discopotato03

Works like this , you have the basic T28 turbine in I think 62 trim and a few turbos got the nice GT28 NS111 turbine in 62 trim as well . It has fewer more open blades than the normal GT28 turbine and in performance apps is a good thing . I don't have time to look ATM but off the top of my head the GT2854R/GT2859R/GT2860R (707160-7) turbos got the 62T NS111 turbine . If you see a GT28 based turbo with a 76 trim turbine its the larger trim version of the NS111 like say HKS spec Garrett "GT2530s" get . Many won't agree but my take on turbine and housing size choices is more about where you want the boost and torque to be than maximum power output up high - in a roadie anyway . Also I doubt theres room on an RB26 style compressor housings to incorporate port shrouding and make it work with a GTRs inlet plumbing . You also take the risk of going out on a limb with GTX compressors and plain comp housings . Its one thing to increase a compressors pumping capacity and another to bank on it not surging . The only way to know is to try and its an expensive exercise if it does surge . The factry style turbo layout on an RB26 was designed for a purpose and the tight packaging doesn't leave much room to make major alterations . IMO you need to try and get them right the first time and if it was me I'd go conservatively with something known like -9s . A .

In a perfect world a compact chamber with a flat or slightly dished piston giving the desired static CR and stopping approx 25 though short of the heads deck face works pretty well . IMO the dama is people using all kinds of weird and wonderful ways to get the CR they want ie thicker or thinner head gaskets . Few of these methods works best and ends up being a compromise . Making changes the worst possible ways can actually give you a low compression ratio engine thats not very detonation resistant . I think if you could emulate a Neo engines pistons and static CR with a deeper dish or whatever you'd have a pretty good solution in a Neo RB30DET . I would have thought by now plenty of people would have buretted std RB30E and ET pistos to get those volumes . Getting either engine to top dead center and placing a feeler gauge between the piston edge and a steel rule across the bore is not exactly rocket science . I bet plenty an RB26 engine builder would have loved smaller chambers and flat or dished pistons . A .

Really need United E85 in Southern Sydney as well . Rozelle is just too far to go and Eflex doesn't sound very consistent . A .

Has anyone done the calcs to see what the static CR would be with a Neo head on a std RB30E or RB30ET short engine ?

The best way to look at is the inlet cam phasing only changes . The exhaust cam timing is fixed in relation to the crank and therefore piston cycles . By changing the inlet cams position in relation to the exhaust cam you can vary the overlap timing . Valve overlap occurs when a pistion is a the top of its fourth or exhaust stroke , at this point all of a cylinders valves are open but by this I mean the exhausts are closing but not on the seat/s and the inlets are opening but not very far off their seats . You possibly need to look at a cam chart because a good one gives you the opening and closing points of the valves in your four stroke cycles . You need to know what these terms BTDC ATDC BBDC and ABDC mean . Basically - Before Top Dead Center / After Top Dead Center / Before Bottom Dead Center / After Bottom Dead Center . If someone said to you my cam/s give these valve timing numbers 20-60 60-20 , it means the inlet valves open 20 degrees Betore Top Dead Center and close 60 degrees After Bottom Dead Center . The exhaust valves will close 20 degrees After Bottom Dead Center and open 60 degrees Before Bottom Dead Center . To work out the overlap duration add 20 BTDC (inlet valves) to 20 degrees (exhaust valves) and get 40 degrees overlap duration . For engines to work smoothly and over a wide range its good to be able to vary this overlap duration to suit the engines speed . Shorter overlap duration works well at low engine (low gas speeds) and longer overlap at high engine (and gas) speeds . Volumetric or cylinder filling efficiency is greatly affected by valve timing and some of this is because the right amount of overlap timing encourages good scavanging (the ability of the exhaust gasses velocity and momentum creating an area of low pressure at the closing exhaust valves which allows the exhaust side to actually help draw clean air through the chambers to purge the last of the exhaust gasses out) . Ok so when you can open up the cam centers by changing the inlet cams position the overlap duration decreases which helps to keep the gasses moving in the right direction at low revs . When the revs get up a bit the gas flow volume and speed is greater so to make the engine scavange well at medium to high revs you close the cam centers up which increases the overlap duration . As a hypothetical example look my earlier 20 60 60 20 valve timing numbers . This is fixed timing like say an RB20 or RB26 has but if you could vary the inlet cam phasing it could for example look like say 10 70 60 20 with the cams opened up and 30 50 60 20 with them closed up . Only the first two numbers which represent inlet valve timing change because only the inlet cam has changed its position . It goes without say that the inlet cam lobes effective profile has not changed so the inlet cam/valve duration can't change . Look back to those inlet valve timing numbers . They can be 20 60 or 10 70 or 30 50 , add any pair together and you still get 80 . You add this 80 to 180 and you will always get 260 degrees inlet duration . Now lets say you have an RB25DET with 280 degree cams and no VCT , assume for a sec that its valve timing numbers are 30 70 70 30 making the overlap duration 60 degrees . Just to prove the 280 duration add the inlet , or exhaust , timing numbers together and add 180 so 30+70 =100 +180 =280 . An engine like this WILL be cammy and a bit breathless at low revs compared to one with tamer cams and less overlap timing . A better overall compromise might be 260 or 270 degree cams and 20 degrees of inlet cam variation - VCT . This is probably hard to fathom unless you have a good understanding of how a four stroke engine works and how valve timing works in relation to it . Its all out there if you search for it , cheers A .

