Andrew's R32 Gtr With Forged Rb30Dett Build

[dorifticon]

Hey all, just thought I'd post up a thread detailing how I have gone about modifying my r32 GTR, and some of the small tricks and things I've learned on the way. Hope it's not too boring! I had a look around and this seemed the best place to post, but by all means move if this is the wrong spot.

My starting base was an r32 GTR with not much other mods than trust front pipes, and cat-back exhausts (HKS). Lots of the usual hassles associated with grey imports, general lack of maintenance etc. My first step after getting it running in OEM-ish condition was to upgrade the turbos.

I picked up a pair of HKS 2530's from a forum member for $2300 – bargain. Included braided lines, which made installation a lot easier, and hks adjustable wastegates (meh? I don't really get these, as boost is controlled via solenoid, but whatever). But yeah, ball-bearing turbine with much larger compressor wheel and slightly larger housings. All in great condition, no shaft play or end float.

To remove and replace the turbos, I just used the procedures in the factory service manual. HOWVER, the best advice I can offer to anyone looking to remove and replace the turbos on an rb26 is to buy a set of ratcheting spanners. Mine were the locking flex-head type, and were $190.00 for a set of all the ones you'd commonly use (Kingchrome). Once you've cracked the exhaust manifold nuts with a normal spanner, these ones make it so much less frustrating to remove and replace. Since I bought them, they have paid for themselves countless times over. Just be careful lending them to your mates, you may not get them back!

[dorifticon]

My next step was the manifolds.

As most of us know, the factory cast-iron manifolds have much smaller ports on the flanges compared to the HKS turbos. I considered upgrading to stainless tubular designs, but didn't want the potential hassle of the manifolds cracking etc, so just got a die grinder and did a basic port-matching job. The manifolds had to come out anyway for the turbos, so I figured what the hell. Given the size of the lip on the manifold before, this just has to improve flow. So a "free" mod.

I considered splashing out on a set of tomei expremes or something, but I'm undecided about my long-term plans in terms of what turbo (single, high-mount twins?) so left it stock for now.

Edited June 20, 2009 by dorifticon

[dorifticon]

Then it was time to turn to the issue of dump pipes.

As you can see here, the factory dumps are very restrictive. Quite a rubbish design when you look at them, really.

I was really only upgrading these because they had to come out of the car to change the turbos anyway.

I decided to just get cheap ones of eBay – big mistake. Buying cheap dump pipes is just false economy. These were $189. The actual quality of the welding and construction etc wasn’t too bad – let’s just say they weren’t exactly manufactured to exacting tolerances…

First, the flange didn’t fit. Needed to grind it out with a die grinder (too bad if you don’t have a high-powered air grinder – dremel would not cut it). I actually checked the dumps against the OEM turbos as well as the HKS to make sure my turbo studs weren’t damaged or something, it was definitely the dump flange.

Then, the separator was removed, but the holes went right through to the other side. Had to use a high-speed steel bit to make enough of a countersink to put some screws in. Held ‘em in with high-temp loctite.

Finally, there is apparently two different thread patterns for the r32 o2 sensors – make sure you know which is which before you order yours. Of course, mine was the wrong one. Ended up brazing a suitably threaded nut onto the bung (after modifying bung with hacksaw to ensure clearance). Too bad if you don’t have an oxy…

Only just fitted in engine bay – the clearance between the front dump pipe and the rear turbo outlet is non-existent. I didn’t send them back because we didn’t realise each problem until we had fixed the last one, by which time we had modified the part extensively. In the end, the seller compensated me for the cost of parts I used, but the 10 hours or so spent modifying the damn things to fit just wasn’t worth it. If I could do it over again, and had I known the level of screwing around that would be required, I would buy some name-brand ones to begin with.

[dorifticon]

Then it was time to consider intercooler options.

As everyone on here knows, Just Jap sell cooling pro coolers in 70mm and 100mm (they have a 120 bar and plate, but they said that would be too laggy to use on the street and is for drag use only). Since the OEM is 60mm, I opted for the 100mm version. They were having a sale at the time, I got it for $399. Installation was pretty straightforward, only thing was needed was to angle grind the front reo bar (pic). The particular one I had required cutting and redrilling of the bottom mounting tabs.

