*NOW BOOKED FOR 2024* Transitmania 15 @ Santa Pod 19th to 21st July 2024 *ALL DETAILS HERE*


Piston reversal.

Use this forum to post technical questions & problems about any Transit

Moderator: Luke

Piston reversal.

Postby andypdq » Sat Jun 26, 2021 5:41 pm

The gudgeon pin, small end, little end, call it what you will, is normally offset slightly to the left in a clockwise rotating engine to lessen the effect of piston slap, noisy engine when cold. If the pistons are reversed on the rods, the offset is to the right, which will give a certain mechanical advantage, similar to an offset crank, sometimes used on performance engines. Maybe an idea?
The first Mk 6 mechanical TDDI, giving electronics the finger, since April 2013

Perfection is reached, not when there's nothing left to add, but when there's nothing left to remove.

YouTube https://www.youtube.com/channel/UCNypVH ... dKUN5eJDyQ
User avatar
andypdq
Transit Devotee
Transit Devotee
 
Posts: 1840
Joined: Thu Feb 03, 2011 6:03 pm
Location: Disturbingly near to Stoke-on-Trent.

Re: Piston reversal.

Postby Mike » Sat Jun 26, 2021 6:29 pm

It’ll reduce power, you’re getting confused about how the crank is offset in some engines. But hey give it a go, it’ll be as good as your other business plans…
Mike
Wind up merchant!
 
Posts: 19592
Joined: Tue Feb 13, 2007 11:08 pm
Location: HP17 0UZ

Re: Piston reversal.

Postby bambi mk 1 » Sat Jun 26, 2021 6:54 pm

Mike wrote:It’ll reduce power, you’re getting confused about how the crank is offset in some engines. But hey give it a go, it’ll be as good as your other business plans…

This time next year we'll be millionaires :mrgreen:
On the sixth day God created a Sprinter on the seventh he gave it away and bought a TRANSIT
User avatar
bambi mk 1
Transit Extremist
Transit Extremist
 
Posts: 8826
Joined: Sat Nov 17, 2012 10:05 pm
Location: 24 Years living next door to Alice

Re: Piston reversal.

Postby Mike » Sat Jun 26, 2021 6:55 pm

:lol:
Mike
Wind up merchant!
 
Posts: 19592
Joined: Tue Feb 13, 2007 11:08 pm
Location: HP17 0UZ

Re: Piston reversal.

Postby andypdq » Sat Jun 26, 2021 8:30 pm

Mike wrote:It’ll reduce power, you’re getting confused about how the crank is offset in some engines. But hey give it a go, it’ll be as good as your other business plans…


Wrong, piston reaches highest point in the cylinder when centre of mains, big end and small end are in perfect alignment, this happens earlier in crank rotation with a little end offset to the left, which standard pistons are in a clockwise rotating engine, than it would with a centred little end, so tdc occurs before the crank goes over centre, with the piston reversed tdc occurs after the crank goes over centre. Think vectors, resolution of forces :wink:
The first Mk 6 mechanical TDDI, giving electronics the finger, since April 2013

Perfection is reached, not when there's nothing left to add, but when there's nothing left to remove.

YouTube https://www.youtube.com/channel/UCNypVH ... dKUN5eJDyQ
User avatar
andypdq
Transit Devotee
Transit Devotee
 
Posts: 1840
Joined: Thu Feb 03, 2011 6:03 pm
Location: Disturbingly near to Stoke-on-Trent.

Re: Piston reversal.

Postby Mike » Sat Jun 26, 2021 8:45 pm

Wrong, if you were right the manufacturer’s would do it. As I say, you’re thinking about it the wrong way.

Time for another sabbatical chap :wink:
Mike
Wind up merchant!
 
Posts: 19592
Joined: Tue Feb 13, 2007 11:08 pm
Location: HP17 0UZ

Re: Piston reversal.

Postby andypdq » Sat Jun 26, 2021 9:03 pm

Wrong Mike, It's done to reduce noise from piston slap, the cost is a slight mechanical disadvantage.
The first Mk 6 mechanical TDDI, giving electronics the finger, since April 2013

Perfection is reached, not when there's nothing left to add, but when there's nothing left to remove.

YouTube https://www.youtube.com/channel/UCNypVH ... dKUN5eJDyQ
User avatar
andypdq
Transit Devotee
Transit Devotee
 
Posts: 1840
Joined: Thu Feb 03, 2011 6:03 pm
Location: Disturbingly near to Stoke-on-Trent.

Re: Piston reversal.

Postby Mike » Sat Jun 26, 2021 9:58 pm

It’s not the only reason, but if you think you’re right, do it and prove me wrong :mrgreen: You are right to think about moving the wrist pin, but not in the direction that you’re thinking. :wink:
Mike
Wind up merchant!
 
Posts: 19592
Joined: Tue Feb 13, 2007 11:08 pm
Location: HP17 0UZ

Re: Piston reversal.

Postby andypdq » Sat Jun 26, 2021 10:58 pm

Hi Mke. All this cropped up through going down the youtube rabbit hole, I believe it's correct having some knowledge of mathematics/mechanics. For no logical reason, I like big American V8s, this point was raised by one proponent as an old trick to gain more power using standard components for a particular class of racing, the rules stated that standard components must be used, but they didn't state the orientation of said components. The winners reversed the piston orientation, they didn't care about noise or longevity. Because tdc occurs after the crank goes over centre, rather than before with the offset little end in its standard orientation, the rod angle relative to crank and piston produces an advantage. Some engines react better than others, due to rod length to stroke ratio, the shorter the rod length relative to stroke, the greater the advantage of reversing the pin offset will be. It's about vectors and resolution of forces. Please explain in detail why you think this appraisal is wrong.
The first Mk 6 mechanical TDDI, giving electronics the finger, since April 2013

Perfection is reached, not when there's nothing left to add, but when there's nothing left to remove.

