Rb30det Neo

[Kao13]

Hey everyone, I have been researching this topic for a while and the opinions are quite mixed,

I have a built Rb30det Neo torque monster built by Lewis engines, the head has been ported out extensively and currently has 272 cams sitting in it,

I want to downgrade my camshafts to be able to retain vct,

My end goal is to produce max torque as early as possible in the rev range (max rpm 7200)

The important bit is i want to engineer the conversion so I need to keep emissions down.

Should I

A) Downgrade to poncams 252 or 260 have heard they can pass emissions test have only heard but can anyone please confirm.

B) Put standard cams back in.

Engine specs are as follows

Lewis engine rb25/30 Neo torque monster

Extensively ported with 24psi spring upgrade

8.2cr

Rips racing plenum 90mm throttle body

Sinco manifold t3 flange

Turbosmart 50mm external waste gate

Planning on

Gtx3076r

Id1000 injectors

3 inch exhaust.

Haltech Elite

I know downgrading the cams will negate the big head work but the application for the engine has changed from a drift car to a 4wd. Any opinions would be appreciated, I will put up a build topic in the future

Cheers in advance

[jangles]

You can get cams up to 272 that allow the use of VCT still.

But I'd still change them back to small ones. Going to be a mad 4wd.

[KiwiRS4T]

You can use Tomei Poncams with VCT or get your stockers reground but either way you will still get some benefit from the headwork

[Dale FZ1]

Ditch the big throttle body and run a standard one. Will give a less sudden response from closed throttle.

Run a bigger exhaust. 3.5 inch will be enough. Under a 4wd you should have plenty of room to play with.

Unless you plan on running a 1.06 turbine housing on the GTX3076, consider a turbo spec that has better match of flow between hotside and coldside. Borg Warner have some pretty good offerings and prices are very good depending on what you choose. Not physically small units, but if it's sitting in a 4wd engine bay then space isn't likely a concern.

What's the advice/recommendation from Lewis about cam spec and turbo for this application?

[Kao13]

Dale, was originally tossing up between gtx3076 with 1.06 or gtx3582 with .82 but opted for the smaller turbo.

I will have a look at the borg warner series though, and with the exhaust size I didn't want to run the 3.5 because I didn't want it to be too loud and don't think its necessary for my goal, which is not outright horsepower but good torque throught the rev range

This motor was obviously designed for a bigger turbo and with current cams was meant to have a massive midrange and top end torque

Because the application has changed I feel as though I don't want to waste the potential of the motor but at the same time be usable as a fun 4wd, the only thing that's stopping me from going all out because I want to make it street legal and engineered.

[wolverine]

Decent mufflers will take care of the noise.

[Kao13]

Definitely but it's much easier to chop a 3 inch system designed to suit the car rather then a full custom exhaust.

[wolverine]

It's easier to buy a Hyundai Excel but if you want to get the best result the first time then you have to buy the right gear.

[Kao13]

That's true, like I said though not chasing outright horsepower though, it wont hurt power output for what I am aiming for with this build.

[Skeeed3r]

Which head gasket do you use ? the rb26 one or the rb2 5one for the neo head ?

[iruvyouskyrine]

RB25/26/30

[Skeeed3r]

RB25/26/30

Thanks can i use an rb26 Head gasket with an rb25 neo head without any modify?

[iruvyouskyrine]

Yes that's not an issue.

[dave1200]

I can't understand why I don't here more discussion on this forum about twin scroll setups. If you're going the GTX3076R get it with the 1.04 Twin Scroll rear housing and get a PROPER split pulse manifold with duel wastegates etc.

I did this on my FJ20 and it runs a GT3071R with the 0.78 rear split pulse and manifold. Makes 21psi at 3500rpm and peak torque just after that yet pulls hard to make around 270rwkw. The engine is a midrange animal.

I can only imagine on the twin cam RB30 with a relatively small turbo (GTX3076R with 1.04 split pulse) You'd probably have full boost before 3000rpm and still make 320rwkw. That to me sounds like the ideal street motor. The added benefit of the proper split pulse manifolds is the improved volumetric efficiency which may negate the need for aftermarket cams at that power level all together.