Twins on an RB25...

[Gavster]

Hey guys....im building up an S14 track car, and I recently bought an RB25. I will be running some sort of EMS and custom fab is not an issue for me whatsoever. I want excellent motor response while still having the potential of 450-550 whp. I believe I have two options...one being the classic single...something like a gt3076R on a custom mani/dp etc would make good power and I believe have good response on the RB25. My other option,(i think) is to try something like twin GT25R's or even Twin GT28R's, both with the small compressors, not hybrids...Does anyone have any experience with twins on an RB25? I was trying to decidce if the displacement was enough to provide good response with twin small BB turbos. If anyone has any ideas or thoughts, please let me know. From what I have thought of, the only real pains in the ass are going to be the downpipe LOL, and oil feed/returns...making the manifolds, IC, etc wont be a problem for me....please let me know! A look at where the motor will be living ;)
http://i62.photobucket.com/albums/h103/gkurey/IMG_1939.jpg
http://i62.photobucket.com/albums/h103/gkurey/IMG_1885.jpg

[theicecreamdan]

displacement shouldn't be an issue, its only .1 liter less than the rb26 and that has twins. IMO it wouldn't be worth the effort when there are single turbos that will make the power you want just fine.

[Gavster]

I have thought of that too...i mean i know i can make the power with a GT30xx, but for the sake of a fun project is mostly why im considering this...i love me some good fab, lol. I guess Im wondering how the response of say a GT3076R or GT30/40R might compare to that of the twin GT25R's or 28R's...if anyone can speculate..and even though its only .1 liters smaller than the 26....the head im sure cant possibly flow as well, which is a big factor is spool capability

[LB.Motoring]

hahaha your s14 looks like a shopping cart :keke: and why would you put babies on a rb25? JK :P

I would just stick to a GT30, much less effort thant running twins, and would be equal or better, the rb has so much output that it will be very responceive, becouse of the starting tourque, then the turbo so it should be fine. I also designed mine for quick responce by building a custom intake manifold




and by the looks of your set up currently I see that your going v- mount? this will also add to responce by having shorter piping, we org were going to do a vmount but there is no room in a stock bay, soon i will have a v mount something in the z, becouse of the space if i use a 4 cyc like a sr or something.



http://i5.photobucket.com/albums/y193/Drift3rx240sx/Limit%20Break/DSC00002.jpg

[steve shadows]

well if your down for the effort, twin 2871r with .64 ar turbine housing would be retarded. Especially if you get the ones with the smaller compressor housing (ie hybridynamics sells).

20 psi on 100 ictane you would be flying and power would drop off around 7000 (start to at least) but the torque and low end would be incredible..plus im interested to see it done lol

[MELLO*SOS]

Your s14 is looking nice!



RB25DETT has been done a couple times, here's one to check out:
It's not an s14 (it's a VL actually), but click the picture to see a bunch more pictures and read the guy's write up.
Sorry for the huge ass pic, this dumbass didn't know how to resize it... (and this dumbass is too lazy to resize it for him).

http://www.members.optushome.com.au/stimps/DSC00170.jpg (http://www.calaisturbo.com.au/showthread.php?t=13913)

[kouki_s14]

^^ that car is RHD, so he didnt have to deal with the downpipe issues and BMC clearance

anyways i think the single is a good way to go, twin sounds nice, but is all the extra work and money going to be worth it?

[PoorMans180SX]

Twins have a smoother response, where a big single hits harder. The only reason twins have slightly less lag is that they recieve more direct pulses, as opposed to a big single (without a tube manifold) where the exhaust pulses get all mushed together. They also recieve more heat from the shorter manifolds. Coat the manifold regardless of which setup you run.

I think it would be cool, especially if you are going to build your motor.
Nice fabrication! Are you really running V-mount on an RB? Only other one I've seen is the TEIN S15, and that motor is pushed WAY back in the firewall. Interesting, keep us updated.