Stock L6 Turbo Exhaust Manifold vs N42 NA Manifold

[JSM]

I was curious if anyone has used or modified an N42 NA exhaust manifold to use as a Turbo manifold. One like this:

 

My thinking is this would make the turbo sit lower, straighten out the down pipe, get the turbine heat farther from the intake and maybe a bit better in performance?

 

Concerns turbo oil return, performance and fit. Thoughts?

[ab0z]

Seems like a lot of work for little benefit.

Your first issue will be the flange that the turbo will need to bolt to. You could fab it, but for all that work you might as well just get a turbo maifold and do a good port job, or maybe even just build a nice tubular manifold.

Not to discourage you though, let us know if you decide to try it.

[JSM]

Thanks ab0Z, anyone else?

 

Fit asside, performance gain or decrease using the N42?

[chb280z]

I have wondered this myself, maybe someone has some good ideas.

[ab0z]

Of further concern is how the exhaust exits the manifold in 2 seperate runners - I'm not sure how you're gonna adapt that to the flange on the exhaust housing of the turbo.

[Six_Shooter]

Of further concern is how the exhaust exits the manifold in 2 seperate runners - I'm not sure how you're gonna adapt that to the flange on the exhaust housing of the turbo.

 

That's easy, use a Y or "merge" pipe, to combine the exhaust pathes.

 

If the idea was to cut the existing manifold and weld a flange to it, then the septum could be removed for a distance back into the manifold, to allow all 6 cylinders to enter the turbine together.

 

I would worry about mounting the turbo too low, if the idea was to basically have the flange where it is or close to, the turbo may hang too low to get proper drain back into the oil pan.

 

Another concern is the steering shaft is right in that area, and may also interfere with turbo placement.

 

Here is a similar N/A exhaust manifold used for a turbo set-up, notice the turbo "adaptor". This was posted on e-bay a few days ago.

 

 

As far as a gain or loss is concerned I can't tell you, would be interesting to9 find out though.

[madmatt48]

The N/A manifold provided that you can get the T3 or T4 flange(rare parts) would flow much better than the stock turbine ex manifold. I find the stock L28et manifold to be quite constricted and not much space to install much larger turbines like the large T88-34D (the T4 turbo I would like to install) The N/A manifold does bring the turbo lower and will help utilize a much larger straight flow down pipe. Great potential, its quite a strong manifold too. Oil lines can be purchased in various lengths to support space away from the oil feed from the block. If I'm not successful with the turbine manifold to T4 fabrication, I may entertain a N/A manifold for a turbine in my project Z.

[steveosupremeo]

old RayJay kit for NA uses that adapter, pop up on ebay every so often.

[chb280z]

there is this place on eBay. http://stores.ebay.com/Precision-Power-Parts_Turbo-Manifold-Parts_W0QQcolZ4QQdirZ1QQfsubZ3269976QQftidZ2QQtZkm

And they have all of the flanges needed.

[ab0z]

Well if the flanges are readily available, then maybe you could turn it into a split pulse header for a twin-scroll turbo?

[Six_Shooter]

Yeah I've been trying to figure out whay the T4 or T3 flange would be rare items, I've seen those flanges offered from many companies.

[Tony D]

That's an old Crown Conversion for a 240/260Z and the tubular adapter is prone to rust out as condensate collects there after shutdown... That was from the 70's.

 

HKS and SK made nice cast adapters for N/A Turbo applications as well that last much longer. Good luck finding one of them.

 

The Stock L28ET manifold will support 500HP without much internal modification at all. The stock EuroSpec Turbo Manifold is much larger internally and generally a better piece overall (the turbo flange area is already opened up for better flow, and the runners are larger than the 1 5/8" tubular headers one 'vendor' was selling! Good luck finding one of theose as well, they are NLA new.

 

Flanges for the conversion are hardly "rare" by any stretch of the imagination. With the stock turbo manifold supporting 400HP stock, and easily supporting 500HP in slighly cleaned up form the question begs 'why?'

 

That the heat is removed is slightly overstated as the rediant surface of the larger manifold will have some effect in that area. And the almost 180 degree turn to enter the turbine will not be the greatest flow-wise, either. The conversions on N/A's shown and spoken about in my post here all were low-boost and low-horsepower applications. They worked decently for what they were, but they were not 500HP setups by a long shot. And as far a making a turbo that sits on the bottom of the flange directly so as not to disturb the flow...maybe in a RHD, but not in a North American Spec car...I'm thinking the steetring shaft as well as other items would be an issue just knowing where the stock manifold exits.

 

Turbo should still be high enough to allow for good drainage in either case. They did fine on my Crown, and the SK EFI conversion (egads, that thing used resistors on pressure switches to enrich the mixture!)

[madmatt48]

Well stated Tony D, Most of my 20 years of tuning were on right hand drive skylines R30, R31, R32, R33, Fairlady S30, S130, and Z31. Around 30 of them total in the 16 years I lived and set up many highly modified Nissans in Japan. I have very little experience with the left hand models. I have only tuned two left hand Nissans including my present 1979 280ZX made-to-be-turbo, soon to be super/turbo....A lot of work