discopotato03

I'm interested to know if anyone's gone any further with Emtron ECUs since this thread was last updated . I was speaking to Scott earlier in the week briefly about them and I like the idea of a more modern EMS that can take advantage of factory knock sensors and tune closer to the edge safely . He said that he is happier to do flex tuning with these systems than earlier ones and make full use use of fuel temp and pressure sensing . I've gone back to 98ULP but I would like the ability to use E70 and be able to gas up anywhere , who wouldn't . Thoughts , cheers Adrian .

The best explanation I have is that aftermarket cams in a street car get you the last 50 Hp , not the first (over standard) . I think there are many better mods to make initially than cams in either flavour RB25DET . Better easier bang for buck . I just happened to go that way since I opted for a second head to modify , saved downtime , and had it all done together . I also opted to have that head decked to get the highest practical compression ratio without making it unreliable , supposed to be around 9.2 - 9.3 to 1 . Not really a relevant comparison but I was told at the time that the GMS GTRs ran about 9.6 to one esp after CAMS forced them to reduce boost to make it "fairer" for the iron ox taxis . I now think that lack of exhaust valve sealing and fuel pressure issues were ganging up on me , first issue fixed and a new pump shortly (no time atm) . A .

Interesting thread , always something to learn by searching . I have a GTR pump and bracket with its high mounted pump and inlet extension hose to the sock strainer . I reckon I have pump or sock probs . I'm on 98 atm and out of time to do mods so may fit a Nismo GTR pump if I can get one tomorrow . Scotty I'm interested to hear about the non return valve trick . I'm still interested in the 460 E85 pump but v time poor ATM . Take care all cheers A .

Seems the Walbro 460 E85 pump is the go , has anyone used one in an R33/34 GTR with the hose down to the strainer . I ask because my 33 has a GTR pump and bracket in the tank . Probably should have kept the original GTS25T bracket which puts the pump at the bottom of the tank . Scotty have PM'd you for a kit to fit one of these pumps , I asked your preferred method of getting larger wiring into the tank . Those bulkhead pins shown above look interesting and I think EFI something or other do something similar . Also can you supply a reliable high current relay . Thanks in advance cheers A . BTW have search my ass off recently about pumps and wiring .

I think the buckets were fine , just a few RS exhaust valve guides . If they don't line up with the seat they don't seal too well . Was ported first time round and had Ferrea (sp) over sized exhaust valves fitted . Head was O ringed to make the OE gasket reliable with extra heat and pressure . Std springs shimmed for a few extra pounds . A .

What actually seals the wires in that fitting ? A .

No extra head mods this time aside from the slightly retarded exhaust cam timing . Just freshened up . Will go to the fuel pump thread and talk to Mr Mafia . A .

Just curious , is this running a GT30 IW style turbine housing ? Cheers Adrian .

Can confirm that my 33 25 now idles fine with Poncams @ ~ 850+ . ATM back on ULP98 and running std base pressure . Need a better pump and people say these injectors spray better with higher base pressure . Cheers A .

Hi all , up for pump soon and was told to look at these machined aluminium fuel tank hat/lids . Just want to know if there is something available here that allows better wiring than OE for higher current draw fuel pumps , and seals against fuel smells . Thanks in advance cheers A .

According to my notes 446179-0032 is a 56 compressor trim GT2871R cartridge . From memory what you have on the cold side is an early HKS type machined inlet shroud which they used on the RB six cylinder versions of their 2530Rs 2535Rs and 2540Rs . The GTRSs had a unique port shrouded compressor housing on the RB versions and the four cylinder versions had a Nissan/Garrett style compressor housing . The RB version used a 52 compressor trim version of the 2871R . I think the 2530 cartridge number was 446179-0021 , the 2535 446179-0019 , and the 2540 446179-0018 . I think the GTRS cartridge is 446179-0067 . To me it looks like someone had a HKS spec turbo and hi flowed it with a Garrett marketed 2871 56T cartridge . A .

I did find it but thanks anyway , time to change the old Nizmo 740 settings . Cheers A .

It was retarded not advanced . The idea being the exhaust valves open and close 2 degrees earlier so the cylinders blow down fractionally earlier in their cycles and the overlap timing is a little shorter . So instead of the valve timing being 8-68 63-13 it would be 8-68 65-11 and the overlap duration 19 rather than 21 degrees . I imagine they set the cam where they wanted it with the crank at TDC , then moved the crank with the modified pulley so the cam would be in the normal position but with the crank 2 degrees after TDC . Tighten the four bolts and cam timings finished . A .

Hardly , if it was being sold which it isn't they'd be told the story and if all else failed to fit a std pulley . If they were smart they'd find a way to mark the cam and pulley before disassembly so they could get it right . The way it is now if it moved it fails safe - provided it didn't spit the bolts out . Personally I think setting the crank where you want it (+2deg) and having the cam lined up on the std mark is way to go but to each their own . Also this engine has new belt bearings seals and water pump so shouldn't be coming apart any time soon . Have to get if back to Insight for tuning probably with a better fuel pump and maybe a bit higher base pressure for those EV14 injectors . Hunt will be on for Neo head and a decent tall short block .