YouTube https://www.youtube.com/channel/UCNypVH ... dKUN5eJDyQ
User avatar
andypdq
Transit Devotee
Transit Devotee
 
Posts: 1840
Joined: Thu Feb 03, 2011 6:03 pm
Location: Disturbingly near to Stoke-on-Trent.

Re: Piston reversal.

Postby Mike » Sun Jun 27, 2021 7:14 am

You’ve answered your own question, think about how a V8’s conrods work compared to an inline engine, I’d also be concerned about clearances at the mid/lower areas of the conrod, they could contact the bottom of the bore if things are tight. I’d suggest looking at what people are doing with inline engines rather than V configuration, it’ll be much more relevant to Transits.
Mike
Wind up merchant!
 
Posts: 19592
Joined: Tue Feb 13, 2007 11:08 pm
Location: HP17 0UZ

Re: Piston reversal.

Postby dumper » Sun Jun 27, 2021 9:43 am

I can understand doing this for a racing or rally engine that has class restrictions back in the day they used to call it blueprinting the engine and use all the tolerances to gain a advantage Ford did it with the mk1&2 escorts they added up all the limits to give a1599 cc engine a capacity of 1601 to run it in next class and overbore it to run it at 1850 for the 1970 World Cup Mexico rally but what advantage are you going to get for a van .
MK 8 L4 H3 Motorsport campervan
Past camper vans
1974 mk1 v4 with 2.0 pinto fitted
1986 mk3 2.5 di swb
1990 190 lwb 2.5 di
1998 100 lwb 2.5 di
2006 350 jumbo 135 tdci
dumper
Transit Extremist
Transit Extremist
 
Posts: 5438
Joined: Sun Jan 20, 2008 2:56 pm
Location: Lincolnshire

Re: Piston reversal.

Postby davyjcb » Sun Jun 27, 2021 9:54 am

+ the fact if you rotate the pistons 180 degrees you will encounter another problem the skirts have a relief notch cut in them to allow running clearance for the piston cooling jets ,the first time you run it could possibly be it's last
96 escort 55 van gone
98 smiley mwb semi high gone
01 90/350 mwb semi high roof gone
05 135/350 lwb semi high roof gone
10 85/260 swb low roof leader gone
09 140/350 lwb semi high fwd
11 115/330 mwb semi high roof
User avatar
davyjcb
Transit Devotee
Transit Devotee
 
Posts: 1086
Joined: Sat Apr 09, 2016 5:49 pm
Location: northern ireland

Re: Piston reversal.

Postby bambi mk 1 » Sun Jun 27, 2021 10:27 am

Go for it, its a no brainer, when will it be perfected, when like the pump at least 15 years out of production :roll: Better off playing with a Dyson as those of us still around will be on electric or a horse :wink: :wink: :lol:
On the sixth day God created a Sprinter on the seventh he gave it away and bought a TRANSIT
User avatar
bambi mk 1
Transit Extremist
Transit Extremist
 
Posts: 8826
Joined: Sat Nov 17, 2012 10:05 pm
Location: 24 Years living next door to Alice

Re: Piston reversal.

Postby V184 » Sun Jun 27, 2021 10:45 am

bambi mk 1 wrote:Go for it, its a no brainer, when will it be perfected, when like the pump at least 15 years out of production :roll: Better off playing with a Dyson as those of us still around will be on electric or a horse :wink: :wink: :lol:


:lol: :lol: :lol: :lol: :lol:
User avatar
V184
Transit Fanatic
Transit Fanatic
 
Posts: 3533
Joined: Thu Jun 08, 2006 8:16 pm
Location: You're right, V184 is a God !

Re: Piston reversal.

Postby andypdq » Mon Jun 28, 2021 11:02 am

Mike wrote:You’ve answered your own question, think about how a V8’s conrods work compared to an inline engine, I’d also be concerned about clearances at the mid/lower areas of the conrod, they could contact the bottom of the bore if things are tight. I’d suggest looking at what people are doing with inline engines rather than V configuration, it’ll be much more relevant to Transits.


Wrong again, engine architecture is irrelevant, all that matters is centreline of main journal, big end and small end, relative to the centre of the bore/piston.

Anyone with any sense who builds a modified engine where conrod clearance could be an issue builds the short motor and rotates it and observes clearances and relieves as necessary, or abandons the project if it's not feasible.

There are other things to consider, such as valve reliefs in the pistons and the concentricity of the combustion chamber in a direct injection diesel piston. If these limitations are not resolvable, it won't work. I have considered it. :wink:
The first Mk 6 mechanical TDDI, giving electronics the finger, since April 2013

Perfection is reached, not when there's nothing left to add, but when there's nothing left to remove.

YouTube https://www.youtube.com/channel/UCNypVH ... dKUN5eJDyQ
User avatar
andypdq
Transit Devotee
Transit Devotee
 
Posts: 1840
Joined: Thu Feb 03, 2011 6:03 pm
Location: Disturbingly near to Stoke-on-Trent.

Next

Return to Technical Problems & Questions



Who is online

Users browsing this forum: No registered users

This site contains affiliate links for which we may be compensated.