GTRNUR

Despite which girdle was used, what he is saying is that the tunnel wasn't measured with a micromoter before and after test fitting the main bearings. So therefore you have no idea what your main bearing clearences are. While you might get away with this for a low power street engine. That the crank spins means there has to be a few thou (or more) clearence in there. With the "competition" engine you need to have the cradle shaved a thou, install the main studs and then have it tunnel bored until the ID of the bearings measure to create at least a 3 thou oil clearence to the crank you are using. Tunnel boring ensures alignment of the main bearing saddles and allows the propper clearences to be set and matched to the crank. Tunnel boring after installing a main stud kit ensures the bearing saddles are round, as torquing the main studs distorts the bearing saddles. Imagine main bearing saddles made out of marshmellow. Steel moves the same when torquing forces are applied, just a lot less. All it takes is 1-2 thou and you have bearing damage, a spun bearing, or a crank that won't turn at all.

Your best off with a standard rb25 pump and pulley. 7000 rpm isn't a lot, and you will find that your average RPM will still be around 5000 where peak torque is. It would depend on your climate and what your doing with the car. If its a street car and your average ambient temps are below 30 degrees then it would be fine.

I've seen oil overflow/restrictor problems with single and twin 2860's. I believe it was BoostedR with his 2860-10 equipped 500kw RB3026 R33 GTR that was also having issues getting his restrictor sizes correct. I also read about someone with a white R34 GTR that saw a fair bit of track time that was having issues stemming from sustained high RPM/high oil pressure. I am not alone in having experienced this. Like I said, one size doesn't fit all applications. A restrictor will limit flow for a given oil pressure, but once oil pressure exceeds a certain point the restrictors must be made smaller. Same principle as the head restrictors. I am sure that even GCG would tell you to run a restrictor if your oil pressures are reaching 100psi+ at max RPM, because the out of the box GT2860-x series turbo's are designed as a bolt on upgrade where oil pressures are that of a STANDARD engine, not a modified one.

Back when I used to listen to what people told me... I had heard that statement many times before as well. I beleived it too, until I had first hand experience with oil in the intake and exhaust because the 3/4" oil return couldn't copy with 75psi oil pressure. Then I was advised to replace the turbo for a new one, only to continue having the problem. Nobody ever asked how the turbo was getting its oil supply, which was a -4 braided line from a main gallery on the block. Magically my oil problems went away when I used the atp turbo restrictor at the turbo.... that everyone told me I didn't need. Perhaps they mean its "built in" to the banjo fittings. While I've not seen a HKS turbo kit new out of the box, I would suspect the additional restrictors would be used for those applications where people are using a high volume pump such as the tomei or HKS pumps with the oil pressures dialed up to 100PSI or more. In those situations an additional restrictor would be needed. There is no one size fits all applications. I can say from experience that the HKS turbo's work fine with the standard oil plumbing and restrictors provided the oil pressures are kept at the factory levels of not more than 7-8kg/cm. Im using GTRS's with factory restrictors, tomei pump(no additional shims) and 20w50 oil with no issues in my car.

I'll save you the search.... all standard and vspec R32/r33/r34 gtr turbo's are ball bearing and ceramic turbine wheeled. N1 options are steel wheel, and ball bearing. All require restrictors. Even bush bearing turbo's require restrictors. If you run any turbo without a restrictor, expect to see oil in your intake and exhaust as the oil can't escape down the drain quickly enough. Only with very big drains will you not get an over-flow issue, but its still not the right way to do it. The Trust T517z's bush bearing 8cm and 10cm kits for example come with restrictors in the banjo fittings that go into the turbo's. They are a different size to the factory restrictor.

Only after market lines use a restrictor at the turbo when you are feeding it with a -4 size hose from a main oil gallery. The size restrictor you need for after market lines can be found on www.atpturbo.com. If you use the factory oil lines, there is no need for an extra restrictor. Where the oil comes from the block, the banjo fitting that goes into the block has an internal restrictor. I think it is labeled with an "M" on it. The factory lines are better quality than anything else on the market anyway. If your coolant and oil lines are looking a little shoddy, take them to a brake line place and have them nickel plated. They will look like new then, and you will also get addicted to plating everything that unscrews from your engine bay!

