The 'Twin' part of TwinVL!

 

Here's some details and what I’m up to with my RB30DETT build.

I've been having problems with blow by and pumping all the oil out of the engine... I tried a dry sump setup using a a/c compressor as the scavenge pump and it worked great but couldn't keep up with the blow by.

So now I’ve made a better wet sump, higher capacity, baffled and trap doors and since I made an external pickup for the oil pump, the oil pickup sticks out the side. Also made a sump breather which is the tube with holes running down the side. I don't know how well that will work, will soon find out. And provisions for an oil cooler. The wind tray is also now bolted in.

The car has been on a major diet now the rego has ran out. Gone is the whole interior, and all the electrics, power windows, mirrors, and door locks. And I’ve finally got a race seat and harness that I cant wait to try out! I've still got a bit of deadener to chip out, but that'll be all gone soon.

I've also setup a proper crank trigger for the autronic instead of using the factory CAS that is driven off a cam. It just guarantees correct engine timing and makes a simpler trigger.

Here it is, not finished yet but working! To begin with, for anyone considering it, twin turbos are a bad idea... At least for a 'making it fit' point of view. To say it's difficult to fit, let alone manufacture is an understatement! I hope they stay there for a long time to come!
The next job for the engine is to fit a water to air intercooler, taking place of the cross over pipes currently fitted. U may notice a stepper motor on the wastegate, this wasn't strong enough so I fitted a cordless drill motor and gearbox. That worked but it needs some tuning, best thing is the autronic can do it directly!
The air splitter from the VZ V8 air box I made up from fibreglassing a wax mould, and takes the 100mm box outlet to the two 2.5" turbo intakes nicely.
The exhaust is made up of 2.5" stainless dump pipes connected to 2.5" engine pipes that join to a single 3" pipe mid way. With a single muffler at the rear. Currently it's a standard 2" muffler but will be a 3" straight through muffler as soon as I find the $$$ for it...
The Injection side of things is handled by an Autronic SM4 ECU, a truly awesome unit!

I have R33 GTR injectors fitted, fed by a slightly modified GTR fuel rail. And twin RB25 throttle bodies feeding the plenum. The bundle of wires coiled up are all spare inputs and outputs.... I'll find a use for them! I've found the SM4 to be very flexible in setup and reasonably easy to tune, although I still have no idea about some function, being a new ECU, I’m lacking in documentation...
This was my original ideas for my engine build! It hasn't gone exactly to plan..

As yet the bottom end hasn't been built but plans are for Wiseco forged pistons set at 8.5:1 compression. Using standard rods and crank. I'm looking for between 500 and 600fwhp. I bought a "N1" oil pump over the net but it turned out to be a R32 GTR pump so I got ripped off a few hundred :( I don't know if I’ll use it yet, I need to find out some real specs. Also a 8 to 10 litre sump will be fabricated.

Top end the head has had the ports cleaned up and the seals replaced. I’m also looking at replacing the valve springs as apparently the standards are fairly soft. After I get the engine running I may look at changing the cams and doing some more porting but that all depends on how she goes! The VVT will be retained with the oil feed for the front inlet cam bearing being ran externally to a tee with the oil pressure sender. For those who don't know, the valve timing is changed by either holding or releasing oil pressure in the front inlet cam bearing via a solenoid. The RB25 block has an extra oil feed to the head that the RB30 block does not. Check the pics of the fitting below.

Exhaust side two RB20 b/b turbos are mounted on custom made 1.25" steam pipe manifolds and will be ran sequential spool up (same as a supra!). This means at low revs, all 6 cylinders feed the rear turbine until max boost is seen when a valve slowly opens allowing 3 cylinders to feed the front turbo to spool it up for high rev max boost. Using these turbos, the boost is limited to around 15psi as they have ceramic turbines. At the moment, I only have the rear manifold made and the gaping hole on the outside is where the crossover pipe joins in, the single 45mm wastegate mounts on the crossover pipe.

On the other side, the inlet manifold has been cut down and a new plenum is being welded on with the runners wearing bell mouths. 2 60mm RB25 throttle bodies will be mounted on top facing over the cam covers where the custom made water to air intercooler will sit. There is a whole 80mm of room under the bonnet behind the engine breathers to fit the IC over the cam covers. She gonna be tight...

I bought this oil pump believing it was the same as used on the mighty nismo built N1 r34 GTR skyline but it is identical to one someone else bought as a standard r32 GTR pump and looking at it internally it would be lucky to be that! The only difference to the RB25DE oil pump I have is there is 1 less tooth on the gears giving it larger teeth but since there is less of them I think they would be very close in pumping volume! This engine I’m building will have a higher demand for oil than most GTR's, having to feed 2 turbos, the VVT, hydraulic lifters, and oil squirters!
Here's a comparison to the RB25DE pump. The GTR pump is on the bottom and the left in the pics.
Just a few pics of my new inlet manifold, almost finished, the plenum volume is over 7l and features bell mouthed runners. Also the injector holes have been drilled out to accept top feed o-ring injectors, with a modified GTR fuel rail. I have a set of 550 cc injectors to suit.
And it's port matched to the head. Twin RB25 throttles are positioned to connect to a top mounted water-to-air intercooler. This makes for very short inlet tract and less lag.
Most twincam head conversions I’ve seen detailed move the timing belt tensioner to above the water pump. The belt I got enabled me to leave the tensioner in the original position and just fit another tensioner in the idler position as an idler. I used a tensioner as the actual idler sits further to the left and makes the belt very tight.
The belt comes close to touching but still far enough!
And the timing covers still fit!

Timing belt details are - Gates T306
it measures 1200mm long, 8mm pitch on teeth, 150 teeth, and 23mm wide. The tooth profile isn't perfect but fits well, and being 23mm with instead of 25mm hasn't caused me a problem. I don't know what car it suits either but it is a timing belt off something!

To aid in tuning I’ve made the cam timing adjustable. The Inlet cam with VVT is adjustable from factory, except the pulley needs removal to adjust. I screwed blots in from the front and welded nuts on the rear so I can undo the locking bolts from the front, simple!
The exhaust side I lathed out the center of the pulley but left enough for it to seat on the cam. I then lathed up a disk of aluminium and drilled to fit over the pulley. Then cut 5 slotted holes and tapped holes in the pulley spokes to lock it all together. Works fine except for the lack of markings to show how much it's adjusted.
Mods to the VVT head to fit a RB30 block.

Here's some pics showing the fitting for the external oil feed to the front inlet cam bearing and Variable valve timing. They are 1/8th bsp tapered fittings to a double flared steel line. The adaptor (middle fitting) has been soldered up with a 1mm hole drilled in it to restrict oil flow as the RB25 block does.
Also the head has been welded, the original oil feed and the edge of the water gallery to match the block.
And the differences between the RB25 and RB30 head gaskets. The RB25 having the extra hole for the VVT oil feed and the water jacket restricting holes are all even as compared to the RB30 having small holes in cyl no. 1 to large holes on no. 6. I believe it is like this due to the much better designed cooling galleries on the twin cam head.
I opened up the r33 gts gear box I got just to take a look, was very impressed with the sheer size of it! It had 55,000kms on the clock of the half cut it came off, looked like new to me!