the phantom

The dipstick assembly is just an iterference fit in the block hole. If you genty twist it you can lossen it and carefully keep turning back and forth until it comes out. Alternatively you could use the correct size drift and tap it out of the block from below.

Thanks Gradenko and Sydneykid, So past a certain duty cycle, the whole argument of sequential vs batch becomes irrelevant, as the distinction between the two then dissapears??? Sydneykid, can you confirm that with standard rb25det 370cc injectors that going from 38 to say 76 PSI fuel pressure doubles the flow to 740cc, ignoring the reliability issues you have warned about??

I used to have a pillar mounted autometer a/f ratio gauge as well. And I thought the exact same thing. It had a spot for a bulb, so naturally I tried putting one in but the internal circuit board seemed to foul any such attempt. I was left thinking that it was just a case of autometer reusing an existing guage cup assembly. There didn't appear to be any form of light guide either.

Hey Steve-SST, Does the Wolf 3d you have mentioned have fully sequential injection for the R33???? Or does it have only the 4 injector drivers requiring a semi batch arrangement. I cant help thinking this is pivotally important in explaining the great power outputs you've achieved with this ECU. According to my knowledge, fuel pressure increases do not equate linearly to injector flow. I know Sydneykid made some calcs previously and relieved his puzzlement, but he also suggested linear flow increases with pressure. Unless someone can confirm this relation, this leaves the sequential/batch argument for the explanation. Does this explain the huge power levels with plenty of reserve duty cycle that keeps being mentioned???? With any batch firing the injector would fire twice for each cylinder rather than once per 2 revolutions as per full sequential, thus explaining the ability of 370 cc injectors with only marginal pressure increases being able to support such outputs. Firing twice would make a 370 cc injector appear like a 740cc, except that half the fuel waits around for a bit before being ingested. In the FC with its sequential firing, does this explain its quick duty cycle limitation. In this system the injector has only a certain number of cam shaft degrees when the inlet valve is open to squirt in the fuel. As it ALL has to be injected at once, and since the inlet valve is only open for so long, the "duty cycle" limit simply means that the valve has closed and so fuel injection can no longer occur. If it were to keep going passed the closing, then the sequential idea would be lost and it would essentially become a batch system. I have no intention of making a wolf/FC comparison here...I just want to know whats going on.....

hey rb20-calais, I meant that the pressure by my calculation (rightly or wrongly) would need to be 69.5 + 18 = 87.5 total at 18 PSI boost. With boost fighting against the fuel as it tries to escape from the injector, at 68 PSI fuel pressure and 18 psi boost, the effective pressure across the injector is still only 50PSI...68-18. The regulators just try to maintain a constant pressure across the injector, unless you have a regulator that is greater than 1:1 when you will then add to the effective pressure.

Thanks for clarifying the dyno point GTS-t VSPEC...fair enough, One query however that puzzles me. Perhaps its wrong and someone can correct me with their experience. I was under the belief that a pressure increase across an orifice such as an injector does not equate linearly to flow, i.e. there is a square root term in there. So for a 39% increase in flow you would need 1.39X1.39 = 1.93, which implies a 93% increase in pressure, i.e 69.5 PSI from 36, not the 50 PSI indicated??? Are you still running the standard exhaust manifold GTS-t VSPEC or do yo have a custom manifold???

The dynopac dyno is a direct drive hub dyno is it not?....Are we not comparing apples and oranges again??? I dont mean to get the absolute power dyno debate going, but without the tyre/roller loss surely numbers are inconsistant. Not meaning to take anything away from the outstanding result, just trying to understand these numbers. Also, on the "411 from stock internals" thread it is mentioned that the standard injectors are running 40PSI. Doubling the pressure would increase flow by 41%, so a 10 PSI or so increase is not much...maybe 15% or so more flow...bringing it up to about 425cc/min per injector....

Hey Steve, Ok, can Steve-SST confirm wether wolf P&P is batch or FULLY sequential....i.e 6 injector drivers, so we can debate knowing all the facts? I know he previously mentioned sequential ignition, but didn't stipulate for injection...or I just plain missed it somewhere.