Correct me if I'm wrong but I believe 184 kw vs ~ 206 . I can't remember what Neos get injector wise but replacing wouldn't be harder than real sidefeed alternatives . I'd like to think ID1000s would drop in but not sure there . A .

Neo hands down , younger possibly fresher and a little more grunt standard . Not sure why anyone would take the R33 engine unless wiring was an issue . A .

I'd just live with the valve train you have in that case .

Wouldn't buying the Neo head be easier and cheaper ? Dunno about Cas drive . A .

Std healthy 25DET , Neo a little nicer , with something like a GTRS and a decent computer/AFM/injectors /fuel pump . This is where my R33 is , still with R34 SMIC , and can't hold traction in the mid range in 1st or second . Runs the Whiteline Bilstein SK suspension kit and 234/45s on 8 1/2" wheels btw . Your call but I wouldn't throw a lot of money chasing big power in a light to medium weight RWD car . IMO GT35 anything silly big for any 2.5L road engine . Given a choice I'd do a budget build with a freshened up RB30E with a Neo head on top . Cubic inches in a mild easy on the engine state of tune would very easily make stupid boardering on unusable torque in a RWD R32 - and you don't need huge turbos or lots of boost to get it . Toss a plain Jane GT3076R 0.82 IW on to the above combination with a bar of boost and try keeping tyres on it . A .

David Buschur in the US usually says that increasing the CR in 4G engines usually makes them feel better off boost but nothing much changes boost threshold wise . I think you need to look at any engine as a combination of parts making it a specific package . There are good and bad ways to increase the static CR and bad ways tend to promote detonation . Leaving piston and chambers for a moment turbo systems are sometimes done differently on higher CR engines . For example if the raised CR engine makes better part throttle torque off boost you can probably increase the turbine housing size because you may not need boost as early , the reduced turbine inlet pressure should help reduce a higher CR engines tendency to detonate . I think effective intercooling becomes more important because lower charge temps ideally means lower combustion temps . Ultimately I think the secret is keeping a handle on combustion temperatures and pressures in the rev ranges tend to detonate in which is usually the low to mid range . I'm told the reason for this is because at low revs the compressed charge has more time to absorb heat from engine components and finds it easier to "auto ignite" . Tuning would be very important and not being too greedy with boost pressure for its own sake would help . My take with any of these performance enhancements is first can I make the engine any bigger because its the same as it was 40 years ago , extra inches (cubic ones) make the easiest horses . Not necessarily the cheapest but more often the easiest . A .

Physically a HKS 2530 cartridge is just the same as any other GT2860R that uses the same turbine . All thats different is the compressor wheel so if you couldn't buy a -21 cartridge new you'd get yours rebuilt or ask for someone to fit your compressor to a new GT2860R cartridge . The expensive or hard to get bits in your turbo are the compressor wheel and the turbine housing . The rest is just like any other GT25BB based Garrett center section . A .

