The Alchemist

my brain hurts

I replaced my sender unit with a new one, had similar problems, and also connected a mechanical gauge and compared the results to the original dash mounted GTR gauge. Interesting results....... While the mechanical gauge can be reading a steady figure say 45psi the Nissan gauge can vary between 2 to 3 KG/cm3 depending on its mood. Also at idle the mech gauge reads 30PSI rock steady the nissan gauge still reads high at around 40psi equivilent. At 4000rpm the mech gauge is up around 80PSI the nissan gauge still reads about 4 kg/cm3. So even with a decent sender the Nissan gauge is really a indicator that you have oil pressure, how much exactly can only be sorted with a good mechanical gauge fitted. Mike

3rd gear usually produces slightly less than 4th gear, say 2 to 3 kw. This is due to the more load on the engine in 4th and the slightly longer time to complete the run allowing the turbo to work a bit more. We do a lot of NA holdens as well and with similar differences of 2 to 3 kw between gears. Cheers, Mike

manifold gasket most likely. Shine a torch in there and look for soot blow outs around edges. It will be very obvious. Mike

Hi, just my 2c worth. I have a R32 GTR and, believe it or not, a FWD mazda 626 with quad throttle body injection on it. Both have aftermarket fuel injection on them. Both have known/measured CC/Min injectors in them. Both have a known fuel pressure at peak power. Both have a known AFR at peak power off the dyno. Both have known duty cycle/ms delivery time at their peak KW/HP off the laptop which allows me to calculate actual fuel consumption for each engine. This fuel consumption directly relates to kw/hp produced by the engine. The formula that defines this relationship does not change after a good arguement ( thank god for that ) Rather than bore you with the calculations here are the results instead. R32 GTR in 2WD mode on a dyno dymanics dyno 260rwkw/348hp> Calculated HP at the engine 530hp or a 35% transmission loss/tire frictional losses etc etc Mazda 626 quad T/B injection 91 FWKW/ 121 hp at the wheels > calculated HP at engine 168hp or a 27% loss for the front wheel drive. These are typical figures on our dyno for most rwd or fwd vehicles > ie: repeatable results hope this helps, Mike

well you gave a perfect description of good ol compressor surge. Unfortunately its a product of the turboes you are using and the engine they are bolted to rather than the intake piping leading to and from them or anything else for that matter. I had surge on the standard turboes on my GTR but only light and only in 5th gear on light throttle. When I upgraded to a ball bearing turbo the surge was so bad it would choo choo at idle, 50km in 3rd or 4th was a joke. Sounded like my blow off valves releasing every 2 seconds. Part of the problem was that I had adj cam gears and tomei cams set up to decrease my standard turbos spool up time. This did the trick but when I upgraded to the ball bearing turbo setup, HKS GT-SS, the cam gear set up was no good at all. It causes the turbos to make boost while the throttle is practically closed. This was confirmed when we measured boost/vacuum on the dyno pre and post the throttle plates. On the engine side I was just pulling vacuum but on the plenum side I had 2 to 3 psi boost !. This causes the air to back up behind the throttle plates and bounce backwards in the reverse direction back towards the turboes > AKA Compressor surge < creating the chuff chuff sound on light thottle openings. I set the cam gears back to zero/zero , widening the lobe centers and decreasing overlap, and the problem almost disappeared except at 100km in 5th where you can just notice it ( back to how it was with the original turboes ). Acceptable but I'm sure I could improve it some more but have not had the chance to experiment further with cam timing. As far as "tuning it out" is concerned I guess ignition timing could have a small effect and I'll try that out too next time I'm on the dyno. Mike

One of our customers car recently upgraded from high flow GTR turboes to HKS GT-SS turbos. He uses it for club racing and is very competitive. Standard heads and cams but had degree wheels fitted. Usual support mods. The only change was the turboes and split dumps and degree wheels, everything else was the same! I could show you the dyno graphs showing a direct comparison between the two but that only shows part of the story. I drove both vehicles after the tune. The GT-SS spooled up about 300rpm quicker than the high flows but felt like 1000rpm on the road. The top end of the GT-SS was 20kw or so up on the high flows but because of the smooth torque felt like 100kw on the road. The GT-SS were very progressive with throttle input because of the roller bearing core vs the sluggish response when you floored it with the high flows. They really are a very good turbo "on the road". The reality of is: There is no comparison. Dyno numbers can become just a game of whose is biggest is best, but thats not always the case. I'd rather drive a 300rwkw GTR with torque from 3500 all the way to 8000rpm with instant throttle reponse than a 400rwkw monster that doesn't do a thing until 5000rpm. Cheers, Mike