I think a bit more scrutiny is required in what exactly injector duty cycle means in batch and sequential systems before one can suggest "better drivers". Correct me if I missed a detail in the previous posts, but the Wolf still has 4 injector drivers??...meaning that 2 cyclinders in a six must be squirted at once? If this isn't the case then you can just ignore the remainder!!! I haven't tested and confirmed what I'm about to suggest, but I would guess both Sydneykid and Steve-SST can confirm or deny. In a sequential system 100% duty does not mean the injector remains open until the next time it is commanded to squirt. Rather, 100% duty means that the injection time has fully occupied the time available when the inlet valve is open. The former would render a sequential system a batch system, would it not? Is the 430 odd rwhp mentioned a result of standard injectors being batch fired rather than sequential, therfore allowing more fuel to be squirted in and just 'hanging' around until the inlet valve opens? What was the fuel pressure, and was any 'rocket fuel' being run or was it just 98 pump. Good effort by the way!

I forgot to stress the assumtion that the BOV be plumbed back to the intake....

Apologies for appearing to hijack your thread and moving off topic. That wasn't the intention, just thought you and others might want to learn more about a related subject in which detailed information is very rare. Even rarer is finding someone with Sydneykid's experience willing to share some of this knowledge...

Hey Sydneykid...how about some further comments on overbalancing....

No, the opposite. If its tight you will get reversion as the BOV doesn't open unless you have been at full load i.e between gears at redline, or otherwise drawing a huge vacuum. For low and medium loads insufficient engine vacuum will exist to overcome the spring, rendering the BOV useless. The subsequent reversion (compressor surge) event will lead to instability as the ECU attempts to follow the wildly varying AFM voltages with your fuel map. If this happens as your comming to idle, a stall is likely to follow, particularly if your AAC valve isn't quite what it used to be, and you have a larger than stock turbo. Therefore a slack BOV will guard against reversion and allow the AFM to provide a 'smoothe' response to the ECU. This is what the traces show in my previous post. In other words....leave it slack....even to the point of it being open at idle. As soon as you get on the power the boost will assist the spring and keep the BOV shut. The trick is to adjust it appropriatey at low/medium loads if street drivability and an extended turbo life are part of your agenda. It is also worth mentioning that even though I have a PowerFC on my car, and swear by it, it has an inferior idle control strategy compared to a factory ECU in regard to AAC valve operation...this may be more relevant to the 'other' thread however, and is a whole other story....

This "fluttering" is also a major factor in engine stalls when comming to a stop. I was investigating stalling issues on my car a while back and did some measurements with an oscilliscope on the AFM. I've attached an image of AFM voltage with a "loose" and "tight" BOV. Note that the "tight" setting produced audible "flutter" through the AFM after a rev, and this is seen as the severe oscillations in the trace indicating reversion due to compressor surge.... phantom

The R31/VL RB30 block hasn't got the integral 4WD sump mounting wings that the RB26 has for 4WD applications.... The Japs do perform this conversion....they resleeve an RB26 with taller cylinder liners and a thick deck plate with a longer stroke billet crank....i.e OS Giken 3.0 and others. Rumour has it that the RB26 block is structurally stronger than the RB30 however....

Having been left intrigued by Sydneykids mention of overbalancing vs crankshaft harmonics I have attempted to dig deeper into theory to try to explain it or at least understand what is going on. Very little is out there on this specific subject however, with only a few good texts found at the local Uni and state libraries, explaining engine balancing and vibration theory for the various engine configurations. Anyway, based on closer scrutiny, I have changed my mind in regard to the previous hypothesis I made regarding the mechanism wherby this is achieved...it is much more complex. Since the crank is essentially a complex torsional tuning fork, two mechanisms exist to alter this frequency. One is material stiffness, and the other is weight. Since there is not much you can do with the stiffness, other than perhaps nitriding or some other treatment, this leaves weight. By overbalancing I can only assume added weight on the counterweights over and beyond the factory level, possibly with a heavier-than-steel tungsten alloy inserts. This would effectively lower the frequency of vibration. Theoretically at least if you double the weight you would also double the inertia. Relations show then that the resonant frequency of each crank throw would also lower by a half. The resonances are still there, but have shifted in frequency leaving the more power productive 7500 RPM plus region clear for a hammering. Ofcoarse this leaves the 3750 RPM band at a peak, but since we are probably talking full on race engines here that isn't a problem, particularly if the critical RPM is quickly passed through and that relatively little power will be made there. I am left curious as to how the standard RB30 crank handles the lateral as opposed to torsional crank deflections at these ludicrously high RPM's. Perhaps this is the reason for the heavy crank girdle made by Nizpro on their powerhouse RB30/26 hybrid with a standard based crank. Although heavier counterweights would help counteract this, the RB30 standard crank has NO counterweights directly over number 2 and 5 crank throws. Compare this to the OS Giken 3.0 billet crank which has EVERY crank throw counterweighted an as such would greatly assist in reducing the lateral deflection. No girdle is used on this engine either, which one can only assume is because of the superior stiffness of the billet crank. These counterweights present opposite all of the crank throws are also significantly bulkier, which is in line with what Sydneykid is suggesting....and the OS engines supposed ability to reach over 10000 RPM. This thread however began with a discussion on light weight accessory pulleys and harmonic dampers, with their lower rotational inertias and theoretical power gains. The MUCH heavier OS crank would have significantly higher inertia, but since the engine can handle such absurdly high power outputs anyway, this is obviously of secondary relevance, even in the super time critical world of drag racing.... I await Sydneykids further input into this discussion with great anticipation...

