discopotato03

I would have to ask why you want the front so low ? You do realise that you screw up all the front geometry by having it low . Caster (radius) rods and the lower control arms effictively triangulate to form a lower wishbone joined to the Macpherson strut at the ball joint . When you lower the body you also lower the suspension location points and the geometry changes . Firstly the lower control arms need to be higher at the cross member end in order to get some negative roll camber change . If they are horizontal at rest when the body rolls the arm scribes its arc upwards and inwards pulling the strut in with it giving positive camber change instead of negative . Not good . Secondly the front of the caster rods are set to give the nose a degree of anti dive under deceleration and braking , dropping the nose reduces this so not only is it closer to the deck - its twice as likely to plow into it . Do yourself a favour and leave the height std , fit slightly larger anti roll bars and something like the Noltec adjustable strut tops . Set the camber neutral and dial in as much positive caster as you can - I'm running +6 and turn in is the best I've ever seen on a strut car - with 205/55 16's . The front easily outgrips the back and it wears 225/50 16's . Cheers A .

Thanks all , I was just curious to know if the RD block would take all the RB30 internals but allow larger bore cylinders for the same external dimensions . I've not looked at an RB block for a while so I'm not sure how much meat there is between the cylinders . SK did the workshop test that one for core thickness ? Thanks A .

My opinions only . Its been said that turbos sized to "spool" at just above highway cruise ie 100-110 generally give good open road consumption as boost , with extra fueling and retarded timing , is not needed . GTST's and GTS25T's were sized to boost in the lets get the thing rolling phase and when at highway cruise revs/load its difficult to keep them out of boost . I suspect the kind of use these cars had in Japan was crawling round the burbs with millions of other cars , average speeds were low and low speed torque was needed . For Austalian conditions you could probably get away with the next size up turbine housing and maybe even the next taller final drive ratio . This should help to load the engine and turbo and be less fussy in the low mid range . From what I read the Nissan ECU's are very quick to go rich/retard and hold off detonation . Now that we are getting better pump fuels and an easier say in the tune (ie PFC) you can retune for torque and crisp throttle response which means not filthy rich 10:1 mixtures and better timing numbers . My theory only but the next size up turbine housing will give less boost at low revs but the potential to advance the timing up a little should pull up the bottom end , and lets face it lowish CR engines need all the help they can get . Uncorking the turbo also benefits us more when on boost and helps reduce the thermal load on the engine which itself helps reduce the onset of detonation . With my engine build I hope to keep the CR around 9:1 which makes for better part throttle torque (raised dynamic compression) a little more than std lift and the GTR head/inlet to have minimal inlet restriction (volumetric efficiency) . Turbo ? This will be the last part of the picture because technology is constantly updating , prices usually fall and there are some new things on the way next year . My thoughts only , cheers A .

A search on TO4Zs may help you're knowing .

Can anyone tell me if the RD28 block is the same deck height as the RB30 ? Also was it cast thicker in the bores allowing larger rebores or did it use liners . Curious to know if more than 3L can be had without huge cost for same external dimensions . Cheers A .

Yep , Garrett engineers (the petrol head ones in Torrance Ca) dont like the GT3040R 56T and Garrett only market it with the largest 56 T compressor . Note the HKS spec GT3040R used a smaller 50 trim comp and .60 rather than .70 a/r comp cover/housing . These don't surge like the one Garrett sells because the map is esentially moved to the left compared to the 56 t comp . As you say the 56t GT37 76mm wheel is a better match and less likely to surge provided its not overdriven by a tiny a/r turbine housing . This is the perfect example of how matching shaft power requirements and airflow to exhaust flow ratio gets the job done . A little O/T but if Garrett optioned the GT3540R with a 50 t compressor and .60 a/r housing it would be more responsive too . The bottom line is the compressor has a lot more say in how a turbo responds that many think . Compressor airflow beyond your power requirements IS NOT A FREE RIDE AND DEFINATELY DETRIMENTAL TO THE TURBOS BOOST THRESHOLD AND TRANSIENT RESPONSE . Turbine power is neither free nor limitless so wasting it to drive an air pump with surplus capacity is an exercise in futility , far better to use a compressor of adequate capacity that can utilise all the turbines power without waste . Remember every time your waste gate opens thats heat energy your wasting and you are paying for that energy at the pump . Cheers A .

