piston failure
10 June 2011, 07:42 PM
#1
Scooby Regular
Thread Starter
Join Date: Mar 2011
Posts: 73
Likes: 0
Received 0 Likes
on
0 Posts
piston failure
hi guys i have a P1 with a 2.5 fitted the front right piston has broke the pieces off between the rings i need to have it bored my question is does anyone know what may have caused this also what pistons are good to use its my first scooby it was running 350 bhp would i need to upgrade rods crank injectors (running yellow) turbo (td05 20g)etc to get more power ? the car has been stood 8 months before it blew Thanks Neil.
10 June 2011, 07:53 PM
#2
Fairly common fault if it was a standard EJ257 piston.
If you have to get it bored then you may as well get it pinned at the same time.
Crank and rods should be fine and good for 400bhp I suggest some Wiseco or Cosworth pistons but get the bores honed to suit which ever ones you choose.
If you have aspirations of going over 400 then now would be the time to swap the rods too.
Here's a pic of my block which has been pinned but other than the pins and a 14mm stud conversion is as it came out of the factory.
If you have to get it bored then you may as well get it pinned at the same time.
Crank and rods should be fine and good for 400bhp I suggest some Wiseco or Cosworth pistons but get the bores honed to suit which ever ones you choose.
If you have aspirations of going over 400 then now would be the time to swap the rods too.
Here's a pic of my block which has been pinned but other than the pins and a 14mm stud conversion is as it came out of the factory.
10 June 2011, 08:10 PM
#3
hi guys i have a P1 with a 2.5 fitted the front right piston has broke the pieces off between the rings i need to have it bored my question is does anyone know what may have caused this also what pistons are good to use its my first scooby it was running 350 bhp would i need to upgrade rods crank injectors (running yellow) turbo (td05 20g)etc to get more power ? the car has been stood 8 months before it blew Thanks Neil.
10 June 2011, 08:53 PM
#5
As mentioned above Neil - det damage to the ring lands is quite common on the EJ257 fitted with the standard Hyperthuretic pistons - these cast pistons do not tolerate det at all and results in the ring land breaking up and damaging the bore in the process. Seems to be No.2+4 cylinders which suffer the most from detted pistons on the EJ257.
Mick
Mick
10 June 2011, 09:35 PM
#6
Scooby Regular
Thread Starter
Join Date: Mar 2011
Posts: 73
Likes: 0
Received 0 Likes
on
0 Posts
Fairly common fault if it was a standard EJ257 piston.
If you have to get it bored then you may as well get it pinned at the same time.
Crank and rods should be fine and good for 400bhp I suggest some Wiseco or Cosworth pistons but get the bores honed to suit which ever ones you choose.
If you have aspirations of going over 400 then now would be the time to swap the rods too.
Here's a pic of my block which has been pinned but other than the pins and a 14mm stud conversion is as it came out of the factory.
If you have to get it bored then you may as well get it pinned at the same time.
Crank and rods should be fine and good for 400bhp I suggest some Wiseco or Cosworth pistons but get the bores honed to suit which ever ones you choose.
If you have aspirations of going over 400 then now would be the time to swap the rods too.
Here's a pic of my block which has been pinned but other than the pins and a 14mm stud conversion is as it came out of the factory.
10 June 2011, 09:39 PM
#7
Scooby Regular
iTrader: (2)
Join Date: Feb 2009
Location: Twickenham
Posts: 1,272
Likes: 0
Received 0 Likes
on
0 Posts
Mick, what is a Hyperthuretic piston? Is it a casting type or a brand name. Cant find anything good info on Google.
Last edited by fastboyslim; 10 June 2011 at 09:48 PM.
Trending Topics
10 June 2011, 09:45 PM
#8
Scooby Regular
Thread Starter
Join Date: Mar 2011
Posts: 73
Likes: 0
Received 0 Likes
on
0 Posts
As mentioned above Neil - det damage to the ring lands is quite common on the EJ257 fitted with the standard Hyperthuretic pistons - these cast pistons do not tolerate det at all and results in the ring land breaking up and damaging the bore in the process. Seems to be No.2+4 cylinders which suffer the most from detted pistons on the EJ257.
Mick
Mick
10 June 2011, 09:54 PM
#9
You are right, pinning is the pinning of the liners, i have edited the pic above to highlight the pins in RED.
these are NOT standard and will strengthen the block.
I have a EJ257 in my RA, done under 2500 miles and i have lost compression on No2 Cylinder. I suspect broken Ring Gland.
Car has been off the road nearly 12 months now due to it.
these are NOT standard and will strengthen the block.
I have a EJ257 in my RA, done under 2500 miles and i have lost compression on No2 Cylinder. I suspect broken Ring Gland.
Car has been off the road nearly 12 months now due to it.
10 June 2011, 10:06 PM
#10
Scooby Regular
Thread Starter
Join Date: Mar 2011
Posts: 73
Likes: 0
Received 0 Likes
on
0 Posts
You are right, pinning is the pinning of the liners, i have edited the pic above to highlight the pins in RED.
these are NOT standard and will strengthen the block.
