4722 replies to this topic

[Nev]

For those of you who might possibly be interested, here is the braking sub system schematic:

 

 

 

I included a dotted outline for a vacuum reservoir, however in practice there is no need for one as the pipework has sufficient capacity for a couple of pedal presses and the vac pump starts within 1/4 second anyway to replenish vacuum.

 

The green dotted pipework indicates what is effectively the storage/reservoir volume of the circuit. If I switch off the entire system it contains the vacuum indefinitely (i.e. a strong vacuum is still there the next day when I come to start the car again).

 

I utilise the weak engine inlet manifold vacuum to help "prime" the UP32 pump. By providing a weak vacuum to the pump it means that the pump can provide an even stronger vacuum to it's outlet side. If desired I have seen a vacuum of -27 in/Hg - which is very strong (probably a few in/Hg more than OEM expectations with a new engine making strong vacuum).

 

The arrows indicate the flow vacuum to the servo.

 

Edited by Nev, 25 June 2016 - 07:08 AM.

[Zoobeef]

Rather than having a switch would it not be better to fit a relay activated by the ignition switch?

[Ormes]

Looks like a master switch to disable the functionality entirely as desired/required, with the short term operation driven by the vac switch (so assume the switch is just left on all the time in general). An option would have been to run it all from a switched live to prevent any battery drain, but this may not be a problem that needs solving?

[Zoobeef]

I would assume it's on all th time while Nevs driving and off when he leaves the car (otherwise it'll start up on its own if the vacuum does drop over time and drain the battery).

Putting it to the ignition switch via a relay would just make it all automated.

[Nev]

Yep, you are right Mark, I should ideally replace the master switch with an ignition triggered live as it is now an anachronism from the old setup. However, I think I can live with the extra effort of switching it on and off manually for each drive for the moment. If/when I take the dash off so I can gain access to a ignition switched live I'll probably put one in.

 

[Mopeytitan]

Isn't the window wiper motor an ignition switches live?...

[Nev]

Poopascoop, bad news.

 

Yesterday I got round to investigating my exhaust leak and stripped the exhaust manifold off the engine. The problem is as I feared, weld failure on the T3 flange, I am sincerely hoping it can be re-welded. I have emailed Jay at Nortech and am hoping he can fix this under the lifetime warrantee.

 

This is the first time the car has been un-drivable for about 3 years now. It feels a bit strange not to be able to just step into him and go for a drive.

 

 

 

 

Edited by Nev, 03 July 2016 - 05:55 AM.

[mbes2]

Nice crack, knowing you that won't take long to resolve When are you sorting the db, must be having lon term effects on your hearing

[Nev]

Well, hopefully Jay (the owner of Nortech Performance) who made it for me will be able to grind and re-weld it under warrantee, he has a good reputation and his business is doing well as a result.

 

It survived a long time, but it only takes a tiny weak point to start a crack. If you look, I think the crack probably started on the 10mm thick T3 plate. It makes one realise the heat and stress on these components. How the turbo turbine blades survive is a testament American engineering, using carefully controlled proportions of nickle, titanium and inconel in the metal..

 

During WW2, only the Americans were "daring" enough to use turbo chargers on their aero engines (e.g. the P38 - one of the fastest prop planes ever). In the UK the manufacturers refrained from doing so, because we could not guarantee access to the precise metallurgy (both the metals and the casting process). Instead we went down the supercharger route for the Merlin etc, so we didn't need the exotic metals.

 

 

Edited by Nev, 03 July 2016 - 08:54 AM.

[Zoobeef]

The turbo is a fair bit of weight pulling down on the manifold. Can you brace it off the block somehow?

[CHILL Gone DUTCH]

Is it just the pic nev or does the mounting plate also look warped

[Nev]

The turbo is a fair bit of weight pulling down on the manifold. Can you brace it off the block somehow?

 

I did look into it, but refrained from doing so, as it's hard to know how much it needs to expand with heat and in what direction. Bear in mind the block + gasket +head itself probably expands something like 1 or 2 mm vertically, and the manifold will probably expand 1 mm laterally. I may end up exacerbating the problem - what do you think?

 

TBH, I don' think the problem arose from the weight of the assembly, more likely simply heat cycles. I think this, because the downpipe which is only 1.5mm to 2mm thick (and hence a lot weaker than a 10mm plate) has not fatigued.

 

 

Edited by Nev, 03 July 2016 - 09:01 AM.

[Mopeytitan]

Not sure how they make the turbo blades but I know that turbine engine compressor blades are actually a crystal grown in a special way through a mould.

[CocoPops]

Is that a broken stud as well? I'm guessing a new 10mm mount plate is best way forward, grind the old one off and realign?

[Nev]

Not sure how they make the turbo blades but I know that turbine engine compressor blades are actually a crystal grown in a special way through a mould.

 

Yea, individual aero engine blades are often made like that, the manufacturing process is incredibly tightly controlled.

 

When I was working for GE Aerospace we had a manufacturing plant in south Wales, you could not even get into the shop floor without loads of steps: a fooking good reason to be there, full military clearance, an authorised escort, body suit + boots + hair net, decontamination, no cameras (or phones), anti static lead. You had to walk between the painted lines - if you stepped out of them or touched anything you might cause a £500,000 item being made to be discarded - along with your own dismissal for gross negligence. If you were caught taking pictures etc you'd likely also be hauled up for breaking the official secrets act, not to mention the Americans kicking up a big fuss.

Edited by Nev, 03 July 2016 - 09:37 AM.

[Mopeytitan]

We learn a small fraction of the process on our courses about how Roll Royce make their turbine blades but it's a very closely guarded secret on exactly how it's done. Very clever though! I would t imagine turbine blades would be the same or they'd cost a ridiculous amount?...

[Nev]

Is that a broken stud as well? I'm guessing a new 10mm mount plate is best way forward, grind the old one off and realign?

 

Broken bolt end, I think it should come out easily enough.

 

I don't think it would be possible to grind the old T3 10mm flange off and replace it sadly, as it would be almost impossible to weld on the new one in precisely the same place. Any offset between the T3 flange and wastegate pipe would mean the downpipe would no longer fit to the 2 places it mounts to. Even 0.5 mm delta would be too much probably, and cause leakage and stress.

[Nev]

Is it just the pic nev or does the mounting plate also look warped

 

It hasn't warped, but it is proud by about 0.5mm where the crack has allowed it detach from the collector. Once welded, it think it will need to be precisely skimmed and then I will use an extra gasket to fill the void where the skimmed material was removed (hopefully).

 

Also, the old stainless steel gasket has melted and sort of fused with the flange face, this makes it look messy but can be carefully ground back - I've had to perform this job 3 times before believe it or not, as the SS gaskets can't take the heat/pressure.

Edited by Nev, 03 July 2016 - 09:41 AM.

[CHILL Gone DUTCH]

What kind of temps do you think your exhaust is withstanding around the turbo part

[CocoPops]

Is that a broken stud as well? I'm guessing a new 10mm mount plate is best way forward, grind the old one off and realign?

  Broken bolt end, I think it should come out easily enough.   I don't think it would be possible to grind the old T3 10mm flange off and replace it sadly, as it would be almost impossible to weld on the new one in precisely the same place. Any offset between the T3 flange and wastegate pipe would mean the downpipe would no longer fit to the 2 places it mounts to. Even 0.5 mm delta would be too much probably, and cause leakage and stress.

Grinding out the old weld should be ok, but how can you maintain a perfectly level face given the crack runs right through the mount plate?