Help !!! Killed the Scoob !
27 July 2010, 09:22 PM
#571
+2 !
Thanks for the input Harvey.
The 'HSB' I am refering to is the marking stamped on top of the pistons that came with a used bottom end I happened to buy.
I'm not saying that I intend to use them but just curious as to their origins ?
The 'standard' pistons that I have encountered on my other three blocks have all been stamped 'HBR' and have a rectangular recess in the top of the piston.
These have four semi-circular grooves which look to mirror the shape of the valves.
I have looked closely, by the way, to make sure they are not just the result of a nasty cam belt failure !
I presume from the similarity in the identifcation marks that they are standard Subaru pistons but I would like to know which model / version they came from ?
I have done some digging on the net but not found any answers yet.
Thanks for the input Harvey.
The 'HSB' I am refering to is the marking stamped on top of the pistons that came with a used bottom end I happened to buy.
I'm not saying that I intend to use them but just curious as to their origins ?
The 'standard' pistons that I have encountered on my other three blocks have all been stamped 'HBR' and have a rectangular recess in the top of the piston.
These have four semi-circular grooves which look to mirror the shape of the valves.
I have looked closely, by the way, to make sure they are not just the result of a nasty cam belt failure !
I presume from the similarity in the identifcation marks that they are standard Subaru pistons but I would like to know which model / version they came from ?
I have done some digging on the net but not found any answers yet.
27 July 2010, 10:16 PM
#572
+2 !
Thanks for the input Harvey.
The 'HSB' I am refering to is the marking stamped on top of the pistons that came with a used bottom end I happened to buy.
I'm not saying that I intend to use them but just curious as to their origins ?
The 'standard' pistons that I have encountered on my other three blocks have all been stamped 'HBR' and have a rectangular recess in the top of the piston.
These have four semi-circular grooves which look to mirror the shape of the valves.
I have looked closely, by the way, to make sure they are not just the result of a nasty cam belt failure !
I presume from the similarity in the identifcation marks that they are standard Subaru pistons but I would like to know which model / version they came from ?
I have done some digging on the net but not found any answers yet.
Thanks for the input Harvey.
The 'HSB' I am refering to is the marking stamped on top of the pistons that came with a used bottom end I happened to buy.
I'm not saying that I intend to use them but just curious as to their origins ?
The 'standard' pistons that I have encountered on my other three blocks have all been stamped 'HBR' and have a rectangular recess in the top of the piston.
These have four semi-circular grooves which look to mirror the shape of the valves.
I have looked closely, by the way, to make sure they are not just the result of a nasty cam belt failure !
I presume from the similarity in the identifcation marks that they are standard Subaru pistons but I would like to know which model / version they came from ?
I have done some digging on the net but not found any answers yet.
28 July 2010, 06:27 AM
#575
Lest not forget (no disrespect to the voices) that despite the OP's spirit this thread is a shining example of how "not to do it" and cutting corners on such an important part of the engine isn't going to work in this case because by his own admission he has a very, very heavy right foot.
He needs the best crank etc money can buy otherwise we will all still be reading about knocking big ends in another 12 months time.
28 July 2010, 09:12 PM
#576
I think Harvey is fairly well qualified to air his views but don't want anyone to fall out over my online therapy session !
I never contemplated running a reground crank, just that with three damaged ones lying around and new ones at £400-500 a time, it seems criminal to just bin them if they are some use to someone out there.
I know that the accepted theory, handed down on stone tablets from the times of the old testament is not to regrind them, just interested to know whether it can be done or not.
I suspect that a better crank is not the answer, more likely better heat management, cooler oil and a set of gauges to monitor what is going on !
I never contemplated running a reground crank, just that with three damaged ones lying around and new ones at £400-500 a time, it seems criminal to just bin them if they are some use to someone out there.
I know that the accepted theory, handed down on stone tablets from the times of the old testament is not to regrind them, just interested to know whether it can be done or not.
I suspect that a better crank is not the answer, more likely better heat management, cooler oil and a set of gauges to monitor what is going on !
29 July 2010, 02:30 PM
#586
I don't know what the HBR letters are and I have asked two other very competant engine builders with far more experience than me but both were in the dark.
I think that when you get a set of Prodrive pistons they are graded and marked for identification and these are normal production pistons but selected.
You will be aware that the pistons are already graded, dimensionally, in the first place, with a stamp of A or B and so on.
As regards reground cranks, this business about not using them on a Subaru or not being able to successfully regrind them is just another one of these myths or bits of disinformation that has entered the scooby ***** along with some other folklore. It is perpetuated by those without in depth knowledge. Same goes for reduced service life on a reground crank as hundreds of owners have proven. Personally I would not want a reground crank on a big power build but if I can afford a 600 bhp build I guess I can afford the £450 for crank and bearings. The reground crank clearly has a place for returning a car to service cost effectively. While referring to cranks, the crank on a Subaru is not a weak point and if you want to build a bullet proof engine, cost effectively, you start by engineering out the weakest points first, starting with, depending on model, rods, pistons, oil supply. I am not sure of the need for a nitrided crank for several reasons but that is another topic.
I think that when you get a set of Prodrive pistons they are graded and marked for identification and these are normal production pistons but selected.
You will be aware that the pistons are already graded, dimensionally, in the first place, with a stamp of A or B and so on.
