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HybridZ

Backward turbo?


Jesse OBrien

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I realize this may be a very bad idea all-around, but I've been considering mounting my turbo backward. It should allow me to put a nice big downpipe on here (it'll be a little long though) and gives tons of room for the wastegate and flange. I'm planning to route the intake to the defrost cowl (the slats in front of the windshield) with sane ductwork so I'm not sucking up rainwater, and the intercooler lines will run behind the engine where the stock hood latch is, through the TMIC just under the hood, and around the front of the engine into the intake. Kind of like the air is running a lap around the engine. I should be able to do it with fewer harsh bends than a FMIC, and have the option to do it shaker-intercooler style.

 

The turbo certainly doesn't seem to mind:

2009-08-03%2016.42.42.jpg

 

So, thoughts, suggestions, or reasons why I'm an idiot for considering this?

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Would it work? Anything would work if you try hard enough. But when you have I/C Piping that long you tend to get less response out of the turbo since it's gotta get all that air moving and has to travel all that distance before the intake.

 

But why not, try it!

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I'm not familiar around the L series...I am on the VG though.

 

Question, can you flip the exhaust manifold around and bolt it up? Try it and take a pic :mrgreen: I have no idea, just a thought. We can do that on the VG.

 

There's an intake manifold in the way, and I'd have to drill all new mounting holes. Also, the way the exhaust manifold is cast, it has 'tabs' to mount it on that wouldn't be in the right place if it were upside-down.

 

Why would you do that on a VG?

 

Would it work? Anything would work if you try hard enough. But when you have I/C Piping that long you tend to get less response out of the turbo since it's gotta get all that air moving and has to travel all that distance before the intake.

 

But why not, try it!

 

I'll measure out the piping that I've been considering, I'm pretty sure it's equivalent to the length of a FMIC setup.

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I was thinking about a similar question. Why would the entire turbo not be centered more in general. This is my OPINION. My thought was Nissan did this for two reasons:

1. To move the heat from the turbine farther away from all the intake runners as much as possible

2. To allow for a longer J-Pipe, again for a little time for the compressed air to cool

I’m not sure the extra piping is going to make that much of a difference in the scheme of things as along as you don’t go crazy. Give it a try.

Though I do think redirecting the exhaust will be a hindrance on over all performance. You going to make it do a giant U-turn?

And you will add a bunch more heat under the entire intake system.

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Allot of turbo applications on piston aircraft engines have the compressor aft, so I don't "think" you would have a problem. As stated before, maybe turbo lag because of the length of piping? The intake worries me, how will you filter it? My Z gets lots of leaves and stuff stuck under that cowl.

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Is it ok that the turbo oil feed is on the bottom? Its pressurized so shouldnt make a difference??

 

Besides, I really dont see what your gaining. Plenty of people are running huge downpipes (4inch or more) out of the turbo on the stock mounting position. Also never seen anyone have trouble with mounting a wastegate. Depending on where you put the wastegate doing it backwards might actually make it harder. Normally with an external wastegate your able to mount it on the back of the exhaust manifold, not anymore the intake housing is in the way. I guess you can always mount it on the front of the exhaust manifold but....

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It seems to me that this setup would have pretty short IC piping with a top mount IC. I've seen some front mounts that have some really long piping. Even if it is longer, the idea that the length of pipe reduces response is mostly a myth. The amount of piping would have to be a lot to really reduce the response time unless you're running a really small turbo and/or giant intake piping. Getting the air from point A to point B really has nothing to do with response time, it's how fast the system can get up to pressure. STS turbo has been running rear mount turbos for years with awesome results and the intake piping runs the full length of the car (and usually through an IC as well). They are pretty well known for great spool up times and good throttle response. On this setup I'd be more worried about the exhaust plumbing and the heat created by it. Just my $.02

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I've been watching all the input so far, I'm going to have roughly 6' of piping, measured around the outside diameter of every piping curve. That's including the intercooler. The intercooler is rather small and the thunderbird intercooler is known for flowing well. I don't think turbo response will be adversely affected. I am concerned about exhaust heat, but I've seen a lot of really funky tubular manifold setups, and if heat soak into the intake manifold is a problem, I'll make a heat shield (might make one anyway).

 

I hadn't really thought about the oil issue. Being as new to turbos as I am, it's not something I would've known to consider. I have a second turbo now that looks like it should fit in the 'standard' layout, and I'm more concerned about getting a wastegate in there. Is there somewhere that I can get a t3 spacer with a wastegate flange on the side quickly? I've been looking around eBay for the past hour or so, and can't find anything that doesn't try to adapt a different type of turbo altogether. I just want t3 -> t3 with a wastegate flange attached to the middle.

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isnt that basically how the turbo tom setup was?

 

oil feed isnt a prob, the centre part will rotate just fine.

http://www.airpowersystems.com/g8/g8_itt.htm

the APS turbo setup linked appears to have the oil drain on the turbos lower (or level) with the bottom of the sump, so obviously the turbos can work with the oil drain under pressure.

i wonder though if the turbo's are modded specifically for that?

as for the wastegate flange, the stock manifold is cast steel, you can weld a steampipe section to it and bolt your wastegate onto that. (or just use an internally gated turbo)

 

obvioulsy its not really viable on the US Left hand drive models, but on mine (RHD), i have moved my battery, and will now use the large empty space for my pod filter. It'll be easy to box the area off, and feed cool air from a vented inspection cover.

 

edit, just another thought, the turbo probably sits too high for the stock inlet manifold to bolt on now, so maybe you'd have more of a chance with a custom built manifold?

At least then you could smoothly incorporate the wastegate flange, as well as moving the turbo forwards a bit more to allow more room around the compressor.

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so obviously the turbos can work with the oil drain under pressure.

i wonder though if the turbo's are modded specifically for that?

 

No they won't work with the drain under pressure. They must be running a small scavenger pump like STS does. This quote is from the STS web sight " The oil is then scavenged from the turbocharger via an electric oil pump which returns the oil to the engines valve cover." A simple and effective solution to low the low mounting point oiling issue.

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No they won't work with the drain under pressure. They must be running a small scavenger pump like STS does. This quote is from the STS web sight " The oil is then scavenged from the turbocharger via an electric oil pump which returns the oil to the engines valve cover." A simple and effective solution to low the low mounting point oiling issue.

 

The only reason they use the pump is because gravity cannot be used to return the oil back to the pan. Since the turbo, in this situation, still sits above the oil pan, he will not need a pump.

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The only reason they use the pump is because gravity cannot be used to return the oil back to the pan. Since the turbo, in this situation, still sits above the oil pan, he will not need a pump.

 

Will the oil even make it into the line if the line is on top of the turbo though?

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I don't think so - he HAS to turn the CHRA upside down to swap ends around....

 

The CHRA should be able to rotate 360 degrees. It's a question of whether or not the exhaust elbow that will essentially be a U-PIPE to work back towards the exhaust will be too close to any other lines like the drain or the coolant lines if any.

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The only reason they use the pump is because gravity cannot be used to return the oil back to the pan. Since the turbo, in this situation, still sits above the oil pan, he will not need a pump.

 

Agreed on the backward setup. I was just referring to the APS Audi setup that nizmozed was talking about, it must have a pump.

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