Stirlsilver's Disco Ute Project

An exhaust manifold design question.
Their is a lot of debate about equal and unequal length exhaust runners. One design will give you more horsepower where the other will produce more torque.
Do these principles play any role when you are introducing a turbo?
I will admit that I have very little knowledge when it comes to fluid dynamics. Most exhaust manifolds are designed to help with the scavenging of the exhaust gasses but it looks to me that they way yours are designed that where the two front exhaust ports join that their will be a lot of turbulence introduced. But then again - does it really matter with such short runners and going into a turbo?

Keep up the good work as I am finding it all very interesting.

The idea is to get the pressure and heat to the turbo. Long runners allow more heat loss. In a normally aspirated engine you try to get the runners of a length so that at a rpm band the headers are tuned to assist with scavenging. The consensus is that short log manifolds are the better option for turboed engines.

Thanks for the questions Crash & your answers Slug. Right at the beginning I wanted to make a 4 to 1 exhaust manifold with 4 equal length short runners. But geez that would have been a nightmare for me to fabricate!! The way I see it is that at least i've used elbows in all locations on my log manifold.

I've seen some very agricultural designs in the past with reasonable performance, so at least I'm a notch up on that with my design!!

So, I've at long last managed to get my test engine back after nearly a YEAR in storage.

I wonder what people would have though following me seeing this crude assembly on a car trailer flying down the Hume Hwy.
https://www.aulro.com/afvb/images/im...15/03/1545.jpg

https://www.aulro.com/afvb/images/im...15/03/1546.jpg

I wired everything back up and by that evening I had the engine started. Very happy that everything is still working!

https://www.aulro.com/afvb/images/im...15/03/1547.jpg

The RH turbo was also mounted on to the manifold in the engine bay. And of course everything fits where it should :D
https://www.aulro.com/afvb/images/im...15/03/1548.jpg

https://www.aulro.com/afvb/images/im...15/03/1549.jpg

https://www.aulro.com/afvb/images/im...15/03/1550.jpg

Now I can get cracking on trying to get those LPG injectors working. That's going to be tricky but will be a major milestone in the project when I get there!!

Quote:

---

Originally Posted by stirlsilver

Thanks for the questions Crash & your answers Slug. Right at the beginning I wanted to make a 4 to 1 exhaust manifold with 4 equal length short runners. But geez that would have been a nightmare for me to fabricate!! The way I see it is that at least i've used elbows in all locations on my log manifold.

I've seen some very agricultural designs in the past with reasonable performance, so at least I'm a notch up on that with my design!!

---

I know this is closing the gate after the horse has bolted, and may help others, you can buy exhaust manifold / header kits that you can build yourself.

Hello everyone, I have some excellent news!! The test engine runs on the LPG Injectors!!!!! Also it was great to meet Allan (aussearcher) who was in Sydney on holidays and swung by the workshop to have a look at the build. All the best with the rest of your holiday Allan!

I still have a bit to go with respect to tuning, but today it was proven that the MegaSquirt 3 is driving the Vapour LPG Injectors perfectly!! Below are the photos from today:

Plenum removed and the old passive LPG system removed. My custom LPG nozzles (which I made by cutting down an old set of injectors) were fitted:
https://www.aulro.com/afvb/images/im...15/03/1551.jpg

https://www.aulro.com/afvb/images/im...15/03/1552.jpg

Some temporary brackets were made up to hold the injectors in position, they ended up needing to be shifted since they fouled with the intake manifold:
https://www.aulro.com/afvb/images/im...15/03/1553.jpg

https://www.aulro.com/afvb/images/im...15/03/1554.jpg

Everything plumbed up and wired up ready to go, even more of a mess of tubes & wires!!:
https://www.aulro.com/afvb/images/im...15/03/1555.jpg

https://www.aulro.com/afvb/images/im...15/03/1556.jpg

https://www.aulro.com/afvb/images/im...15/03/1557.jpg

And she was up and running!! That's Derrick who gave me a hand for the day (thanks mate):
https://www.aulro.com/afvb/images/im...15/03/1558.jpg

A short 30sec clip of the engine running. You can hear the injectors ticking away:
[ame]http://vid8.photobucket.com/albums/a16/stirlsilver/Discovery%20Build/WP_20150308_17_25_22_Pro_zpsi0llv0s3.mp4[/ame]

If the above doesn't work, surely good old YouTube will:
[ame]http://youtu.be/Jg4DBwxLdBk[/ame]

Must be very satisfying to get the engine going on gas. How are the turbos coming along?