From the US - ATM Garrett have released BB shaft TO4 P trim and TA34 76 trim (what Turbonetics call Stage 3) turbines and the aftermarket says they can hang any compressor you like off them . If Garrett does the GT32 turbine this will nicely bridge the gap between the GT30 and GT35 turbines and offer Cubes the middle ground he wants ! Seriously it would be a better match for the larger 56 trim 76mm GT37 compressor or a smaller 50 trim 82mm GT40 comp . If used with a 71mm GT35 comp it could trounce the "highflow" with higher tech wheels ... Cheers A .

Looks like a TO4S compressor side (7 blade wheel with cast iron backplate) . Turbine side looks like TO4 turbine (74.2mm) in small A/R housing , that will drive the "S" comp better than Mafia's cropped 56.6mm GT30 turbine particularly in a native housing . The HKS manifold and gate free's up the range of turbine housings available to you . If anyone has the HKS RB26 cast single low mount manifold I NEED one ! Money on ice . Cheers A .

Garrett has been releasing some T3/T4 CHRA's to convert turbos to BB and using the existing turbine and compressor housings . They're supposed to use the larger bearing pack found in GT40R and GT42R turbos , the optional upgrade costs ~ US $499 . I'm trying to find out what is available ATM , the Americans are saying that in the future just about any combination will be available to order in BB CHRA . Hopefully this means all the spares will be available to build pretty much whatever you want and you won't be tied to Garretts generic combinations . Also if you damage a wheel it may not cost a new turbo or CHRA . Bush bearings may be on the way out . Cheers A .

BHDave I'm only offering my views . What I said was the compressor with the lower number of blades will draw less air for a given shaft speed . This is desirable because at low engine speed the engine doesn't want/need too much shoved down its throat . Ideally you want the engine and the compressor to to accelerate in step so the compressor can maintain the desired pressure head over the rising demands of the the engine from a volume point of view . Obviously the engine has a speed range - so does the compressor . The way I see it if you feed an engine a fair chunk of boost (like 22lbs) at that point of the rev range its probably used up more of the compressors usable rev range than the engines . So as the engine revs rise the compressopr could run out of capacity lower in the engines rev range than desirable . This makes the broad asumption that there is not very high turbine inlet pressure choking the hot side of the engine . To recover enough exhaust gas energy to move air at that pressure(22psi) I can only wonder at the gas speed through the turbine housing and what it will be like at 6000 rpm crank . Does the boost fall off at higher revs ? I'll quote someone we all know here as well - boost pressure is a measure of resistance to air flow not a measure of airflow itself . Why I thought the 22 psi at 3200 rpm sounded weird was because the dynamic compression must be very high . It would be interesting to play about with boost and ignition to get the best torque at that point . From my experience when the timing gets much below about 12 on boost at lowish revs less boost and a little more advance worked for me . Cheers A . T300 - that's a new one on me , any details or pics ?

48 , 52 , 56 Trim TSO4 Maps - the real ones . The last one is the GT30R's 76mm 56 Trim GT37 compressor from cartridge no 700382-12 . It lives in the real GT30R and the HKS GT3037 56 Trim . Cheers A .

Craig of Allen Engineering in Mallala once explained to me why overbored turbine housings don't work . The explanation was that once its bored for a larger OD turbine the side of the internal passage facing the blade tips opens up . What happens then is the gasses enter the blades at a different angle than the one intended by the original turbines designer . That example of 20lbs boost at 3200 rpm sounds weird , I'd be real curious to know what it makes at 2000 and what was done to control detonation - what full load ignition timing does it run between 2-4000rpm . Cubes if you were running with integral gates fixed open and generating boost then clearly the gas flow capacity of the exhaust housing is too low . The fact that those Hitachi's all used the same sized turbine indicates that it was a manufacturers compromise and not intended for super performance duty . Even with a large a/r housing (VG30) the turbine inlet pressure can be manageable , the short blades (small dia ceramic turbine) can only make so much shaft power . Its always a trade off between shaft power and resistance to gas flow . The adequate sized compressor will not overtax the turbine (power supply) nor push excessive air into the engine creating unmanageable volumes of exhaust gas which the turbine housing may not be able to cope with . Cheers A .

