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Turbo exhaust manifolds


Guest Anonymous

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Guest Anonymous

Any tips on making turbo exhaust manifolds? I don't have the skill to make manifold like I want, and various high quality header shops scare me with their rough estimates. I'm looking to mount a turbo front and center on a vg30t engine in a 240z body.

So far I've come up with solidly mounting the turbo to the engine and using bellows in the manifolds. Seems like this would greatly reduce stress on the headers and let me get away with lower quality units?

Jet hot won't coat inside of turbo manifolds because they're afraid their stuff will slag off if the metal is glowing, so I want stainless.

Suggestions?

 

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Morgan morgan@z31.com

http://carfiche.com

http://z31.com

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Morgan, what you are trying to do is the correct way to do it and I do not want to discourage you, but it will be expensive. If you have to do it, then fashion it from the way it was done in the Buick GN.

 

The picture below shows the GN in my car and hopefully you can see what I am trying to point out. The GN drivers side header sweeps down and has a crossover pipe that connects to the rear of the pass side header. The pass-side header flows forward and if you look to the left of the DP you see part of it (silver). It turns up in front of the head and the turbo sits on top of it. For bracing, you see a thin strip of metal that bolts to the side of the head but the main brace is a bracket that bolts to the turbo and the front of the head. You can see part of that bracket where the 2 bolts are securing the heat shield. Because of the VG30t wastegate design, you would need to have the turbo facing front to back so the DP faces the rear. Hope that made sense.

 

engine-right-side.jpg

 

What makes more sense is to leave the stock setup and work on making clearance. Your clearance problem will probably be the steering rod. Because of the angle of the rod, the further back the engine is placed, the more clearance you will have. However, an old hot-rod trick is to put a u-joint in the steering rod and that is what my car has. It is common practice and would cost a few bucks. The u-joint is about $60 but you would have take the rod to a machinist to have it splined. Hell of a lot cheaper than a complete set of custom manifolds. This is the mod in my car just before I installed the drivetrain.

 

HTH, Scottie

 

enginebay.jpg

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Guest Anonymous

Well, the reason for moving the turbo up front was two-fold..... it would be out of the way of the steering, and it would also allow me to eliminate the crossover pipe behind the engine and thus sit the engine another 6-8 inches further back. It would also allow the exhaust to exit through the passenger floorboard and out the passenger door, thus being easily able to have a 4 inch exhaust. It would also ease and greatly shorten intake plumbing.

Grrr. I have some pictures of a car a friend took..... said that there were 3 additional u-joints in the steering to allow the turbo to fit in with the stock manifolds. That doesn't sound like fun to me. Other option is a RHD car, but I'm not gonna pay $3500 for a suspensionless, cageless RHD body. Plus it'd just be goofy driving on the wrong side of the car smile.gif

So how do you add a u-joint like that? You just cut the shaft wherever you need the joint and have the ends splined and put it in? That doesn't seem too hard.... Do you just weld bearing supports in wherever appropriate if you have more than 2 u-joints? Where do you get u-joints? From a wrecked Z, or do you have to buy something special or what?

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Don't you need an even number of u-joints, with the same included angle at each pair (a pair being those that are adjacent in the middle, and then those next to them)?

 

I thought this was how you got the "speeds" the same at the end of the steering rod. If the angles aren't matched and the joints phased correctly, I'd think it would get a bit weird steering wise. For the angle that Scottie's car shows it's probably not a big deal that he has three joints, as the one at the firewall looks to have a very small or no angle now, so the two nearest the steering rack are probably equal angles.

 

Sorry for the rambling.

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Guest Anonymous

No. Even with 2 equiangle u-joints and phased ideally, there will still be speed variations. That's the nature of u-joints, and why CV joints were invented. Kept to a minimum I can't imagine it being noticable on steering, but with a much more rapidly spinning driveshat(or u-joint 1/2 shafts) that are tranmitting large amounts of power, even small changes are readily noticable.

 

 

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Morgan morgan@z31.com

http://carfiche.com

http://z31.com

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Guest Anonymous

I read that already... twice.... First they're using cast iron pipe, which will rust eventually. Second, that's a simple little manifold, what I would need would be much, much larger and much more complex frown.gif Moving the steering is sounding better and better, but I wish it wasn't so incredibly expensive to have nice stainless manifolds made frown.gif

 

 

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Morgan morgan@z31.com

http://carfiche.com

http://z31.com

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Pete, being the engineer, you might be correct about the number of u-joints, angles, et al, but I have noticed no difference in the steering feel and action since making the swap. Of course I reduced the front-end weight, and do not know if that has any effect on a possible difference.

 

Morgan, being a V-design engine, you cannot eliminate the crossover pipe unless you run twin turbos, which BTW, would make the manifold design simpler wink.gif but the I/C plumbing more complex. You could use 2 small stock turbos requiring smaller DPs.

 

BTW, why do you think you need a 4" exhaust?

