Datsun Roadster Forum-311s.org

Thanks all for the advice. After discussions with the fabricator we went with 1/4" top and bottom to keep it ridgid for the gasket seal, and 1/16" for the body portion. As said earlier, I would have liked a little more space around the trumpets in every direction, but, space is tight in that engine bay.
Just have do do up some gaskets and it will be ready to go.

Your fabricator did a great job Daryl.
Look great!
Dan

Wow, really cool. Are you going to mount it directly to the head as a unit like it is now?

Thanks Dan, the fabricator was very attentive when I was explaining what I wanted and it came out exactly as I'd planned it. I was impressed with his work....and his car...a 600+ hp twin turbo V6 awd Audi.

Greg,
Yes, if it will fit in as an assembly and I can get the wrenchs on to bolt it up it'll go in all together.

Looks good Daryl!

Daryl Smith wrote: Mon Apr 26, 2021 10:37 pm Thanks Dan, the fabricator was very attentive when I was explaining what I wanted and it came out exactly as I'd planned it. I was impressed with his work....and his car...a 600+ hp twin turbo V6 awd Audi.

Greg,
Yes, if it will fit in as an assembly and I can get the wrenchs on to bolt it up it'll go in all together.

It's a really nice piece. My biggest concern will be bolting it up if you can't do it as a unit direct to the head. There's so little room between the inner fender and the box that getting a tool in there to bolt the box to the TBs may prove frustrating. I tried all kinds of box designs and that was one of the biggest barriers. How will you check airflow balance? Can you get a unisyn/snail in there? I really really hope you have answers cause you know I'm a fan and am following in your foot steps, but... I hope I'm wrong!

I think you may want a rear vent inlet / tube too

red,
Rear vent/inlet tube? Not sure what you mean there....

Greg,
Re: Balance
I was very concerned with the balance of the ITB's when split apart. Apparently it's the major part of getting a good idle with ITB's/DCOE type carbs.
With that in mind, I had a 'connector' piece (Pictures attached) made to connect the two throttle shafts after they were split apart. The single pull throttle cable also connects to this part, so no adjusting separate pull mechanisms. It was assembled fully closed, so I'm expecting they should still be balanced as came from the factory. If not, there is a connector piece to adjust/balance. The round portion of the connector piece for the throttle cable was sized to allow for the full pull of the cable when you put your foot to the floor (40 mm diameter vs 30 mm diameter of the MC).
I am concerned, tho, with the idle which I assume I will have to adjust as these are off a 600cc motorcycle. I expect for the first install to be without the airbox to adjust the idle and, if needed, balance.

Front ram air streams often have buffeting that totally hampers a smooth carb flow .
Recently on my CRF 230 I tried to improve the air flow , I wanted to see what no air filter did for performance , it's a small filter. It has a rear facing intake tube , this is pretty buried undr the seat , seems like it would be out of much air stream. It disrupted the running terribly I tried different combos of the air cleaner top but it hated it . If you look on most importcars the intake tube goes to the core support frame and it narrowed and facing down , some for moisture eleminating , I'd say your lucky if the design doesn't have problems across the power band
The carbs need to be sucking air any instance of pressure they malfunction

red,
I think I see what you are pointing to....
No ram air will be happening, although I also expect a dip or two due to resonance, possibly...not much of an intake tract to begin with, I'm just going to stick the filter on the end of the intake tube that you see in the pictures. As a 'tube' it is only a few inches long, where it is welded it is all open to the airbox. The filter will sit approximately in the space where a left side alternator would sit, maybe a bit higher. I may extend it forward and down towards the bottom left corner of the radiator, later, if I think it needs some cooler air.
Also as far as pressure, it is EFI - not carbs, so, any 'pressure' is compensated for by the computer, to a point I guess, it's not mapped out for boost. Other than a backfire, I have no reason to expect any more than atmospheric pressure according to the altitude I am driving...

My 'to do' list:
Gaskets
Drill and tap base of airbox for intake air temp sensor
Find an appropriately sized vacuum 'tube' and lines from each runner to it, and from it for the fuel pressure regulator, and manifold pressure sensor.
Modify and mount throttle cable.

I KNEW you'd have a solution! I'm glad cause I have some small idea of how this works and the time/expense involved. Next up is Tuning! I'm learning a lot, the ITB mode is working great, and I'm beginning (slowly) to understand the enrichment system and how to set parameters in Tuner Studio. Watching YouTube and reviewing data logs I'm Megalogviewer is amazing. Takes time and work though, but unlike the pre-computer days there's no guessing at what's happening... I can see it in a data log... just too cool. I look forward to sharing info and experience!