As you can see, based on the sheer volume of the thing, it has to be better at cooling inlet charge than the stocker. I couldn’t notice any increase in lag, but the top-end was slightly (but noticeably) improved.

Hint: Use factory service manual for removal of front bumper bar etc. there are a couple of trickly little clips and such.

[dorifticon]

Other miscellaneous mods:

Radiator

Again, picked up a cooling pro radiator from Just Jap, 40mm (massive). I think it was between $300 and $400, not that much more than the cost of reconditioning a factory-style radiator. Turns out my OEM radiator had a snapped outlet neck, so this was written off as a maintenance cost, LOL. Although, I just was NOT able to refit my radiator shroud, the fan kept fouling on it. Oh well, might switch to thermos at some point anyway.

Fuel injectors/rail

Scored a set of 1000cc injectors off eBay for $405. It included an earls-fitted rail, but I didn’t use it. They were second hand, but when they were tested all flowed within 1 per cent of each other, so perfect. Got these fitted at the same time as I had my vipec fitted and tuned at ESP racing. At least I know this is the first and last injector upgrade I will need to do!

Fuel pump

I know the OEM pump is meant to be good for 300rwkw, but being nearly 20 years old I didn’t want to take the chance, so decided to upgrade. I was originally going to buy one of those bosch 044’s but then I read the write-up on here about what is actually required to fit them, and though ‘screw it’. I mean I have the mechanical ability to do it, just couldn’t be arsed. The tomei one was a straight bolt-in, took all of 45 mins and only cost around $500. Was worth it for the piece of mind alone.

[dorifticon]

Then it was time to think about engine management. In addition to enabling me to run my bigger injectors and more boost, the ECU upgrade will also give me a future platform for the future mods I am planning (more about those shortly.

I had my Vipec installed by ESP racing in Queanbeyan, by Glen. He did an awesome job, and found some general maintenance issues and other problems which I missed, despite all my time spent under the bonnet. But the cost of the ECU itself was $1666, and Glen charged me under a grand for tuning. There were other costs associated with replacing a blocked cat converter and fitting the injectors, supplying clips etc.

I can’t recommend ESP highly enough. I think tuning is a make-or-break kind of thing, and this tune really made the car. Better driveability, massive top-end power increase, and same fuel economy (well, it’s probably improved, because I get the same k’s to a tank even though I am driving it harder). Despite the conventional wisdom that map-based tunes and/or 1000cc injectors prevent a smooth idle, you would not be able to pick the difference from stock. As you can tell, I am well pleased.

End result was 279kw at all four wheels (dyno dynamics dyno) and a very happy customer.

[dorifticon]

Intake

My air flow meters are now redundant, so will be replacing the complex system of flanges, afms, convoluted rubber etc etc with some straight metal pipes and some pods. Welding in progress…

Now that phase I is over, I am preparing for phase II - the RB31dett conversion, with big lumpy cams, balanced forged 3.1 bottom end, and a ported head, and some other things like bigger inlet plenum and sump baffles etc. Am currrently looking at purchasing a pre-built bottom end 'off-the-shelf' and screwing the long motor together/installing myself.

[VSPEC-Boy]

with hks 2530's you should have made considerably more than 279awkw's.

Did you only run a mild tune or something?

[dorifticon]

with hks 2530's you should have made considerably more than 279awkw's.

Did you only run a mild tune or something?

It was 17psi, the theory was that the OEM cams were holding it back. This is all on 98 pump fuel. Very safe afrs. Bear in mind I have no idea what condition the bottom end etc is in - it starts and runs fine, but I haven't run a compression check on it.

I was hoping for at least 300's, and was a bit dissappointed, until I drove it

Edited June 20, 2009 by dorifticon

[Johnny]

Amazing write up mate, loved reading it and congrats on the power increase - glad you went for less boost on ur stock motor as if you went a tad more, perhaps you would only enjoy it for a week before its back in the shop again.

how are the turbos for lag? obviously not the same as stock but daily driviable?

[R324DR]

Great write up. I always enjoy a technical thread. I have to say i would have expected more power with all those mods (at least 290-300kw at 17psi). Have you considered adjustable cam gears? i think they are one of the best bang for buck modifications.

