discopotato03

Fair enough we we seemed to have learned that there is (was) a VG30DET that had a single ceramic BB turbo . Not being a big fan of Z31/Z32's I didn't know this engine option was available in other same (32) era Nissan luxo's . It does make sense that these OP6 VG30DET turbos were always a bit thin on the ground if these luxo's were more expensive lower volume cars rather than sporty R and Z series cars . Anyway the thing is that the value in this turbocharger is the slightly larger turbine housing in a BB package with a slightly smaller compressor than RB25DET turbos have . AFAIK they should go straight onto an RB20DET with the correct sized water banjos/bolts and slight mods to the RB20s compressor outlet elbow - or possibly one off an RB25DET . From memory the VG30 part is a straight hose barb adapter where RB20/25 versions were a right angle bend . I think the 20s comp housing uses a slightly smaller PCD bolt circle and its adapter may have a slightly smaller ID . RB25 elbow I think bolts on and may be the simplist way , cheers A .

I managed to buy a Neo Turbo fuel rail yesterday so when I get SKs spare manifold and the injectors and colars I can make some progress . I'm told R34 era Stagea engines and bits are more common here than R34 GTt parts which is handy . Slightly OT but someone at JJ was telling me that Neo's are different to earlier RB25s in the cam change hydraulics , if someone was to plonk a Neo head on an earlier RB25 block are mods needed aside from pistons and comp ratios ? Only reason I ask is because if I ever had to rebuild my engine I'd consider using the later rods pistons and the Neo top end and inlet manifold - Neo wearing std engine number basically . Cheers A .

No thats not true , there were single turbo versions of the SOHC (per bank) VG30"ET" and DOHC VG30"DET" . The one most people know about is the VG30 "DETT" Which had twin inlet manifolds and forward facing TBs . And a hybrid T2/T25 turbo on each exhaust manifold . The single turbo ET and DET versions had a crossover pipe behind the heads to feed one turbo from two exhaust manifolds . The ET or Z31 (SOHC) version from memory had a plain bearing ceramic turbo with a smaller center section and no preload bolt head visible on the side . Have a look at the last couple of pics in this link and note the "Ceramic Turbo" badge . http://www.geocities.jp/ayanami31rei/Z31-report/656-ayanami300ZR/656-ayanami-with-vg30det.htm Cheers A .

Yep the right ones from the Z32 300ZX quad cam single turbo cars are BB . Really the only usefull thing on them is that OP6 sized turbine housing and it's arguably too big for an RB20DET . So , many people just fit an RB25 turbo because they are common and generally cheap . Compared to a std 20s turbo the 25s one has a very slightly larger turbine housing and the same sized turbine . The compressor wheel is larger as is the compressor housing and it also has a kind of anti reversion groove machined into its snout . Your call but I think an RB25s turbo is a better suited to an RB20 and they are much easier to find . Do a few searches and see what others thought about 3L turbos on 2L engines . A .

They involve more complexity than a single turbo but to make a direct comparison to low mount twins you need the big single to have an integral waste gate too . With two of everything you get two integral wastegates and the turbos housings can remain reasonably compact . With current technology you could probably use quite compact turbos on an RB26 if 209 Kw was the ask . In favor of singles they're less complex but show me a twin scroll twin integral wastegate turbo and a cast manifold to suit . Then make it compact enough to drop the body shell over on the production line . The answer in a current Skyline is to use a 3.5 or 3.7 litre V6 and if that isn't enough hang compact hair dryers off each bank . I'm not to sure how you go trying to shoehorn a huge single into a current GTR and expect to register it . The downfall of the GTR/RB26 was lack of cubes pulling too many kilos in road form . Fine for a stripped out racer driven flat footed mostly but it's never the same in a luxed out emissions and noise legal road offering . Most homologation based road cars are like this , or I should say were like this because there effectively is no production based tarmac racing any more . The V8 Super Farts were a huge joke and nothing remotely like what you can buy new . A .

Yep thanks for that . Nissan must have thought they needed a damper on the supply and return sides . I've got some time off soon so will be chasing a complete Neo turbo fuel rail to work with . Cheers Adrian .

I though guilt hit the wall at about 360 RWKW on an RB30 running E85 with Nismo SF 740s . A .

