Knightrous

B24
If I can get the mold sorted, I can have a manifold casted for under $500. Now who has that 3D printer..

Send me the motor for a few weeks and I'll see what I can do ;)

I could send up the manifold as the engine will be getting worked at the local machine shop. Will let you know in a few weeks.

track_mr2
They do look like a good option price wise. They look paired up though, so do you need to cut one pair to split them on each bank? For reference 6 48mm on a  3.1L were slightly bigger then necessary. The correct size for me to run would be 6 45mm throttle bodies but that was 3.1L with a single over head cam. So on a 3.5l quad cam 48mm should be about right, maybe even 50's are doable..I think you'll still find some challenges using the 4AGE setup but they will just be small things, like pedal feel through spring return rates, syncing issues etc...but I'm sure you'll be able to find solutions for them as they pop up. I have noticed some other V6 ITB kits for sale that are just above the 1k mark for things like VQ53's. Possibly one of these kits adapted to the 2GR might an option if the 4age setup doesn't pan out. 

I have contact the people selling the VQ35 throttle bodies but they do not sell anything separately so I cannot go down that path. Also not sure on the exact spec of there throttle body. From what I can gather, the tapered units are the best option. The 4AGE units are tapered but I cannot find any available at this stage. There is also the option of fitting three twin throttle bodies if I cannot find anything in the next few months.
 
Have you heard of water injection being used in NA application? It would be great to hear the plus and minus of this option.
How much fluid per hour would be a helpful figure.
Would it be best located in the plenum/air box or utilize the injector ports as the injectors will be located higher in the inlet port/ with the injector or simply add a bung to the inlet runners then fit the spray nozzle.
My car has the water injection set up from the turbo engine so if there is a gain without too much pain from using the water/methanol injection, I may give it a go.
 

Seems like we are going around in circles here with regards to what works and is good...
 
Both EFI Hardware and stock blacktop AE111 throttles will work great with this setup (AE111 have none of the issues listed in anyone else's conversions, that is the beauty of something stock) but there is a huge price difference between the two and Steve has already mentioned his budget does not extend to some brand new billet gear.
 
So moving on.
 
Water injection has been done, but it is really not necessary. A friend of mine ran this on a race bike years back. Whilst he made a extra 2 peak horsepower he also lunched the engine when one of the nozzles came loose hahaha.
 
Regardless i don't think it is worth the pain (and the weight penalty) here is a great example though. I have also added a picture of the exact measurements of the AE111 throttles behind the plate. If i find any AE111 throttles i will let you know Steve, They are definitely out there but as they are more desirable due to their larger size you will find the smaller silver top throttles in abundance.
 
 

I've never seen water injection on a  NA so can't really comment on any gains or issues but personally I wouldn't have thought it to be worth while for the effort especially considering the amount of work ahead of you for the build. What RPM are you planning to run from this engine, I'm guessing it will be spinning quiet high to warrant the ITB setup? I can give you some power figures that might be useful from my own experience. On my single OHC L28 stroked to 3.1L with 10.5 compression, mid level cam (74 degree's), port work etc...with 6 48mm throttle bodies in a  240z I was 165rwkw with a  7,000rpm redline. I could have run tuned length headers and a 78 degree cam to make closer to 200 rwkw with a 8,000 redline but I didn't want to lose my bottom end torque as the car was used on the street too. By comparison another guy fitted a RB25 with 6 45mm ITB (same EFI hardware gear), exhaust etc...and was only able to make 125rwkw, on a RB with twin cams and cross flowed head. So its not always a bolt on and gain with newer engines, I think they really need to be spinning some high rpm to get the full gains. He was quiet surprised as he changed from an 2.8litre single OHC L28 to this RB25 expecting to gain but lost out. His old engine L28 with those throttle bodies was making just under 150rwkw's.

Thanks Trav, appreciate you looking out for the throttle bodies.
Track: It certainly looks like it can be hit and miss depending on the approach of throttle bodies. There is certainly a science with how to get it right so there is a bit of work ahead.
While the throttle body is part of the build, there are a few more important aspects before they get fabricated and fitted.
Thanks again 

The biggest problem (IMO) from my observations is that when people convert to ITB's, they do not maintain sufficient length of intake runner. What this does is requires you to use higher RPM to get the same wave order as the stock intake or you end up using a lower wave order at the same RPM, which has less power potential (anything after the 5th wave is pretty marginal).
 
Example. The 4AGE 16V Bigport has runner lengths around ~450mm long before reaching the main plenum chamber, but when fitting ITB's with an adaptor, that is easily brought back to ~300mm or less. With a 480mm runner length, 7000RPM is approx the 4th wave order. If the intake runner is shortened to 320mm during the ITB conversion, this puts it on the 6th wave order at 7000rpm and you lose the performance, hence why you need to rev it harder... On the flip side, if you can get the runner to 600mm, you can get it onto the 3rd wave order at 7000rpm but you will also pick up the 5th wave order at 4200rpm.
 
Toyota did similar things with their ACIS intake design to ensure that they could have good low down torque by having long runners through a divorced chamber with a butterfly that would open up later on in the RPM, essentially shortening the runner length.
 

This is found on the 3VZ and 1MZ motors as well.
 
The other thing to consider is, just because your going to ITB's doesn't mean you have to go to an open air velocity stack design, there is plenty of performance available with a plenum design (F1 is an example).

B24
I have contact the people selling the VQ35 throttle bodies but they do not sell anything separately so I cannot go down that path. Also not sure on the exact spec of there throttle body. From what I can gather, the tapered units are the best option. The 4AGE units are tapered but I cannot find any available at this stage. There is also the option of fitting three twin throttle bodies if I cannot find anything in the next few months.

I'm not sure what your budget is and I know your keen on the black top units but these here off ebay are around $1500 delivered from a vq35.
http://www.ebay.com.au/itm/OBX-Individual-Throttle-Body-ITB-Nissan-350Z-VQ35DE-3-5L-V6-SF51-Taper-/181097852126?pt=Motors_Car_Truck_Parts_Accessories&hash=item2a2a45ecde
They are 48mm according to the add with tafer bores. Two sets of ram tubes, linkages, fuel rail and all. I don't know the specs of what the GR2 ports are like but possibly you could use this with a  new intake manifold or create a manifold to adapt this one. Again I don't know if this is in your budget or not or how much two sets of black top 48mm throttle bodies will come to with fuel rails, ram tubes and all but I would think it is camparable? I hada  hunt for those black top 48mm and yeah they seem very rare, can't find a single set let alone two.
 
 

Be careful with OBX, there have been many stories about throttles sticking with their gear. Just a FYI (looked into these myself before purchasing what i have now)
 
Here is a video of the M3's water injection. You can tell by watching this it is not ideal (pooling, splotchy spray at times, not fine enough and in general too much water) but it gives you a idea.
 
http://www.youtube.com/watch?v=EyPrYBbUB3w

don't touch obx junk. horribly made, way too much slack in linkages etc, butterflys dont seal properly and stick. they nearly caused me a nervous breakdown trying to balance.

Good to know. When I saw the price I blown away by how much cheaper it was then what it cost me to do with EFI Hardware gear, which was around 5k all up by the time I had finished. If I had to go down the path again I would have bought these on price before hearing your guys stories about it.