Dale FZ1

^ +1 The original post leads me to suspect your ECU is stock RB20 without mapping adjustments. If so, of course it will run poorly. Time for a remap.

Sticking with the general theme of the thread, who can share experiences regarding oil pump spec and restrictor sizes regarding lifter bleed out? Clearly this relates to 30/25 with a non-Neo head. I'd presume very few of us would be running dedicated track cars with this setup, so quiet/smooth operation is still high on the list of priorities. ie. I want to avoid bleed out due to too much reduction in oil delivery to the top end. My setup is 25DE oil pump (stock) non VVT head internal oil drain-backs in head + block drilled oversize to 9.5mm restrictors 1.6mm (F) 1.2mm ® and (hopefully) catch can with drain-to-sump engine speed < 7000rpm application: road, motorkhana, club sprint

It will be getting a good clean out, no worries about that After spending max 30 mins from start to finish on removing the original restrictors, I'm now of the view that there is no reason to leave them in. Very simple - drilled the hole oversize, tapped in a 5 x 0.8mm thread, sat a socket or tube over the top and then wind in a metal thread. VERY EASY. I was expecting something difficult, given the various threads that promote the idea of knocking them down further.

I also have little idea of fluid dynamics, but the restrictor is just that - an orifice rather than a tube. So restriction would be causing the reduction in flow rather than friction I would think. All the same I don't want too much in-depth analysis but threw up the idea given your start up noise. If it is lifter noise only then maybe not a problem. I've heard from more than one source that using a 10W60 oil is an important part of the equation of making this setup work optimally. Interesting to hear that your mate with 2 x 1.1 restrictors had problems with noisy lifters. So at the least it appears to be important to stick with SK's guide and go 1 x 1.5mm and a bung in the rear?

It'd be nice to have that as a viable option and not spend a lot of $$ achieving it. The increase in combustion chamber volume would require a corresponding increase in piston dome volume to maintain static CR. I suppose forgies are available in that configuration. Going the budget route of stock 30E type pistons, limited boost (1 bar) and rpm should see a healthy result but means retaining the quench to even keep CR ~ 8.3:1. Any comments from those who have done the build and know their desired clearances? At this stage the minimum of 1.00mm is still winning out.

If the cold start-up noise is somehow related to the elimination of the rear feed, I can see the logic in retaining both feeds. Here's a variation on the theme, using the idea that a single 1.5mm restrictor otherwise supplies enough volume during operation: MIG tips are available with a 1.2mm orifice. Cross sectional area - 1.13 sq.mm SK's preference of 1.5mm restrictor provides cross sectional area of 1.77 sq.mm Install 1.2mm restrictor front and rear gives ~ 2.25 sq.mm so slightly more flow than 1 x 1.5 but way less than 2 x 1.8 or 2.0mm as stock. Similar end result and maybe avoid the issues Cubes identified. Could be wide of the mark and solely related to hydraulic lifters but worth raising. Comments?

Thanks My only thoughts were for avoiding pushing it too far down and becoming a floating obstruction. If removed I guess it gives me some access to clean galleries before installing the new ones.

What is the typical piston : head clearance targeted by any of you RB30 builders using a head with the quench retained? I've measured my 25DET bottom end, found the lower flat areas are proud of the block by .011" @ TDC. I'm intent on retaining a similar relationship between piston and quench in specifying how much to deck the RB30 block. Discussing this point with a mate, he's suggested a minimum clearance of 1.00mm to allow for rod stretch, and carbon buildup. His view makes sense. If I specify .015" decking, this would yield 0.97mm clearance when using a 1.3mm HG. Any ideas / experiences / warnings?

Looking at the oil feeds, who here follows the method of driving the original restrictors further into the block, and who has taken them out before installing new ones? If removing the old ones is it a screw and slide hammer job?

What are the typical torque settings any engine builders here have used on their RB30 bottom ends?

