Project Rb31dett. The Development Of My Open Deck Rb Engine And The Quest For More Torque!

[N1GTR]

Wow you werent kidding, thats a crappy, crappy surface

[Rolls]

What is the advantage of this over an rb30 with oversized pistons?

[GTRNUR]

Just took me an hour to read through this thread and i must say i am very, very, VERY impressed! Keen to see a dyno graph with the cam timing alterations too!!

Glad you found it interesting.

The lead dyno operator with the most skyline experience at the dyno shop I use resigned last week, so I am back to making finishing tuning changes on the street for a bit till I can warrant the time off work again. The workshop is also moving and they have to build a new dyno room which will take a month as they are also using their equipment at a local car show inside the next 2 weeks.

A car show that I have entered to do a dyno run in, provided that they bring the AWD rig along and not just 2 rollers. Since its a competition though there wont be any tuning changes. Only power runs, so I need to finish optimising best I can.

What is the advantage of this over an rb30 with oversized pistons?

Advantages:

Retains an RB26 block so no gearbox mods are required to accomodate the sump adapter plate height changes where the bell housing doesnt line up to the holes in the AWD sump.

Height increase is only 20mm, so only the power steering pump mount and the induction hoses required lengthening. The plumb back pipe needed a little massaging to allow it to clear the front HKS wastegate actuator nipple. An extended front pipe is also needed, same as you would with an RB30.

The intake plenum clears the clutch master cylinder while still retaining the booster.

No spacers are used under the cross member.

No bonnet clearance issue. Stock bonnet, stock clearances and no massaging or cutting away of the bonnet framework.

The crankshaft has an 87mm stroke with the same journel offset as a Nitto RB30 90mm crank, so strength is retained.

Retains piston oil squirters.

19mm rod journals, 22mm gudgens. Sleeved block retains cylinder wall thickness for larger bore sizes compared to boring a standard Rb30 to the same bore size without sleeving.

Piston design makes the engine non-cam interference, like a 2jz.

When the timiing belt covers are on and the factory breather system is retained the engine would pass for stock the the average person. The only thing that gives it away is the hose extension on the drivers side. The passenger side is hidden by the intake snorkel.

I think that watching the RB30/26 R34 build thats going on in this projects section will give us all a better idea of why everyone doesnt have an RB30 in their GTR. Yes it can be done. It just isn't that easy for mere mortals to achieve. Not that Im trying to market my engine (yet), but my engine design really is easy to put together and it fits close to stock.

Actual displacement is 3140cc. This spools a pair of GTRS's to 1.7kg/cm at 4500 rpm. Only a sleeved RB30 block with a custom 89mm bore will get yo more displacement, unless you shell out for a stroker crank for the RB30.

Edited September 6, 2011 by GTRNUR

[nick81xd]

Taking the 26/30 path in the 34 has certainly giving us plenty of challenges to overcome but hopefully with some careful thought we can get it not only done but fitting propely.

Your build is beyond WOW. you have put so much thought into the engine its rediculos. Big ups to LEAPING outside the box and trying something new

Edited September 6, 2011 by nick81xd

[GTRNUR]

Taking the 26/30 path in the 34 has certainly giving us plenty of challenges to overcome but hopefully with some careful thought we can get it not only done but fitting propely.

Your build is beyond WOW. you have put so much thought into the engine its rediculos. Big ups to LEAPING outside the box and trying something new

Thanks for the feedback. The satisfaction I've gotten from building this engine and overcoming all the hurdles has been a great experience for me. Every time I drive the car it puts a smile on my face.

Im sure that you will have the same experience from your 26/30 R34 build. You have a different set of hurdles to overcome to achieve the end result, but still once your behind the wheel its all worthwhile. If I were to have gone RB30 though I would have definatly gone down the Nitto 3.2 stroker crank path as well. The extra displacement makes a huge difference. Imagine an 800hp rated turbo starting to make boost at 1800 rpm and be at full boost at around 4k.

