vosadrian

Thanks for that. Who knows RB heads. Is Lewis engines a good option? Just looking for someone knowledgable who can set up porting and valve train optimised but at a fair price? Thinking I might send the heads somewhere to get them done. Possibly someone who might set up the bottom end also and supply a complete long motor. I might contact them first and make sure I am getting the right bits for them to work on.

So if I want to build an RB based NA engine, which (reasonably priced and accessible) head option is going to give me the best result? It seems the RB25DE NEO has small ports and may not be easily ported for the best result. I believe the non NEO heads are the same casting between turbo and NA? So would either of those options be OK... or better to go turbo as perhaps the valve springs are OK for cams? Or are NEO turbo heads a better option due to solid lifters, so better for high RPM?

I get that the RBs in NA form are not the best engines around. I'm not looking for the highest power NA engine around. We are really doing NA for sound and feel and we want to keep to the Nissan/Datsun family and we want to keep it straight 6. Obviously we could stick an E46 M3 engine in or something and that is a good NA straight 6. But we want to keep it in the family. Does that then leave just L series and RB series engines? Another point, is we want it EFI (I have worked a lot in aftermarket EFI and I enjoy working with it and tuning etc.). My take is that by the time you adapted an L series to EFI and modified it for good power, you would be down more $$ than doing the same with RB series. Have I got this wrong? And we don't need huge power.... but we do want to optimise what we have. But not to 110%. I'm all for finding some easy extra revs with an oil pump upgrade and some decent cams and valve train... but I don't need fully lightened balanced for 12k RPM at very expensive $$. As I said, it is more about the sound and feel. But if we can spend a few $k on getting the bottom end to rev reliably and the top end to flow to good revs, we would go that far. Is RB the right choice for this? Is there another option I have missed?

WIth the RB26 ITBs, you get the linkages and everything sorted. There seems to be full RB26 setups around for $5-700. Can I do it any cheaper with DCOE? I thought I read somewhere that the early VCT on RB25 heads was prone to failure if run with aggressive cams/springs and that the NEO was better? Any truth to that? Also if doing port work, does it make any difference whether you start with NA or turbo heads? I would have thought the NA engine would be more sensitive to ports than a turbo so I am surprised they have worse flowing ports. Turbos normally get over poor flowing heads with boost.... they typically flow less volume but at higher air density. I know a good L series can make good power... but a good L series is close to a mild RB25DE. A good RB25 should excel, and should be easier adaptable to EFI etc. I don't want carbys. And I think with aggressive cams and VCT, the potential for a nicer running wider power bands is better on an RB engine.

@GTSBoy, School me on the ITB options!! We are not committed to the RB26 option. For us it is all about the sound and feel of the car. Big power figures are not required. Any RB25 NA engine is going to be a big power increase on what an L series NA can do. It has to run well on 98 fuel. I run my WRX on E85, and I like it on a big boost turbo, but it can be a hassle to get at times. The S30 has to be able to go on a cruise and get fuel in little town 2 hours from a major city. So that will probably set the comp. Then we will get the heads done and some not too wild cams. I think revving for max power around 8k (limit to 8500?) as it will cost lots to get a bottom end to stay together much higher. That should set the cams. We want to run the NCVS which is one of the reasons I wanted the NEO head. Some nice headers with the ITB should do OK for power and sound great. Light flywheel so it is snappy free revving. We just have to find the right engine to start with first!

Thanks! I'll check out the ASR options. The website does not have much info on standard products, so will give them a call. Our plan at this stage is to stick a stock engine in and get it running, debug any issues and registered etc. Our eventual plan is to do some mods... and we don't want to solve all the problems again for a different sump arrangement... so if we go AWD setup and then change to an RB30 bottom end again, we have to do it again. So RWD is preference for compatability with any block we might change to. The plan is definately to make it brap! Eventually we were wanting RB26 ITBs (with velocity stacks) and porting with cams and a bottom end for 8-9000RPM. It will still make a lot less power than a basic DET setup... but it should sound and feel old school cool like the 260Z should! There are some cool high revving NA RBs with ITBs running around that sound and look cool. The S30 is light so it should go OK even without a turbo. I also have a 500hp GC8 WRX I use for motorsports that does a high 10@125mph. This car is more about fun cruise/meets than taking it to the drags.

Thanks again! I did some research on the AWD NEO oil pan. It seems in the AWD the front shafts go through the oil pickup location the RWD block uses. So the AWD block has a different pickup location in the casting. The mounting points for the RWD pickup are still there but it is not drilled into the oil pickup gallery... and apparently the casting does not have a gallery, so you can't just drill it. The AWD block does have the mounting bolt holes for the RWD sump, so it seems a common solution is either to cut/weld an AWD sump to remove the shaft holes, or to fit a RWD sump, but modifify the internal baffling for the moved pickup. Unfortunately neither are an option on an S30 since you need a "rear sump" oil pan to clear the cross member, so neither AWD or RWD oil pan for a "front sump" pan will work. So on an S30 I needed another sump anyway. Typically when fitting an RB (RWD) to an S30, they either get a very rare sump from a rare Sxx model that had an early RB engine... or they get a Nissan Patrol RB oil pan which is rear sump, but it needs some modification to clear, but seems fairly minor.... or they get an aftermarket oil pan made for the purpose. But none of these options are available for the AWD block that I can see. So getting that working would be full custom oil pan which would be expensive and a one off. So I will do my best to get a RWD block. I am surpised that noce of the RB25DE NEOs I see for sale are listed as AWD or RWD... but many are listed as Auto. Hopefully the Auto means RWD... but I will have to get pics of the sump to see if they have driveshaft holes.

Thanks for the info! For some reason in the places I am looking for RB25s, I am mostly seeing RB25DE NEO with Auto. A couple are unspecified. Are the RB25DE NEO Autos all RWD? On carsales when I look for an R34 with Auto, they are all RWD. I am wondering if it is safe to assume that a NEO auto has the RWD block and is therefore easier to source an oil pan for? There is an aftermarket oil pan available for the RB25 fitting to an S30, but it states it does not support NEO, and I assume it is because of this oil pickup location issue on the AWD variant of it. I presume an RWD NEO would be the same in the oil pan as older RB25/30 and should fit this oil pan. That is a good point about the deck height changing the position of things. Will have to consider if we want to go that way.

Hi All, We are doing an engine conversion on an S30 (260Z 2+2). We want to maintain the character of the car, but have a reliable engine, so we want to stick with an NA straight 6. Looking into this and it seems the RB25DE NEO engine is a nice NA straight 6 engine that would suit, but I have some questions: * It seems these came in AWD and RWD with AWD being more readily available. It seems the AWD has some differences requiring oil pan modification and the oil pickup location is changed making it incompatible with RWD sumps. With an S30 this is further complicated as you need a rear sump oil pan to clear the cross member. So is there a way to get an AWD NEO into an S30 without too much effort, or is that too hard, and I should just limit myself to RWD engines. * What cars came with the RWD NEO? Many NEOs seem to come with Auto. Are they AWD or RWD or both? I presume all Stageas are AWD. Are all Skylines RWD? * Can all the usual RB manual transmission options bolt to any NEO engine block? Is the Auto block and AWD block compatible with any RB25 manual transmission? * Has the NEO engine got any special engine management requirements that make it difficult to run with an aftermarket engine management computer? Is the NVCS system a simple on/off system? We are considering later swapping out the block to RB30 for more capacity which I believe can be done with the NEO heads. I'm just wondering if we do that straight up to avoid the hassle with the AWD block differences. Thanks for any advice!