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

[GTRNUR]

Hi everyone,

I thought it was about time I did a post for my project, especially since I’ve had some great success!

Quite a few of you may have heard that I've been working on this little engine project. The goal was to develop a reliable and cheap *cough* *cough* engine that would deliver a huge amount of mid range torque where the RB26DETT's really lack it. The simplest way to do this was to add more displacement.

So as you all know how to do that right? Tomei/HKS 87x77.7mm 2.8lt stroker kits that deliver 2770cc, or an RB30 bottom end, and a whole lot of grief in fitting it under the bonnet. I didn’t want either of these options. Frankly 2.8lt isn’t enough, and RB30... I just didn’t want to go there. So I decided to go about this my own way.

My engine is based on an RB26 block but has been sleeved to increase the block's deck height, allowing me to use longer rods and a much larger crankshaft. My design has similarities to OS Giken engines, but is entirely my own design. The design is intended to be cheap to manufacture and simple to assemble. Long term I would like to be manufacturing and selling pre-assembled bottom ends (kit engines), but that’s a long way off at the moment (so please don't ask just yet). I still have a lot more R&D to do.

I have set a bunch of goals for the project and what I want to achieve with this first engine. This engine block and sleeve setup will in theory, reliably support a maximum of around 900hp(flywheel). But the goal of this engine is monster torque, not outright power. Its designed for the street, not the drag strip or to win dyno comps.

The engine must also idle like a stock RB26. In fact I want the whole engine bay to look like the engine is stock except for the strut bar will be a little closer to the engine covers (to help avoid the attention of those blue uniformed people).

I want it to have at least 1.5 times the torque of an RB26 below 3000 RPM. Transition onto boost should be at least as responsive as stock turbo’s on a standard RB26DETT. Power wise, I’m after 600hp or 450kw at the tyres.

With the exception of the rotating internals of the block, the engine is pretty standard, albeit good quality components. Nitto oil pump, N1 water, R34 Vspec 2 head, and a pair of HKS GTRS turbo’s.

The crankshaft is a customised RB30 crank which now has an 87mm stroke. It has been grub screwed to facilitate proper cleaning, and fitted with the jun oil pump drive collar. To get it to fit the 26 block the counterweights are also modified a lot so they clear the oil squirters and edges of the cylinder bores. I am using Pauter SR20 rods and some custom 87mm Wiseco forged pistons. Bearings are all ACL race series. The engine itself now displaces 3104cc. (87mmx87mm).

My spacer plate system uses a custom gasket under the plate to isolate the water passages and the oil returns from the head. I use an external feed to supply the head with oil, and machined my 1.5mm restrictor into the spacer plate. This eliminates any risk of an oil leak occurring between the block/spacer/head. I’ve used a Nitto head gasket on the top of the spacer under the head. The whole lot is clamped down with ½” ARP head studs.

I’ve assembled the engine as you would pretty much do a standard engine. No special internal material coatings, though the (wiseco’s are molly coated on the side skirts from factory). The exhaust manifolds are standard cast items but are match ported to the turbo’s. I have ceramic coated the manifolds and turbine housings internally and externally, and fitted the manifolds each with an EGT sensor system, to aid in achieving that ultimate tune. Only the power steering pump bracket has been welded to accomodate the raised deck.

I'd like to send out a huge thanks to all the pro's out there in Skyline/RB world that have let tid bits of information loose here and there, that have allowed me to piece this project together. The project has been in the works a little over 12 months now, and finally has netted some results.

VIDEO! Alive at last!

These are the results after about 15 minutes of stuffing around with basic mapping, and unfortunatly no AFR meter at the moment (its presently installed in another car ). All in all Im smiling from ear to ear!

http://www.youtube.com/watch?v=keGL6_GEShI

http://www.youtube.com/watch?v=pvO2z8NlkLk

More to come in a few months time...

Cheers,

Ian Swinkels

[N1GTR]

Very happy to see it's finally done

Be careful of the shuffle from those turbos though

Can't wait to see this in the car and boosted hard!

[XRATED]

Awsome, cant wait to see the results.

I'm digging the square bore/stroke ratio too... Even though I'm partial to my under square "revvy" japanese stroker kits.

As long as the sleeves/spacer plate stays square and true, it should be a good thing. Nice and fat in the middle, with enough capacity to all but eliminate compressor surge with the GTRS's.

Good Luck

Justin

[N1GTR]

Nice and fat in the middle, with enough capacity to all but eliminate compressor surge with the GTRS's.

Good Luck

Justin

Just a note on that, mines rb30 with 87mm pistons, and the turbos surge. Ian will need a bit more than displacement to get rid of the surge

[astrotristan]

are you for real?!

this shit is aawwesome! good work dude!

[GTRNUR]

I'm digging the square bore/stroke ratio too... Even though I'm partial to my under square "revvy" japanese stroker kits.

As long as the sleeves/spacer plate stays square and true, it should be a good thing. Nice and fat in the middle, with enough capacity to all but eliminate compressor surge with the GTRS's.

