Rb34 / 24U (Rb26 + 800Cc) - Project RB high deck engine (and related builds)

[No Crust Racing]

I've planned to buy another GT-R for a long time, and when that time comes I've planned to need to rebuild or replace the 26. Most of the time, I keep coming back to the RIPS setups, but this is far more appealing to me.

[robbo_rb180]

why the change from twins to the single?

you couldn't resolve the shuffle issue?

[GTRNUR]

why the change from twins to the single?

you couldn't resolve the shuffle issue?

Yes the shuffle was a bitch to resolve, but its not the reason for the switch. The divider in the twin turbo pipe and tuning sorted that out for the most part with the RB315. The shuffle was never gone completely, but with a lot of tuning I got it to happen lower in the rev range. It would shuffle around 1900 rpm, which was below where the engine drove for the most part. It was stable above that, and would spin both turbo's up nicely to 24lb by 3700ish. It was actually very nice to drive around town in traffic, wickedly quick even below 4500 rpm.

The real reason is that I have seen what these turbo's do on the 3.4lt 2JZ engines. The cam profile and displacement is extremely close to the 3.4lt testing that Sound Performance did with the 6266, 6466 and 6766 on a few other 2JZ's, the dyno results are all over the internet. Im sure you have seen them.

I must admit that part way through the front pipe and wastegate pipe manufacturing I was thinking twins again. It takes so long to get it right, and making a 4" system there isn't a lot of room to move.

The old twin setup would have needed to be revised as well. The dumps and front pipes were too small so I would have been after some old tomei or midori dumps and a big front pipe. Also the GTRS's would have had to be replaced with some GTX28's.

If there were to be a second reason, it would be simply because it looks bad ass! The visual impact of a high mount precision combined with how this engine sounds makes all the effort of building it worthwhile it for me.

[NYTSKY]

If there were to be a second reason, it would be simply because it looks bad ass! The visual impact of a high mount precision combined with how this engine sounds makes all the effort of building it worthwhile it for me.

This!

[GTRNUR]

Moving on...

Time came to fit the engine to the car. Much thanks goes to Lee Holman at a local workshop called SVS, as he essentially rented the use of a hoist for 2 days. This was the first time I had done a GTR engine R&R before, I usually just pay someone else to do it.

As the sump from the old engine was being used, the engine was just un-bolted and lifted off the sump. This meant no stuffing around with the front diff which was good.

When I stripped back the RB315, I removed the hot side of the engine when it was in the car. This allowed me to remove the AC Compressor from the engine and rope it to the side of the engine bay, so I didn't have to re-gas the system.

The reason it took two days was I found a couple of surprises when I remove the Exeedy Carbon clutch from the RB315. The locator dowel on the flywheel had a different size than the dowel in the back of the crankshaft A stepped dowel was made from a drill bit to correct this issue.

The initial install was done and I discovered the clutch master cylinder/greddy plenum contact issue, so the MC was just pulled out at that point. I later had some spacers laser cut from 10mm alloy to lower the k-frame a little. This gave me the clearance I needed.

[GTRNUR]

Exhaust fabrication.

I used a 3.5-4" transition from the turbo, and fabricated a 4" front pipe. The system uses v-bands for all joins, which makes removing and re-fitting it a very quick and easy process.

It was extremely helpful having the old RB315 there to mock up on, as there is only 1mm difference in height between the two engines.

As you can see, the whole exhaust is wrapped in black lagging. I haven't gotten around to it yet, but will at some stage plumb the screamers back into the front pipe with slip fit joins to the existing screamer pipes.

Edited November 8, 2013 by GTRNUR

[Shoota_77]

Beautiful work on the exhaust. Seems to step down a fair bit into the cat/decat?

Fark it's gunna sound insane with those twin gates screaming!

[GTRNUR]

Seems to step down a fair bit into the cat/decat?

I kept the pipe work close to the header at first and as far away as possible from the firewall as I have a custom crankcase breather bolted to the side of the engine block. I am using the rear turbo train as a means of venting the crankcase and pulling it into a vacuum.

[reaper]

Any photo's of the crankcase breather setup? Would be interested to see it Great work with the exhaust!

[Joshbigt62r]

Very impressive work. Full credits go out to you.

Edited November 8, 2013 by Joshbigt62r

[Tai1or Made]

My pants are as tight as that exhaust wrap.

Truestory.jpg

#twingates

[Juan_2_3]

Just a question, with all this R&D done in increasing displacement in search of increasing the 'area under the curve'.

Have you looked into developing a variable cam timing for the intake or exhaust or even both ie. vcam???

[GTRNUR]

Yes, I have an few ideas for a dynamic cam belt tensioner system that aims to reduce ignition timing variations caused by timing belt stretch at varying high engine speeds.

As a side effect of how that system works, the cam timing can be altered at various engine speeds. The challenge is fitting it in the 20m of space created in front of the engine by the spacer plate.

Its on the list of things to develop, but I have too many other projects on the go at the moment.

Also, I think less of "the area under the curve" than I do of moving the curve to the left. Some of the most fun I had with driving the previous engine were had while driving the engine at half its RPM range. Not to say that I don't love strong top end and no lag as well, but they are side effects of the displacement increase.

[No Crust Racing]

Forgive the ignorance, but is there a reason you'd rather do all of this custom, and I'm guessing costly, development rather than fit your basic 2JZ stroker? Can make the same displacement, gain variable cam timing out of the box (I thought) and cheaper?

Or do they not fit easily?

Genuine question, I'm a gtr lover, just wondering as you seem like a guy who does his homework so I'm guessing you've done the numbers.

[jangles]

Forgive the ignorance, but is there a reason you'd rather do all of this custom, and I'm guessing costly, development rather than fit your basic 2JZ stroker? Can make the same displacement, gain variable cam timing out of the box (I thought) and cheaper?

Or do they not fit easily?

Genuine question, I'm a gtr lover, just wondering as you seem like a guy who does his homework so I'm guessing you've done the numbers.

It all started with it being over 3000cc and looking stock.

Im guessing a 2JZ doesnt fit that category

[No Crust Racing]

Ok, so RB30 stroker no good?

Again, genuine question, just curious.

[GTRNUR]

Fitment is one of the main reasons I choose to develop the RB26. Retaining the AWD system with no modifications to do so is the first step in doing that.

I've never heard of someone using a 2jz in a GTR and retaining the AWD setup. It would be an interesting challenge but not one I'd want to try. It poses the same challenges as an RB30 conversion, except that the exhaust would foul on the steering as well. I've done the whole engine conversion thing before, and it just gets way too messy.

Another reason to use the RB26 block is that GTR's can undergo this modification without any need for a mod plate, and it fits a lot easier than an RB30. Also I believe that RB30's aren't able to be legally fitted to R34's in some states, as the RB30 stopped production in 1998, and the R34's are a 1999 manufactured car. Although I believe that many states have different rules regarding this too.

[jangles]

.

[No Crust Racing]

All makes sense, thanks for the explanation.

[Tyranus]

Very interesting. Wonder how a 51R/62R SPL would run on this kind of engine setup.