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

[OMGR33]

I love the look of a turbo

[r33_racer]

What part will you be o ringing? The head or block? If block, will it be on the top deck plate or within the wall thickness of the new sleeves?

[GTRNUR]

What part will you be o ringing? The head or block? If block, will it be on the top deck plate or within the wall thickness of the new sleeves?

In this case just the head has been o-ringed, so I can use a cheap standard head gasket and till retain the necessary seal for the power levels I am after. This is the same block and sleeves as the first version of the engine. The spacer plate has has minor changes made to it, and it still seals with just the alloy gasket and some hylomar applied to all sealing surfaces.

As of 11:30 tonight the engine is now 100% assembled again. It only needs a flywheel and it can be bolted back into the test rig and it can be started again. I may well have it running again tomorrow afternoon if my workload turns out to be light.

Cheers,

Ian

[paulR32gtr]

I may well have it running again tomorrow afternoon if my workload turns out to be light.

Make it happen Ian! I think we all can't wait to see this thing running, better yet in a car!

[GTRNUR]

Well I had a GREAT day today!

This afternoon I installed the completed engine in my test rig and fired it up. It started and ran instantly too first go too. The only issue was that I didnt have enough vacuum line to run to the ecu's MAP sensor so Ive done the first run up with TPS load sensing only. Having a map that has a 1/2 decent tune in it made the whole experience a lot better too.

The engine has been run to 85 degrees with an un-pressurised cooling system, and then shut down. It will cool down overnight, after which I drain the cooling system, remove the cam covers and release and re-torque the head studs. Then it will get an oil change and its ready for more testing.

I still need to source a pair of Tomei or HPC 3" dumps, so installing it in the car is stil a little ways off. I'll be waiting till after my accountant does my end of financial year tax return unless I have a few well paying jobs come up. With any luck what I dont have to pay the government will put dump pipes on the engine, and the engine in the car.

Final specs of the version 2 engine are:

87mm stroke , modified RB30 crank (I used the version 1 crankshaft instead of the larger one I was considering)

87.5mm CP pistons, 22m gudgens, flat tops with valve pockets, so the engine is now non-interference

Pauter SR20DET Rods

Tomei oil pump

ACL race series main and big end bearings

1/2" ARP head studs

O-ringed R34 GTR vspec2 head, standard cams, tomei gaskets on the intake, greddy on the exhaust.

Standard head gasket - around 8.5:1 compression

20mm spacer plate

1.6:1 rod ratio

3.147cc - Close enough to call it an RB315DETT.

And here's the video. Excuse the quality again. I have had to use a digital camera in video mode for this as I cant download footage off my DV camera at the moment.

http://www.youtube.com/watch?v=bZsbzUO0fm8

Crappy video quality aside, I think its going to be a bit of a beast. No more being dragged off from the lights by toyota prius taxies! The rate the motor gets revs from barely cracking the throttle is inspirational. Its exactly what I have been hoping for.

Cheers,

Ian

[r33_racer]

Excellent achievement! Cant wait to see this thing in the car and and putting ponies to the ground! No doubt you will enjoy it even more when its doing so!

Did you use stainless or copper wire? Also was it the 1mm(.041") stuff?

Edited June 25, 2010 by r33_racer

[GTRNUR]

I used 0.8mm stainless wire. The ring slot in the head is 18thou deep leaving around 14 thou of the ring exposed. The sleeves in the engine are a little taller than the spacer plate too which has the same effect o-ringing.

Time will tell if this is the correct sort of setup. There isnt a lot of information around on how to do this sort of thing, especially for a skyline engine. Those in the industry with the actual knowledge keep it a well guarded secret too.

[r33_racer]

I believe its based off of how thick your headgasket is. Protrusion needs to be about 25% of the headgasket thickness.

Try this info. It may help.

Going by that i guess max is .012". Im not sure if it is different for doing the head instead of block. Being stainless and head alloy, maybe the head groove can distort or compress once all torqued down???

Edited June 26, 2010 by r33_racer

[GTRNUR]

I hadn't come across that information but it confirms im on track with a 0.060" head gasket and around 14-18 thou protrusion.

The data I came accorss for plain copper head gaskets is different again. They recommend 10% of the gasket thickness as the protusion clearance, as the copper doesnt compress like a conventional gasket does.