I regret not knowing a few years back that RB25 Neo heads had more compact chambers because I spent good movey improving an R33 era one . Nissan obviously changed the later 25DETs for a reason and since the satatic CR is the same I have to assume they were trying to reduce detonation in leaner burning (possibly ULEV) engines . I reckon having smaller chambers and a deeper dish in the middle of the piston crown allows them to have good quench abilities and not having a large aluminium mountain across the middle would make them breathe and scavange better . If I was doing an RB25 that was a pure E85 engine I would go up half a ratio to say 9.5-9.75 to improve the off boost performance and still have it low enough to run sensible timing at a sane boost level . Since I don't think too many have played with higher CR turbo Neos and E85 the CR is something that would take a bit of trial and error to get it right . My conservative reasoning is that its less of a problem if its a tad lower than perfect than if its a bit too high a gives detonation grief . That aside I wonder what the CR ends up being when you bolt a Neo head onto a stock standard RB30 NA , if it's around 9.0 - 9.5 that a pretty cheap dirty 30 build . A .

News to me , the 60mm 63 trim compressor I believe was only used in the HKS specific "GT2530" which is technically a GT2860R in todays speak . If you didn't have anything to start with surely the GT2860RS cartridge could mimic 98% of what the 2530s can . Maybe even look at a GTX2860R . If you really are keen on the HKS spec compressor contact GCG and ask them if they can bring in a 446179-21 cartridge and have them machine a new or used compressor housing to suit . They may even be able to source a 2530 compressor housing if you can find the part number because from memory most of them used Garrett castings . A .

The GT37xx turbos are bigish turbos - based on the BB GT4088R . Basically all Garrett did was fit a smaller lower temp spec diesel turbine into a GT4088R and use alternative housings . If you were going to race a 3 litre either of these could be good things for I'm guessing a 4-8000 rev range . IMO road driven engines need to have good torque down low but even an RB30 I reckon would have felt better with 9-9.5 static CR and particularly with bigish camshafts . The first thing bigger cams lose is cylinder trapping efficiency at lowish revs , if the combustion pressure was already low with the lower statcic CR and the cams lose even more then it probably feels pretty doughey down low . I tink the trap people sometimes fall into is trying to build something that can run higher cylinder pressures without detonating - but forget where you can drive like that on public roads . I believe a good road engine has a good spread of power and I don't think you can have that and have it pulling well at 8000 revs . Anyway your call but I think you went a bit big in the cams and turbo and a bit low in the CR . I doubt a GT37 would do much at part throttle anywhere and take its time winding up at full throttle . I think you could have made the same if not better power with a std GT3582R (maybe the port shrouded version) but even these are hardly responsive things in 1.06 AR form . Surely a GTX3076R could do 320 on a 1.06 housing and be "reasonably" responsive . If memory serves me correctly Mafia had someting like 320 Kw from a plane Jane GT3076R using the smallest 0.63 turbine housing . With the 0.82 you could probably ditch the WMI if you didn't want it . To me power at revs is a bit like owning a Penthouse , fine if you spend all your time there but a bit pointless if you only go there occasionally . A .

Dales post at the top of this page is what people need to think seriously about - the bit about driving around below 4500 revs . I would even suggest thinking about what happens below 3500-4000 revs because thats where 95% of cars spend most of their time . Realistically most petrol heads will be under that as well much of the time and really only wind it up for the odd squirt . The killer is that people start out thinking I want (for example) 400 Hp but they've never been in a 400Hp GTS25T so they don't really know how such a car drives in relation to where the increased torque starts . Its that number be it 400 600 etc etc , big numbers sound good but in reality the result can be lackluster . Generally manufacturers size turbosystems conservatively because they know where people want power rev wise and it needs to be early so people don't have to deliberatly rev their cars . The perception is that a car with no low down "pull" is gutless and hopeless if you have to rev it to make it go . I have not spoken to wolverine recently to see where he is up to and no BTW my R33 has not been tuned yet . He went as mentioned from a GTRS which my car now wears to a 2835 Pro S but I didn't realise that the power didn't change significantly . IMO the important thing is does it do what he wants as in did the bigger dryer make more torque where he needed it to - note needed not wanted . Its no secret that all turbochargers are a compromise but often , GTS25Ts are not a good example , standardish ones can work pretty well in normal use . The hardest thing to do is partly mimic what the OE one does and increase the low to mid range torque from what the manufacturer had to the limit of traction - and have it rev reasonably freely . Anyway GT30 based units often get mentioned for RB25s and they can make great power - but mostly not from 2500 revs with 0.82 turbine housings on them . I don't think they were ever used as an OE turbocharger on anything and probably really need to be on a 3L engine to feel good for the masses . There has been a lot of screwing around in recent years making different compressor ends for them ie GTX and FPs HTA machined wheels and some seem to be very effective . Recently I was sniffing around Evolutionm.net to see where David Buschur was up to and he's really chuffed with the FP modified "HTA3076" and has good some pretty good results on his RPM spec 2.3L 4G63 . I think the numbers were something like 610 Hp and 609 foot pounds of torque (peaked at 4700 revs) and this is in a 0.82 TB31 turbine housing . I don't know much about David Youngs (Forced Performance) HTA wheels (Hydraulic Turbine assist ?) but the word on the street is that they spool earlier than Garretts ones and make strong mid range torque - which is what most crave in reality . If I was looking for a GT30 based turbo today I'd be having words with Mark from GT Pumps because he has dealings with FP and may be able to get the necessary compressor and matching ported T04S housing to make them up . Probably not a cheap way to go but dialed in things rarely are . The HTA3073 may also be worth looking into but theres not much feedback on these yet , possibly only 4-500 Hp is seen as wussy in a Lancer Stateside . Seems I'm not the only "local" lurking around Evom , cheers A .

