Turbocharger Posted June 25, 2011 Author Share Posted June 25, 2011 The gasflow efficiency isn't in question, performance is more than adequate - I need to add reliability. The turbo needs to sit roughly where it is now to get the inlets and outlets pointing the right way and clear of the other manifold, and keep the oilways draining properly. Plus it all bolts up ok to the downpipe as it is. It's not clear from my photos but my brace is adjustable, it sits between two nuts at the lower end to allow the turbo to be slightly 'jacked up' statically, though I'm sure this preload will change when the whole thing gets hot. The standard 200Tdi exhaust manifold isn't braced between the webs - I guess I'll put this failure to collateral damage from before the brace. I'll weld it up, check it for flatness (skim it again if it's a problem) and bolt it up with a new manifold-to-head gasket. Quote Link to comment Share on other sites More sharing options...
Diff Posted June 26, 2011 Share Posted June 26, 2011 The gasflow efficiency isn't in question, performance is more than adequate - I need to add reliability. The turbo needs to sit roughly where it is now to get the inlets and outlets pointing the right way and clear of the other manifold, and keep the oilways draining properly. Plus it all bolts up ok to the downpipe as it is. It's not clear from my photos but my brace is adjustable, it sits between two nuts at the lower end to allow the turbo to be slightly 'jacked up' statically, though I'm sure this preload will change when the whole thing gets hot. The standard 200Tdi exhaust manifold isn't braced between the webs - I guess I'll put this failure to collateral damage from before the brace. I'll weld it up, check it for flatness (skim it again if it's a problem) and bolt it up with a new manifold-to-head gasket. I could be wrong, but the crack appears to be at a ground down 'weld joint' where the elbow has been welded to the straight when the manifold was fabricated. If this is so, it could be that there wasn't quite enough weld penetration, or the weld was ground back a little too much. Some localised reinforcement or leaving the new weld unground may suffice. Regards, Diff. Quote Link to comment Share on other sites More sharing options...
CwazyWabbit Posted June 26, 2011 Share Posted June 26, 2011 On a 300 tdi manifold the two outer arms aren't welded to the centre boss, they are just pushed in and sealed with exhaust paste. That may also be a way to reduce stresses. Just a thought Quote Link to comment Share on other sites More sharing options...
kiwi_110 Posted June 26, 2011 Share Posted June 26, 2011 Dare I suggest that the manifold is too light? What wall thickness is that tube? I suspect that as your manifold expands and contracts you're getting enough movement to cause stress failures, even with the strut under the Turbo. that strut is not going to stop the turbo moving in an arc as the manifold heats up and pushes it away and pulls it back as it cools. You may need a thicker walled tube, or an original cast manifold and a heavy adapter housing. My conversion uses an original cast manifold with a box welded up from 10mm plate to adapt to the turbo. It's Nissan engine and a Toyota turbo, but the issue being addressed is the same as what you are now dealing with. Great concept though, to retro fit a VGT, on yer!. Ray. Quote Link to comment Share on other sites More sharing options...
inaine Posted June 26, 2011 Share Posted June 26, 2011 that manifold is gash. use a 200 manifold with a support. Quote Link to comment Share on other sites More sharing options...
MECCANO Posted June 26, 2011 Share Posted June 26, 2011 Don't know if this is any help, a guy on the rover tech forums knocked this up using schedule 40 pipe elbows/tees. Its a pretty common way of doing it and seems to last. Schedule 40 manifold Quote Link to comment Share on other sites More sharing options...
dirtyninety Posted June 26, 2011 Share Posted June 26, 2011 Don't know if this is any help, a guy on the rover tech forums knocked this up using schedule 40 pipe elbows/tees. Its a pretty common way of doing it and seems to last. Schedule 40 manifold Now that is very smart! I think, as previously mentioned, a heavier gauge steel would help tremendously. Quote Link to comment Share on other sites More sharing options...
jad Posted June 26, 2011 Share Posted June 26, 2011 the disco 200 manifold already has a support so seams like a fairly logical choice...... Quote Link to comment Share on other sites More sharing options...
rusty_wingnut Posted June 30, 2011 Share Posted June 30, 2011 Jon I think your support is possibly to rigid, you need to eliminate the vibration, that is what appears to be causing the cracking. The support should be sprung enough to eliminate a large proportion of the vibration but still allow the mnaifold to expand and contract freely. PS love the useful comments such as "that manifold sucks" Love to see some of those guys efforts if you care to share? Quote Link to comment Share on other sites More sharing options...