Ignore anything you've read about ADM vs JDM variances - there is none in that regard. The difference in flow capacity comes from whether the vehicle was fitted with an auto or manual transmission. MT = 450cc/min - terracotta brown colour AT = 370cc/min - purple colour R33 spec RB25 = 370cc/min, exactly the same as the S15 AT. Flow rates are @ stock fuel pressure. IMO the S15 injector is a good bolt in upgrade provided your ECU can be adjusted to recognise the different flow capacity. Same situation for upgrading the AFM really.

Cheers Dave, good info that makes sense. I expected that the pump delivery should be geared to the bearing clearances, and what you say is logical. I'm relying on the ability of my machinist, but want to be sure I'm going about it the right way. Somewhere I'd seen a comment advising against the use of plastigauge to check journal clearances during a dummy assembly. Anyone care to advance a reason why?

I want to have an idea of what range the various clearances should be at when screwing together the RB30 bottom end. So to those who have solid, experience based opinions, could you give an indicator of Mains Big ends Thrust clearances that should be the acceptable range? As an amateur builder I'm interested to see what others chase. Engine to be set up for street + occasional track, RB26 oil pump, head feed restrictors, 6500 limit and ~ 15-16psi boost. Stock rods and +0.5mm cast 30E pistons.

Good information, thanks both of you. So what is the source/spec of the spring to use with the additional tensioner? Or are you going without?

Nearly caught myself out there with moving the tensioner mounting point. You're obviously referring to moving it further towards the right side of the car, or further left of centre as you look at the front of the block? ie the "other" right? Makes sense and an easy adjustment to make before drilling/tapping - thanks fellas. Clearly the suggested use of two tensioners in the guide is another approach to address the issue of getting enough belt slack to make installation easier. So are there many people who've done this, and was sourcing a second spring for the additional tensioner difficult? It's all minor detail stuff, but interested to find out anyway.

I’m looking for ideas / experiences with the idler / tensioner setup on the 30DET. Having checked out the guide, I’ll be going with one high, one low. I do see clear value in moving the position of the bearings. The question is whether there is any net benefit in using 2 x tensioners – other than saving a few $$ on the difference on the higher priced idler? It appears that either setup works quite ok, so is there any consensus on what is “best”? And does the use of two tensioners require a different spec timing belt. Timing belt wise, I’ll be using either a Dayco 94407, or Bosch T866 which are both listed as 152 teeth x 25mm wide.

Try a couple of searches, but some threads over the past 6-10 months or so indicated people were having a few problems with adequate boost control. Comments were generally directed towards boost creep (rising with revs, rather than hitting a target and staying level). It may be an issue limited to particular turbine rotor : housing combination so you'd have to inquire with those users which particular spec cartridge was used with their turbo. FWIW, the cropped 56.5mm version of the GT30 turbine comes in an 84T and 90T spec. I don't know for sure, but suspect the 90T would have better venting and flow capability than the 84T. But there is a fair bit of science in getting the match right between rotor and housing so that internal aerodynamics work ok. Regardless of who you're buying from, the advertised "bolt on" units are evidently built around a copied version of the OEM Nissan/Hitachi OP6 turbine casting as used on the Neo RB25 and VG30DET. I believe there are other sellers in Aust besides those mentioned who are shifting the same product. Due to the mix'n'match of rotor and housing, it is viewed as a wildcat and there is not likely any technical info available from either the seller or Garrett. Worth doing a bit of searching and maybe a PM or two to those owners to see how they ended up working out. Let us know how things go please.