As regards reground cranks, this business about not using them on a Subaru or not being able to successfully regrind them is just another one of these myths or bits of disinformation that has entered the scooby ***** along with some other folklore. It is perpetuated by those without in depth knowledge. Same goes for reduced service life on a reground crank as hundreds of owners have proven. Personally I would not want a reground crank on a big power build but if I can afford a 600 bhp build I guess I can afford the £450 for crank and bearings. The reground crank clearly has a place for returning a car to service cost effectively. While referring to cranks, the crank on a Subaru is not a weak point and if you want to build a bullet proof engine, cost effectively, you start by engineering out the weakest points first, starting with, depending on model, rods, pistons, oil supply. I am not sure of the need for a nitrided crank for several reasons but that is another topic.
29 July 2010, 03:39 PM
#587
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a builtup and reground crank or a simple regrind & bearing size change on an impreza crank is doable, the biggest issues being
1/ finding someone willing & sufficiently competent to do the job
2/ cleaning the contaminants out of the crank after the job is complete.
This is a bitch due to its construction ( pressed ***** in oilways ) if you miss anything you can be sure it will come out in service & undo your efforts.
A couple of guys up in Aberdeen have done this, one has had no problems and has put a good 10k miles on it.. the other ... engine died a couple of days later... its risky & I wouldnt advise it myself, having siad that I replaced my bottom end with the cheapest & dodgy-est (SP?) ebay job I could find & its still going... surprisingly enough..
luck of the draw I guess
SS
1/ finding someone willing & sufficiently competent to do the job
2/ cleaning the contaminants out of the crank after the job is complete.
This is a bitch due to its construction ( pressed ***** in oilways ) if you miss anything you can be sure it will come out in service & undo your efforts.
A couple of guys up in Aberdeen have done this, one has had no problems and has put a good 10k miles on it.. the other ... engine died a couple of days later... its risky & I wouldnt advise it myself, having siad that I replaced my bottom end with the cheapest & dodgy-est (SP?) ebay job I could find & its still going... surprisingly enough..
luck of the draw I guess
SS
29 July 2010, 03:57 PM
#588
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A lot of engines use ball bearings and other plugs in the oil galleries... it's standard practise to remove them to prep and clean prior to assembly.. what's the difference here? Forum paranoia?
29 July 2010, 06:01 PM
#589
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Wow, I read the first 10 pages of this thread and I now feel a lot better about my situation. I came out of work, started the car to come home and,
I've caught the dreaded rod knock 
OMG my **** fell out.
I too was weighing up my options.
1. Engine rebuild
2. Ebay special
3. The petrol and lighter method
After reading this thread I took the car in today for a rebuild. I would rather batter the credit card than put up with half the crap that you endured, there would have been murders.
I've caught the dreaded rod knock OMG my **** fell out.I too was weighing up my options.
1. Engine rebuild
2. Ebay special
3. The petrol and lighter method
After reading this thread I took the car in today for a rebuild. I would rather batter the credit card than put up with half the crap that you endured, there would have been murders.
29 July 2010, 08:16 PM
#593
There is no need for that tone mate. You can't agree with everyone on the internet and no need to try to steam roller me into agreeing with you.
Lest not forget (no disrespect to the voices) that despite the OP's spirit this thread is a shining example of how "not to do it" and cutting corners on such an important part of the engine isn't going to work in this case because by his own admission he has a very, very heavy right foot.
He needs the best crank etc money can buy otherwise we will all still be reading about knocking big ends in another 12 months time.
Lest not forget (no disrespect to the voices) that despite the OP's spirit this thread is a shining example of how "not to do it" and cutting corners on such an important part of the engine isn't going to work in this case because by his own admission he has a very, very heavy right foot.
He needs the best crank etc money can buy otherwise we will all still be reading about knocking big ends in another 12 months time.
Last edited by prodriverules; 29 July 2010 at 09:18 PM.
29 July 2010, 09:54 PM
#595
Thanks for that Mick. Funnily enough when I wanted to know I thought about giving you a ring but desisted in case the management thought I was taking a lend. 
Great info as usual.
I think the key is to finding a competant, consciencious machine shop that as I said in my first post will carry out the work properly. The engineering on the Subaru is not radically different to most other engines.
Great info as usual.
I think the key is to finding a competant, consciencious machine shop that as I said in my first post will carry out the work properly. The engineering on the Subaru is not radically different to most other engines.
29 July 2010, 10:07 PM
#596
They run a higher comp ratio on the Twin Turbo HSB pistons (smaller volume/bowl on the crown) so not really suited to the Impreza and the cast pistons are just as fragile as the HB/HBR cast pistons in regards to det.
Bottom end is the same in regards to crank/stroke/thrust position and rod length - it would be prudent to pull it apart and check the condition of the big end's,mains and crank journals.
Mick
No probs Harvey
Bottom end is the same in regards to crank/stroke/thrust position and rod length - it would be prudent to pull it apart and check the condition of the big end's,mains and crank journals.
Mick
No probs Harvey
Last edited by merlin24; 29 July 2010 at 10:09 PM.
30 July 2010, 07:16 AM
#598
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It could strike at any time. The worrying thing is mine just went for no reason, I dont thrash the car (Two child seats are permanent fixtures in the back) I change the oil regularly (Shell Helix Ultra 5w 40 fully synth). It has never burnt oil, the level on the dipstick never changes, no oil warning light and the temp gauge has never been above normal. What can you do
30 July 2010, 09:19 AM
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It could strike at any time. The worrying thing is mine just went for no reason, I dont thrash the car (Two child seats are permanent fixtures in the back) I change the oil regularly (Shell Helix Ultra 5w 40 fully synth). It has never burnt oil, the level on the dipstick never changes, no oil warning light and the temp gauge has never been above normal. What can you do
