BenR

Nah, I read it on your first post. Thanks.

26 has 70cc chambers.

Firstly, I wasn't aware that I had to, again, justify any choice I made as to which engine I've decided to use, and I wasn't aware I had to get my sanity certified by the board of sane engine tuning representatives. I seriously dont see how its really such a travesty to yourself, as to be honest, it has nothing to do with you or your money. Why not sit back and enjoy watching someone doing something else and not following the herd. If everybody has buying 25 neos, then it would be an incredibly boring choice, and lets face it, half of the fun of building a car you own is uniqueness and character. If everybody was running clones, well, maybe you'd enjoy that. But 25 neo prices would be sky high due to demand and your cheap option would no longer be cheap. On the subject of cheap........I'm not even knocking on the door of AUS $10k yet and I've got a fully forged motor, tomei cams, custom billet cam pulleys, valve springs, a twin scroll long brand manifold, twin scroll 78mm comp wheel turbo, a RIPS custom CNC inlet manifold, an extra capacity baffled sump, external oil pump setup. Not exciting enough for you? As for the extra capacity, it would help generate more torque yes, but thats not something I require. In most race cars you are traction limited anyway, so excessive torque just breaks gearboxes, increases wheel slip angle and lower lap times. A lower torque amount but a higher usable rpm limit results in the same about of BHP usable at the wheels with less of the excessive torque. I will also never be running below 4000rpm, so I wont ever have to worry about low rpm torque. I mean, most people know that power is a function of force x distance, and if you have a large engine or a small engine, it has little effect on how much power the engine will make. All said and done and all factors equal, capacity simply shifts the torque curve. Its a prime example yourself, your car spins its wheels through 1st and 2nd, and you dont even have a lot of power. Imagine twice as much power and more traction. THe VCT system is useless to me. Its an added complication, a PITA to adjust base cam timing on the engine and a possible point of failure. The VCT system itself would not bring anything to the table for me in regards to the torque curve either, I'm beyond its usable spectrum in the rpm range. On the road, sure, its usable, but I dont need it. As far as a system goes, its pretty basic stuff and not what I really consider an even remotely sophisticated VVT system. It would actually cost me more to retain VCT on a non VCT equipped car and ECU, and have a custom cam profile ground up to run in the head. Turn that around, and an RB25DET neo engine here costs approx AUS$3000, so thats a huge wad of any budget spent on buying a base motor I would then have to build anyway as I'm not about to trust stock pistons with the 25's track record......even the neos. Comparatively, a whole RB20det costs AUS$ 650........and I didnt need one, I just picked up a Neo head for AUS $170. Overall, cost wise, power wise and purely badass wise....I've got more for less than your RB25 Neo swap. If you want to get picky. But again, why dont you simply chime in with something interesting to say to help the build rather than, ironically, being the actual troll in this thread.

*sigh*....deep breath *sigh again* My mother always told me that empty vessels make the most noise. I guess this sort of attitude is more disappointing than an enthusiastic chav who bolts every LED onto his car.......this is pure opinionated narrow-mindedness at its peak. Why is a wonderful question.....Why bother, why are you running an RB25 Neo when a 1jz.....hell, why bother with an RB at all? Tomei make virtually unbreakable oil pumps buy using toyota components, so why not just use the rest of the toyota and put in a 2jz?.........Bugger it, why bother at all, why arent you running an LS3? after all, for the money it is better. Frankly the considerations as to why someone does anything is purely down to their own working parameters. So lets start with mine. The engine will be used in race series where the class is fairly open, you cannot increase capacity......so a 2.5 or 2.5 or even 3ltr rb vs a 2ltr evo isnt fair in their eyes. When building a race engine, one that lasts, you're going to spend money irrespective. Forged rods and pistons are the same price irrespective if they go into a 2ltr or 2.5. Same goes for rods/pistons/valvetrain/MLS gaskets etc etc etc.........I have spent no more on this build then I would on any other RB. Neither is it any of your concern to worry about how much I spend, but thanks for the concern. I wont mention the custom plenum and long branch manifold I'm having made....that might completely send you over the edge. As for pushing shit up a hill. My original engine, before the crap design oil pump decided to eat itself, was making 420bhp, so as much, if not more, as your rb25 neo. With the new build it will be making circa 500-550bhp...........and that sounds crap doesnt it. The fact that my shit little 2ltr runs on average 3-4 seconds a lap faster round a comparable circuit than the 600-700 GTR's.......but maybe that says more about me than the cars. I dont even know why I'm validating my decision, I feel like I'm talking to that guy in the pub who drinks VB and thinks the 'local pub is for local people'. But anyway. VCT is useless to me in a race car..........the engine will be operating purely between 4000 and 9500rpm. Likewise, too much torque is of little use to me when I'm traction limited, so a wide powerband with a gentle torque curve is of more use. You've seen all the 900bhp racing GTR's.....they become point and squirt machines. I mean, what do you want me to say, to concur with you that its a waste of time? I personally find it great fun doing something nobody else has done. Tell you what, you might hate this as well, I build Ferrari engines for a living.........they are all of a shit design........RB them as well? Christ, I wont mention any of the totally crap historic motorsport engines I have to deal with, and the totally absurd amounts of money the owners spend on them. And I notice your on your second engine after the first one didnt work out.......could of saved yourself some money there if you did it properly the first time around. But you must be pretty warm in the winter with your own cash fire roaring away. Now why dont we agree to disagree on the merits of the project and simply enjoy the journey.