Stirling,
Great to meet you and Derrick on Sunday and thanks for letting me interrupt a busy day.
In the flesh this is an even more impressive project than the pictures show. There is an integrity to the design (and execution) that surpasses many factory offerings. A great pity that LR did not offer a Disco Ute!
I look forward to the results of your turbo project; I have absolutely no doubt that you will achieve what you are seeking to do.
Alan

Thanks Alan, you are too kind. And sorry for the misspelling of your name!

A quick update. Starting to get some quotes to get the Plenum parts cut & fabricated. I was concerned that my original design of the plenum was way too narrow and wouldn't provide enough space for between the face of the cooler core and the trumpets inside. It would have meant that the air stream on the bottom half of the cores would have to wiggle its way between the trumpets and work its way upward before going down again. This would have had a pressure drop impact. So I've made the plenum 30mm wider on either side to address this. I

I now need to check if this is going to give me grief by clashing with the master cylinder on the right hand side... I'm starting to run out of space over there!

https://www.aulro.com/afvb/images/im...15/03/1559.jpg

https://www.aulro.com/afvb/images/im...15/03/1560.jpg

Another rather productive weekend.

First up, I was getting a little concerned that I might get a complaint from running the test engine without a silencer. The neighbour's house wasn't so far away from the workshop I was renting. Though I think I might have gone a little overboard with the size of the silencer!
https://www.aulro.com/afvb/images/im...15/03/1561.jpg

Anyway, on to more interesting things. I moved on to fabricating the dump pipes for the turbos. First of all, I did a quick trial to ensure that the bypass valve would clear the flange I had laser cut. Thankfully all looked good :)
https://www.aulro.com/afvb/images/im...15/03/1562.jpg

https://www.aulro.com/afvb/images/im...15/03/1563.jpg

Next, came the fabrication of an insert which would create a reasonably smooth path from the outlet of the turbine into the dump pipe. A lot of people leave a massive cavity so that the bypass and turbine exhaust flows through one pipe, but in my mind that is a compromise since a lot of turbulence would be present on the outlet of the turbine which would mean increased pressure and therefore less performance!
https://www.aulro.com/afvb/images/im...15/03/1564.jpg

https://www.aulro.com/afvb/images/im...15/03/1565.jpg

Welding in the insert. My TIG skills are improving :)
https://www.aulro.com/afvb/images/im...15/03/1566.jpg

Then came the fun part of checking alignments for the positioning of the elbows and splicing the elbows together. And lots of welding... All on one side of the flange which resulted in a slight bow forming on the flange. The gasket should take that up though and hopefully it will pull straight when it heats up.
https://www.aulro.com/afvb/images/im...15/03/1567.jpg

https://www.aulro.com/afvb/images/im...15/03/1568.jpg

Trial fitment in the engine bay.
https://www.aulro.com/afvb/images/im...15/03/1569.jpg

https://www.aulro.com/afvb/images/im...15/03/1570.jpg

The left hand side dump pipe was the same story, just slightly different angles.
https://www.aulro.com/afvb/images/im...15/03/1571.jpg

https://www.aulro.com/afvb/images/im...15/03/1572.jpg

Trial fit up, a little tight but it all clears :)
https://www.aulro.com/afvb/images/im...15/03/1573.jpg

I was going to finish the rest of the dump pipe, but then I realised that didn't buy any 40mm ID straight pipe for the exhaust bypass line. No idea how I'm going to get hold of such a short piece of this pipe!!
https://www.aulro.com/afvb/images/im...15/03/1574.jpg

So I moved on to the throttle bodies. These came off a couple of Holden Astra's.
https://www.aulro.com/afvb/images/im...15/03/1575.jpg

After a lot of degreaser/scrubbing and the removal of some un-necessary fittings, hey turned up quite well.

https://www.aulro.com/afvb/images/im...15/03/1576.jpg

In addition to all of the above, I did some more tweaking of MegaSquirt to try and make the engine easier to start on the LPG injectors. It has improved quite a lot but it is still pretty rough to start the engine. More work is needed. Despite my effort with the silencer, I still got a complaint from the neighbours!!

That's all for now.

shesh this is such an awesome build, loving the detail!