Hey Sydneykid, I was wondering how long it would take for you to bite... Yes harmonics are indeed a fascinating subject. Hmmmm...overbalancing...an intriguing concept...and one that I've only rarely seen made a frustrating mention in my theoretical travels. This will no doubt occupy considerable brain time on my part. My inital hypothesis of the notion is that an artifical harmonic is induced through the overbalance, such that it destructively interferes with the troublesome primary natural harmonic at 7500RPM.... I assume you have built engines to this specification. How do they perform and survive the onslaught? The Phantom seeks harmony from the Oracle....

I just tapped the hole and used a socket head grub screw with a bit of loctite to be sure it never leaked....done 50000km in it and havent had an issue....

Hey DESCR8, I was under the impression that ATI dampers are a twin ring elastomer type af damper. According to their website actually. They have some good info there. The only fluid type damper I know of is the "Fluidampr" marketed by another American company. I am also building another RB30DET although not as intense as yours, just as intense as I can go still keeping it daily driveable...read reasonable engine lifetime. I've done a lot of research on fluid type dampeners and I personally am looking into using one although I'm not yet sure if I really need to...I dont plan to go past 7000. Many others have mentioned some bad harmonics on RB30's past 7500 odd...I'm still trying to find out more on this. Lots of different sources claim good properties from fluid dampers but as usual there are a few that dont like them. What reason does your engine builder give you for not liking fluid dampers??? Curious to know his opinion. Have you seen the Autospeed and Zoom articles on the mega RB30 Nizpro in Melbourne built...900 odd horsepower from memory. They went to the trouble of making a huge solid one piece main cap/brace that bolted to all the sump bolts, and, modified a GTR 4wd sump...for added stiffness presumably. If you spot the Autospeed article, note the balancer used. It looks like an RB30 unit but with a much enlarged ring....hope this is of some use to you....