Dragging up an old post but heres my setup tuned on the 12 psi wastegates that come with the Gt-SS turbo kit. 257 RWKW at 12 psi on 95 octane pump gas. The torque curve is exceptionally flat with a slightfall off when the wastegates first crack open, at 3200rpm, as I'm not using my boost controller yet they take a while to reach 12 psi, at 4200rpm. Boost response with the throttle is instant requiring only small throttle openings to bring on the boost. Problem with that was the surge!!! I had the cams set on my original turbo settings of plus 2 inlet and -4 exhaust (tightening the lobe centers)but this certainly didn't work with the faster spooling GT-SS turboes. I had to widen the lobe centers back to standard setting the cams back to zero/zero to control the surge problem. I was getting surge at 50km/hr on light throttle on any gear. Sounded like a choo choo train and was really loud. Now I have it pushed out to 100km/hr in 5th gear and almost gone in 4th gear also at 100km/hr > drivable now at least. Will adjust the cam timing later once I've done a few miles and have some time to do more tuning. Air flow mods include: Tomei cams 260/260 at 9.15mm lift. HKS degree wheels. New uprated valve springs that will allow up to 11mm lift Major head flowing/porting job. 8.8:1 compression Greedy turbo inlet/outlet piping kit and filter kit which eliminates the turbulance where the 2 turbo outlets , meet. The air flow meters have been changed to 80mm RB25 AFM's as the 65mm GTR units were maxed out at 5.1V back at 230RWKW with the original turboes. HKS Super Drager exhaust with no cat. HKS split dumps pipes. Plenum is standard running the standard 6 T/B's. Exh manifold is standard. Tuned by myself with a Power FC using FC Datalogit software. Will post more dyno graphs showing cam timing adjustments and more boost as they come along. Cheers, Mike

R32 GTR rebuilt engine with all the usual support mods etc etc Airflow improvements: Tomei cams 260/260 9.2mm lift HKS cam gears set at zero/zero at the moment... HKS GT-SS turboes with HKS split dumps HKS Super Drager exhuast system with no cat Flowed and ported head ( work of art actually ) Greedy inlet piping kit 8.8:1 compression 0.5mm over forgies PFC computor tuned with FC Datalogit by myself > awesome software a must have! Boost running on the 12psi wastegates boost controller turned off 257rwkw on a dyno dynamics 2wd dyno on pump gas 95 octane at 12psi boost Will post dyno graphs very soon cheers, Mike UPDATE: boost increased up to 18 psi and made 290rwkw. Boost dropping off though at 6000rpm onwards. Made 324rwkw on av-gas in another car at 22psi. Pretty much at their max at this level.

hey guys, cool thread, much repeated info found elsewhere on the forums, but hey never helps to cover your bases again eh? If you have done, checked all the things covered in earlier postings on this thread and the thing still idles high... grab a can of brake cleaner and make sure its one with the tiny white plastic tube you insert in the spray can tip, and on a slightly warm engine, remembering that this stuff is flammable, squirt along the intake manifold joins ( it splits into two parts ) and along the join to the cylinder head. Some parts are a but tricky to get to but you get the drift. Also check the injector seals where they press into the manifold. Any vacuum leaks and the engines's rpm will stutter or increase as it sucks in the brake clean and burns it as fuel. A simple clever trick that will usually find a vaccum leak in 5 minutes or so and solve all your problems once you have fixed it My RB had a blown inlet manifold gasket between 3 & 4 and also 3 out of the 6 injector seals very leaking like a pig!. Fitted new seals and a new gasket and welcome 800rpm idle

Hi guys, I brought the tech edge kit 3 years ago and have brought the later model one 6 months ago. I built both of them and have found them to be excellent in form and function. I output the 0-5v to my FC-Datalogit and datalog AFRS whle I tune on the dyno. Also useful for checking 4WD's on the road as we only have a 2wD Dyno Dynamics dyno at work. Great product!

