Twin Throttle bodies on RB20

[AlexR31]

Skyline People,

I have managed to get my hands on 2 complete RB20 ECCS manifolds and am trying to work out the best way to go in building an intake with twin throttle bodies. I need to move the throttle body to the front of the plenum to reduce heatsoak on my intercooler plumbing so.....

Which would be the better option in your opinion:

- Running two throttle bodies side by side on the front of the plenum may have to customise it a bit

- Running basically two intakes, one throttle body has runners that feed cyls 1,3,5 and the other feeds 2,4,6

- Running basically two intakes, one throttle body has runners that feed cyls 1,2,3 and the other feeds 4,5,6

Just trying to work out what would be more efficient. Would there be any dramas with additional injectors? Would I get equal air flow if I just put a fork in the intercooler plumbing before the throttle bodies?

Thanks

[Gradenko]

The 3rd option is probably the way to go, if you really want twin throttles. Myself, i'd be looking towards a custom forward facing upper manifold.

Pics of a twin throttle intake someone made for a rb25det.

[Gradenko]

Workmanship looks good.

[AlexR31]

Gradenko,

Yeah that's what I want to do. Pretty much the same as the pictures you posted but facing toward the front so I can shorten the intercooler plumbing. Will probably have to mount the throttle bodies one on top of the other so that I can fit them.

Who owns the car in the background? Any other details on it? Who did the work on the manifold?

Thanks

[Gradenko]

I don't know whose workshop it is or who owns the R30 in the background.

Are you sure mounting the tb's on front will clear accesories around it? Is there enuf space on the forward face to fit 2 tb's one above the other?

I'm hesitant to modify the factory plenum to feed from the front because its been designed to disperse air coming from the passenger side. We don't really know how much air is going to each cyliner after the factory plenum has been hacked, cylinder 5 & 6 may end up running lean in low pressure conditions. Maybe a flow test is before and after is needed just to be sure.

[AlexR31]

That's why I was thinking about running two intakes. 1 throttle body will feed cylinders 1,3,5 and the other will feed 2,4,6. If I just cut the crap out of both manifolds and have it set up like a 2JZ supra engine I think it will work OK.

I'm pretty sure I have enough room. The other option is to get somewhere like Nizpro to custom make a plenum for me.

[Gradenko]

Does the 2JZ intake look anything like the 1JZs? Feeding alternating cylinders sounds like a lot of work.

Nizpro will rip you a new one if you ask them for a plenum chamber. Have you read this thread? http://forums.skylinesaustralia.com/showth...s=&threadid=553 Theres a link in it to a guy who makes RB plenum chambers for a decent price.