Rb20 Neo

[StevenCJR31]

Fuel economy between a 2.0 and a 2.5 RB? Really? Buy a Fkn push bike.

buy a fkn push bike??

why dont you come to WA and pay what we pay for fuel and you will soon get your big ass on a bike

[666DAN]

They have cool sounding technology fitted....like a' lean burn head' with plasma swirl jets!

This all translates into ULEV and that's about it really

[StevenCJR31]

wonder if the stud pattern on the head bolts etc are the same as a 32 RB20DET ?

would make for a good RB20DET/RB20DE neo hybrid

[BlueRB240]

I had a chance to get a RB20 neo head a while back but passed on it because I wasn't sure if my Tomei cams would work in that new head. Wished I would have just beat the guy down on the price and got it. The ports look bigger and closer to the RB25.

[StevenCJR31]

Sounds like like these motors mite be v good to use. . With a slight drop in compression they would be good to turbo. . Good port size,vct etc.have look on a few engine impoters web sites but havnt sen any listed as yet

[migs]

So will the head work on a det block?

[BenR]

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.

[GTSBoy]

Sounds like the correct answer is the first one that comes to mind on this topic! Which is "25DET Neo" engine swap. It's hard to believe that all your effort will be sufficiently rewarded.

[StevenCJR31]

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.

thanks for the info, well done on your research

[discopotato03]

It sounds like they intended the 20 Neo to be a high revving thing and it's a shame Nissan didn't turbocharge it . I'm surprised they changed so many things in the last years of the humble RB straight six and now it seems all V6s .

The old L Series engines also went through changes getting into the emissions era , eg L24Es had long skinny conrods with small gudgeon pins and possibly small crank pins . Nissan cast iron liners into the exhaust ports you'd think to keep the exhaust temps up .

I suppose the value in a 20 Neo is the head if it has shallower chambers and a few valve train mods to make them hang together at high revs . I agree that the way to tie it all together is to fabricate an inlet manifold and maybe even reproduce an RB20DETs lower half to suit the 20 Neo head .

I think people would only ever do these things if they really had to have an RB20 and if they had the freedoms an RB25T Neo would make a better base . Actually IMO the best RB20 you could ever make would be a shorter stroke RB25 because it would rev well and benefit from all the bigger bore RB bits like heads manifolds etc . One off crank would be exy but the overall potential would be huge .

A .

[StevenCJR31]

the cast liners in the L series were there in conjuction with air injection nozzles in the exhaust manifold, i would assume it would be there for some kind of afterburner effect to clean up the exhaust emissions. . . good thing we have ecus/cats to do this now!

[BenR]

Sounds like the correct answer is the first one that comes to mind on this topic! Which is "25DET Neo" engine swap. It's hard to believe that all your effort will be sufficiently rewarded.

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.

It sounds like they intended the 20 Neo to be a high revving thing and it's a shame Nissan didn't turbocharge it . I'm surprised they changed so many things in the last years of the humble RB straight six and now it seems all V6s .

The old L Series engines also went through changes getting into the emissions era , eg L24Es had long skinny conrods with small gudgeon pins and possibly small crank pins . Nissan cast iron liners into the exhaust ports you'd think to keep the exhaust temps up .

I suppose the value in a 20 Neo is the head if it has shallower chambers and a few valve train mods to make them hang together at high revs . I agree that the way to tie it all together is to fabricate an inlet manifold and maybe even reproduce an RB20DETs lower half to suit the 20 Neo head .

I think people would only ever do these things if they really had to have an RB20 and if they had the freedoms an RB25T Neo would make a better base . Actually IMO the best RB20 you could ever make would be a shorter stroke RB25 because it would rev well and benefit from all the bigger bore RB bits like heads manifolds etc . One off crank would be exy but the overall potential would be huge .

A .

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.

[GTSBoy]

They almost certainly changed the rods and bearing sizes and all that to reduce mass and friction and so make the 20Neo as fuel efficient as possible. After all, the whole Neo exercise was about making a LEV capable engine to meet the new rules in Japan.

[BenR]

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?

[StevenCJR31]

you are probably outta luck with an off the shelf kit, can you use 32 gtst turbo gear etc ?

[BenR]

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.

[BenR]

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.

[StevenCJR31]

so its pretty much the same amount of work as boosting a rb25de neo , the only difference in my mind is that the 25de neo would take boost better as it doesnt have the disavantage of the light weight bottom end that the 20neo has

[Rolls]

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.

Well if that is how you get your jolleys why not take it a step further and put a CA18E motor in your skyline and spend $15k making it perform almost as well as a stock rb20det? It just sounds absolutely mind boggling retarded pushing shit up hill with a motor like this, cost more, takes more time, won't work as well, basically everything is worse, more difficult and the end result is worse than a stock rb25det neo in absolutely every single regard.

Just throw it in the bin and buy a motor that was designed to do what you want, not try and hack up the piece of shit model to almost do what you want. You can get a sense of achievement studying an engineering degree, spending $10k on a boat anchor or a motor isn't a sense of achievement, it is borderline retardation. I will never understand why people do things like this, there is good reason why it has never been done before...

edit: you've gone and removed the one feature that would have made this a half decent motor.. VCT. Now I really have to ask are you just doing this to troll us?

Sounds like the correct answer is the first one that comes to mind on this topic! Which is "25DET Neo" engine swap. It's hard to believe that all your effort will be sufficiently rewarded.

Yep pretty much you might as well just throw all your cash in your fireplace otherwise!

so its pretty much the same amount of work as boosting a rb25de neo , the only difference in my mind is that the 25de neo would take boost better as it doesnt have the disavantage of the light weight bottom end that the 20neo has

It also has an extra 25% capacity so drives infinitely better along with having VCT

Edited August 18, 2013 by Rolls

[niZmO_Man]

I will never understand why people do things like this, there is good reason why it has never been done before...

Keeps builders/machinists/shops/etc. in business though