The data to calculate the propper ring gap is in the CP pamphlet that comes with the pistons. There is a multiplier that is used to calculate the correct clearences for each of the ring packs which is based on the bore diameter and the application of the engine. The multipliers are based on the known thermal expansion that the rings will undergo during combustion. Different piston manufacturers use different ring materials, so the multipliers will be different for all ring manufacturers. If you are using special rings like Total Seal rings, then use their specifications and not CP's. A similar rule applies to the piston to bore clearences. Many people belive 0.003" is correct, but this is not true. The engines purpose combined with bore size and piston composition, are the factors that determine clearences. If you really want to make your head hurt, think of what piston coatings do to the equation. Using coatings to make the pistons run cooler means they will expand less, and as a result you get more blow by as they don't expand to seal the cylinder bore 100% correctly. Since nobody has a means of knowing the piston crown temperature reduction, there is no real way to be sure of how much tigher you can make clearences. If you haven't filed rings before, go very slowly. You will quickly learn how the rate material grinds off the rings works with each different type of ring. Each of the rings (top, middle and oil control) will file at different rates due to material and thickness. You can't add material back if you go to far. It might be overkill, but I also measure the ring gap in the bore with the ring sitting at the height that it will be when installed on the piston at TDC. Just use a vernier caliper with the adjustment lockout to set the ring height from the deck.

He's keeping the RD28 block and replicating what he had with some improvements. Availibility of the block is the main factor though. RD28 blocks are easier to source than RB30 are for him.

Possibly on the GTR UK forum. Its from an 8 second R32 GTR in Urkaine. He ran an 8.16 with this setup. A rod went through the side of the block though, and now a new engine is being built to replace it.

I'd be interested in a Ross balancer with a smaller drive on the AC compressor. Even on 38 degree days my aircon can crank the interior temp down to a good freezing temperature, yet at idle speeds its loading the motor up more than it needs to.

Im pretty sure that most of that strength advantage of the RD28 block begins to dissapear once you start boring and stroking them. The only thing that would help a little is the external coolant return from the head near the back of the block on the right side. The standard bore being 85mm does make the cylinders thicker, but in order to maintain coolant flow between the cylinders in the block, the OD of the sleeves is still around 92-93mm maximum. So 4mm cylinder wall thickness at best with a 85mm bore. The ability to run the squirters would dissapear with larger strokes as well unless you were to slot the crankshaft like an OS giken crank, or like I did when fitting my modified RB30 crank to the RB26 block. You have to clearence the sides of the block for the rods when the stroke is greatly increased. See the attached picture and how close the No3 rod bolts are to the side of the case, and the required case clearencing. This is an RD28 with a 90mm stroke. There will be 1mm clearence from the rod to the crankcase. The main caps are billet alloy and the main studs are offset drilled from the standard 10mm holes, to 14mm. The standard RD28 cradle wouldn't clear the 90mm crank. Being in Australia its really hard to pass up on the RB30 block just for how easily they are obtained and adapted to an RB26 head. In my opinion, there are other opportinities such as sleeving that people should really consider a lot more befoer heading down the RD28 conversion path.

I for one am plesently surprised to see someone put together an engine/turbo combination where the turbo isn't running at 50-60% of its capability. While the motor may run out of legs at the redline, really who cares! It will still make 700hp and its mid range power will be simply monsterous. And if you want to go faster you just change gears.

Great stuff Bobby. So I guess the pipes for the header slip inside the recess in the flange, and then they are internally tig welded? 321 stainless is an interesting material and it doesnt thermally expand in a linear fashon like many other common engineering materials. The hotter it gets the more its expansion rate increases. Will John be seperating each of the exhaust outlets once the welding is all done, so as to allow each header flange to move with the expansion of the head?