dunno, like I said we just dynoed it and the owner had his own tuner.... I had a good overview though of what was going on. The larger wastegate was a Tial 45mm boost started at 12psi at around 2500rpm gradually increasing to 17 psi by the end of the run at 6200rpm. It did exactly the same with the smaller 38mm gate when the head was standard. Spoke to the engine builder the other day and he said that the std valve springs weren't coping causing the lose of the valve following the cam at high rpm....... and hence the power maxing out > a possible explanation maybe. The modded head had solid buckets like on a GTR head, heavy (new) valve springs, special cams and valve seats fully flowed head etc. All I saw is that it made a massive increase in power at the same boost....it appears just by sorting the head and fitting a larger gate. ALL good!

could have been valve spring float....

Hi R31 Nismoid, like I said, I'm only sharing information and details of what happened.....This was our experience only. What do you think could have been causing the restriction then? Only the head and the wastegate was changed between dyno runs. turbo remained the same as did the boost . Bottom end wasn't changed, neither were the manifolds (inlet & exhuast). What do you think? cheers

hey, only sharing my experiences, tryin to help here....its not even my own car..thought you may just be interested thats all.

250rwkw is a lot of power to acheive and requires an investment in some major hardware and not just the turbo. Selecting a turbo to acheive this power level is the easy part..... As one of our customers found out, having a Garrett roller bearing turbo with an external gate capable of 500 to 550 hp at the engine and a RB30 bottom end/RB25 head with a Haltech running the show only produced 205rwkw with the torque disappearing after 5000rpm. 205rwkw is approx 400hp at the engine on pump gas (calculated using brake specific fuel consumption figures not just by applying a percent conversion, although it actually works out as a 30 to 32% drive train loss) Further investigation revealed that the restriction lied in the standard RB25 head which although in good condition could only flow enough air to support 205 KW at the wheels or 400hp at the engine. Clearly the turbo was capable of flowing more air as it was rated at 550 hp but the head wasn't up to the task. Boost creep was an issue with the 38mm waste gate struggling to control boost levels rising from 12psi up to 15 psi at 5000rpm. The run was stopped at 5000rpm as the torque and power disappeared. The engine was removed at the head fully worked with the lifters replaced with solid buckets, larger valves with copper berilium seats, large cams similair to a "stage 2" cam spec (undisclosed specs), special valve springs, full port and polish job. Believe it or not over $4000.00 NZ worth of parts and labour went into that head! Back on the engine with a larger 45mm gate fitted the car was dynoed this weekend at my work and the results were astounding! At 12 psi moving up to 18psi at 6000rpm the engine made 282kw at the wheels or 564 hp at the engine right on the airflow limit of the turbo as rated by Garrett. The run was stopped at 6200rpm as the TURBO was now reaching its flow limit! B) Thats a 75 kw gain from doing the head and gate although most of that gain would be from the head. Nothing else was changed on the engine. And remember this was on pump gas. Point is this was a great learning curve and in sharing with you guys straight from the dyno operators mouth so to speak , will help you realise just what is required to reach those dream world power figures we all read about in the mags and on the net. Take home points: Std RB25 head seems to only flow enough air to support 205 rwkw, give or take a few kw. It costs a lot of money to develop a RB25 head to flow enough air for 250rwkw plus. Doesn't matter how big your turbo is or where it came from or who made it, if your head can't flow the air you won't make the rated power of your huge turbo. At the very least CAMS DO MATTER as they will increase the air flow through the heads and therfore help the turbo make power up to its flow limit. When going for big power figures fit the big 45mm gate don't muck around with smaller ones. These are realistic real world results done in a controlled test environment on a dyno dynamics dyno in shoot out mode. This customer is a competitive drifter here in NZ and now has a top rate engine, perhaps one of the gruntiest in the D1NZ.

