Discussion
jontysafe said:
Stevie do you reckon it will be ok to run 1.8bar on a 1mm oversize 200block or am I looking at getting it lined?
"block strength" has very little to do with boost pressure, and everything to do with cylinder pressure (usually Pmax, ie the peak cylinder pressure reached). For any given level of boost, changing the ignition angle by a few degrees will affect Pmax enormously. For most blocks on highly boosted engines,, the bore strength is not important (because Pmax occurs at a very small chamber volume (ie the piston is right up the bore!)). What is important is block deformation and cyclic fatigue.For example, you might make say 300bhp by running 1.5bar boost with advanced timing, and the same 300bhp with 1.8bar running retarded timing, and Pmax in both cases could be identical. Generally, due to detonation phenomena, highly boosted engines tend to have a long(in terms of crank angle), non peaky, "lazy" cylinder pressure profile which actually gives the block and easier time of things
Having said all that, ime, 1.8 bar is not an issue for a properly put together YB.
Much above 550-600 you would need liners installed like Ford did themselves with the wrc cars.
My block has some scoring on one of the bores so will need it taken out to +1mm.
It's a bit of a how long is a piece of string question really (block cracking) as it's down to the individual blocks and in particular wall thickness.
I won't be running hugely high boost pressures and as max says it will be mapped to keep Pmax as safe as possible.
Long term plan is custom tubular manifold and twin scroll turbo which will take it to over 500bhp to the point where gearbox integrity is more of a worry!
My block has some scoring on one of the bores so will need it taken out to +1mm.
It's a bit of a how long is a piece of string question really (block cracking) as it's down to the individual blocks and in particular wall thickness.
I won't be running hugely high boost pressures and as max says it will be mapped to keep Pmax as safe as possible.
Long term plan is custom tubular manifold and twin scroll turbo which will take it to over 500bhp to the point where gearbox integrity is more of a worry!
jontysafe said:
Much above 550-600 you would need liners installed like Ford did themselves with the wrc cars.
My block has some scoring on one of the bores so will need it taken out to +1mm.
It's a bit of a how long is a piece of string question really (block cracking) as it's down to the individual blocks and in particular wall thickness.
I won't be running hugely high boost pressures and as max says it will be mapped to keep Pmax as safe as possible.
Long term plan is custom tubular manifold and twin scroll turbo which will take it to over 500bhp to the point where gearbox integrity is more of a worry!
I'd say as long as it isnt one of the weak turkish blocks you would be fine.My block has some scoring on one of the bores so will need it taken out to +1mm.
It's a bit of a how long is a piece of string question really (block cracking) as it's down to the individual blocks and in particular wall thickness.
I won't be running hugely high boost pressures and as max says it will be mapped to keep Pmax as safe as possible.
Long term plan is custom tubular manifold and twin scroll turbo which will take it to over 500bhp to the point where gearbox integrity is more of a worry!
You certainly do not need a fancy manifold to achieve 500hp, but they do look nice.
Easiest and most cost effective would just be a BW EFR on a 2wd manifold if you have the room for that.
What box are you using ?
Boost pressure is a measure of restriction as it is measured outside of the combustion chamber, to say you are going to raise the boost pressure and therefore create X amount of power isn't always the case.
You can make 500bhp on 1.5 bar on one engine, but a more restrictive engine could need 1.8 to make the same.
You can raise the boost pressure from 1.5 to 1.8 and the cylinder won't see all of it if no other modifications are made, it will just back up into the plenum or pipework where it is measured. Porting the head and fitting wilder cams will see boost pressure come down, but the power stay at a similar amount.
To say A or B engine was fed X amount of boost is not really saying anything unless:
Engine A makes 500bhp on 1.5 bar
Engine B makes 500bhp on 1.8 bar
All this proves is that engine A is much more efficient than B and the cylinder pressures are probably the same or similar.
You can make 500bhp on 1.5 bar on one engine, but a more restrictive engine could need 1.8 to make the same.
