external wastegate question

[shinny]

Pretty much agree, and you make some good points about EWG being better than IWG. However you lost me here:

having the valve open, or anywhere other than shut will delay the boost building, cause your turbo to work harder to produce the same amount of boost (and therefore you'll have hotter charge temps)

Surely less exhaust gas going through the turbine means you get less boost? Not that the turbo somehow works harder to produce the same amount of boost off less exhaust gas. In fact slowly building boost must work the turbo less hard (it's doing less work at the end of the day) but it's sub-optimal for performance.

[dylan5084]

I'm a welder, I reckon a couple of 1 inch welds will hold for the duration, you can hang 1 tonne off a 1 inch weld

[shinny]

I'm a welder, I reckon a couple of 1 inch welds will hold for the duration, you can hang 1 tonne off a 1 inch weld

I didn't say they weren't strong. My concern was about cracking them through expansion and contraction. But, like I said, I'm not an expert on welding

[dylan5084]

Depends on how nicely it welds to be honest, I'd imagine it would be made from some sort of cast steel, should be ok with flux cored mig wire, and should be able to grind it back to original, if needed later to sell Or return to standard.

[shinny]

Depends on how nicely it welds to be honest, I'd imagine it would be made from some sort of cast steel, should be ok with flux cored mig wire, and should be able to grind it back to original, if needed later to sell Or return to standard.

That garage who did mine removed the flap entirely and welded solid the wastegate hole and the hole for the flap. It's never going back!

[C35Rob]

Pretty much agree, and you make some good points about EWG being better than IWG. However you lost me here:

having the valve open, or anywhere other than shut will delay the boost building, cause your turbo to work harder to produce the same amount of boost (and therefore you'll have hotter charge temps)

Surely less exhaust gas going through the turbine means you get less boost? Not that the turbo somehow works harder to produce the same amount of boost off less exhaust gas. In fact slowly building boost must work the turbo less hard (it's doing less work at the end of the day) but it's sub-optimal for performance.

absolutely.. sorry I was talking b0ll0cks, can I blame being tired? for some reason I was thinking boost leak, but yes, you're right.


as for welding cast iron.. it's easy, as long as it's a good casting. make sure it's clean, heat it up in a rod oven, use a proper rod for cast and then allow it to cool slowly by putting it back in the oven overnight.

or, knock all the coating off the cast iron rod and use it as a filler rod to Tig it up, although there's little difference in the outcome







that manifold was cracked 360 degrees, vee'd out nice and deep and tigged up, was still going strong when the car was scrapped.

[dylan5084]

is it defo cast iron? It looks like cast steel to me, I'll be able to tell when I hit it with a grinder, unless someone actually knows for sure?

[C35Rob]

is it defo cast iron? It looks like cast steel to me, I'll be able to tell when I hit it with a grinder, unless someone actually knows for sure?

cast iron

[dylan5084]

[shinny]

BTW, it's a pity this isn't a standard CT20b... I'd very happily swap you a pre-welded turbine housing for a working one!

[dylan5084]

BTW, it's a pity this isn't a standard CT20b... I'd very happily swap you a pre-welded turbine housing for a working one!

I like the way my turbo spools, and it doesn't drop off to the redline... Might be the boost creep though lol it's night and day to the standard ct26

[2mad]

if you're set on not welding the poppet valve shut, you could remove the actuator and bracket and fabricate a new bracket to which you could attach a threaded rod, so that you could mechanically hold the poppet valve shut, whilst maintaining a degree of adjustment to ensure the valve is seated correctly

having the valve open, or anywhere other than shut will delay the boost building, cause your turbo to work harder to produce the same amount of boost (and therefore you'll have hotter charge temps) boost creep is caused because the turbo speed cannot be regulated (i.e gas diverted from the turbine) efficiently - this could be due to a faulty actuator, the poppet valve being too small, or not opening properly, the turbine wheel and or housing being too small among other things. The boost creep is a symptom of a larger problem.

also, a big downside of the IWG is that it dumps its gas into the flow of the turbine, which causes more of a restriction in getting the gas through the turbo and out the exhaust.. add to that, with an EWG the dumped gas doesn't have to share the downpipe (in the case of having a screamer) or at least the flows merge further down the system where it will not be as much of a restriction - win/win.

poppet valve = External wastegate

Swing valve = internal wastegate.

