Time to go Stage II!

[kidglok]

You've got me curious. Where do you see the 90 deg angle? The old Stage I setup was 90 degrees. I don't see it on this one. Please enlighten me.
This new wastegate plumbing is more favorable compared to the old Stage I setup, and the way this wastegate controlled boost with the old setup, where the flow did have to make a 90 degree turn, was without a hitch. If anything this new mounting should be an improvement, but I really doubt I'll be able to notice the difference. I just thought this way of plumbing it made more sense from a flow perspective.

im sure its not an issue, what i was looking at is the header pipes are on a downward slope to the turbo, then the wastegate is sort of point upward away from the exhaust, so the gasses would have to change direction to exit the wastegate. it could be just the angle of the pics, but either way im sure it will work, im just thinking out loud lol

 

[Alky V6]

im sure its not an issue, what i was looking at is the header pipes are on a downward slope to the turbo, then the wastegate is sort of point upward away from the exhaust, so the gasses would have to change direction to exit the wastegate. it could be just the angle of the pics, but either way im sure it will work, im just thinking out loud lol

The important angle to look at here is the point where the wastegate plumbing attaches to the main collector tube. In my opinion, as long as the tube is 90 degrees or lower (favoring flow direction) you won't have a problem. If the angle is lower but not favoring collector flow direction, then the wastegate may not be as effective since the flow through the collector would tend to suck flow from the wastegate rather than push flow to the wastegate. At least, that is the theory. Of course, there is pressure in the exhaust system that is higher than atmospheric, so that pressure would tend to cancel some or most of the sucking that would occur with an unfavorable mounting angle.
The angle of the wastegate tubes that are attached to the main collector tubes is 55 degrees, favoring collector flow direction.

 

[kidglok]

The important angle to look at here is the point where the wastegate plumbing attaches to the main collector tube. In my opinion, as long as the tube is 90 degrees or lower (favoring flow direction) you won't have a problem. If the angle is lower but not favoring collector flow direction, then the wastegate may not be as effective since the flow through the collector would tend to suck flow from the wastegate rather than push flow to the wastegate. At least, that is the theory. Of course, there is pressure in the exhaust system that is higher than atmospheric, so that pressure would tend to cancel some or most of the sucking that would occur with an unfavorable mounting angle.
The angle of the wastegate tubes that are attached to the main collector tubes are mounted at a 55 degree angle.

I knew there was a scientific explanation behind it

 

[Alky V6]

I knew there was a scientific explanation behind it

lol

 

[Alky V6]

No one's picking up on the NACA ducts?

 

[kidglok]

No one's picking up on the NACA ducts?

Is that what you cut into the pipe to weld the Wastegate tubing over?

 

[Alky V6]

Is that what you cut into the pipe to weld the Wastegate tubing over?

Yes.

 

[Dusty Bradford]

The closer the gate is to the turbine entry, the more important the entry angle becomes. Don's placement is as good as you can get considering how close the collectors are to the turbine. You would think the huge pressure difference between the atmosphere and the crossover pipe would be enough to maximize flow but it doesn't. The angle of entry has a huge effect on how well the gate works.

 

[Alky V6]

Though the holes feeding the wastegate plumbing are not a true NACA duct shape, I'm hoping they will work somewhat like a NACA duct. The reason why I didn't go with a truer NACA duct shape is because it would have cut down on the total area of the hole. I didn't want to cut down on the area too much. The holes do have to feed a 60mm wastegate.
The shape of the holes will hopefully keep the flow in the collecotors streamline as it travels over the holes, causing a lesser degree of disruption to flow than a normal hole. Under 'balls to the wall' mode, I don't expect the wastegate to be open.

 

[Alky V6]

A more laymans term explanation that I came up with for a person not familiar with cars. I thought I'd copy it and post it here, too.

The piping you see is part of the exhaust system that directs exhaust flow to the turbocharger. The holes branch off of the exhaust collectors (what you see) to a small bit of plumbing that will feed a wastegate valve. The wastegate dumps to atmosphere excess exhaust energy, which allows one to control the speed of the turbocharger, and hence the intake manifold boost level, and engine power level.
In my engine configuration, I don't plan on the wastegate being open to dump exhaust energy when the engine is at 'Balls to the Wall' mode, so I want the flow in the exhaust collectors to be as smooth as possible feeding the turbo.
The shape of the holes you see are not a true and accurate shape, but hopefully they will act similar to a NACA duct. NACA ducts are an aerodynamic shape for a duct entry that is known for keeping disruption to smooth flow to a minimum. Google NACA duct.