TobyMellin Posted June 30, 2011 Share Posted June 30, 2011 PS love the useful comments such as "that manifold sucks" Love to see some of those guys efforts if you care to share? Exactly! I bet they wouldn't even try this. Keep up the good work! You'll get there Toby Quote Link to comment Share on other sites More sharing options...
Turbocharger Posted July 4, 2011 Author Share Posted July 4, 2011 Thanks for the comments and ideas. I'm thinking the tube wall is too thin on the manifold, but it's what I've got and I don't fancy starting again so I'll live with it for a few more failures before I declare it a lost cause - I've got a welder. It was properly cracked, all the way round: I tacked it in place, on opposite sides and with minimum heat (while it was still bolted up to the head!) to maintain the alignment: Then welded it all the way round, nice wide zigzags to spread the joint and any stress in the area (maybe just moving the next crack upstream to the weakest point?) Then painted it with silver VHT paint so I can see the witness marks of any future cracks, and reassembled. My brace is clearer in this pic, it goes down to two nuts on a stud on top of the engine mount so it is adjustable to take the weight. It may be too stiff, or the cracking may be from before I braced it - time will tell. Thanks for the constructive and less helpful comments re manifold design. As I said, I'm comfortable with the gasflow compromises - this is a structural vibration problem. However, the Schedule 40 manifold looks sturdy but I've got a couple of my own comments: The T-pieces on cylinders 2 & 3 have the effect of diffusing the flow at the port, slowing the gas and raising the pressure. This isn't the case on 1 & 4, and will give strange flow effects and balancing problems. The EGT probe is after the turbo which is strange (depending on what they're trying to measure) and the flow isn't so pretty where the collector branches to the turbo flange. I'm not saying mine's a paragon of gas-flowing virtue and I bet his hasn't cracked anywhere due to the weight of the turbo like mine... My point: if you're sure about your changes, get your welder out and show me how it should be done! Unfortunately I can't test-drive it at the moment because I got a bit enthusiastic with the blowtorch and "annealed" one of the spill-rail copper washers into a melted blob of copper, so I need a trip to the shops first. Quote Link to comment Share on other sites More sharing options...
MECCANO Posted July 4, 2011 Share Posted July 4, 2011 Turbo Charger, Wasn't meant to be a "how you should do it" sorta pic. Just thought you might want to copy the working design you have, in a heavier gauge. ( Although the 300tdi manifold bits are pretty substatial anyway i believe???). I have no idea on manifold design Just thought it might give some inspiration! Other than sharpe angles = bad... i'm sure some one will come and tlel me this isn't necessary true straight after posting this! The honda engine is pretty crowded, I'm sure you could improve on this with the space you have under a landy bonnet, Even create some sort of tubilar master peace if you have the time to spare. Quote Link to comment Share on other sites More sharing options...
discomikey Posted December 6, 2011 Share Posted December 6, 2011 hows the VNT going now after a while? Quote Link to comment Share on other sites More sharing options...
NRS91 Posted December 6, 2011 Share Posted December 6, 2011 yea im interested in this conversion myself if i could find a cheap enough turbo and the 4 stud manifold is of similar size to the 200tdi one i could do the rest easilly as ive found an alternative control method off a VW TDi forum and im developing a way to adapt it onto a land rover just wondering about how yours has gone? Quote Link to comment Share on other sites More sharing options...
Turbocharger Posted December 6, 2011 Author Share Posted December 6, 2011 Its chugging along well, plenty of low down luggability. Cracking appears to have calmed down since I braced it too. It now needs me to for the bigger intercooler which I have had for 8 years(!) before I start playing with the fuelling again. You're welcome to come and have a look if you're in Glos. Quote Link to comment Share on other sites More sharing options...
discomikey Posted December 6, 2011 Share Posted December 6, 2011 might be able to come down and have a look at some point in the nott too distiant futre as a uni mate lives that way. Quote Link to comment Share on other sites More sharing options...
Gazzar Posted December 20, 2011 Share Posted December 20, 2011 Fascinating thread! Is it just me, or are the earlier photos missing? I'd love to see the actuator - any chance of a re-post of the pictures? G. Quote Link to comment Share on other sites More sharing options...
discomikey Posted December 20, 2011 Share Posted December 20, 2011 yes the earlier photos have gone walkabouts but as ive seen them before i didnt need to complain. Quote Link to comment Share on other sites More sharing options...
Turbocharger Posted January 1, 2012 Author Share Posted January 1, 2012 I'm not sure what I posted originally anyway! Here's some of the early VGT pics I've got - they're in no particular order, no commentary and not necessarily of the finished product: Quote Link to comment Share on other sites More sharing options...
discomikey Posted January 1, 2012 Share Posted January 1, 2012 tasty Quote Link to comment Share on other sites More sharing options...
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