Whoops, sorry steve, didnt realise it was you posting, thought it was someone else....this forum isnt the easiest on the eye when scanning through. The det manifold will bolt straight on, but the rest of the work with IC, injectors, management etc etc.....seems just as much work to boost an installed neo as it is to hybrid a neo engine onto a det install.

Lol, if you read my post you'd see that I'm fairly up to speed with what I'm doing. I was just wondering if someone has actually boosted a neo engine and seen how much it can take for interests sake.......the japs always do weird stuff like that.

Thats probably true, but it still uses the old geometry from the single cam. Either way, its probably not the best for boost. Depends how well its made. The crank could well be able to withstand some stick, and the rods might be a wonder of engineering.......but the lean burn piston design probably wont be too effective with boost. I dont suppose some obscure garage in japan has a turbo kit for the ER34 2.0 gt?

It depends how you define reward. If its simply resultant numbers, then I could have a pretty damn good RB30 running with the costs..........but then again, how many people are running those and what sense of achievement is there is buying off the shelf? The effort I put in will hopefully be rewarded with the fact that it works and that I provided solution after solution to problems. A sense of achievement and figuring out what nobody else has done already......being first to the answer is sometimes just as fun, and providing useful information to the community. I also hope that it will go pretty fast.......haha I'm also planning for the eventuality that racing regulations will limit me to engine capacity. I dont think they changed it for any purpose such as rpm as the manifolding and cams just dont allow it. I think its more of a fact that its a parts sharing exercise with the 25 neo to reduce costs. The crank is actually the same as the earlier single cam rb20's I think.