[GTRNUR]

Quick update.

Ive re-worked the tune a little further and am now squeezing in 1.75kg/cm of boost (25PSI). There seems to be a little more headroom left so I may still be able to take that to 1.8-1.85 yet. I havent had the car on the dyno again yet, but I can say it feels far stronger in top end. The last dyno session had boost dropping to ~20psi at 7000 because of a boost controler issue as well as incorrect cam timing, so with these issues fixed I am hoping it is now over 400kw to the tyres and well past 700nm.

I am entering in Cairns Auto Spectacular (2 day car show) this weekend and have registered for every event class. These are the Show and Shine, Go-woah, Motorkarna and dyno. So I will get to see what power the engine is putting out then. I am really looking forward to the go-woah most of all, as last year a stock R34 GTR set the best time by a fair margin with average tyres. So long as a local semi slick wearing 400+hp 2.3lt stroked evo 8 doesnt show up I should have virtually no competition!

[045HOW]

wicked!

keen to hear more! good luck!

[GTRNUR]

First day of Cairns Auto Spectacular has gone pretty well. I decided to go all out and setup a propper display considering I havent done this in a few years. I scored the first display spot as you walk in the front door of the pavilion, which was great because I needed the room.

No judging results as of yet, but I did speak with one of the judges and my points are apparently at champion level. I doubt i'll get it though as there are some very pretty muscle cars there as well. Time will tell on that one.

I am leading the pack in the go-woah event with a 6.1 second pass. Best speed was 80km/h so sayith the AVCR on speed recall. My next quickest pass was a 6.26, which was also the same time of the nearest competitor which was a 1000Kg fiberglass bodied blown V8.

I launched the car at 5000 rpm and had a lot of wheel spin despite the rubberised launching area. Im not sure of the length of the go-woah area, but I think its less than 100m. I'll try and find that out tomorrow.

Here's a video of the run. Ive also attached a couple of pics of my display and one of the Rat rod that is my closest competition in the go-woah.

http://www.youtube.com/watch?v=7aZZEmEcpeU

Till tomorrow!

[r33_racer]

Looking good mate! Hopefully you slam the events. Stick it to the v8 mob

[GTRNUR]

Looking good mate! Hopefully you slam the events. Stick it to the v8 mob

Thanks, and YES that is what ended up happening!

I took out the GO-Woah event and also Top Jap Import in the show and shine. If they had the AWD dyno there I'd have had that too as the highest power 6 cylinder car was a turbo'd v6 3.8 GM ute that made 380hp.

The Go-Woah was great fun again. The 39 willys got quicker and managed a 6.1 second pass, but I managed quicker too and did a 6.06 at 84km/h. Very close competition.

Had a chat to the guys running the car and aparently it weighs a lot less than 1000kg, its more like 850. Its engine was a 351 clevland with a 671 blower geared to 14psi. No idea of power though as its never been dyno'd. Probably around 600-700hp. Their fast pass was made possible by adding weight. They put the heaviest people they could find to sit in the back seat which is right over the diff.

So all in all it was an awesome weekend! First car show I've put in an effort to win in and came away with two trophies. The editor of Queensland Street Car was there and also wants to do a feature on my car in their magazine too, which should be good fun.

I've set the next goal for the engine now to be getting the final power result of something well into the 400kw range, which it is already doing but I don't have the dyno sheet in my hands yet. Its going to be a few weeks till the local workshop has their AWD dyno back together again, so this may well happen at SAU Nationals instead if there is a dyno there.

Trophie pic attached!

[r33_racer]

Great work mate. Congratulations!

[045HOW]

Congrats!

[Marko R1]

The Go-Woah was great fun again. The 39 willys got quicker and managed a 6.1 second pass, but I managed quicker too and did a 6.06 at 84km/h. Very close competition.

congratulations mate! btw, your signature image/billboard looks awesome. its a good design, has that japanese feel about it, must the colours

that 39 willys must have had some serious brakes on it & this just shows how awesome the gtr is, keeping in mind that he was carrying pretty almost half of the weight of your r34!