Sorry if im wrong

[bobhatton]

So I had sneaking suspisions that My manifold had cracked, so I've took off the heat wrap, some of the heat wrap had turned into glass... Pretty hot! and yep it is cracked so I'll defo take your manifold mate

means I can cut off the flange of both and weld my one into the other without feeling like I've wasted money that could have been recouped from selling the old manifold

Just won A tial wastegate on eBay too so it seals the deal for me

I'll weld the old one just now so I can still use the car, as the crack is accessible from to top anyway

Heat wrapped manifold will give problems with cracking, it will also be the cause of your over boost problems.

No need to do anything with the stock waste gate, it can be run with the external one as long as you feed the same boost signal from the manifold to both.

[2mad]

So I had sneaking suspisions that My manifold had cracked, so I've took off the heat wrap, some of the heat wrap had turned into glass... Pretty hot! and yep it is cracked so I'll defo take your manifold mate

means I can cut off the flange of both and weld my one into the other without feeling like I've wasted money that could have been recouped from selling the old manifold

Just won A tial wastegate on eBay too so it seals the deal for me

I'll weld the old one just now so I can still use the car, as the crack is accessible from to top anyway

Heat wrapped manifold will give problems with cracking, it will also be the cause of your over boost problems.

No need to do anything with the stock waste gate, it can be run with the external one as long as you feed the same boost signal from the manifold to both.

Twin gated ..... I like it


Edit.. Can a boost controller control internal and external valves simultaneously

[dylan5084]

So I had sneaking suspisions that My manifold had cracked, so I've took off the heat wrap, some of the heat wrap had turned into glass... Pretty hot! and yep it is cracked so I'll defo take your manifold mate

means I can cut off the flange of both and weld my one into the other without feeling like I've wasted money that could have been recouped from selling the old manifold

Just won A tial wastegate on eBay too so it seals the deal for me

I'll weld the old one just now so I can still use the car, as the crack is accessible from to top anyway

Heat wrapped manifold will give problems with cracking, it will also be the cause of your over boost problems.

No need to do anything with the stock waste gate, it can be run with the external one as long as you feed the same boost signal from the manifold to both.

Right, so I'd be better not wrapping the next one? Was thinking I could put a blanket over it.

So to send the same signal to both gates, would just require a T piece and some vac lines?

[2mad]

So I had sneaking suspisions that My manifold had cracked, so I've took off the heat wrap, some of the heat wrap had turned into glass... Pretty hot! and yep it is cracked so I'll defo take your manifold mate

means I can cut off the flange of both and weld my one into the other without feeling like I've wasted money that could have been recouped from selling the old manifold

Just won A tial wastegate on eBay too so it seals the deal for me

I'll weld the old one just now so I can still use the car, as the crack is accessible from to top anyway

Heat wrapped manifold will give problems with cracking, it will also be the cause of your over boost problems.

No need to do anything with the stock waste gate, it can be run with the external one as long as you feed the same boost signal from the manifold to both.

Right, so I'd be better not wrapping the next one? Was thinking I could put a blanket over it.

So to send the same signal to both gates, would just require a T piece and some vac lines?

You'd have to ask Bob or shinny .. never twin gated myself .

[shinny]

So to send the same signal to both gates, would just require a T piece and some vac lines?

I've only just gone twin gated but yes, a T-piece was all that was required. I tried to ensure the two had similar spring pressures (which was tricky given I don't know the exact spring pressure on either of my EWGs) but I can report that the combination is holding boost better than I'd expected. I've not yet turned on boost control to increase the boost but I'm sure that'll be fine

[dylan5084]

I'm only going to 1 bar of boost, but I'll give this a go, seems the easiest way, T piece and vac hose- sorted

[shinny]

I'm only going to 1 bar of boost, but I'll give this a go, seems the easiest way, T piece and vac hose- sorted

The less boost you want to run on a given turbo, the more wastegate you need... it's about the only bit on an engine that needs to get bigger as you lower your power goals.

[dylan5084]

I'm only going to 1 bar of boost, but I'll give this a go, seems the easiest way, T piece and vac hose- sorted

The less boost you want to run on a given turbo, the more wastegate you need... it's about the only bit on an engine that needs to get bigger as you lower your power goals.

makes sense