has a v6 sti got forged pistons?
11 November 2008, 11:31 AM
#31
Right. So because the block happens to expand at the the same rate as these pistons, you don't have to allow for any extra clearance within the bore (other than the absolute accepted minimum)?
Does this mean that 'normal' pistons expand more, so extra clearance has to be allowed for, so as to stop them from seizing in the bores?
Last edited by joz8968; 11 November 2008 at 01:33 PM.
11 November 2008, 01:28 PM
#33
Former Sponsor
iTrader: (4)
Join Date: Jul 2003
Location: @Junc 12, M40 Warwicksh; 01926 614522 CV33 9PL -Use 9GX for Satnav. South Mids Alcatek ECu dealer
Posts: 6,377
Likes: 0
Received 3 Likes
on
3 Posts
[quote=joz8968;8261187]A bit like L'Oreal 'Replumper'
Right. So because the block happens to expand at the the same rate as these pistons, you don't have to allow for any extra clearance within the bore (other than the absolute accepted minimum)?
Does this mean that 'normal' pistons expand more, so extra clearance has to allowed for, so as to stop them from seizing in the bores?[/quote]
That would be my take on it,
David
Right. So because the block happens to expand at the the same rate as these pistons, you don't have to allow for any extra clearance within the bore (other than the absolute accepted minimum)?
Does this mean that 'normal' pistons expand more, so extra clearance has to allowed for, so as to stop them from seizing in the bores?[/quote]
That would be my take on it,
David
11 November 2008, 01:44 PM
#36
I can confirm that the V5 and V6 do have forged pistons.
These are easy to identify from cast pistons too. The cast pistons have casting marks underneath the pistons and will display a criss cross pattern on them.
Forged Pistons have a very smooth underneath.
Here is a set of V5 forged STI pistons (which are for sale btw) as you will see the underside of the pistons is smooth.
These are easy to identify from cast pistons too. The cast pistons have casting marks underneath the pistons and will display a criss cross pattern on them.
Forged Pistons have a very smooth underneath.
Here is a set of V5 forged STI pistons (which are for sale btw) as you will see the underside of the pistons is smooth.
11 November 2008, 02:01 PM
#37
Former Sponsor
iTrader: (4)
Join Date: Jul 2003
Location: @Junc 12, M40 Warwicksh; 01926 614522 CV33 9PL -Use 9GX for Satnav. South Mids Alcatek ECu dealer
Posts: 6,377
Likes: 0
Received 3 Likes
on
3 Posts
I can confirm that the V5 and V6 do have forged pistons.
These are easy to identify from cast pistons too. The cast pistons have casting marks underneath the pistons and will display a criss cross pattern on them.
Forged Pistons have a very smooth underneath.
Here is a set of V5 forged STI pistons (which are for sale btw) as you will see the underside of the pistons is smooth.
These are easy to identify from cast pistons too. The cast pistons have casting marks underneath the pistons and will display a criss cross pattern on them.
Forged Pistons have a very smooth underneath.
Here is a set of V5 forged STI pistons (which are for sale btw) as you will see the underside of the pistons is smooth.
Nice sales pitch Daz, wish I'd thought of that
David
AND
regarding ring gaps and clearances I have no idea, as we don't use the B/S pistons.
BUT generally, 3 thou per inch of bore.
David APi
11 November 2008, 02:57 PM
#40
How many rings does the Impreza piston have: 2 or 3?
Are they called:
1) 'Top ring'
2) 'Compression ring'
3) 'Oil control ring'
What are they technically called and what is each one's 'job'?
Are they called:
1) 'Top ring'
2) 'Compression ring'
3) 'Oil control ring'
What are they technically called and what is each one's 'job'?
Last edited by joz8968; 11 November 2008 at 03:01 PM.
11 November 2008, 07:12 PM
#46
Top ring - Compression control ring + takes most of the heat from the combustion process. Most top rings are coated eg moly/chrome/gas nitrided to reduce wear and improve the durability in the harsh environment they work in.
Second Ring - Compression control and oil control, they provide a secondary seal and help dissipate heat. Most have a Tapered lower edge to scrape the oil from the cylinder wall to prevent it getting into the combustion chamber.
Oil Control Ring - Does what it says on the Tin.
This is a good bit of high speed camera work
YouTube - From Inside a Working Petrol Engine
Mick
Second Ring - Compression control and oil control, they provide a secondary seal and help dissipate heat. Most have a Tapered lower edge to scrape the oil from the cylinder wall to prevent it getting into the combustion chamber.
Oil Control Ring - Does what it says on the Tin.
This is a good bit of high speed camera work
YouTube - From Inside a Working Petrol Engine
Mick
11 November 2008, 07:54 PM
#47
Wow. That's fascinating and rather beautiful (gayer ).
Really illustrates the flame front's controlled burn when the spark plug fires.
I'd love to see footage of an engine detting or pre-igniting!
).Really illustrates the flame front's controlled burn when the spark plug fires.
I'd love to see footage of an engine detting or pre-igniting!
Last edited by joz8968; 11 November 2008 at 08:10 PM.