Hi guys, I thought I'd chime in with my experience so far. My RB20DET had the oil pump fail in feb this year at its first track day, and I'd only owned it for a few weeks. This took out the crank and cam bearings, so I was looking for parts. I actually stumbled across this very thread and learnt about the neo engine and thought the head looked pretty useful (i'm an airflow junky as its what I do for a living). However they are pretty rare here so I didnt think too much of it. Anyway, found a good low mileage crank and was going to rebuild with off the shelf forged pistons and just enjoy the car. However, when I collected the crank I noticed the guy had a Neo engine under a sheet (only noticed due to the distinctive ports!), and before I knew it I was walking out with the head. I didnt take the block because it didnt have provisions for turbo feed/drain, and I had no more cash on me. And its a good thing I didnt. Its basically junk the short motor. Mains bearings - 55mm Big ends - 42mm Gudgeons - 19mm So there is zero cross compatability, and even getting bearings would be a hassle. So if you did use the whole motor, you'd have to get custom rods and pistons made as there is nothing on the shelf. You couldnt even get custom rods made with big gudgeons and 42mm little ends, and off the shelf pistons as the CR would be sky high, circa 11:1. And who knows how much boost the stock spindly rods and fancy pistons could take....and they are fancy, wish I took a photo. So, I'm half way through my build and whilst I'm enjoying the learning curve, I could of had a fully forged monster of an RB20DET by now. To answer the question, the head does bolt on........but thats about it. The gasket lines up apart from the coolant return from the manifold, and the VCT provision oilway. You can block the vct oilway easy enough though. First major problem....CR DET pistons = a super high CR and no gasket will drop the comp enough. The chambers are approx 10cc smaller and sit shallower in the head with slightly different radial valve clearance so you need to keep an eye on that. And wild cams might have clicking clearance issues between inlet and ex valves. Valve sizes are the same but use longer valves with different angle retainers and collets, so you cant swap anything over. The stock cams are junk, well not junk but even milder than DET cams, so they might spool well for a streetable turbo setup, but I'm looking for more. Luckily RB26 cams drop straight in and have the right BCD for the solid lifters. Aftermarket solid lifter cams for RB20det and 25det wont work as they have a 3mm smaller bcd. And you cant run hydro cams on solids for obvious reasons. But if your planning on revving, the shim over bucket design isnt a known quantity so I've designed a shim under bucket design to run the 29mm bcd aftermarket cams. But because of the ridiculous tip heights on the valves you need to run solid lifters from a renault on the exhaust side and solids from a ka24de or a toyota tacoma on the intakes, and you'll need 1.5mm shims on the inlet and 3mm on the exhaust. Oh, the buckets are 34mm OD compared to the 31mm for the DET. Valve springs are soft as anything with seat and nose pressures of 55lbs and 114lbs respectively.............Same size as RB25 Neo springs though so most aftermarket setups should work. You wont need too much as the lifters and valves are super light. I've found an eibach spring out of a mazda that fits and gives me 70lbs on the seat and 160lbs on the nose. Ah, I saw a thread on here about how some guy had massive wear on his exhaust buckets in his neo. Its not wear, its just a funny wear pattern that occurs because they run aluminium ex lifters with a funny coating. no idea why. So thats the valvetrain sorted. Next is manifolding. Exhaust is fine, its all common and the det manifold bolts on.....with a little elongating of the holes. The inlet is a massive problem. Stock manifold is junk, dont even look at it. DET manifold wont bolt up as the Neo uses the RB25 bolt pattern and the coolant rail return is in the rb25 location.......so you cant bolt up a 25's manifold straight either. If you get crafty with welding, well your next problem is that the ports shape doesnt match any rb25 even remotely, closest is the rb25de Neo's, but they would need porting out to size and other modifications. I had designed an adaptor plate to fir the rb20det manifold to the Neo, and it works, but pushes it out 2" so you'll have to check strut tower and master cylinder line clearance. Oh, and the manifiold sits about half an inch higher as the ports sit higher in the head to accommodate the down draught nature. Thats about the basics...... If your wondering where I'm sitting now....I've got custom pistons made with a nice design to offset the quench bias for a nice burn and 8.5:1, forged rods, setup head and custom ex and inlet manifolds being made. Single stage external oil pump to safeguard my investment (dont get me started on the inherent design flaws on the stock pump drive system), an HX35 and hopefully in a few months, a running car that will probably break my gearbox. There is more to getting it all to work, but its taken me months of research to get it all sussed as I've not had any engines to compare parts between and I'm learning RB's as I go.....talk about a steep curve! Hope this helps anybody with specific questions about the neo engine.

I'm in the middle of a decision point with my project and I'm stuck between two choices. Firstly, I'm using an RB20DE Neo head, but we'll argue that point later. It has the same valve train as the rb25 neo heads, which is the same solid lifters with shim over bucket (biscuit type), and I'll be running single coil springs with a seat pressure of 75lbs and 160lbs nose assuming 10mm lift or so. My first option is the easiest, and that is to run the original biscuit shims and chuck in a set of RB26 aftermarket cams. My main concern is if the shims being spat out and I want to see if anybody has had any experience with the neo engines at high RPM, say 8000-9000rpm. I've never had any problems with biscuits on the european tin I work on (ferrari/jag classic and historics), but tbh they dont get as much of a thraping, even the race cars. The second option is to convert to shim under bucket (top hat), which was my original plan. Simply because I thought all aftermarket solid lifter cams ran a BCD of 29mm (please remember this is my first foray into RB's) and I've only been looking at RB20/25 aftermarket cams until this point. I could run the original lifters with 29mm bcd cams if I ran a 1.5mm top hat as a packer shim, but I really dont like the idea of running both top hat and biscuit shims. To run top hats I would have to run a set of renault clio aftermarket buckets on the exhaust side and a set of supertech KA24DE lifters on the inlet side. I would then need to run approx 1.5mm thick shims on the inlet and 3mm on the exhaust. The inlet wasnt such a problem, but the exhaust shims would only have a 1.5mm skirt depth as the collet sits 2mm below the tip of the valve stem. So a shim with 3mm up top and 1.5mm location below I wasnt so sure about... This also works out incredibly expensive at over a grand for just valvetrain components, compared to a set of r32 RB26 cams from tomei/kelford etc etc. So, before I pump for the cheap option, I'd really like to know if any of the big tuners out there have ever run a neo to high outputs/rpm and spat a shim. I really dont want to spit a shim as I've got a one off engine build with custom head, adaptor plates, custom pistons, custom head gaskets, custom ex manifolds........and a spat shim would destroy that investment and make me cry quite heavily if a rogue valve went exploring around the engine. But it is over a grand cheaper.