Lith , what do you think would happen with a HTA3076R using a bigish - say 1.06 AR turbine housing ? A .

At the time I was happy to buy a clean mostly std 96 without ABS , just more crud you can't legally remove and expensive boxes that can fail . Couldn't escape the drivers handbags though . If I had to rebuild a 25 short I'd use Neo style rods pistons and lid . A .

gotRICE I gather thats a Neo in an R33 ? Damn I wish I'd known the differences in Neo and R33 heads and inlet manifolds before I got into porting and Tomeis . A .

If you had to engineer it I'd do an RB30ET to get the numbers right , actually I think pov pak GQ STs had an RB30S (NA carby) std . Anyway with an RB30ET you get to have an Australian legal engine option - and then if one morning you woke up and found it'd grown a twin cam head in the night - whos to know ? Engine number stays the same . You're talking about a truck thats 800 Kg more than a 1400 kg R33 Skyline so every low down Nm of torque is a god send A .

Everything I read about "E10" suggests that it's not enough ethanol to get back what you lose consumption/power wise . Most of those people were not talking about 98E10 , mainly the lower octane stuff . When they say 98E10 I'm curious to know what grade ULP they mix the 10% ethanol with to end up at the 98 oct number . The cynic in me reckons its whatever the cheapest means of making something that engines can burn and be tested to show 98 octane numbers . The best option would be blending straight ethanol with 98 oct PULP but where can you get pure anhydrous ethanol so you can tip 5.5L in yourself ? It's possibly better to work how how much E85 contains 5.5L of ethanol , pour that in a fill up with say BP 98ULP . A .

My guess is that RB26s have the breathing abilities inc those throttles to enable sustained high rev running . An RB20 is probably more dirable if thrashed everywhere because of its shorther stroke and smaller diameter lighter pistons . Having the same block deck height means longer rods and a better rod stroke ratio . If you could do it legally a Neo 25 would be a good upgrade path IMO and has conventional shim on bucket (non hydraulic) valve train . Maybe even a 26 how far do you want to go ? A .

I'd just go with E70/85 and if you really want to play evaporative cooling move the injectors further from the head flange . I really don't think intercoolers are a biggie especially when you can get ones like the Blitz return flow that can't be seen in the bay - at all .

Now really confused . I was looking for more pics and came across this thread which just happens to have pics of a Neo 25 in the FPR area . http://zilvia.net/f/engine-tech/329467-neo-rb25-bogs-then-dies-im-about-shoot-myself.html Am I looking at two FPRs because the two gadgets that look like them both have what looks like vacuum lines , do Neos have two rail outlets and regs to avoid boiling issues ? Cheers A .

Hi all , as some know I'm interested in using top feed EV14 injectors in an R33 spec RB25DET and if at all possible using an OE R34 GTt fuel rail . I have a couple of pics of Neo GTt rails but one has me a bit confused . The first shows the FPR up the front where the secont one has it mounted to a different separate section I've not seen before . It's a little hard to see but I think the user mounted one of those barb adapters in the usual FPR mount and has it now on the other bit . Can anyone used to playing with GTt rails see whats going on ? Also are all Neo fuel rails the same on Skylines and Stageas ? Cheers Adrian .

Compared to the tuners initial settings I changed a couple of reference modes around so the plug in controls a few things differently . Firstly cam solenoid control went from TPS to MAP and accel load from MAP to TPS . The next one I'm thinking about is the warm up enrichment which at the moment is TP referenced . I'd like to have a go at using manifold pressure as the reference because it doesn't take a lot of throttle movement to reach 100 kpa/atmo pressure so MAP load may give better mixture control . Also I find that once it's fired up it doesn't need AFRs like 0.85 L to idle as well as it's going to . Off idle is a different story and you probably have a scale of around 40-100 kpa to work with . Guilt one thing you may be able to tell me is how to turn some of these single row scales into tables because I think having two dimensional control of some things would be better than just one . I know there are limits to how many tables you can have and I have a few free . Thanks for your input , cheers Adrian .