I do wonder if some of you guy's just love working on your cars for the hell of it. I hate pulling plugs and get paranoid about scratching the paintwork on the engine when I have to. There is nothing wrong with using iridium plugs in a modified engine provided you tune the car for it accordingly. You will be able to get a better economy tune with Iridiums as well, because they will survive higher combustion temperatures much longer than a copper plug. Im using BKR6EIX re-gapped to 0.8mm, standard coil packs, and run 1.75 kg/cm boost with easily over 500hp atw and the engine never miss-fires. About 18,000k's on the engine now too and have only pulled the plugs to compression test it. You can't keep your AFR's extremely rich (10.5-11) with the iridiums though, as they will carbon up faster than a copper plug due to there being less plug surface area. I feel the most common reason people (or some tuners) go for a copper plug is that they allow that super rich or "safe" tune to still run once you have drowned the plugs in fuel. Really, copper plugs are the "old school" approach of allowing a rough/rich tune to still run. But if you tune it to run 12:1 at full load and richen up to 11.8 - 11.7 past 6500-7000 rpm and you will make better power and be able to run the iridium plugs. The richer AFR's past 7000 keep your EGT's safe where they need to be while you will get better power and torque from down low through mid range RPM's. You can also easily run 15.5:1 at 100km/h cruise speeds on an RB25 and crank in the ignition to achieve great fuel economy. Im running 16 - 16.2:1 cruise AFR's (@ 100km/h) with my stroker motor and still have safe EGT's. The leaner cruise combustion temps will burn off any carbon build up from when you are hard on boost. Try that with a copper plug and they just don't survive the sustained 800 degree plus combustion temps.

HKS Vcam? I'd laugh if that allowed you a choice of 3 gears for any corner!

I agree with you, but look at the JZ piston designs. They run a massive crown thickness above the top ring. If the 2nd ring and oil rings are intact then you won't get oil above the piston crown and in the combustion chamber.

My money is on that the rings aren't broken, but the ring land for the top ring has failed. Listening for where you can hear compressed air escaping from most when doing the leak down test will give you more clues. Sump, head, intake exhaust. If you hear anything in the intake or exhaust, its valves/seats. You shouldnt hear anything (or very little). If its either of the other two, combined with a bad result and its a head off/engine out deal looking for bad valves and seats, or a broken piston/rings. Stem seal leaks will only have an effect on the cylinder when a valve is open, and have no effect at all on cylinder compression.

Great stuff Paul, and those data logs are interesting. Has me wondering if anyone has thought of putting a dynamic tensioner on the timing belt to try and keep the cams more stable. The EJ20s uses a high tension spring loaded tensioner on the slack side of the belt to take up the belt stretch when the engines RPM accelerates. It makes sense for those motors as the belt is a lot longer than an RB26 belt. It would be worth looking at how the 1UZFE handles belt tension too, as well as they have a crazy long belt.

In my opinion getting a good result that will last more than 5 minutes after you drive it off the dyno is going to take a little more than just a tune. There are too many unknowns. I only just noticed the stock rods that were spotted by someone else. That alone raises questions over the quality of the rest of the build. The engine is going to need to rev to 8000 with 35-40lb boost get the most out of it, yet only some of what is needed to make it reliable at that speed is there. And especially there is a question mark over what the clearences the engine is setup with too. Clearences will determine if it spins a rod bearing 5 minutes after the dyno tune. The small wastegate will present run-away boost control issues when the boost is cranked up. It will potentially climb out of control as it won't be able to flow enough exhaust gas despite being wide open. This will only present as an issue once the boost is really cranked up. It should have something around the 45mm size minimum, with at least 25psi of springs in it so it can have a hope of holding boost pressures once your boost controller starts regulating the valve. Regarding the head and the combustion chamber. This is a standard combustion chamber: This is has had both pads removed: Less pads = more head cc's and less compression. The Microtech isn't technically holding back the capability of the engine, but it does limit which SKILLED tunners will be willing to tune the car. My recommendation is to have the engine pulled down and re-assembled by someone that can set it all up the way it should be. That same person will be responsible for tuning the engine (or at least be able to communicate well with the tuner). The tuner will be the one that will determine what ECU you should be working with as well. Link or Vipec would be the most common and no doubt the best way to go for the big power setup you are after. You are going to have to take your time and be patient with sorting this out as well, or it will cost a packet load more money. If you come up short trying to find a builder that you can trust, I would recommend contacting Paul at Red R racing and send the engine to him to have it rebuilt. He could do the forensic strip down and reassembly of the motor and set it up specifically to make the power you are after reliably. Once that is done you could have confidence that it isnt going to turn into an expensive bomb when you least expect it. As it is at the moment, anyone that tunes it can only tune it to be safe. Least they begin to lean on it hard and something might fail, and then the have to face the expensive repair bill potentially caused by the builder.