No I don't - get it . Yes when water does a phase change to steam it does at at huge expansion rate - at sea level atmospheric pressure or one bar absolute . Putting water on an a fire in an enclosed space is fun , really cooks you up in the nomex gear if you spray too much . Anyway W or WMI injection done properly works well . A .

Thats my belief too . Water doesn't burn and the only reason its a good fire supression agent is its heat absorption abilities . I don't think its sufficiently well known that the heat energy to take water even from 99 degrees to 100 in ambient conditions is huge . Also generally water is cheap clean and readily available . I think there will be a water to fuel/air ratio beyond which more water does SFA for you . You have to remember that its heat gained from the burning reaction that generates the cylinder pressure to drive the pistons down on the power strokes . More water means more heat absorption and below detonation threshold temperatures the heat loss will mean pressure reduction . As for water boiling and the steam boosting combustion pressures I think you'll find the volume of water going into each pot is quite small . Everyone probably poo hoos Corkys Maximum Boost but I sure it has a diagram of cylinder pressure vs piston position and the pressure rise as combustion starts . Outa time cheers A .

I am another non believer of W or WM injection having anything to do with compression ratios be they static or dynamic . Firstly you have to compress the charge air and fuel before the mixture is fired so anything going on before the fire is lit is a pre not current combustion event . Maybe what people are trying to say is that the water vapour changing state increases the combustion pressure but I find that a bit hard to believe as well . Many years ago David Vizard wrothe a book called How to modify Ford SOHC Engines and he speaks about using water or water methanol injection as being as anti detonant injection . He quite rightly states that water doesn't burn and you need to take a minimalist approach meaning just enough water to supress detonation and no more or performance suffers . I think to understand how the process works we have to understand what causes the detonation so we can find ways to prevent it . In my mind its often heat and pressure in the chambers that cooks the mixture off and ignites it at an unintentional place and time . I believe all the water mist can be expected to do if metered properly is drop the combustion pressure/temperature to the point that the mixture doesn't light up at all unless the ignition system innitiates it . Where your extra power (torque) comes from is being able to run ignition timing numbers aimed at the most efficient combustion rather than most efficient means of preventing the engine killing itself . Also as mentioned methanol has large evapourative cooling effect and lower charge temps means lower combustion temps all else being equal . This added to the fact that methanol is a flammable gas (vapour) means you counteract the fact that water doesn't burn so an around 50/50 mix starts to look pretty good . Everyone has their own theories and atm from what I've read and spoken to people about these seem to make sense to me anyway . A .

How can you get power from 91 octane fuel ? Low octane fuel burns more readily that high octane fuel , the major difference is that one is harder to ignite than the other which is why it resists detonation . Its probably getting narrow focused but if I was doing an RB25 head today it would be a Neo one because these were getting into the ULEV era of RBs and they probably had chamber and piston crown designs that better resisted detonation than earlier versions . Low emission/low consumption engines needed better chamber and port cooling from water jackets to deal with hot spots that promote detonation - particularly in lean burn situations . If you can beat detonation in other ways it reduces the need for high octane fuels and richer AFRs .