Hokay give it a shot , just remember smaller a/r turbine housings achieve the higher exhaust gas velocity by using smaller passages - and will reach maximum flow capacity sooner . A little later on you'll come to realise that a smaller compressor can easily lower the boost threshold purely because the turbine can drive it faster sooner . I'm just looking at the 48 and 52 trim TO4S maps and they pass the choke line (60% efficiency) at 2 pressure ratio (1 Bar positive) at ~ 46 and 50lbs . If you assume that 1lb of air for 1 Hp thats enough airflow for 460 and 500 Hp - and Mafia's asking for 270Kw or 360Hp . The compressor from the GT28RS (60mm 62T 6 blade GT family) pushes 36lbs of air at 60% efficiency but is on its limit . The 56 trim 71mm GT wheel from some 2871's + 2835's does it at ~70-72% and maxes out at ~ 45lbs flow . The 76mm GT compressor from the real GT30R and HKS GT3037 56T maxes out at ~ 50lbs at 1 bar positive and does it 10,000 rpm faster than a 52T TO4S . Compressor efficiency is important but mainly from a heat rise in the charge temperature point of view . I don't know how else to say this but less blades means less air drawing capacity at low compressor revs . It gives the turbine a better opportunity to zip the compressor up to a workable speed and that's what spool is all about . Changing to a larger a/r comp cover will do jack for compressor surge because its the inability of the engine to swallow all the air a compressor wants to give that is the issue . Challenge : Disconect a turbos air outlet and rev it to destruction , didn't surge did it ... I'm not sure how electronic boost control cant help prevent surge although if it could regulate boost at very low pressures it may not surge - the low boost won't get us much go either . It's easy to think that a waste gate is a pressure relief valve in the exhaust side but its not the case , its there to by-pass enough gas to control the turbine/compressor speed and hence boost from compressor speed . Waste gates are generally regulated by boost pressure which totally disregards exhaust manifold pressure . Challenge 2 : connect your waste gate actuator to you're exhaust manifold and see if you get ANY boost when its regulating off exhaust manifold pressure . Acid test to see if exhaust manifold pressure is way higher than boost pressure . Gas velocity through the turbine blades dictates how much energy the turbine can recover . Once the flow limit of the housing is reached all that goes up is pressure and heat - bad very bad ... Someone said earlier that 2-2.5 times exhast manifold to inlet manifold pressure is the thing to aim for . Start crying because the yanks are gettting equal pressure on SR2DET's (front drive Sentra's) with 52T GT3037's and .73 turbine housings . They spool at ~ 25-2700 and make close to 400 at the treads . I think the term they use is crossover to describe equal or even higher boost to exhaust manifold pressure . Every turbo engineer will preach to you the benefits of achieving this , the developement of turbo F1 engines shows it up too . Tis a great pity it ground to a hault in 1987 when they were banned because turbo development could have continued with the advantage of huge financial resources . On a parting note , is anyone still awake ? , early truck turbo diesels had no form of waste gate and were said to be free floating . The turbine and housing were sized to allow maximum exhaust flow (minimum restriction) and JUST enough compressor size/capacity to reach the desired maximum boost up near the red line . This is why diesels generally have such large exhaust housings and they don't overboost . Cheers A .

I can relate this smaller RB25 housing from the VG one from one of my own bastard hybrid turbos . That one actually used a Ser 5 RX7 turbine and a -24 B wheel , going down to the smaller turbine housing only made it surge . My turbo was a copy of what Bill from ATS did for the JMS S-13/RB20 DET car . There are times when going smaller in turbine housing works but its only generally when the compressor is smaller in relation to the turbine . The desire to speed up the rotating group with a small a/r housing is valid but not with compressor being the size and style of that one . In this case the compressor is the culprit , the non native turbine is less than ideal but not the greatest drama . Its a bad feeling to be in the dark and clutching at straws - been there done that . The answer is staring you in the face - lose the S compressor and use a propper turbine housing . Nothing you can do with turbine and compressor housings will help much because the cartride is a Garrett factory flop . It may have worked in some obscure diesel app but fails dismally with petrol engines . I can nearly hear people thinking this guys full of shite BUT on a parting note show me a HKS BB turbo that uses 7/14 blade compressors - you won't find any . They had their pick of Garretts full range but you won't see a GT3037 or GT2835 with an "S" wheel . Cheers A .

