I know nothing about TDI's but so do they have a DV ???
Interesting problem is the 'stalling' juddering happened under acceleration.Maybe when the boost pipes unswell they cause too much air to flow back to the turbo .... causing it to stall or wear on the bearings in a way they're not designed to work?
......DV would only get rid of excess boost, not residial boost from pipe expansion?
Interesting problem is the 'stalling' juddering happened under acceleration.
I can't see that - or reverse flow. I don't think there will be excess pressure.
Not clutch its the engine / turbo stalling / juddering. Doesnt do it with OE stuff.Odd - are you on DMF or SMF?
How can you make that analysis not knowing what actually happens i.e. how much the pipes swell, where the pipes swell, how long the lag lasts for?Come on guys. Even if the SFS hoses were balloons, we're talking about the system being under a certain pressure, whatever it was set to when it was mapped.
The systems not at a higher pressure just because it has ballons for hoses. The pump blows up the ballons till it gets to 30psi, OK they'll be much larger than the solid alloy pipes, but they're still only holding 30psi, the same as the alloy pipes.
The volume of air however will be greater, as the balloons are larger but we're not talking balloons, we're talking a 75mm pipe which may "swell" up to 85mm across 2M length (OK I am exaggerating here!). In reality this gives 2500cm3 extra air which is exactly the same as having an extra 2.5cm of hose in the system. You're going to tell me that having a longer hose causes something other than lag? Like turbo's to die, black smoke etc?
Remember, the system knows how much air is in there, thats what the MAF/AFM does.
If the hose clamps weren't holding the hoses's properly and air was escaping, that would cause an issue, fuelling would be wrong, boost would be lost, the system would be in a mess. But given the air is remaining within the sytem, everything will be OK.
Ballooning SFS hoses will do nothing more than give you a nanosecond more lag, as mentioned above, the same as having 2.5cm more hose in the system. And thats if they swell up 1cm each side, which is really not going to be happening.
I've taken a worst case scenario of the pipe swelling 1cm each side of a 75mm pipe over a total length of 2M. Was your swelling worse than that?How can you make that analysis not knowing what actually happens i.e. how much the pipes swell, where the pipes swell, how long the lag lasts for?
The sheer fact that I have gone back to OE pipes today and the problem has been resolved in terms of lag, juddering and overall smoothness confirms my suspicions.
The pipes were swelling around 30-35% (in some cases it looks more tbh) of there size in my section of the pipe work thus building up pressure before going into the turbo. I agree it doesn't matter where the pipes swell but I am pretty sure that the turbo, ecu trying to control the boost and other parts of the engine didnt like the increase in pressure / the huge lag before the excess boost was forced in. In the mean time whilst the boost/pressure is building up the car is chucking in lots of fuel expecting there to be air to compress and burn which could cause the this juddering / choking?I've taken a worst case scenario of the pipe swelling 1cm each side of a 75mm pipe over a total length of 2M. Was your swelling worse than that?
It doesn't matter where the pipes swell, extra volume is extra volume.
When you went back to OE pipes, you changed the hose clips back to the OE ones.
You changed the volume of air in the system, so you need to change the map to accomodate as you'll now be running different boost, different charge temperatures etc.
Could well be the map wasn't right. Was it remapped with the SFS hoses?
What torque were the new hose clips done up to?
SFS Hose Update
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Right a real positive update.
I spoke to a chap called Lee there. He explained to be in detail about how they make the hoses and it sounds like the ones I got are dfectective i.e. made wrong as they shouldnt expand or in his words "shouldnt expand anywhere near 30-35%". Lee understood deisels well and said the pipes should hold 2bar no problem.
I am getting the pipes sent back to SFS. Lee will be talking to the engineers about making the pipes wirereinforced (this may be very difficult due to the complexity) or reinforced with more silicone so they are as strong as possible for me. He will call me later this afternoon once he has spoken to his colleagues and figured out how best to fix the problem.
So quite positive results. I am happy that I spoke to Lee and the best thing about it, they should come this week.