Im using a 100mm Nismo z-tune core and the bar had to be trimmed a little. The tags that hold in the mesh had to go, as well as a few notches to accomodate the welds. This didnt worry me though as I was intending on getting a nismo front bar eventually anyway. Regarding engine temps, they aren't a problem provided you use a GOOD core like a Nismo or something else high end. Today in traffic I saw 44 degrees as the air intake temp on the MFD. Engine temp will sit around thermostat 68-70 and oil at 80-82. Sitting in traffic stationary with the aircon on will see the water temps rise up to 80ish which is still very safe. Dam I miss the cool climate of Victoria, and seeing air temps of 10-11 degrees!

How about some maths. RB30ET pistons have a 10cc dish. Assuming a 87mm bore, standard stroke, standard head gasket and zero deck height on the block, the HIGHEST your compression ratio will be is 7.37:1. That is assuming your head's combustion chamber hasn't been re-worked. Now factor in the head work. Considering its a RACE PORT head, which doesnt really elaborate on what has been done, the head CC's are really an unknown. But for calculation sake, lets assume that one of the quench pads has been machined out, then the head CC will be near on 68cc. This puts the compression ratio down to 6.93:1. But wait, it gets worse. Those camshafts with their combined overlap and duration will lower your dynamic compression to at least 6.5:1. What all this means is, your cylinder pressures are all pretty much spot on for how the engine is setup. Compression ratios directly effect the cranking compression of the compression test. With standard cams a 3lt motor: (also depending on how they are dialed in) 8.0:1 will net about 115-120 psi 8.3:1 will be about 140-145 psi 8.5:1 will be around 150-160 psi Compression ratio is your main issue. Your options? Well you if you aren't disapointed with the off-boost drivability of the car, there really is nothing stopping you from really cranking some serious boost into the engine. Around 30psi at least would be where I'd start the re-tune at. With this level of boost you should be seeing at least 625-650hp at the tyres. You will have to watch the fuel closely though as the injectors will me maxed if your reving 7500-8000. It could really do with a set of ID1000's or bigger. Once you up the fuel injectors a little, you should be able to crank it up to 40psi. Keep in mind that I have said this with no idea what the engine has been built for. If your builder understood that you would be leaning on the engine a lot to make some big numbers and the bearing clearences are setup accordingly then you should be fine. You will pickup a little more dynamic compression and off boost drivability by advancing your intake cam a few degrees, but this should be done with great care and only after consulting your engine builder. Lest you end up bending valves. Short of swapping out the pistons for flat tops or domed pistons you won't pickup more off boost drivability any other way. This engine will not tune even remotely like a normal RB. It will tolerate considerably more ignition while under load/boost than an 8.5:1 cr engine. So much so that if you run values that would work in an 8.5:1 engine your combustion temps will be elevated and will induce knocking early. (making the tuner put in a soft tune) At 20lb boost this engine will still have at least 24-25 degrees of advance at peak torque(6000-6500 rpm or so). That would kill most RB's instantly, but not yours. Making this motor work will be all in the tune.

Hi all, I have a set of CP 87mm custom design pistons that are setup for use in a stroker motor. There are a lot of possabilities with these pistons. A few of these that are easy to achieve would be: RB28 stroker: 77.7mm stroke, Rb26 Stock length 121.5mm rods, 1mm head gasket, 8.11:1cr (64cc stock head), 8.34:1cr (62cc shaved head) Brian Crowler RB28 Stroker: 79mm stroke crank, Rb26 Stock length 121.5mm rods, 1.6mm head gasket, 8.23:1cr (64cc stock head), 8.46:1cr (62cc shaved head) (0.65mm positive deck height) RB30 options: RB30 cranks up to 93mm can also be supported with a stock length rod and a zero deck height. 94 would be a 0.5mm positve deck. If you wanted to do something with offset grinding an RB30 crank and using 19mm GTiR sized journals, and 87mm stroke with a 6.125" rod would also fit nicely. I can make a crank to suit if this is something that interest you. SR20 rod journals remove about 50-75 grams of recipricating mass from each rod, and about 50 grams from the crank. Full specs of the pistons are: 87mm bore 28mm compression height (32 is standard) 5cc RB26 Dome profile 21mm wrist pins 5.5mm crown thickness These were a custom piston I had made for an early design of my open deck engine, but were never used due to a design change. The only time the packaging has been opend has been to photograph them. Cost me $1500 to have made. Will sell for $950 delivered in Australia. Also open to offers for swaps. PM me if you need more detail. Ph: 0434 147 478 Cheers, Ian

Dumps are sold.

Sold and shipped.

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