Housings , the Garrett marketed edition uses garden variety TO4 P trim turbine housings in a variety of single/twin entry T3 or T4 flange patterns . I think there is a choise of TO4S compressor housings or an "R" ? housing still researching that one . The HKS edition uses a unique turbine housing in twin entry T4 flange pattern , it is not a true split pulse housing because the divider only goes in a short way . The compressor cover is a huge thing with a 70mm outlet rather than the usual TO4S housings 60mm outlet . It has a fancy drilled port shroud fitting on the front as well . There are some people in Perth using them who say that the compressor wheel (TO4R) is not prone to surge and non port shrouded covers work well . Just to throw some variety into the mix Full Race in the US offer the same compressor with the GT35 turbine (GT3567R) which is a recent development and looks good so far . This turbine is a little smaller than a TO4 P trim and possibly lighter for approx the same exhaust gas flow rate . For the propeller heads the GT35 turbine is a 68mm 84 trim , TO4 P trim is a 74.2mm 76 trim . I also found mention of a GT4067R which is the GT40 turbine with the TO4R compressor . For some reason the Americans call a compressor by its inlet diameter ie TO4R is 84.2 x 66.7 so it gets called 67 ? Cheers A .

I did some research ito fuel octane and detonation and have to wonder why the ethanol was added . I sort of though that the alcohol helped to make any condensation soluble but I'm beginning to wonder if slower burning high octane fuels need a bit of help at the cold start phase . The mighty 3 cyl G11 ran like a hairy goat at the first cold start on the Shell 100 but runs fine on it now . If anything it make a little better part throttle torque and the choke (showing its age here) is never needed . It will be interesting to see if the other flavours of 100 octane fuels will have ethanol in them . Cheers A

An interesting topic this one , I get the idea that good synthetic oils are less viscous at lower temperatures than mineral oils so oil drag is less of a problem . There is one school of thought that says lower coolant temps can make more power because less chamber heat is conducted into the fuel/air mix before it is ignited by the spark . So if the detonation threshold is lower a little more full load advance can be used all else being equal . It probably a case of std thermostat for road and lower for race , its hard to imagine the oil being too cool in a hard worked engine on the track . Cheers A .

Cubes there's no reason not to try a GT30R with big housings its just that it may struggle if you put lots of boost and revs into it . I tend to think the 35R with the middle sized .82 should be good , my comment about the XR6T is because of the flange and gate type . SK tells me that we should not be scared of the 1.06 housing if the CR and tune is right on a 3L . Anyhow its probably safe to say that VG30 housings work on RB25/VG30 turbos and the GCG hi flow . For anything else including Ser 4/5 RX7 hybrids its a waste of time and money . Cheers A .

Yes Dale FZ1 confirmed turbo specs , 90 trim cropped GT30 turbine with 52 trim TO4S compressor . The only available housing that suits it and has a hope of working is one of the HKS ext gate T3 flanged housings . From memory both HKS GT2835 Pro S housings are for the 84 t version of the cropped turbine . Still leaves you with the water pump grade compressor though . The turbine housing on the XR6 edition GT3540R (GT3582R) has the T3 flange and a unique dump pipe pattern . This housing is not manufactured by Garrett and has FORD cast onto it . I have seen one and remember thinking that it would have a hard time bypassing (wasting) enough exhaust gas on a hard worked GT3540R - but it also has a .50a/r TO4E compresser cover on the cold side which probably limits airflow . Ford went to a lot of trouble to kill the fun with much more than a blurts worth of boost in std form . Reasonably cheap, compact and make torque from cranking revs on the bloated toad mobile . Got the legs on the 8 though ! Honestly I think the HKS housings are better , much better cast finish and the critical nossle/volute section is a bit nicer than Garretts Diesel housings . With HKS Pro S housings , a lot of effort has been spent on making the waste gate capable of a lot of flow with less resistance than your typical Garrett integral housing . The flap is huge in comparison and the gas port has been shaped to flow easily beyond the valve itself . I'd say its an attempt to make an integral gate housing work properly with high pressure ratios (boost) but they're pretty selective of which compressor they use at the other end . Have you noticed how they don't want to sell you a .87a/r housing with the GT2835R version and trying to get the .68 housing on the GT3037 Pro S is probably difficult . Its all to do with avoiding surge and high exhaust manilold pressure which promotes boost creep amongst other nasties . I've lost interest in 2L 4's (FJT) and aim to jump over the short stroke short rod RB25/26's to an RB30DET so GT30R's/GT3037R's are not what I'll need . If I did I would have tried to get either a 52T version of the GT3037 or the REAL GT3071R and used a HKS Pro S exhaust housing . The cheapest option would be the XR6 turbo but I think I can do better . SK said he had a bit to do with a 30DET with an .82a/r GT3540R and it worked very well . As always the issue is the waste gate which must have been external , its a pity HKS didn't make a Pro S version of the GT3540R but then they didn't see many 3L's did they . Cheers A .

