The Baconator's latest victim

[jonrb 0]

Hey Kev! Long time no see :wave:

 

You still throwing crazy money at that old bag of bolts then? ;)

[Kevin Bacon 5]

Nothing like as much as I used to :D

 

Cheers for the welding info Timbo, very useful :salute:

 

Good info on the 24V T stuff guys. I don't know a lot about that engine with forced induction, so it's all worthwhile! I like the R32 block / 2.8 head combo, a neat way round the management. I'll stick with the 2.8 lump and my standalone can control the VVT and DBW throttle, so no worries there :D

 

Another trick people do is the 2.8 block with R32 crank, modded pistons and R32 head, which gives you a very strong 81mm bore block, but 3 litre and high flow 8)

Not sure I'll go mad with the 24V. Just a spacer and modest boost I think.

[coullstar 0]

James did something similar with the manifold thats on my car. Seems to work ok and as far as I can tell its not had any problems. Its is a heavy lump though that hanging of it. Might take it off over the winter and double check it.

 

I woudlnt like to run the standard inlet on the 24v. I could see mine pulsing as standard, I reckon a bit of boost would quicken the fatiguing.

[Kevin Bacon 5]

Yeah that's the way to do it really. You can see the OE headers have strengthening ribs on them, so should resist the flexing forces quite well. As Pete says, the risk of fatigue fractures would be massively reduced with some support bracing. You can bolt one end to the turbo flange and the other to the pretapped holes in the block which would hold the CV heatshield in place, but which the VR6 never had fitted. The brace also needs flexible couplings (rose joints often used) to allow for heat expansion movement.

[boost monkey 0]

Nice work on the manifold skimming Kev! Setting something like a manifold up on a milling machine and prepping it so that the surface you're skimming was perfectly flush would take more than 5 mins, let alone the time to pass an initial cut and then adjust from there. My 2p.

 

You could use an iron-carbon equilibrium diagram to find out which "state" the metal of your manifold is passing into everytime it is heated and cooled. The rate at which this is done will inform you of how the grain structure of the metal is changing internally. I mean, if it's getting red hot or glowing after a long boost session or a hard drive, you can be sure it has passed through a couple of phases (and it prob heats up faster than it cools down too). Might be worth some research. I'll try to dig out the diagrams.

 

TIG should really only use pure Argon for the inert gas. And back purging is very useful. Seen that used when welding a rally car exhaust system. You can literally duct tape over the open ends, than make a hole and run a little hose into the manifold to purge the oxygen out and make sure the only gas in proximity to the back of the weld is the Argon.

 

My 6p altogether :lol: :salute:

[Kevin Bacon 5]

Cheers Mr Monkey! Good to have you back by the way. I wondered where you'd gone!

 

Heat cycling did cross my mind actually chap. The one I 'skimmed' got red hot and sub zero cold regularly last year, so I'm hoping it's stabilised and won't warp any more. It used to glow orange on part throttle mate, let alone boost!

 

I think I've nailed that one though, with lots more cruise advance. I've been seeing 650 deg on the way to work this week (80mph cruise) which is much more like it.

 

Yeah all that back purging and Argon stuff sounds a bit too complex for my basic DIY ability! I wouldn't mind having a stab at making one though, but just tack it together and then hand it over to an expert for the purging and argoning. Is Argon anything to do with Argos? :D

[Rob_B 0]

Cheers Mr Monkey! Good to have you back by the way. I wondered where you'd gone!

 

Heat cycling did cross my mind actually chap. The one I 'skimmed' got red hot and sub zero cold regularly last year, so I'm hoping it's stabilised and won't warp any more. It used to glow orange on part throttle mate, let alone boost!

 

I think I've nailed that one though, with lots more cruise advance. I've been seeing 650 deg on the way to work this week (80mph cruise) which is much more like it.

 

Yeah all that back purging and Argon stuff sounds a bit too complex for my basic DIY ability! I wouldn't mind having a stab at making one though, but just tack it together and then hand it over to an expert for the purging and argoning. Is Argon anything to do with Argos? :D

 

yeah you can buy argon from argos, you need the special code to ask at the counter though

[boost monkey 0]

Hey matey, I've been drinking rum for about a year, put on a stone and now back trying to lose it ready for wedding in May :nuts:

 

Just finishing up uni this year too, finally!

 

I've found a basic I-C Equilibrium diagram for you, a nice colourful one :D:

 

 

So the x-axis is percentage Iron-Carbon and y is Temp in Celcius.So for a cast iron manifold, you'll be over towards the right and heating past 710 deg C will put you into Austenite & Cementite. Austenite is ok, the metal will recover from this (although if it's cooled slow then it will generate deposits called pearlite which aren't ideal [i think they're very soft or something]). Cementite is very brittle though and I would guess, with my 2nd year Material Science opinion(!) that this is what would be making the manifold crack. When you repeatedly heat up something that is brittle, it will eventually crack or fracture. Everything under the 710deg line is basically no state change. Probably will glow though :D

[Kevin Bacon 5]

That's a great diagram mate. I don't fully understand it, but it looks pretty :lol:

 

Yeah I'm hovering around the 710 line with motorway cruising. Fart arsing around town it's way lower, 550-600. Boost is obviously an issue where that diagram is concerned as it's around 850, but I'm not up there for long though, usually just a few seconds.

