Jump to content

300Tdi VGT project


Recommended Posts

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.

Link to comment
Share on other sites

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.

Link to comment
Share on other sites

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.

Link to comment
Share on other sites

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?

Link to comment
Share on other sites

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:

post-277-0-62991700-1309808386_thumb.jpg

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:

post-277-0-47231300-1309808392_thumb.jpg

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?)

post-277-0-10439900-1309808395_thumb.jpg

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.

post-277-0-46741000-1309808383_thumb.jpg

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:

civic_turbo1.jpg

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. :blink:

Link to comment
Share on other sites

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 :ph34r: 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! :D

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.

Link to comment
Share on other sites

  • 5 months later...

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?

Link to comment
Share on other sites

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.

Link to comment
Share on other sites

  • 2 weeks later...
  • 2 weeks later...

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
×
  • Create New...

Important Information

We use cookies to ensure you get the best experience. By using our website you agree to our Cookie Policy