The head stud re-torque has now been done, and I have hot run the engine a few more times. After re-setting the ignition timing (which was out 10 degrees) and adding a little extra fuel in the idle cells on the fuel map the engine is now purring sweetly at 875-900 rpm.

I really like the tomei oil pump too and how it delivers good flow at low rpm. Idling at 875 rpm it sits on about 40psi and at 2000 rpm which will be the (optimal cruise rpm) it jumps to 75psi. I wanted more oil pressure lower in the rev range, to help the engine tolerate two negative aspects of the shorter rod ratio. That being rod bearing side loads and pistons rocking in the bores.

So I've run the rod bearing clearences towards the loose end of the recommended scale, so that combined with the extra pressure at low speeds should deliver good oil flow at the bearings keeping them nicely cool and safe. The higher oil pressure will also have the oil squirters working earlier in the rev range, helping lubricating the cylinder bores well as well as cooling the pistons better.

Thats all for now.

Ian

[cribba31]

done some research, good luck with it all

[thestig75]

done some research, good luck with it all

Hi mate , this by far the most interesting project i came across on RB engine. i was glued to the screen and read all your Rb31dett projects up to page 4 without blinking my eyes . The engineering you put up here was really awesome..i wish more to come ...the sooner the better..by the way since the topic is Rb31dett projects, anychance I can learn from you how to put in the same beast into my cefiro A31? Juz a thought mate.... A31 ceffy with Rb31 engine...is a good rhyme...ha..ha..can produce a chemical romance...

u take care and god bless.....

cheers

thestig75

[GTRNUR]

Finally, a good quality HD video.

http://www.youtube.com/watch?v=oFQG4KibJLw

[Willis]

Love your work GTRNUR, will be following this one closely!

[drag-on silvia]

come on ian, your leaving us hanging

[GTRNUR]

Sorry I haven't made any more significant progress with the engine lately, although I can report that the engine is still surviving on the test rig with the periodic testing that I've been doing.

I have been periodically heat cycling the engine while pressurising the cooling system to try and force another coolant leak. The spacer plate and head gasket are continuing to hold their seal so far. So my confidence is high.

I haven't been able to move forward with instaling in my car because Ive been left carrying a bag of debt thanks to one of my clients having had had their accounts frozen and receivers and managers are appointed. So money I had put aside to get the engine into the car has had to go to paying my outstanding accounts. These are the joys of running your own business. I hope to be back on track again in a couple of months.

[Gunzla]

I know you said your not ready for production as there is still alot of testing u need to do to get ur design perfect.

In the future when you do sell these motors is the design going to be set in concrete or will u be able to change things

such as better pistons, different rods. i know its probably not going to be an ideal way of supplying these motors as the testing

was done with different parts, but if measurements are the same there shouldnt be any problems.

I'm definitively no expert when it comes to putting engines together but im so impressed with what you have achieved so far.

I hope you continue your work as you probably already have many people out there wanting to buy one.

One more thing, would it be ok to go with 2560 -5s for even better response or would they just be too small. I have them on my 26 now and

really like them. But, i just cant get how they would be with a 3 lt plus engine. Dont think many cars besides mabye Lambos(if that!) could keep up with a

gtr with your engine in it.

Damn its gonna be fast from point to point!!

[GTRNUR]

I know you said your not ready for production as there is still alot of testing u need to do to get ur design perfect.

In the future when you do sell these motors is the design going to be set in concrete or will u be able to change things

such as better pistons, different rods. i know its probably not going to be an ideal way of supplying these motors as the testing

was done with different parts, but if measurements are the same there shouldnt be any problems.

I'm definitively no expert when it comes to putting engines together but im so impressed with what you have achieved so far.

I hope you continue your work as you probably already have many people out there wanting to buy one.

One more thing, would it be ok to go with 2560 -5s for even better response or would they just be too small. I have them on my 26 now and

really like them. But, i just cant get how they would be with a 3 lt plus engine. Dont think many cars besides mabye Lambos(if that!) could keep up with a

gtr with your engine in it.

Damn its gonna be fast from point to point!!

My thoughts on the future possabilities for selling these bottoms ends would be that I would setup all the blocks the same, using the same sleeve configuration, same 20mm spacer plate, head sealing system etc. Then customers could choose to run whatever sized crank in the block they wanted, and set a 0 deck height by choosing pistons with the appropriate pin height. You can run 2.9lt to 3.2lt in the same block just by choosing different internal combinations. There are a lot of off the shelf pistons that will suit the applicaiton too, so you don't have to go custom (expensive).