I have a EJ257 in my RA, done under 2500 miles and i have lost compression on No2 Cylinder. I suspect broken Ring Gland.
Car has been off the road nearly 12 months now due to it.
these are NOT standard and will strengthen the block.
I have a EJ257 in my RA, done under 2500 miles and i have lost compression on No2 Cylinder. I suspect broken Ring Gland.
Car has been off the road nearly 12 months now due to it.
10 June 2011, 11:19 PM
#12
Scooby Regular
iTrader: (10)
Join Date: Oct 2003
Location: berks
Posts: 1,174
Likes: 0
Received 0 Likes
on
0 Posts
get yourself a set of uprated pistons and rods.
lateral performance are very good and not to expensive for what you get. as in parts are very good.
cheers mickyboy
lateral performance are very good and not to expensive for what you get. as in parts are very good.
cheers mickyboy
11 June 2011, 08:29 AM
#13
cashyn: if I were you, running 350 or so, I'd not even be tHINKING standard pistons.
AFAIK, they are called hypereutectic pistons, and are made from an alloy which is MEANT to not expand as much, so has lower clearances.
However, in an engine running above the standard hp, they CAN expand enough to "pick up", or melt in the bore due to insufficient clearance, so less oil, plus the skirts below the ring lands are brittle, and break off if the engine dets at all.
When I went 2.5 after cooking my 2 litre, I was told be TWO respected engine builders to find a short engine at a price that would allow me to split it and fit AT LEAST forged pistons. I was lucky enough to get one that was unused, still in it's crate, at a price that allowed me to afford forged rods too.
AFAIK, they are called hypereutectic pistons, and are made from an alloy which is MEANT to not expand as much, so has lower clearances.
However, in an engine running above the standard hp, they CAN expand enough to "pick up", or melt in the bore due to insufficient clearance, so less oil, plus the skirts below the ring lands are brittle, and break off if the engine dets at all.
When I went 2.5 after cooking my 2 litre, I was told be TWO respected engine builders to find a short engine at a price that would allow me to split it and fit AT LEAST forged pistons. I was lucky enough to get one that was unused, still in it's crate, at a price that allowed me to afford forged rods too.
11 June 2011, 08:49 AM
#14
Scooby Regular
Thread Starter
Join Date: Mar 2011
Posts: 73
Likes: 0
Received 0 Likes
on
0 Posts
cashyn: if I were you, running 350 or so, I'd not even be tHINKING standard pistons.
AFAIK, they are called hypereutectic pistons, and are made from an alloy which is MEANT to not expand as much, so has lower clearances.
However, in an engine running above the standard hp, they CAN expand enough to "pick up", or melt in the bore due to insufficient clearance, so less oil, plus the skirts below the ring lands are brittle, and break off if the engine dets at all.
When I went 2.5 after cooking my 2 litre, I was told be TWO respected engine builders to find a short engine at a price that would allow me to split it and fit AT LEAST forged pistons. I was lucky enough to get one that was unused, still in it's crate, at a price that allowed me to afford forged rods too.
AFAIK, they are called hypereutectic pistons, and are made from an alloy which is MEANT to not expand as much, so has lower clearances.
However, in an engine running above the standard hp, they CAN expand enough to "pick up", or melt in the bore due to insufficient clearance, so less oil, plus the skirts below the ring lands are brittle, and break off if the engine dets at all.
When I went 2.5 after cooking my 2 litre, I was told be TWO respected engine builders to find a short engine at a price that would allow me to split it and fit AT LEAST forged pistons. I was lucky enough to get one that was unused, still in it's crate, at a price that allowed me to afford forged rods too.
11 June 2011, 09:24 AM
#16
Scooby Regular
Join Date: Dec 2002
Location: Sunny BELFAST
Posts: 19,408
Likes: 0
Received 0 Likes
on
0 Posts
anything that will raise temperatures in the cylinder will help promote detonation. This rise in temperature could occur many different ways: very lean air/fuel ratios, heating of the charge air prior to entering the combustion chamber, compression of the air molecules from forced induction, or poor heat dissipation through the cooling system. Increase of cylinder pressure will also prompt detonation. Camshaft profile, compression ratio and quench area all come into play. Design criteria as to combustion chamber shape and mixture motion, spark plug location and piston design can all make an engine more or less inherently prone to abnormal combustion. Naturally, spark timing and fuel quality round off the list.
11 June 2011, 11:44 AM
#18
Mahle Piston are excellent you'll not go far wrong with them. Due to your damage I'd go for an over size piston (99.75mm) and get the bore honed to suit these pistons. For your aim of 400 you'll be fine with the standard block but anything above 400 and I would advise getting the block pinned. It's not very expensive but its very effective.
12 June 2011, 10:14 AM
#20
Mahle do a piston in the powerpak range that is 99.6 which is enough oversize to rectify most bore minor bore faults, including broken ringland marks.
Part No WRX209921P22
If you must put OE pistons back in i have dozens off them all ready to weigh in for scrap, some new.
