD]
[/TR]
[TR]
[TD="width: 71"] PA25-3
[/TD]
[TD="width: 340"] 2,5 AAC Special
[/TD]
[TD="width: 43"] [/TD]
[/TR]
[TR]
[TD="width: 71"] PA25-3RC
[/TD]
[TD="width: 340"] 2,5 AAC Special-RC
[/TD]
[TD="width: 43"][/TD]
[/TR]
[/TABLE]
Diferences are new crankcase with internal CNC machining, new con-rod, carburetor, racing ventury, Quality BB, etc.
I have versions of ABC and SSC.
I have also wrenches, mounts, etc.
I have some units, then please tell me if you are interested.
For two or more engines and spares available discounts.
[TABLE="width: 16"]
[TR]
[TD="width: 71, bgcolor: #D9D9D9"] PA
[/TD]
[TD="width: 340, bgcolor: #D9D9D9"] PARRA MOTOR - PARRA ENGINES
[/TD]
[TD="width: 43, bgcolor: #D9D9D9"] [/TD]
[/TR]
[TR]
[TD="width: 71"] PA25-1
[/TD]
[TD="width: 340"] 2,5 SSC-Special
[/TD]
[TD="width: 43"]
115
[/TR]
[TR]
[TD="width: 71"] PA25-1RC
[/TD]
[TD="width: 340"] 2,5 SSC- Special RC
[/TD]
[TD="width: 43"]
125
[/TR]
[TR]
[TD="width: 71"] PA25-2
[/TD]
[TD="width: 340"] 2,5 ABC -Special
[/TD]
[TD="width: 43"]
125
[/TR]
[TR]
[TD="width: 71"] PA25-2RC
[/TD]
[TD="width: 340"] 2,5 ABC-Special RC
[/TD]
[TD="width: 43"]
135
[/TR]
[TR]
[TD="width: 71"] PA25-3
[/TD]
[TD="width: 340"] 2,5 AAC Special
[/TD]
[TD="width: 43"]
135
[/TR]
[TR]
[TD="width: 71"] PA25-3RC
[/TD]
[TD="width: 340"] 2,5 AAC Special-RC
[/TD]
[TD="width: 43"]
145
[/TR]
[/TABLE]
Ray
09-16-2013, 08:05 PM
#64
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09-16-2013, 08:13 PM
#65
Locals are successfully using Leaded Steel to make pistons in lieu of Cast Iron.
There's a whole body of knowledge about the rubbing properties of lubricated metals called Tribology.
It's been determined that the optimum for low friction and good wearing properties compared with good sealing, is between a hard surface and a soft one.
Hence hard chrome for cylinders and something much softer, with about the same coefficient of expansion, for pistons.
Where's Wicky?
Ray
09-16-2013, 08:17 PM
#66
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Is that a reference chrome plating on the inner working surface of the liner; or just the type of steel?
I guess that to many my enquiry may sound niaive; but can't find anyone local to me who can provide the answers.
I guess that to many my enquiry may sound niaive; but can't find anyone local to me who can provide the answers.
Last edited by fiery; 09-16-2013 at 08:19 PM.
09-17-2013, 05:41 AM
#70
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fiery - to back up Ray's explanation, here's what Alberto writes on the Parra 2.5 part of his site
"
- Aluminium-Chromed cylinder (AAC) and light weight aluminium piston , at lastets technology, maximum heat dissipation"
"
- Steel Chromed cylinder (SSC), because chrom is more solid as the hardened steel. Also the coefficient of friction of the steel piston is more low from all materials.It improves the power capacity.
- Brass Chromed cylinder (ABC), and light weight aluminium piston, perfect adjust in warm conditions.- Aluminium-Chromed cylinder (AAC) and light weight aluminium piston , at lastets technology, maximum heat dissipation"
10-02-2013, 04:30 AM
#71
There's some freshly published CAD images of the T3 and T4 from Alberto.
As expected, the T4 does look like an R320. While the web page does give some more information it doesn't actually confirm the displacement.
See: http://www.clubtamaran.com/Parra%20T3.htm
Ray
As expected, the T4 does look like an R320. While the web page does give some more information it doesn't actually confirm the displacement.
See: http://www.clubtamaran.com/Parra%20T3.htm
Ray
Last edited by qazimoto; 10-02-2013 at 04:38 AM.
10-02-2013, 02:48 PM
#73
Ah Greg,
well I did take delivery of one of the new SSC 2.5cc diesels last monday.
Ran it yesterday, and it's loverly. It's destined for an Anduril.
He did give me a small discount, but I suspect that he just likes Australians.
Big turnout at Mannering Park yesterday!
Ray
well I did take delivery of one of the new SSC 2.5cc diesels last monday.
Ran it yesterday, and it's loverly. It's destined for an Anduril.
He did give me a small discount, but I suspect that he just likes Australians.
Big turnout at Mannering Park yesterday!
Ray
10-02-2013, 05:24 PM
#75
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Always wondered about that "anti snag combat prop driver" and thought that the PAW 'combat special' domed driver that goes back over the bearing a better idea.
Shorter, more compact, protects the front race better from dirt ingress - or am I missing something?
Thanks.
Shorter, more compact, protects the front race better from dirt ingress - or am I missing something?
Thanks.