You can raise the boost pressure from 1.5 to 1.8 and the cylinder won't see all of it if no other modifications are made, it will just back up into the plenum or pipework where it is measured. Porting the head and fitting wilder cams will see boost pressure come down, but the power stay at a similar amount.
To say A or B engine was fed X amount of boost is not really saying anything unless:
Engine A makes 500bhp on 1.5 bar
Engine B makes 500bhp on 1.8 bar
All this proves is that engine A is much more efficient than B and the cylinder pressures are probably the same or similar.
jontysafe said:
Apparently don't fit on 2wd mani, Mark Shead is trying a 4 wd mani next week.
I don't have room for 2wd mani, would have to be a custom made twin scroll mani.
Looking forward to a Ring trip in March.
If it's in Mark's hand's you'll do well.I don't have room for 2wd mani, would have to be a custom made twin scroll mani.
Looking forward to a Ring trip in March.
He has some very nice tubular manifolds too
Everyone seems to use CP in high spec builds. I had Wiseco in before and they were pretty good, ie not too much rattling when cold and they actually stood up to the det ok as well.
CP are bloody expensive like £780. I liked the idea of using cosworth racing pistons, have a very good rep and a damn site cheaper.
People say the Wossners rattle a lot when cold but I'd have thought that would be a too wide piston to bore clearance?
CP are bloody expensive like £780. I liked the idea of using cosworth racing pistons, have a very good rep and a damn site cheaper.
People say the Wossners rattle a lot when cold but I'd have thought that would be a too wide piston to bore clearance?
Evoluzione said:
I'm presuming you've spotted the cracks?
It suggests to me that major overheating of the exhaust valve and seat area (the causes of that are numerous) has brought on det, i'd be interested to see a pic of the piston, if you can, hopefully you can also tell us which way round the crown was in relation to the head.
It seems you do have eagle eyes.It suggests to me that major overheating of the exhaust valve and seat area (the causes of that are numerous) has brought on det, i'd be interested to see a pic of the piston, if you can, hopefully you can also tell us which way round the crown was in relation to the head.
Cracks between valve seats, engine builder says he can fix but could cause probs in future.
Now looking for a good 4x4 cylinder head.
Anyone help?
jontysafe said:
Everyone seems to use CP in high spec builds. I had Wiseco in before and they were pretty good, ie not too much rattling when cold and they actually stood up to the det ok as well.
CP are bloody expensive like £780. I liked the idea of using cosworth racing pistons, have a very good rep and a damn site cheaper.
People say the Wossners rattle a lot when cold but I'd have thought that would be a too wide piston to bore clearance?
All of the names mentioned are good, really wouldnt have any concerns with either.CP are bloody expensive like £780. I liked the idea of using cosworth racing pistons, have a very good rep and a damn site cheaper.
People say the Wossners rattle a lot when cold but I'd have thought that would be a too wide piston to bore clearance?
And as you say in most cases rattly pistons are down to bore clearances. SO more a machining case these days than a fault of the pistons.
But different materials, designs etc will warrant different tolerances. Really wouldnt worry me much either way
Cracks...harder to say. Certainly on Subaru heads 2001+, cracks around the plug boss and between valve seats are common. I've never heard of a failure or actual problem caused by this. In fact you'd be lucky to find a head that didnt have cracks.
But maybe materials etc are different with the Cossie ?
jontysafe said:
Everyone seems to use CP in high spec builds. I had Wiseco in before and they were pretty good, ie not too much rattling when cold and they actually stood up to the det ok as well.
CP are bloody expensive like £780. I liked the idea of using cosworth racing pistons, have a very good rep and a damn site cheaper.
People say the Wossners rattle a lot when cold but I'd have thought that would be a too wide piston to bore clearance?
Check the pin offset, sometimes Wossner change it to zero offset which causes slap. It is to no detriment and apart from that they are as good as any other, certainly ok for the price.CP are bloody expensive like £780. I liked the idea of using cosworth racing pistons, have a very good rep and a damn site cheaper.
People say the Wossners rattle a lot when cold but I'd have thought that would be a too wide piston to bore clearance?
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