Part No WRX209921P22
If you must put OE pistons back in i have dozens off them all ready to weigh in for scrap, some new.
Last edited by MOTORS S GT; 12 June 2011 at 10:17 AM.
12 June 2011, 06:35 PM
#21
Scooby Regular
Thread Starter
Join Date: Mar 2011
Posts: 73
Likes: 0
Received 0 Likes
on
0 Posts
Mahle do a piston in the powerpak range that is 99.6 which is enough oversize to rectify most bore minor bore faults, including broken ringland marks.
Part No WRX209921P22
If you must put OE pistons back in i have dozens off them all ready to weigh in for scrap, some new.
Part No WRX209921P22
If you must put OE pistons back in i have dozens off them all ready to weigh in for scrap, some new.
12 June 2011, 09:28 PM
#22
Scooby Regular
Thread Starter
Join Date: Mar 2011
Posts: 73
Likes: 0
Received 0 Likes
on
0 Posts
Fairly common fault if it was a standard EJ257 piston.
If you have to get it bored then you may as well get it pinned at the same time.
Crank and rods should be fine and good for 400bhp I suggest some Wiseco or Cosworth pistons but get the bores honed to suit which ever ones you choose.
If you have aspirations of going over 400 then now would be the time to swap the rods too.
Here's a pic of my block which has been pinned but other than the pins and a 14mm stud conversion is as it came out of the factory.
If you have to get it bored then you may as well get it pinned at the same time.
Crank and rods should be fine and good for 400bhp I suggest some Wiseco or Cosworth pistons but get the bores honed to suit which ever ones you choose.
If you have aspirations of going over 400 then now would be the time to swap the rods too.
Here's a pic of my block which has been pinned but other than the pins and a 14mm stud conversion is as it came out of the factory.
BMnt-K4L(Q~~_12.JPG)
26 June 2011, 10:34 PM
#24
Scooby Regular
Thread Starter
Join Date: Mar 2011
Posts: 73
Likes: 0
Received 0 Likes
on
0 Posts
head gasket
Fairly common fault if it was a standard EJ257 piston.
If you have to get it bored then you may as well get it pinned at the same time.
Crank and rods should be fine and good for 400bhp I suggest some Wiseco or Cosworth pistons but get the bores honed to suit which ever ones you choose.
If you have aspirations of going over 400 then now would be the time to swap the rods too.
Here's a pic of my block which has been pinned but other than the pins and a 14mm stud conversion is as it came out of the factory.
If you have to get it bored then you may as well get it pinned at the same time.
Crank and rods should be fine and good for 400bhp I suggest some Wiseco or Cosworth pistons but get the bores honed to suit which ever ones you choose.
If you have aspirations of going over 400 then now would be the time to swap the rods too.
Here's a pic of my block which has been pinned but other than the pins and a 14mm stud conversion is as it came out of the factory.
27 June 2011, 10:20 PM
#25
Scooby Regular
Thread Starter
Join Date: Mar 2011
Posts: 73
Likes: 0
Received 0 Likes
on
0 Posts
head gasket
Mahle Piston are excellent you'll not go far wrong with them. Due to your damage I'd go for an over size piston (99.75mm) and get the bore honed to suit these pistons. For your aim of 400 you'll be fine with the standard block but anything above 400 and I would advise getting the block pinned. It's not very expensive but its very effective.
28 June 2011, 10:06 PM
#27
Scooby Regular
Thread Starter
Join Date: Mar 2011
Posts: 73
Likes: 0
Received 0 Likes
on
0 Posts
pinning
Fairly common fault if it was a standard EJ257 piston.
If you have to get it bored then you may as well get it pinned at the same time.
Crank and rods should be fine and good for 400bhp I suggest some Wiseco or Cosworth pistons but get the bores honed to suit which ever ones you choose.
If you have aspirations of going over 400 then now would be the time to swap the rods too.
Here's a pic of my block which has been pinned but other than the pins and a 14mm stud conversion is as it came out of the factory.
If you have to get it bored then you may as well get it pinned at the same time.
Crank and rods should be fine and good for 400bhp I suggest some Wiseco or Cosworth pistons but get the bores honed to suit which ever ones you choose.
If you have aspirations of going over 400 then now would be the time to swap the rods too.
Here's a pic of my block which has been pinned but other than the pins and a 14mm stud conversion is as it came out of the factory.
06 July 2011, 09:58 PM
#28
Scooby Regular
Thread Starter
Join Date: Mar 2011
Posts: 73
Likes: 0
Received 0 Likes
on
0 Posts
Mahle Piston are excellent you'll not go far wrong with them. Due to your damage I'd go for an over size piston (99.75mm) and get the bore honed to suit these pistons. For your aim of 400 you'll be fine with the standard block but anything above 400 and I would advise getting the block pinned. It's not very expensive but its very effective.
Thread
Thread Starter
Forum
Replies
Last Post
Matt_182
Wheels, Tyres & Brakes
19
07 October 2015 01:05 PM
bluebullet29
General Technical
9
05 October 2015 02:17 PM