I will get to that but can't bend over engine bays ATM .Voltarin makes life livable . That aside I had a look into injection timing because mine was set to a single point - 360 crank degrees at end of injection . I noticed a table option so I opened that up and when you click on the table icon you get this . I have had a few lifetime mechanics tell me that sequential injection timing doesn't matter and I suppose beyond a certain rev/gas speed point it becomes less important . My theory is that at low engine speeds the stop go of air and exhaust through the manifolds and valves may need a bit more precise injection timing to get the best use of the fuel injected . Theory aside , and because yep I'm well used to the F3 and F4 keys , I used their generic injection timing table and if anything it does feel better at part throttle round the burbs revs and speeds . The TE Wideband display , the smallish rectangular LCD numeric one , shows the AFR changes with varying loads (MAP) being a bit more inline with what I'd expect to see ie higher pressure/load with increasing AFR and vice versa but reacting a bit faster in both directions than in single point injection timing mode . One thing I struggle with is slight rich spikes when backing off particularly at smallish throttle openings low revs . Ultimately fuel consumption shows how things are and I reckon if drivability and consumption is good then yo've gone in the right directions . As you know I burn EFlex and the tune doesn't have to be very far out to being going through lots of it , the best I ever got out of it consumption wise was with the PFC Z32 and no closed loop control . It's frustrating not knowing what settings the Datalogit was using where we don't have access to like injection timing etc . A .

I'd like a look at the black rail too plz . A .

The late ViPec does 6 coils but not sure about any other difference . I'm interested to know if the V88 top board does anything else differently . A .

Yeah the dynamics of an inline 4 are very different to an inline 6 and particularly when the 6 has a shorter stroke and 20% greater capacity . SK Gary used to compare engine size difference as in what percentage of extra revs the smaller one has to turn to pump approx the same amount of air . It will never work out real world because the 6 gets a power stroke every 120 crank degrees where the 4 has 180 between power strokes . Its probably fair to say that an Evo spec 4G63T makes more torque per litre than an RB25 does mid range and being AWD means they get it to the ground more easily . I'm not so sure Mitsubishi intended the 4G63 itself to be a Grp A rally engine because that engine goes back a fair way , being a medium rev (restrictor limited) class means big revs and piston innertia are not a big problem and having a short (along the crank) engine makes it compact overall . Maybe the slightly longer stroke than bore size was an advantage when looking for lots of torque without lots of revs . Other members of this engine family like the 1800cc version in the Evo 3 era Lancer GSR I think were also similar bore/stroke ratios . I think the RB25 and 26 grew out of RB20 sized heads and blocks and there's limits what stroke you can get into that deck height . Also the length of the block determines how big the bores can get so its not like you can reliably get 89 bore with whatever stroke gets you 2568ccs into an RB26 engine . Anyhow that aside I'd reckon a 400Kw 2L 4 would be a bid wild for anything with number plates . Doable but I'd rather do it with an RB25 or 26 because at least its usable off boost and around the sun dial . Yeah power to the ground and I can't get full bore with 245 Michelin PSS and supposedly 271 at the wheels . My gut feeling is that the 3073HTA in an 82 housing should be a good all rounder in an RB25 provided you don't mind having what looks like a GT3582R under the lid . A .

Dredging up old thoughts , well mine uses MAP sensing and while its working better than I thought it would I can't quite get the fuel consumption I had with MAF/PFC . All thats changed aside from the board is the intercooler which is a Blits rtn frow instead of the GTt one . My guess is that the MAF signal works out a little better right where you go into positive pressure and have to ensure the mixture doesn't lean at that point . My IAT sensor is in the back of the factory crossover pipe and shows some reasonably high temps (high 40s) when idling for a while . I have to wonder if the temp of the pipe affects things here . I must ask Scott if there are any inputs unused so a MAF signal can at least be viewed A .

Sorry people this was the link I forgot to put into post number 76 . Check out the pics of the machined port shrouding in the GTX2867 compressor housing . http://www.audizine.com/forum/showthread.php/490300-A-tale-of-two-turbos-OR-Sneak-peak-HTA2868-vs-GTX2867 Though it would be better than this , cheers A .

Is it the same story with a factory std car ? A .

I didn't fit this system so didn't set the base timing etc . What happens if you do use the white loop ? Cheers A .