RB31.5 Street Attack Build

[4jo3]

Hello,

My motor build is coming to a close and I thought I would start a build thread to get some ideas and some input. First off, this is NOT the OS Giken 3.15L. We decided to build this motor from a bunch of different suppliers and they are mostly custom parts. The crankshaft was sent out to a shop, where stroke was increased. We also increased bore size by 0.5mm.

I'm building this car for response. I have future plans to turn this car into a time attack car but for now it will remain as a street car as I don't really want to thrash on it the first year that it is built. Don't be mistaken though, it will see track days this year but I won't push the limits as my build has many weaknesses that will be addressed in the future. I have had the car for 3 years now and it has sat in the garage / outside most of its life. I drove it for a total of 5 or 6 months, I think. It wasn't long before I decided to pull the boost restrictor and blew my rear turbo. After a year, I put upgraded turbos and replaced everything on the turbo side with upgraded parts, injectors and ecu. Well after about a week of running, the intake valveguide broke and scored the bore. So I parked the car again.

This brings me to now. I imported a bunch of rb30 blocks and the build begins. Right now, my car sits at my shop and looks like this...

[MarusGTR]

Good job on getting me stoked for your build lol

[jdms13rhd]

Hello,

The crankshaft was sent out to a shop, where stroke was increased.

Your using the std rb30 crankshaft, right?

Im always happy to see more guys with 30's. Free power!! More people should hop on that boat. Even more so for the rwd guys! Conservative people need to think out of the box

[Super_Dude]

Offset ground rb30 crank. Im excited to see how this comes along. What are you doing with bearings?

[Speeddm]

About time someone here did this. Good for you man using old V8 tricks.

[archaeic_bloke]

VERY excited to see how this turns out, If I'm ever near belleville, (which I may be in the coming months) is it cool if I shoot you a PM and arrange with you to do a write on your RB3.15 build for my blog? that would be very cool, if you're down.

[4jo3]

You are correct. Its an offset ground rb30 crank, I honestly forget what bearings we are using. We have been building this motor since October and planned it out then, so I kinda of forget. I have a good idea but I don't want to say in case I'm wrong. It will probably show up on the bill, so I could tell you then. The motor should be complete very soon, we are just waiting for the pistons to be coated, then we can put it all together again. It was all together a week ago but we had to make sure the pistons and valves wouldn't collide before we coated them otherwise it would have been a waste.

[NismoS-tune]

Your using the std rb30 crankshaft, right?

Im always happy to see more guys with 30's. Free power!! More people should hop on that boat. Even more so for the rwd guys! Conservative people need to think out of the box

I did want to go RB30 once but the extra custom work scared me off though in the end it'd be so much cheaper for the same power (but with more torque). Maybe my next engine will be an RB30... in my LHD R34 lol

[gtrjon]

i want more!!!!

[4jo3]

I went and saw my motor yesterday. It's still going to take a while. The guy who is milling my pistons for valve clearance went on vacation. Some of my motor specs have changed but it's little things like which retainers and springs we are using. It is still the 3.15L. I will post up motor specs when it is done. Rods, pistons and bearing were ordered and received along time ago.

I'm also in the works of upgrading my fuel system right now. I'm just trying to figure out details. The only thing that is for sure is there will be a surge tank, 2 - 044 external bosch pumps, custom fuel rail, and a nismo in tank pump. Plumbing is yet to be determined but there will be -8AN and -10AN lines. I'm still undecided whether I'm going to run my current injectors which are greddy 786-788s.

I have more parts on order, hopefully they will come in this week. They are nothing really big though. Just some insurance parts and some finishing stuff. Greddy oil cooler, oil cap, hicas lock out, and a bunch of gaskets and stuff.

As for other plans for the car which I will be doing are obviously hicas is coming out. It is getting a complete overhaul and everything is coming out. My power steering pump is being modified but it is more than just the normal taking the fins out. ABS is coming out. I have an N1 brake master. I haven't decided 100% but I'm thinking of relocating my battery and getting rid of the rear wiper as it is a much cleaner look. I'm also doing a wire and fuse box tuck.

[Chewy]

[NismoS-tune]

You don't need a nismo intank pump. A $100 oem pump can lift enough fuel into the surge to feed even 1000hp cars (through your 2 044s). Save that $300 for a better support mods. No kidding,

[4jo3]

I agree but I already have the nismo. I was running it last year with my upgraded turbos. Not really worth the hassle of swapping back to an oem. I have it so I will use it.

[Speeddm]

Ideally you hould put in a HV Low pressur lift pump to feed your swirl pot that way you will have way less heat in your fuel.

[archaeic_bloke]

minor details no? lol

As for other plans for the car which I will be doing are obviously hicas is coming out. It is getting a complete overhaul and everything is coming out. My power steering pump is being modified but it is more than just the normal taking the fins out. ABS is coming out. I have an N1 brake master. I haven't decided 100% but I'm thinking of relocating my battery and getting rid of the rear wiper as it is a much cleaner look. I'm also doing a wire and fuse box tuck.

I did all of that same stuff too, the wiper, the battery, wire tuck, left the fuse box tho for easy access, just put a cover on it instead...

I had a question about how you arrive at 3.15L though... did you run this through an engineering program to determine engine characteristics like Ricardo (the program) to see how the engine will run with that stroke and bore? or is it more just, you wanna try it out and see what happens? I have a friend at bombardier who designs Gulf Jet engines, Im gonna ask him if he could do a quick mock up... if there is such a thing as a quick mock up lol.