 

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Scottie

71 240GN-Z

http://www.mindspring.com/~vscott911/gnz.html

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Guest Anonymous

Yeah, but I don't want 2 turbos. Still the issue of clearing the steering. 4 inch exhaust is just enough damnit! I want it because I can smile.gif

What was the steering shaft interfering with in your car? It makes me wonder just how much it would have to be moved, considering the nissan v6 is similar in size and configuration to a GN engine, but with the added bulk of a turbo on the side of the engine.

The car I saw pictures of(But no good pictures of the steering linkages) had the steering shaft actually running parallel to the box section of the body at the bottom of the inner fenders('frame rails' if you will). That seems like a buncha u-joints and makes me wonder about the durability of if all.

I would greatly prefer to just move the turbo, but the cost of headers really surprises me.

Another possibility, you can swap the v6 manifolds side-to-side, placing the turbo above the passenger side manifold. I wonder if it would clear the hood, and if the crossover pipe would interfere with the transmission of not.

Any new ideas? smile.gif

 

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Morgan morgan@z31.com

http://carfiche.com

http://z31.com

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If you are not in a big hurry, give me this weekend to study it by looking at a turbo engine that is out of a car. I can then take pics to help you visualize what can be done.

 

If I recall, the turbo is down low and towards the rear of the engine but the crossover pipe runs over the bellhousing. That make swapping sides difficult. This engine came in almost every mid-sized Nissan vehicle including FWD. I can see what the various exhaust manifolds look like to see if there is something factory can be used or adapted.

 

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Scottie

71 240GN-Z

http://www.mindspring.com/~vscott911/gnz.html

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Guest Anonymous

Morgan,

http://www.geocities.com/toohighpsi has a couple of cars that the builder flipped the stock NA shorty headers over. Then, he built some connecting piping to the turbos. It is for a twin turbo setup, but it might give you some ideas.

 

 

quote:

If I remember correctly the turbo sits right were the motor mount is normally on an N/A VG30 . I too have studied the VG30ET looking to throw one in place of the my N/A VG30ET .


 

Couple of years back Morgan's z31 page (and Morgan) really helped a friend of mine (and me) swap a VG30DET into his NA 300z. The amazing part is it still runs after our butchering! :-) You'll need a turbo crossmember if you're talking about putting a VG30DET into a z31.

 

Scott

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Guest Anonymous

Hmm. Problem is that all the stock manifolds exit rearwards and would require a 180deg bend to go back forwards. Grrrrrr.

I'm starting to think it's just better to move the stupid steering shaft.

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Yeah, I know about u-joint speed variation being present if there is any angle at all, even if correctly setup (same angles) and phased. But the issue is if you ask too much of them (u-joints) with lots of large angles and don't pay attention to the phasing and equal angles, you get weird monkey motion, even in steering linkage. Some of the early Cobra kit cars had this problem. Just bringing up the point as something to look out for.

 

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Pete Paraska - 73 540Z - Marathon Z Project - pparaska@home.com">pparaska@home.com -

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If I remember correctly the turbo sits right were the motor mount is normally on an N/A VG30 . I too have studied the VG30ET looking to throw one in place of the my N/A VG30ET . One possiblity is to find a good style manifold off of any different VG30 and blank the outlet off, and add a hole and flange to the side of it.

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Study the pic below. When I first saw it, it immediately came to mind that the engine could be moved back at least another 3-4 inches.

 

It is possible the person who did the swap used the original motor mount tower forcing the engine to be more forward. Note that in mine, new mount brackets were build to move the engine back. Also, it looks like they left clearance for the heater hose fitting and that could easily have been redone. Steering aside, there should be nothing at the lower rear of the engine that would cause clearance problems.

 

I would do the steering rod mod, but when you do the trial fitment, focus on getting the engine as far back as possible. Remember, the steering rod angles away from the engine the further back you go.

 

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Scottie

71 240GN-Z

http://www.mindspring.com/~vscott911/gnz.html

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Guest Anonymous

Yeah. See how much farther back the engine could go without the crossover pipe behind the engine? That's what I wanted to get rid of. That's a maxima intake manifold too, not the Z unit. It would go back at least another 6-8 inches!

But anyhow, the engine's CG is still lots farther rearwards than the L6 engine, and the enegine is lighter than the L6 engine also(but probably comprable weight with turbo and a beefier transmission). So anyhow, it's still fine, but getting rid of that crossover pipe would be sweet.

I asked Michael, he said that that car had only 3 total U joints, not 3 additional(5 total) joints like I thought at first. So if it's just adding 1 joint it's not a big deal at all.

But I still want some fancy headers. Grrrr.

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Whoa, that is some neat stuff! Really enjoyed reading about the budget buildup. A lot of thought went into that system, thats for sure.

 

Hmmm, 10 second car for under $6000. Pretty hard to beat!

 

 

 

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Drax240z

1973 240z - L28TURBO transplant on the way!

http://members.xoom.com/r_lewis/datsun.html

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