 

[Alky V6]

One other thing about the shape of the holes feeding the wastegate.
The shape of a NACA duct promotes smooth flow over and into a duct passage. What is also great about it is, when you attempt to reverse the flow, say try to flow from the wastegate into the collectors, the shape of the hole does a great job of acting like an anti-reversion device. So, if someone is trying to keep crossflow from one collector to the other through the wastegate ducting, like what I'm using, to a minimum, then having something that acts like an anti-reversion device would be the ticket. Assuming that you're not using a dividing wall just under the wastegate to physically separate the two sides.
I tested my theory out with my trusty air blowgun, and the flow is drastically cut down when trying to blow in the direction from the wastegate into the collector.

 

[Alky V6]

Arrg! What a waste of a day. Spent all day making up the bungs for the Y pipe, drilled a pilot hole through them, welded them to the Y pipe, bitchin welds, then went to drill and tap them. I must have burnt up close to 100 bucks worth of drills and taps. Broke one tap off in one of the bungs, but luckily the tap extractor tool worked like a charm getting the broken piece out.
I must have accidentally picked out a piece of 300M material out of my pile of scrap metal to make the bungs out of. In the back of my mind, while I was cutting, machining and drilling the stuff, I thought the material was being kinda tough to work with. Well, after the heat from welding, they hardened up on me. Even my special set of drills burned up trying to drill through them.
Tomorrow I'll be cutting the bungs off and making up some new ones out of mild steel. I will drill and tap them BEFORE I weld them to the Y pipe.

 

[kidglok]

sometimes you gotta put down the bung and pick up the bong

 

[Alky V6]

The bungs are finished. I cut the defective nitrous bung off and welded on the new one. The EGT bung was too difficult to get to with the cutting wheel so I simply welded the new bung on top of the defective bung.
The next project will be to fabricate some brackets that I'll fit to the engine that will be used for lifting the engine. Every time I get around to taking the engine out of the car or putting it in, I have to work to remember how I rigged up the hoist hardware to the engine so it would properly balance on the chains. I want some brackets on the engine that I can go straight to without having to remove other bracketry when it's time to rig the chains.

 

[Street Lethal]

Very nice welds.

 

[Alky V6]

I figured out that the piece of metal that I originally made the bungs out of, was in fact 300M material. It was the same piece of stock that I normally use for making band anchors for the 200-4R out of. Oh well. It's fixed.

 

[kidglok]

What kind of effect on the egts can be expected while injecting nitrous?

I would guess lower because of the cooling effect? or maybe hotter because of the increased burn?

 

[Alky V6]

What kind of effect on the egts can be expected while injecting nitrous?

I would guess lower because of the cooling effect? or maybe hotter because of the increased burn?

That's an interesting question. I don't have an answer for you on the EGT, but I do know that the turbo does spool up quicker with the afterburner. Is it the increased exhaust mass? Is it an increase in EGT or a combination of both?
I don't think I'll ever have an answer to that, even with an EGT sensor right at the nozzle. The system is only on for about 1.5 seconds, maybe even less with this new engine combination, and I don't think that is enough time for my type of EGT sensing equipment to climb and stabilize at a peak temperature value.

Another interesting question is, does the afterburner mixture ignite from the help of cylinder mixture still burning in the exhaust system? Or, does it auto-ignite due to the exhaust temperature near the turbine housing?
If it does auto-ignite, what is the temperature threshold needed to get auto-ignition of the afterburner?

 

[kidglok]

Another interesting question is, does the afterburner mixture ignite from the help of cylinder mixture still burning in the exhaust system? Or, does it auto-ignite due to the exhaust temperature near the turbine housing?
If it does auto-ignite, what is the temperature threshold needed to get auto-ignition of the afterburner?

interesting, i read somewhere the auto ignition temp of nitrous oxide is 565*C (1049* F) so the exhaust should be hotter at that point

im not sure what the conditions were that determined that point, tho

 

[Alky V6]

interesting, i read somewhere the auto ignition temp of nitrous oxide is 565*C (1049* F) so the exhaust should be hotter at that point

im not sure what the conditions were that determined that point, tho

The auto-ignition point for methanol is lower than that. Nitrous auto-ignites by itself?