[R31Nismoid]

It was 17psi, the theory was that the OEM cams were holding it back. This is all on 98 pump fuel. Very safe afrs. Bear in mind I have no idea what condition the bottom end etc is in - it starts and runs fine, but I haven't run a compression check on it.

I was hoping for at least 300's, and was a bit dissappointed, until I drove it

Cam's are not holding you up mate. You just need a set of cam gears for one thing

Plenty of people have made 380rwkw on 20-22psi with 2530's... that's with factory R33/R34 dumps, stock cams, stock manifolds and so on as at the end of the day, the turbine housing is where the restriction is, not the manifolds/dumps.

I'm making 280rwkw on 15psi with GT-SS's which are smaller than the turbos you have... Stock dumps, cams, manifolds etc etc.

I think something is a miss to be under 300 on that level of boost, it should be closer too at the very least 330

[dorifticon]

Hey guys thanks for the positive comments.

RE: the cam gears, I have considered those, as well as dropping in some poncams. However, in phase II of my build, I will be including some pretty lumpy cams, and springs and cleaned up cylinder head, so thought I would end phase I without cams. I will be assembling a separate long motor and then swapping them out to minimise downtime and the risk of this turning into another "performance parts selloff" thread. I will also be addressing some of the other failure points, including the crank collar and oil pump. I have assembled a spare head and alloy sump/baffles already.

As for the turbo lag, I noticed no difference in response (and I was looking for it). However, I should note at the same time as I swapped the turbos, I ported the manifold flange and replaced the dumps with the higher-flowing ones, so I may have been giving lag with one hand and taking away with teh other. THe amoutn of work involved in swapping turbines ruled out back-to-back controlled testing. End of the day, they give factory-style boost response with heaps more top end. Having scrolled through teh turbo upgrade thread, most people choose 2530's, and I think there is a good reason for it.

Finally, on the power level, I am of the view that dynos are good for comparing power levels between vehicles on teh same dyno, on the same day, and that is it. I mean, I have seen claims of 300rwkw on stock turbos, and I just don't think it's feasible without significant measurement differences. Any particular dyno will give you a ballpark figure on your power level, but I don't think it's a technically sound base for comparing power levels across dynos. There could be something wrong with my motor, but as I said I am building a new one so it doesn't bother me greatly. End of the day, my afrs are good, my fuel consumption is normal, idle quality and driveability is fantastic and the top end power is completely transformed, so I am not going to fault the tune. I'm not holding my car up as something to aspire to, just an example of what can be achieved with a few basic tools and a willingness to get your hands dirty.

[R324DR]

totally agreed. all dyno's a different and atmospheric conditions are different on any given day....but there is a point at which you start thinking there is either a problem with the car or a problem with how the dyno is calibrated. i think your stated power output is over that point where you start to wonder what the hell is going on. I am just keen to see your car reach its potential and there might be something simple holding you back from a fair chunk of extra power and torque.

Once again, thanks for taking the time to do the write up. I wish i had taken photos and done a write up when i did mine.

[zonbie]

Well done on an excellent write-up dorifticon. I too enjoy a technical article, and the information you have gathered is quite informative.

Well done.......

[KuZiBrO]

Excellent write-up dorifticon, I too have a R32 GTR that is stock atm so this is very interesting article.

Good Work

[R31Nismoid]

Finally, on the power level, I am of the view that dynos are good for comparing power levels between vehicles on teh same dyno, on the same day, and that is it. I mean, I have seen claims of 300rwkw on stock turbos,

Take it down the 1/4

You should be around 126mph (going by how much power you should have @ that boost level).

If your significantly down on MPH, then i would really go looking for why/where the setup is falling over

Then you'll know if the dyno is reading horribly wrong, or its telling you there is indeed something wrong being the very low figure

[dorifticon]

With the air-flow meters now redundant, it was time to go about fabricating a new inlet system.

This achieved two purposes - eliminating the afms, as well as the flanges and concertina-like bends in the existing system of ducts, which just has to slow down air flow. We all know what they look like.