Good Luck

Justin

Yeah that is a lot of "loose opinions" around about running lowish rod ratios in motors. Everyone seems to focus on the negative aspects (or claim the opinions of other builders as their own), but like all things there are some good positive aspects as well. The main two I like is more immediate torque and vastly superior throttle response from low RPM's.

There is no chance of the spacer plate or sleeves moving at all. The plate is dowelled to the head and block with two dowels in the standard location that go through the plate and protrude from both sides(does that make sense?). The fitment into the dowels to the head and block is machined to zero thou. That combined with the plate having been drilled to fit 1/2" head studs means that even before the head went on the block the plate wouldnt move sideways at all.

The sleeves are pretty hard core as well. Realistly you'd have to blow apart a piston before you'd come close to cracking a cylinder at the top of the sleeve. In the porsche world with alloy Nikasil cylinders, they are running upwards of 140hp per cylinder with cylinder wall thicknesses of less than 0.250". The iron cylinders im using are thicker than that at the flange, and iron of course... stronger.

Whats this im hearing about turbo shuffle? Is this an issue Im going to have to contend with? Where should I read more about it?

Edited March 31, 2010 by GTRNUR

[GTRNUR]

Just a note on that, mines rb30 with 87mm pistons, and the turbos surge. Ian will need a bit more than displacement to get rid of the surge

Yeah its only 70cc larger than your engine. 35cc per turbo probably isnt going to be a vastly noticable improvement.

[r33_racer]

Nice work. Good to see its finally coming together. No doubt you will be impressed with your own efforts, I would be. The whole project is awesome. Love it!

[ezy_09s]

Interested to see the power & torque curve when its tuned GTRNUR.

[Swiper the Fox]

Yeah its only 70cc larger than your engine. 35cc per turbo probably isnt going to be a vastly noticable improvement.

you wont have shuffle...pm me if you do and want it gone.

[N1GTR]

Paul why won't he have shuffle with the same turbos and manifolds as mine?

I would throw the other manifold on but cbf with all that effort right now.

[GTRNUR]

I did a bit of research yesterday about the shuffle issue and there is a lot of theory's about why it happens. Everything from intakes, to bovs, then manifolds and the HKS balancing manifolds, which Paul got a bad result with, yet Gav (2.8Lt) got a good result with... I guess time will tell.

I have pressurised the engines cooling system now to 1.3 bar and hot run it a few more times. All good so far still, and no signs the cooling system/oil system cross contamination. Im planning on running these tests for another week or so and then will be getting an oil analysis done to be 100% sure everything is ok before putting it in the car. I still need to source some 3" (tomei or something) dump pipes for it yet.

[SABBAi]

Great project. Congrats for getting it up and running. I look forward to the results.

[robbo_rb180]

good work. can't wait to see how your other designs go.

[GTRNUR]

Update.

I performed a tear down inspection on the engine today. Much to my delight there was no visible signs of any issues with the spacer place or sleeving seals. I will be having a lab perform an analysis on an oil sample I have taken from the engine next week. With luck this will confirm there is no coolant contamination (or hidden issues with the engine).

Re-assembly will be finished tomorrow. There is still a couple more parts to source before I can fit the engine to my R34, but my confidence in the success of this project is now very high.

good work. can't wait to see how your other designs go.

Thanks Robbo, the next engine is an RB28 (2830cc from memory) built in an RB26 block. I want to run a pair of 2530's on it and set it up for ultimate response. Ive have to buy another GTR to run the engine in though, so in car testing for that engine might be quite a while off. I have too many projects on the go at the moment...

[Swiper the Fox]

I did a bit of research yesterday about the shuffle issue and there is a lot of theory's about why it happens. Everything from intakes, to bovs, then manifolds and the HKS balancing manifolds, which Paul got a bad result with, yet Gav (2.8Lt) got a good result with... I guess time will tell.

I have pressurised the engines cooling system now to 1.3 bar and hot run it a few more times. All good so far still, and no signs the cooling system/oil system cross contamination. Im planning on running these tests for another week or so and then will be getting an oil analysis done to be 100% sure everything is ok before putting it in the car. I still need to source some 3" (tomei or something) dump pipes for it yet.

I got a good result with them but i feel they 'softened' the car up a little bit.

[Cartman]

good to see its up and runnin

[stimps]

mmmmm this is indeed quite nice. I have been away from RB engines for a bit, but after having picked up an R32 and gotten the old bug back to up the power, and seeing this.....im back !

[Beer Baron]

big congratulations from me mate. I was so very pleased to get to hear it the other night. wish I could have been there in person to see it go.

hmmm, test car for the 2.8 eh? I happen to have a 32 that has sat in my garage for the best part of 2 years.... cough cough. we should talk more when the time comes.

[GTRNUR]

Thanks Mr Baron. Yes we should talk if you really are keen. The RB28 will be being assembled in about 6 months though. At the moment its just a collection of parts on the bench and I havent made a block for it yet. I've got to build an airconditioned assembly room in my new workshop before I build any more engines.

What happened to that cranky modified R34 N1 NUR engine you had built for your car? Ive seen the build pics of the headbeing ported and modified in japan at prime garage from memory.. on the here forum somewhere. Why arent you driving the car already!