Bit more of the puzzle . Turns out that head and cams was done for me 8 yrs ago , one I bought 2nd hand off Wolverine . Was ported and fitted with Ferrea OS exhaust valves and wire rings fitted in grooves in the heads deck just behind the gaskets fire rings . Also got 33 Poncams and head decked for a 9.2-9.3 static CR . Once removed and stripped the problem was found to be worn exhaust valve guides some quite badly . Obviously the inconsistent issue was exhaust valves sometimes lining up with their seats and sometimes not . Obviously when they didn't decent running went out the window along with erratic idle speed and quality . So all exhaust guides replaced and all seats and valves resurfaced , spring heights and tensions reset . Heads deck is perfect and will go with a new genuine Nissan head gasket , actually all genuine gaskets and seals . Manifolds were port matched last time . This time around going with Sydneykids recommendation to retard the exhaust Poncam 2 degrees . They found in their day that this gave a little more power and fractionally more boost at around 3200 revs fine tuned on the dyno . My engine builder doesn't like aftermarket cam pulleys so they are going to set the crank pulley to 2 degrees and alter the std exhaust cam pulley to allow it to line up with the std marks - basically 0-2 adjustment and can't damage anything if it moves . With luck it'll be together and running tomorrow so I can redo all the idle and cold start stuff and retune all the light load low to medium speed ranges . Then it will be going back to Scott at Insight and quite likely be final tuned on straight 98 ULP . For how I drive these days I don't think I'll need the ethanol any more . If I ever do another RB the plan would be an RB30 with an RB25 Neo turbo head for the valve train updates . Anyone got a complete standard Neo top end in good nick for sale ? More soon , cheers A .

Wanted in Sydney , complete RB25DET Neo cylinder head . I have a complete stripped R33 RB26 head if needed . A .

Did everything possible brain wise , derivative gain/proportional gain/anti stall gain all maxed . Mucked around with stepper base position and idle screw and all the conditions to do with closed loop idle and idle ignition timing . This is a mechanical issue and when fixed should make the tuning part much easier .

50/50 E70/P98 - E35 . Problems atm confirmed this afternoon - leaking exhaust valves on no2 and when cams come out will see if it has bucket issues or valve/seat probs . Hoping in a way that head comes off tomorrow so top end can be freshened up . This 163K/20 yr old RB25 breathes absolutely zip when running with filler cap off so bottom end should be good . 5 of the 6 plugs looked mint though no so much on 2 . The opportunity exists to refit the standard cams and Id be interested to hear what Stao thinks of std vs Poncams in a 33 spec 25DET . Will probably leave the Tomeis in because a few things like better turbo and injectors have changed since those cams went in - 70K back . I don't know how long the valve issue has been there and probably blamed some of its antics on the larger side feeds I ran before the ID750s went in . Car ran like a dog today with a weak stalling idle made worse by using AC and headlights (defog in heavy rain) . Will know more tomorrow cheers A .

Does anyone have a link to the Nissan R34 engine manual in English please . Cheers , Adrian .

I'm trying to work the 25T Neo valve timing from Tomeis duration and lobe centre numbers . Works out 236/232 durations and 119/115 lobe centers . In theory the inlet duration halved minus the lobe centre angle should equal the inlet opening time ie 236 halved is 118 - 119 = -1 . Duration is 236 so 236 - 180 = 56 . 56 - 1 = 55 so inlet timing must be 1-55 . Exhaust 232 x 0.5 = 116 . 116 - 115(lobe centre angle) = 1 degree before top dead centre so exhaust valve timing looks like 52-1 overall 1-55 52-1 . Overlap 2 degrees ? Does anyone know how many degrees the inlet cam moves on the hydraulic actuator ?

I've been trying to find the R34GTt Nissan engine manual to get the standard cam timing numbers , does anyone have a working link to the Neo 25 WSM . Cheers A .

Search Tomei USA Cam Cards . On this computer Internet Explorer fails so try Firefox instead . R34 GTt Type A 252/9.15 lift cams . 4-68 59-13 on 120 and 115 deg (in/ex) lobe centers . Overlap 4+13=17 degrees . R34 GTt Type B 260/9.15 lift cams . 8-72 63-13 on 120 and 115 deg (in/ex) lobe centres . Overlap 8+13=21 degrees . Personally all I think you learn from measuring duration with the valves off the seats is how fast or "aggressive" if you like the valves open and close initially . Obviously rapidly increasing the lifting and seating at these points would indicate "steep" lifting and closing ramps on the lobes . If you search Tomei USA Cam Cards they give effective durations at closed and a few clearance levels . Too busy atm but later I'll compare the R33 hydraulic and R34 shim/bucket durations at the given seated and clearance points mainly because I want to see what Nissan achieved ramp wise with the R34s "soild" buckets . We know they went to higher lifts with from memory shorter durations on the later system and that is the way to breathe without long durations and extended overlap from the end of one cycle to the beginning of the next . Later cheers A .

From Tomei USA . R33 RB25DE(T) Early . Inlet 8-68 so 8+68+180=256 , Lobe center 120 deg . Cam actuator pressurised I assume 28-48 . Exh 63-13 so 13+63+180=256 , Lobe center 115 deg . The way most people look at the figures its 8-68 63-13 , or (I'm assuming) 28-48 63-13 cam actuator pressurised . Overlap 8+13=21 degrees . Cam actuator pressurised I assume overlap timing is 28+13=41 degrees , so not surprised ole 25 won't idle in this state . A .

From the R33 Engine Workshop manual . Bear in mind variation in inlet cam timing . Inlet 0-60 inactive (0+60 +180=240) Inlet 20-40 early (20+40+180=240) Exh 57-3 (3+57+180=240) These numbers line up with the 240/240 durations and I thing the lobe centers were 120 inlet and 117 exhaust . Note the overlap timing would be (inactive) 3 degrees and (early) 23 degrees . A .

I don't suppose anyone knows what the actual opening and closing points are valve timing wise , I wouldn't mind knowing what the overlap period is . A .