 

I'm guessing OE cast turbo manifolds have superior quality materials to stop the cements deposting in the Austen Texases?

[boost monkey 0]

Yeah I'm sure the OEM turbo manifolds have different metals and alloying involved to stop these things happening.

 

You could always stick your manifold flange face, all nice and shiny now, under a microscope and see what the grain structure of the metal looked like!

 

Does your turbo spool (and stay on boost) when on motorway for example? Perhaps that's where the manifold fatigue is coming in. Food for thought :-)

 

speaking of which, lunchtime! :norty:

[Kevin Bacon 5]

LOL, stay off the rum :wink:

 

I've seen manifolds made of Inconel alloy, which is what modern turbine blades and housings are sometimes made of.

 

Nah my turbo isn't like 1.8T mate, it needs a good stoke before it churns into action. Engine is always

 

I got it as lean as 17:1 AFR @ 80mph and it was smooth and det free, but the EGTs got a touch warm :D.

[Jim 1]

And remembering the old top gear review of the McLaren F1, wasn't the exhaust system on that made in part from Inconel?

[coullstar 0]

Most likely. It is expensive stuff. We make dowhole tools from Inconel 925 / 725. You can guess that there not cheap when the tools are near 9in OD and 10ft long. Pocket change to the like of BP etc though.

 

17:1!!

What sort of mileage do you get from a full tank of petrol out of interest?

[Kevin Bacon 5]

17:1!!

What sort of mileage do you get from a full tank of petrol out of interest?

 

Not sure. Only did it over half a tank during testing. The DTA does both galls per hour and miles per gall, so I'll have to check through the logs.

I average 27mpg when the cruise AFR is 14.7-15, so I would imagine 17 would be in the mid to high 30s :D

 

17 is the absolute limit with normal port injection though, any leaner and there isn't enough fuel to burn and it misfires. 16-17 is fine on really light cruise, but 80 mph (29% throttle opening) was taking it too far :D I don't mind experimenting with this engine though. Good way to learn. If it blows I'll just stick the 24V in 8)

[coullstar 0]

Thats not bad. I get roughly 19mpg out of mine. It is definitely running rich though as the plugs do soot up.

[boost monkey 0]

I've seen manifolds made of Inconel alloy, which is what modern turbine blades and housings are sometimes made of.

#

 

I always find turbine blades a funny thing from an engineering point of view. I mean, they pass their melting point easily when in use but they're flushed with so much liquid nitrogen that they stay solid. Insane.

 

In the simplest possible way I can explain it: It's like putting your oven on Gas Mark 9, placing an ice cube on the top shelf and it not melting. Insane.

[coullstar 0]

Thats why I love engineering!! Making the seeming impossible, possible.

[Kevin Bacon 5]

Thats not bad. I get roughly 19mpg out of mine. It is definitely running rich though as the plugs do soot up.

 

Sooty all over?

 

Mine look like this....

 

[coullstar 0]

Just recently, they were like yours but took them out last night and they were all black.

[WigsVR6 0]

Read the whole thread and its simply amazing how much thought and effort as gone into your car. I think the only common part that our cars share now is the rear anti roll bar :lol: Just a quick question though - with your skills and knowledge why did you use the Corrado as a starting base? When you could have chose any car really.

[Kevin Bacon 5]

Cheers mate :D

 

When I bought the Corrado, I certainly didn't have any of this planned for it! It just kind of happened. I've always been into VWs so the Corrado was a logical progression from the MK1s and 2s I had previously.

 

I've always enjoyed tinkering and working on engines so the car has ended up being a rolling engineering project :lol:

[WigsVR6 0]

If this is tinkering then.............. :lol: 7 years worth of project is fantastic dedication I hope you keep it forever. :notworthy:

[domwells27 0]

I always find turbine blades a funny thing from an engineering point of view. I mean, they pass their melting point easily when in use but they're flushed with so much liquid nitrogen that they stay solid. Insane.

 

In the simplest possible way I can explain it: It's like putting your oven on Gas Mark 9, placing an ice cube on the top shelf and it not melting. Insane.

 

Eh? Since when has liquid nitrogen been used in GTEs? Fairly certain they are just cooled with air from outside the combustion chamber. TBCs also help prevent them melting

 

Have to agree though, in engineering terms they are f*cking incredible. The amount of tensile loading they are subjected to is unreal!

[blue95 0]

Wow had a read thru...car looks great in every pic! have to say the RH ZW1 pic is my fave

[Kevin Bacon 5]

Thanks chap :D

 

I have to say, the ZW1s were my least favourite wheel in terms of maintenance and handling. They weigh about the same as an oil rig and you simply cannot go anywhere near water with them, or the laquer 'spider legs' under the split rim bolts :(

 

Stunning wheel though :D