A compressor map shows the flow capacity and efficiency of a given compressor across a range of pressure ratios. Doing all the calculations will get you into the ballpark of what the compressor can do to support a targeted level of engine performance/output. But you can't ignore two things: 1. The compressor ultimately feeds, and is driven by, a turbine. So turbine flow capacity and efficiency is as much a determinant factor on what the turbocharger is capable of. A bigger turbine A/R can liberate more max hp, but it may be detrimental to overall engine performance if it slows down turbocharger response too much down lower in the (engine) rpm range. 2. Engine airflow efficiency is also a governing factor of output. It is entirely possible to achieve more hp from a given engine:turbocharger combination by virtue of improved breathing into, through, and out of the engine via manifolding, porting, valve size increase, and cam spec. There are various ways of getting that bit more. Some approaches are going to prove expensive and add just a small % overall improvement, while others are much more productive. As the power output gets larger, so too do the hurdles (financial and engineering) you face to make good % gains and maintain reliability. Don't view the numbers you've quoted as absolute, but as a pretty good guide and you'll do ok. By way of example, two members here are running GT3076 combinations on a RB25 and and RB30/25. Both have hit a ceiling of ~ 310-320rwkW, which puts them around 500 crank hp. That is right what Garrett rate that turbo's capacity at. Hope that helps clarify things a bit.

RB25 doesn't have the pressure feed on the comp housing for wastegate actuation - there shouldn't be a fitting there. RB25 housing is noticeably (visible to the eye, and measurable) larger in cross section which means it has a larger A/R and flows more. RB25 compressor impeller is larger in all critical dimensions - inducer and exducer. That means as you look into the throat of the compressor, it will look bigger. Verniers should measure up the throat larger too. If you pull the comp covers off you will see very quickly.

As I see things, you have a nominal vs actual volume. They could be the same, might be different. It should be measured if you are trying to select correct parts to achieve a target CR. That aside, I believe the chambers for a 25 and 26 are the same. Mine measured at 65cc consistently. Searching recently, I saw a comment from Sydneykid in an old thread that he had seen ~64cc. Nothing wrong with my gear, so it's reasonable to expect some variation. Hope that helps.

What sort of race duration do you call long distance? Have you checked out the fabricated manifolds done by Full-Race? High quality items, and sale of the HKS units you have would probably cover the purchase of one. Send them a message and find out. Alternatively speak with 6boost and get something direct from Australia - he has an excellent reputation. Either way you'd be getting away from cast iron if you have concerns about the HKS gear being able to survive circuit race use. They (HKS) might crack, but I doubt they'd fail. Turbo-wise you'd best consider using an external gate setup. For the required power IMO it would be hard to beat a single GT3582, probably in 0.82A/R for a balance between lower rpm response and high rpm breathing capacity. I have nothing against twins, and there is plenty of experience on this board with the various GT2560 combos, but I think the single would lose nothing in terms of response and be easier to access for general maintenance/inspection work. What is the targeted useable rpm range BTW?

If this is occurring during/after a session, have you considered the type/grade of oil you're running? I wonder if once the oil is hot that it is simply a bit too thin to maintain adequate pressure in the hydraulic lifters and they are bleeding out a bit? Maybe something like a 10W60 is what you need.

In much the same way as increasing A/R size of the turbine housing, extrude honing should allow the manifold to increase its mass-flow capacity. ie. it can just put more exhaust flow through more efficiently. You have to look at it from the perspective of pressure gradient across the engine, not just inlet boost pressure. That the car did not make any higher peak power supports the general observation that the stock manifold is good for ~ 300rwkW of flow, and a 2835 with 0.68 A/R turbine is a touch short. Waiting for comments from those who have exceeded 300kW with those components, but also want to know how comfortably and reliably it was done...

Could you have a graph overlay posted up showing before/after comparison? Shame that there was no quantifiable improvement, but it'd be interesting to hear if there was any different on-road feel to how it drives. I tend to agree that ~280rwkW should be pushing the max flow capabilities of the 2835. What sort of price range to have the extrude hone done?

Probably firstly depends on the crank journal sizes - how much difference is there between the VG and RB rods? You'd need things side by side to measure up, and maybe look at a dummy assembly if you can get the bits at low cost. Alternatively, why not look at just using RB25 pistons and deck the block by the required amount? Sure you might be retaining cast pistons and stock RB30 rods, but gets the result you want. There should be a number of viable ways to achieve a similar outcome. It takes $$ to put in the parts that make for a stout 30DET, but the lower spec pistons and rods would still make for a good street build IMO.