[GTRNUR]

congratulations mate! btw, your signature image/billboard looks awesome. its a good design, has that japanese feel about it, must the colours

Thanks, and yes the O should be suspiciously familiar to anyone that buys Nismo product!

that 39 willys must have had some serious brakes on it & this just shows how awesome the gtr is, keeping in mind that he was carrying pretty almost half of the weight of your r34!

Yes its not an original '34 rod. Awesome piece of gear it was though and it sounded amazing. Ventilated 4 wheel disc brakes helped it stop, and those rear wheels were at least 12" wide. Its probably a 9-10 second car for anyone that is brave or silly enough to try. The owner had never dragged it or even dyno'd it.

[GTRNUR]

Quick update.

Im getting ready for a drive to Sheperton VIC for SAU Nationals. Which means replacing tires (new RT615k's), brake pads (EBC Yellows) and continuing with the fine tuning of the engine. The engine is continuing to run sweet as.

And now for a little story:

My Catch Can Adventures...

(Its a long read but if you struggle with oil control its worth your while.)

Truthfully, I have had a few problems getting a breather/oil control system sorted out that actually works properly. On two occasions I had filled the catch can and created a huge mess under the bonnet to clean up. One of those occasions was after the high speed attempt down Ingham's runway, and cleaning up a huge oil mess in front of a croud of people was not a fun thing to have to do.

To try and resolve the issue I did a lot of research. Starting with looking at other people's setups, pictures on the internet etc. But none of these told me what I needed to know to make a crank case breather system that actually WORKS VERY WELL.

I also read a heap of forum topics on the subject and came across pictures of people's engines where they were running 2-3lt sized catch cans so they didnt overflow on the track. The HUGE oil catchment area stopped the over flow issue, but it didnt control the blow by issue. And I wouldn't dare think of how empty a sump would be if a catch can could hold 3lt. It seemed that nobody has a good fix.

The first atmospheric breather setup I tried was using -10 size hoses to a catch can from each cam cover, which is typical of most of the high power setups you will find pictures of. The concept is basically the same as the High Octane catch cans etc. Two big hoses and a forward mounted catch can next to, or replacing the washer bottle.

This first setup fills the catch can very quickly, and was responsible for both of the oil baths I gave the engine bay.

I finally had a break through when I had a closer look at how the factory setup works. For the most part the factory setup works ok for street cars, but struggles to keep things under control under track driving conditions. I say street cars, because when driving on the street most of the time the car isnt operating above 5000 RPM. The factory manufactured car isnt designed to operate on a race track.

The key to the factory setup is that it has a little hidden secret that makes it work. That secret is that the breather hose that connects the passenger side cam cover to the rear turbo air intake is more than just a hose. The hose contains an oil bubble breaker and oil trap.

The reason I think this has been overlooked by so many people is that the hose itself is covered with an aluminium foil heat deflector to protect it from radiated heat from the rear turbo. You can't feel the restrictor through the foil shield, but tear off the alloy heat reflector and cut the hose apart and you will find what looks like an 8mm restrictor with a wire christmas tree like attachment. This is the oil bubble breaker and oil dam.

In factory form at high RPM (and tune) the cam covers fill with airated oil which begins to bubble out the breathers. As the passenger side breather is lower than the drivers side, some oil but mostly oil bubbles will come out there first. The bubbles move up the hose and are burst by the wire christmas tree bubble burster located before the restrictor (oil dam). Oil begins to dam up against the lip on the restrictor and blow by gas can escape through the restrictor into the engines intake.