I did my cams with Tomei POncans......almost all the shims needed changing. Takes ages to do as you have to measure all the clearances, then remove the cams, measure the shims, calculate the new shim size thru simple mathmatics, get new shims and install under buckets, reinstall cams and check clearances again and hope they are all within spec. Assemble rest of engine. Results , once the adj gears where set up, was dramatic with an extra 25rwkw and a 15% increase in midrange torque and boost arriving at 14psi at 3400rpm.....500rpm earlier! Figures off my own dyno dynamics dyno at the workshop so no creative dyno figures, I'd only be cheating myself! Sure you don't have to redo the shims if the clearences are within spec and 'hey', we all live in a perfect world eh?

pfc will leave it for dead anyway....even if it has a sticker on it called SWAT in the end its still a std GTR ECU.....

mmm looking more like a real engine now....if only I can get it back in the engine bay....

HKS GT-SS turboes fitted and engine ready to go in:) yay! heres a few piccys

looking for posts on fuel regulators, came across this one....I have a small problem I hope some one can help me with. Dynoing a car today RB26 in a R33 GTS-T, rebuilt but run in engine with high flow turboes std housings. std head std cams , making 272RWKW at 18psi boost on a 2WD Dyno Dynamics Dyno, running a Bosch 044 pump & surge tank with a (dear I say it) Malpassi reg. The AFR showed a slight but sudden lean out at 6000rpm from 11.6:1 to 12:1 despite the fuelling numbers on the computor increasing to try & compensate. made no difference. We checked the fuel pressure gauge (one of those cheapy's that go in the other side of the reg) during subsequent runs and found that at about 5800rpm the fuel pressure would go from 80PSI steady and drop down to 70PSI. Obviously this is a symptom of the lean out but what is the cause of the presure drop? Has anyone had problems with malpassi not holding line pressure? WHAT about fuel supply line diameter, at what point do you need to increase from dash 6 standard line size to dash 8 or bigger? cheers Mike

that would be good.....didn't have a camera handy when I took the N-1 apart bugger it...thats why I took all the details down on paper.

$850 NZ. The Rb25 and the R32 GTR pump are indeed the same. We also happened to have one off a dead Rb25 and compared the two. Interesting how the relief spring have the same spring rates eh? Isn't the HKS pump worth a small fortune ?? Mike

got my N-1 oil pump yesterday and took it apart to compare to my std R32 GTR oil pump...(2 screws worked loose as they do ) here are the differences for interest sake: 1: the relief spring std has a twin spring system N-1 has a single...both measured identical spring rates at 3 different heights starting from the installed height. Interestingly the N-1 relief plunger has a small oil hole drilling about 8mm down from the top edge, level with the relief oil passage in the pump housing. This would have a dampening effect on the way the relief valve works as the spring cavity would have a head of oil in it that would have to squeeze out the small oil drilling first. Plunger size was the same and relief valve cavity was the same. 2: the oil pump gears are where the biggest difference lies. The N-1 inner gear has 1 less lobe (11) vs the std which has 12...this allows the internal volume of the pump gears to increase using a redesigned shape on the outer gear/inner gear meeting surfaces. We didn't CC the difference as the N-1 was obviously much larger than the Std R32 gear. 3: The gear hardness and material... a hardness test was performed using a proper hardness tester in the machine shop. The std gears were a 0.56 and the N-1 scored a 0.96 a marked difference! Also the gears were made out of the same material!! Sintered steel. The major reason , I believe , that the N-1 gears have been hardened is that in order to increase the pumping volume the outer gear wall thickness has been dramatically reduced thus hardening is required to keep the strength up. 4:Internal channels are all larger in the pump housing and redesigned to increase flow 5: the pump backing plate has a redesigned screw fixing arrangment with an extra screw on the N-1 ( 8 screws vs 7 in the std ) Also the backing plate is 0.5mm thicker ( 6.5mm on the N-1 vs 6mm on the std ) A note worth noting the backing plate screws were not lock tighted, needless to say that they where during reassembly!!! Cheers Mike

Tomei 9.15mm 260 duration...a very nice cam for a std GTR...Also just a note..upon setting up the head during my recent rebuild I watched the machinest setup cam lift and spring clearences etc ...worth noting is that the 9.15mm lift is the biggest that you can go comfortably with the std GTR springs due to coil binding problems. Anything over about 9.8mm and the coils become bound up...not good. I fitted slightly heavier, around 10 lbs when fitted, springs with less coils so I can fit a larger lift cam later on if I need to. cheers Mike