I have a version 3 engine in the works at the moment that aims to be a much simpler and cheaper engine to put together. Ive gone with 10mm flanged sleeves that are keyed to fit each other, so it will support the gasket better around each cylinder and more importantly have much more room for a stainless steel o-ring to be fitted to the top of the sleeve. The goal is to make the engines cheaper to assemble yet just as strong and reliable. You cant beat a stock head gasket for sealing and they are cheap as chips.

Ive changed the spacer plate to aluminium as it is vastly cheaper to machine than mild steel. Cutting the mild steel spacer plates with a CNC waterjet cutter has cost $1100 each so far. Switching to aluminium makes this much cheaper as the softer material waterjet cuts a lot faster. Also, some machine shops are not able to surface mild steel, and can only surface cast iron (engine blocks) and aluminium as the material is softer. Aluminium opens up more posabilities to allow component fabrication to be cheaper.

Im pretty sure that putting 2560-5's on a 3.1lt would definatly have them choking for flow around the 6000 rpm mark. There have been quite a few people that have used them on RB30DETT's, and the general concensis is that they are too small for the volume of gas the 30 pumps.

Racepace reportadly use the same turbo's on their 2.9lt engine (search for RPMGTR, RB29 wow thread).. As many suspect, that car has a lot more going on under the bonnet than just a few extra CC's to achieve the results they do with it. Amaters like me cant hope to achieve anything like the results of Racepace do, due to their years of tuning experience. I'll just settle for the caveman approach to tuning and say BIGGER is better, and then by a ported cylinder head from Red R Racing.

[TiTAN]

Im pretty sure that putting 2560-5's on a 3.1lt would definatly have them choking for flow around the 6000 rpm mark. There have been quite a few people that have used them on RB30DETT's, and the general concensis is that they are too small for the volume of gas the 30 pumps.

Racepace reportadly use the same turbo's on their 2.9lt engine (search for RPMGTR, RB29 wow thread).. As many suspect, that car has a lot more going on under the bonnet than just a few extra CC's to achieve the results they do with it. Amaters like me cant hope to achieve anything like the results of Racepace do, due to their years of tuning experience. I'll just settle for the caveman approach to tuning and say BIGGER is better, and then by a ported cylinder head from Red R Racing.

i would disagree with the -5 turbos being too small for a 3L, the high octane R34 is running them to great effect and would be the setup i would use had i had a GTR (My gtst is running a 3L with a 3582 and gives ok response for around town and easily enough flow to spin it up to my 7500rpm limit, the -5's offer even more flow than the GT35 does, though acceptable response varies greatly with the user).

i feel the -7/-9 turbos would be the bare minimum you should go for with the 3L (or slightly larger capacity setups), as they have similar flow to a GT3076 which is about as small as you can go without choking the top end and should keep making power to 8000rpm if you want to spin it that hard

Too small is the stock RB25 turbo, it falls over badly at ~5000-5500rpm, any stock RB26 setup should actually cope with the 3L without creating massive backpressure though sticking the stock 26 setup on a fresh 3L+ engine is hardly worth the trouble.

[Marko R1]

i get awesome response with -10s on a rb26/30, much better top end than -5s so for me its a double wammie winner

[N1GTR]

i would disagree with the -5 turbos being too small for a 3L, the high octane R34 is running them to great effect and would be the setup i would use had i had a GTR (My gtst is running a 3L with a 3582 and gives ok response for around town and easily enough flow to spin it up to my 7500rpm limit, the -5's offer even more flow than the GT35 does, though acceptable response varies greatly with the user).

i feel the -7/-9 turbos would be the bare minimum you should go for with the 3L (or slightly larger capacity setups), as they have similar flow to a GT3076 which is about as small as you can go without choking the top end and should keep making power to 8000rpm if you want to spin it that hard

Too small is the stock RB25 turbo, it falls over badly at ~5000-5500rpm, any stock RB26 setup should actually cope with the 3L without creating massive backpressure though sticking the stock 26 setup on a fresh 3L+ engine is hardly worth the trouble.

5's and 7's yes, 9's no

Ever driven a stock supra twin turbo? Im certain 9's on a 3L would feel the same, its too responsive and feels like it seriously lacks top end

7's, build rb26/30 with 260 cams and lots of boost. Try catching that on a hillclimb!