Before I give my opinion on that we need to know what the original goals were . Where you wanted it to go from and how much top end . For fast road you probably want it to go from ~32-3300 rpm and have good mid range torque . GT30 turbines really need GT30 turbine housings to work properly - the nossle area of the housing needs to suit the exducer tips of the turbine blades . Garrett make turbine housings to suit in .63 / .82 / and 1.06A/R - external gate T3 flanged . As far as I know only HKS make propper integral gate GT30 T3 flange turbine housings that work . These are intended for HKS's bolt on version of the real GT30R , they call it GT3037 Pro S but it uses the identical cartridge (700177-7) as the real GT30R (unit no 700382-12) does . I think you have 4 choices here as usual based on cost . 1) Buy and fit the HKS Pro S integral gate housing in .68 or .87 , it would need the HKS or copy dump pipe to suit . 2) Buy/fit the HKS cast manifold and external gate and use a Garrett housing . 3) Buy/fit HKS 2835Pro S or 3037Pro S kit . 4) Get your original turbo Hi flowed and fit it back in with the standard fittings . People say it works well with the VG30 housing but you'll need another as your one is machined out differently but check it out anyway . I found out the hard way years ago that expensive one off bits are a pain because they only suit one combination and if it doesn't work the doughs already spent . Yours is an easy situation to get into and an expensive one to get out of - how expensive will depend on what you can sell the bits you don't want for . Can the moderators make this a STICKY . Buy Garrett Ball Bearing turbos with 7 bladed TO4S compressors at your own risk . Nothing about these compressors is desirable and the results are bad . A propper version will have GT (Garrett Technology) turbine AND compressor and an "R" or rolling element ball bearing cartridge . The turbine housing should be a match with the turbine in one of the available A/R's .

I thought I posted again but it must have got lost . That TO4S wheel is probably not helping much but the GT30 turbine in a non native VG30 housing is almost certainly causing some restriction . That housing was intended for a much smaller ceramic turbine and in low boost form (7-8lbs?) good for 190Kw on a 3L V6 . I know the high flow makes more but its 76T XXXX turbine is of lower tip height than the 84T GT30 and somehow works . Its 71mm XXXX compressor is smaller than the 76mm TSO4 so it is better matched to its turbine . Actually for its age its compressor is quite efficient . I can't emphasize enough that its the TURBINE/housing combination that drives a turbocharger . The best car in the world is stuffed if the engine is a dog and the same is true for turbos if the turbine/housing combination is not sorted . This is always the hardest part to get right and often OEM mounting flange / integral gate convienence brings it all undone . This is why firms like HKS go to the trouble of making model specific kits that bolt on . Yes its expensive but it BOLTS in reasonably quickly and easily and is generally a known quantity . Mafia , I dare say you found out the cost of many fiddly one off bits adds up to a tidy sum and on top of the turbo price could be reaching up to that of a complete kit . I think you're choices are limited to fitting an exhaust housing that works or changing the turbo for something more suitable . At the end of the day even if you can get around the detonation dramas its doubtfull if it will reach your power goals . It sounds like the exhaust restriction is causing heat probs within and detonation . An easy way to find out is to connect your boost gauge to somewhere on the engine side of the turbo (exhaust manifold or turbine housing before the turbine) and check the pressure . Don't be surprised if its double or triple that of you're inlet manifold pressure under boost . Waste gates generally "blow open " because exhaust manifold (turbine inlet) pressure is much higher than boost pressure . If you have three + times the boost pressure acting on the flap valve and one times boost pressure acting on the actuator I know who's going to win every time . Out of time again , cheers A .

I'm interested to know why Jun would remove the quench zones of the chambers . I thought conventional thinking was good quench zones and static CR set by the piston crown . Wouldn't this make for better detonation resistance and combustion efficiency ? A lower "hump" on the crown may help scavenging with with long period cams . Gary whats your thoughts/experience ? Cheers A .

Mafia I don't remember which turbine housing your GT30/TO4S used , but the 2835 Pro is a good match for RB25's . Hate to say it but I think you're going to have to do something else turbo wise for good street performance . Cheers A .

David Vizard spoke of an evacupan system where exhaust gas velocity past a tube (anti backfire valve) facing down stream in the exhaust could vent the crank case . It was more for open pipe n/a race engines using high CR's . Cheers A .

If you miss it that much put one in a GTST , got a good spare if you want one and even a modified bellhousing to suit the GTST box . Wattlewattlewattle -vroooom ! Cheers A . Hard to imagine a 2L R32 with torque......... oops incoming .