The dammed up oil can then be drawn back into the cam covers when the engine is operating under vacuum conditions and during gear shifts. The breather hose fittings on the cam covers are at 90 degrees from each other for a good reason as well. Moving oil carries momentum like any moving object. When the liquid is drawn back into the 90 degree fitting, it woild have to change direction 90 degrees twice (with the linked cam cover hose), in order to be drawn into the PCV valve. So instead as the oil enters the fitting, most of it will fall back into the cam left cover and only a very little bit of oil will ever make its way into the right side cover where it can again return to the engine.

So for moderate bursts on the street this is why the factory setup does for the most part work. Its only when your regurly reving well past 6500, and are pumping in higher boost levels most of the time (track conditions and long dyno puls), that there isnt enough vacuum conditions to pull oil back from the oil dam into the engine. What happens instead is that it overlflows into your intake.

The downward angle of the breather hose, and its oil dam volume are the limiting factors of its effectiveness. If the factory hose had only gone up as high as possible to the bonnet, and then over the top of the output pipe from the rear turbo and then into the intake it would have been a much better system.

This brings me to my revised setup. I have silver soldered two -10 fittings to replace two of the slip on hose fittings on my breathers. I have also altered the positioning of the hose fittings on both cam covers by turning them 90 degrees towards the center of the engine. This is to allow oil to drain completely out of the fittings and hoses.

Both cam covers are linked again with the factory linking hose.

The key part that makes this work is that I have inserted the wire christmas tree/oil restrictor into the passenger side hose, so that it is about 2/3 of the way in towards the strut tower brace.

Last of all, the hoses now go over the top of the strut tower brace not under it. This provides a greater downward angle for oil to gravity drain back into the engine, and also makes it harder for oil to flow forward when being pushed that way by blow by gas.

There is a few reasons this new setup works so well.

1. The restrictor in the passenger side hose means that more blow by gas will leave from the drivers side cam cover, which is higher therefore and less likely to blow oil and bubbles into the catch can. This allows more blow by gas to escape the engine before oil bubbles even begin to be pushed out the top of the engine.

2. The wire bubble breaker and oil trap in the passenger side hose serves as an oil dam, preventing oil flow and bubbles to be blown into the catch can. The -10 size hose holds much more volume of oil as well. The higher downward angle from the oil drain greatly improves drainage back to the head too.

3. The hose that links the cam covers provides additional out-of-head oil/bubble holding area, and it returns to both covers via a 90 degree connection which will cause oil to drain back into the engine.

The catch can is about a 1/2 litre in capacity. I have had this arrangement in place for 3 weeks now, and so far not a single drop of oil has made its way to the catch can. I haven't exactly been babying the car around either. 1.75kg/cm boost and frequently revving the engine to 7000ish. This 3 week period includeds 9 full power launches of the car where I revved the engine a little past 7600 (go-woah competition).

I hope someone finds this a little useful.

That is all.

[BOZ22N]

Good read

Do you have baffled cam covers or restrictors in the block?

[GTRNUR]

Good read

Do you have baffled cam covers or restrictors in the block?

Thanks, glad you got something out of it.

The spacer plate under the head has the equalivent of a a 1.5mm restrictor drilled into it for head-oil supply.

All of the head-sump oil returns are all drilled out a little, and are the same size from the top of the spacer plate through to the sump.

The cam baffels are standard.

[BOZ22N]

Thanks mate, I have been having a similar problem with mine ever since I moved the location of my catch can.

I have been thinking about using some steel wool or similar as a baffle material under the baffles.

[GTRNUR]

Thanks mate, I have been having a similar problem with mine ever since I moved the location of my catch can.

I have been thinking about using some steel wool or similar as a baffle material under the baffles.

Hard to say what kind of effect that would have.

If I were going to mess with the baffels i'd be looking closer at the mines ones to see what they've done. I'd imagine they would have tried all sorts of things before settling on their super expensive special baffels.

[Marko R1]

My catch can setup and sump was designed by robbie ward @ rips racing, he insisted on 2 return lines back to the sump and it worked very well on my 400awkw setup. The hoses were 23mm diameter by memory, massive diameter