I was originally running the APEXI pod filters, but they have a specific cast adapter -flange for the r32 afms and not a normal "clamp-on" neck. So I decided to replace them with conventional pod filters and straight pipe.

My HKS 2530 turbo setup retained the existing 2.5" inlet system to the turbos. With that in mind, I decided to opt for 2.5" mandrel bends all the way through.

Materials required:

1) 4 x 2.5" mandrel 90 deg bends - mine were mild steel bends from an exhaust shop, and were about $40 each (ouch!). You may be able to score a better deal.

2) various other sections of pipe that replicate the PCV inlet, the vacuum line inlet, and the outlet to the blow-off valves.

3) 2 x air filters with 2.5" inlet neck - these were surprisingly hard to find. I went to supercheap/autobarn etc, and the vast majority of the filters had 3" necks. The rare few 2.5" necks really didn't look sufficiently large or of sufficient quality to put on a GTR that was sucking 17psi worth of air (even allowing for the fact I was using 2 of them).

After wading through the K&N filter catalogue, I eventually decided on part no. RX-4950 (refer pic). It has the best combination of filter area (the top part is open, unlike most) and compact dimensions. It is a washable, oiled filter, and the best deal I could find was AUD$280 for both of them, delivered to aust, from simpleautosports.com. I paid via paypal and they arrived at my door about a week later. These turned out to be ideal for my application.

4) you will need 3 x sections of silicone joiner (see pics), 2.5", and about 6 hose clamps.

Edited July 30, 2009 by dorifticon

[dorifticon]

Steps:

Basically I tried to replicate, as far as possible, the existing inlet system shape. The main hint here is to cut your sections of pipe slightly larger than you expect, then stickytape them together and see how they sit in the bay. Cutting is easier than joining. Keep cutting and taping, and sitting it in the bay each time, until you are happy it will fit nicely, clamp together nicely and not be too difficult to take apart. You need to have it sitting in there with the filters, because they take up a lot of space, and you need to be happy with the angle of the pipe into the filter and how it clamps on. Once you are pretty happy with the shape, TACK-WELD it together only, and dummy fit it in the engine bay - including filters, siliconer joiners, hose clamps, etc. Then try to get the bonnet closed!

It's not as easy as you think, getting everything to sit in there - especially getting the rear pipe to fit neatly under the strut brace. The front section is basically two sections of 90 deg bend joined together, but each bend is cut quite significantly to give the final shape. The rear section uses 2 full 90 deg turns, with the section closest to the turbo requiring numerous attachments to be welded/brazed in.

Once you're happy with how it all sits, weld it up. Remember to throroughly clean any swarf that might have gotten into the pipes during cutting etc before fitting - clearly you don't want that going into your turbos/engine.

By far the more difficult section is the rear turbo inlet, because it has all those attachments coming off it. Due to the varying thinness of the metals, the smaller outlets (PCV and vaccuum hose) were brazed on. It helps to heat the thicker metal first, then get an assistant to hold the attachment in place (with pliers!), then braze that on. You need to be careful to sit the PCV inlet in the right spot on the elbow so it sits under the collector pipe.

You will see I have a silicone joiner in the middle of my rear pipe. This is not *strictly* necessary - you could weld them together. However, leaving a join in there will make disassembly much easier, as you can remove the front section without removing all the PCV's etc.

Edited July 30, 2009 by dorifticon

[dorifticon]

Once it was all welded up securely, I grinded off the welds and painted it matt black. It was high-temp paint that needed heat to cure, so I cooked it in the oven at 180 deg for 15 minutes (or until golden brown, baste regularly and season to taste... LOL). It set nicely and looks pretty boring, so won't jump out during any under-bonnet inspections.

RESULTS:

Well, I wasn't expecting much, but I think there is a small improvement in response, especially with regards to turbo spool-up. There is no discernible difference in the sound. Maybe if my car was more modified, and flowing more air, it would make more of a difference?

Would be interesting to do another dyno run now with this mod - might try and organise. Would enable me to quantify the flow restriction from the afms.

Ideally, I would like to make up a heat-sheild out of alloy sheet or similar, to sit between the pods and the engine bay. Might fold up a dummy out of cardboard first and then try and make one out of sheet?

Edited July 30, 2009 by dorifticon