RB25/30 Neo clearance in 25GT-T

[NiHaoMiaoMiao]

Hey all,

I have spent the last 2 days trawling the forums for information relating to bonnet clearances or mods required for clearance in a GTT.

A lot of people had issues in R32's that required spacing the chassis and/or modifying the the bonnet brace.

Has anyone had experience with a stock GTT bonnet? I watched and read John's RB25/30 build and he had to mod his bonnet but it was an aftermarket one.

   Any information would be a god send! 

Ps. I will be trying to retain the factory manifold for ultimate low end torque. I am also using a return flow cooler so no piping over the top of the radiator fan area.

Cheers!

Daniel

[Binarydata]

Hi, sorry can't help, but was wondering if you had a done the swap yet? I've getting ready and haven't seen much in the way of this. 

[NiHaoMiaoMiao]

On 1/8/2021 at 1:12 PM, Binarydata said:

Hi, sorry can't help, but was wondering if you had a done the swap yet? I've getting ready and haven't seen much in the way of this. 

Hey mate, not yet. Build had a few delays but should be together soon! Got the bottom end assembled. Will update here for future reference 👍

Cheers!

Daniel

[Binarydata]

What are you doing for the bottom end? Are you going to use the Neo head? I've got a NEO turbo head and waiting to get a bottom end for it. Not sure if i want to go factory 30 for forged

[NiHaoMiaoMiao]

On 1/12/2021 at 8:38 PM, Binarydata said:

What are you doing for the bottom end? Are you going to use the Neo head? I've got a NEO turbo head and waiting to get a bottom end for it. Not sure if i want to go factory 30 for forged

running standard crank, forged internals (cp pistons, spool rods, acl bearings).

0.5mm bore and hone to suit pistons and the usual things to do while apart such as linish crank, grub screw crank etc.

the stock rb30 bottom end will take a beating if its in decent condition. i just went with forged as i was already there and will go for bigger power later down the track.

[robbo_rb180]

https://rbfactory.shop/collections/nissan/products/copy-of-nissan-skyline-silvia-cefiro-180sx-25mm-engine-x-member-spacer-kit

we use these for rb30 in s chassis to get clearance

[R32GTS-t RB25DET]

in my experience, throw a forward facing plenum on it - removes the excessive height of the crossover intake pipe.
cut the engine mounts (the metal ones attached to the block) down by about 15mm, still clears the crossmember (check it anyway) and lowers the engine enough that the turbo/cam gear timing cover wont hit the bonnet.

[NiHaoMiaoMiao]

Hey everyone,

Just as an update for future reference, it will foul the stock bonnet, definitely touching the cam gear cover and possibly the front corner of the intake plenum. Will look into it more and update here.

@robbo_rb180  Would I need to extend the steering column/intermediate shaft to be able to space that far down? and would there be drivability issues such as vibrations etc. from the change of geometry?

@R32GTS-t RB25DET I have fathomed that option but $1500+ for a Greddy, then cutting holes into the body for the cooler piping gives me shudders lol. Also want to retain the low-end torque that the stock plenum provides.

Would anyone have any experience of it fitting with just the resizing of the engine mount holes only and some trimming of the bonnet brace? specifically for an r34?

Thanks in advance! 

[robbo_rb180]

no issues but we have installed a aluminium spacer to replace the rubber bush.
Plazmaman plenum is the best way to retain drivability down low https://plazmaman.com/product/rb25-r33-inlet-plenum/
can also use rb30/vl engine mounts or any 40mm thick ones (cortina are ones work)

[NiHaoMiaoMiao]

Thanks for the advice @robbo_rb180.

I ended up cutting the metal brackets for the engine mounts and dropped the motor 7.5mm cold side and 6.5mm hot side. The washers on the bolts restricted how much further down I could cut without fouling them when refitting.

So far so good... just the TCS module on the throttle body touching the middle brace.

I have two options here,

1. Cut out the fouling point of the brace.

2. Run a R33 throttle body.

From reading some ancient posts on here, they are pretty much the same throttle body minus the TCS module. Of course I would be re-using the R34 TPS.

Just wanted to see if anyone has had any issues with fitting a 33 throttle body on a 34 or just yolo and go agricultural on the bracing?

Cheers,

Daniel

Edited April 4, 2021 by NiHaoMiaoMiao