It was just intended to give a bit of background on why there is ethanol blended in some general use pump fuels and why its only around 10% - mostly . The driver is green optimism at best .

I wouldn't think $2/L is someting you'll see in the near future , but if it did it may make the viability of locally produced ethanol more economic . Something else to think about if you want to run lower octane (cheaper) pump fuel is water or water/alcohol injection . Its much easier/cheaper to supress detonation by adding charge cooling only when you need it rather than running a higher octane fuel all the time . From memory one of Mafias original reasons for using WMI was that he couldn't get pump 98 easily in his neck of the woods at the time .

I just have to wonder at the value of anyting like a 1000 hp street car . I wouldn't want all that stuff in the boot for safety reasons and if you got pulled over and checked out theres no hiding it . Better I think to use one higher volume fuel system and set up a flex fuel capable computer eg a Vipec and ethanol sensor . That way you can vary the amount of ethanol you throw in and even use power kero (91ULP) as a basis though I don't know why you'd bother . Anyway the risks are safety , yours , and if anything screws up detonating your engine which isn't cheap to fix . I believe its possible to build an engine that can make lots of power and still be tuned to give good fuel consumption - for the engines size - when driven sanely . Whatever you build will cost money and then the saving on fuel concept goes out the window . One thing to note in that RX7 was the "auto" trans and the tall final drive gearing , that could sort of work with a higher stall converter if it had a lock up mechanism for highway driving . They had the huge advantage of a turbocharged 7 litre V8 which in a light car can light em up easily . I very much doubt that thing gets good fuel economy and the build cost must be huge .

It can all be argued both ways including shipping crude oil around the world and refining it into 1001 usable products . I would prefer people not fall into the trap of believing that every scrap of a plant crop material is exhausted when making ethanol alcohol from it . Plenty of usefull things are left over from the process to fuel man and beast as well . Personally I'd rather see Australian farmers hang onto their land a grow sugar cane or corn for ethanol because selling out to the Chinese so they grow food for their own screaming hoards does SFA for us here . What I will say is that the left wing socialists goal of producing less C02 emissions is a crock because its a known fact that E10 gives lower consumption figures that straigh 91ULP - in this case its used as a spreader or landfill for fuel volumes . Epic fail you could say . As a means of reducing the reliance on imported crude there is some merit but you have to produce huge volumes to make it viable . As a performance fuel it can work well but the legacy is that many vehicles out there couldn't cope with much more than 10-15% ethanol and understandably the fuel suppliers don't want to deal with clots that used the wrong fuel . The thing is if you can make fuel grade ethanol dirt cheap people will find ways to use it , LPG is rapidly going through the roof price wise and a cheap alternative is needed to replace it . I wonder if a simple gas carby can be converted to meter ethanol so the taxi and fork lift mobs could use it ? Creating a market can be one of the ways to make it happen .

In my opinion the whole ethanol thing in pump fuels , for the masses , is driven by eco nazis and those in the fuel supply who seek to rip us off . They want you to believe that 10% ethanol makes your pleb fuel significantly cheaper but when you work out how far you don't go on it your effectively going backwards . Ethanol doesen't give the same burning heat value as ULP and its heated air and fuel that drives you down the road . I really hate legislation thrown at cars nowdays because it forces the once optional things like stability control/hand bags/ABS on evertone yet flex fuel capability is something very few cars get . The socialist greenie crack addicts are hypocrites and if they were genuinely interested in the environment AND the cost of living it would show in cheaper high ethanol content fuels and flex fuel capability in everything . I think the current situation is that most cars can about stomach low percentages of ethanol in ULP without causing internal damage , because they were designed to work with ULP specific AFRs running higher percentages of ethanol burns them long term . If however flex fuel cars were using 20-30% alcohol you could see a benefit from ethanols advantages without the disadvantages of running it in ratios as high as 85% . Pun intended the burning question is where is the trade off in ethanol fuel percentages for most current production engines ? Is it 20% 30 40 ? Obviously the higher the ethanol content the more specialised the engine and its fuel system/tuning needs to be . From a replacing petrol point of view E85 could be seen to be a good start , from getting the most performance with the least agro viewpoint I think a lot could be achieved with lower percentages than E85 . A .