Having given the comments that followed my last post some more thought, I have formulated an alternative argument that can be applied to the previous calculation example. In hindsight, it isn't that far off what we are discussing after all. Bear with me.... Consider two 'ideal' Skylines. Everything is EXACTLY the same, except one runs 5 PSI of boost and the other 10 PSI. They are both rolling at 60 kph in third. On a signal both cars have the throttle cracked open simultaneously. Which one will hit the redline first? I would suggest the 10 PSI Skyline, because it has more power (and mathematically proportional torque). Put enough weight in the boot however and the other will redline first. In essence the engines predisposition to rev is limited by the weight it has to lug through all the gearing, given no tyre slip. Increase the power some more and you will negate the additional weight in the boot. Remove some rotating mass and the power that was absorbed by the rotation becomes available to the tyres to help accelerate the vehicle at a greater rate, and thus through all the gearing, also allow the engine to accelerate at a faster rate. In essence, making it feel more responsive. Rotating mass is thus equivalent to static mass that is present in the vehicle. The only difference being that it's effect is variable and determined by the gearing at the time. So the 0.6 kW that went into accelerating the dampener is now available to the wheels instead. Which brings me once again back to the example. The power absorbed by the heaviest of all 'pulleys' the damper, amounts to a miniscule amount. Furthermore the alternator pulley that probably only weighs a few hundred grams becomes even more insignificant. Remember that the inertia of the alternator rotor is FAR FAR greater than the pulley its connected to anyway. The other pulleys again weigh bugger all so the argument is the same. The weight of the water moved by the pump and the heavy pulley mounting flange on the pump under the pulley, again makes it rather insignificant. The power steering pump, with its complex vane arrangement and so forth...surely more significant in rotaing weight and hydraulic losses than its driving pulley. And what about lightweight flywheels. Using the previous example, and remembering that a 'flat disk' is more appropriate for the flywheel inertia, meaning that the inertia effect is halved, plugging in all the values for an 11kg flywheel, with all else being the same, amounts to almost 3kW. Significantly more than all the pulleys, and about 5 times more than the damper in the example. Also far easier and cheaper to perform. Yes lightweight flywheels are marketed by all the big name houses. And they all promise the earth....they are also trying to sell you something. Something made on a CNC machine that costs almost nothing. But is a lightweight flywheel included in the standard 'roady' upgrade list of "exhaust-intake-FMIC-ECU"....not really. If in fact it was so miraculous, every man and his dog would be rushing out to buy one and take advantage of the 'huge' benefits for the relative poultry sum of 500 bucks. I tend to agree with Steve...up the boost a tad and the effect will be the same!!! Every one of us however is entitled to our own opinion. I dont wish to hinder anyones ideas and plans. This is all just one mans take on the situation that I wish to share for the sake of discussion. I hope to hear the result of the lightweight pulleys the other guys are having made....backed up by test results of coarse )...and be proved way off the mark. I also want to add more to the contentious issue of the damper/NVH "device". I took one off a spare RB25DET I have lying around to take a closer look. It is actually a more complex component than first thought. It is a three piece device, with two sets of elastomer linings. The inner hub connects to the crank snout and protrudes outwards forming the outermost pulley for the power steering pump. The inner belt lip of this pulley bends back toward the crank forming an open ended cylinder around the central hub. On the outside of the cylinder is a rubber lining which carries the AC and alternator/waterpump belt pulleys. On the inside of this cylinder however is a heavy metal ring that is held by the other rubber lining on the inside of the cylinder. The inner radius of this ring is floating in air and doesn't touch the central hub. Also of interest where the 3 balancing holes on the back of the innermost pulley as a result of dynamic balancing. In my personal opinion this constitutes a harmonic damper. Even though I dont believe that the outer lining is for NVH purposes due to the rubber accesory belts anyway as mentioned previously, if I assume it is, then the inner ring most certainly forms a harmonic dampening device. It is a typical example of such a thing, albeit on the inside rather than the outside. I also looked at an RB30 damper and discovered that it is different in construction although similar in principle. As I only studied this breifly, the major points of note were that it had a similar central hub but this time holding all the pulleys. There was a lone thin disk however on the inside edge that had the typical rubber lining seperating it from the hub. On the point of crankshaft balancing, the inline 6 configuration is inherantly extremely well balanced and vibration free. All primary and secondary inertia forces and moments can be completely eliminated through balancing and couterweights alone. The only exictation present is through combustion impulses which leads to torsional vibration compounded by crankshaft length. This is opposed to the inline 4 for example which cannot achieve cancellation of secondary vertical shake through balancing and counterweighting and is usually, but not always, addressed by using counter balance shafts.

Yeah OK Enrico, point taken...I concede that the example did stray from the original point, that being acceleration response rather than power and therfore not entirely relevant to the issues that have come up on this thread. I'll try to come up with some equations and examples to quantify response as well. The important issue regarding flywheels is that inertia is related to radius squared, and with a flywheel being significantly heavier but more importantly much larger in radius the effect is considerably more significant. This also applies to Steves question regarding the positioning of the weight. I shall return...

Hey rev210, Your are absolutely right in making a note of the misnomer in "harmonic balancer". I'll try to be consistant from now on and call it a harmonic damper. Indeed none of this argument applies to this form of device, only to devices with a central hub and outer ring and/or pulley seperated by an elastomer material, for internally balanced engines. I remain unconvinced that a rubberised "pulley" has a significant effect on NVH levels as a result of accesories. Connecting all the engine driven accesories is a very soft, pliable and flexible rubber belt. Very little if any vibration can get transmitted through this by the accesories to the engine or vice versa. In effect it does a wonderful job of isolating vibrations on its own. Such a rubberised pulley as described constitutes a harmonic dampener. Sure it may look different and small but that is a result of it being tuned for the engine under consideration. I agree that modern techniques and materials have altered the dynamics of torsional vibration such that the crankhaft is a much stiffer item than that of yesteryear. This forum is about Skylines however, and all RB's I have ever seen have a more traditional harmonic balancer OEM mounted on the front of the crank, presumably for torsional issues present in this particular design. And if it could be reliably replaced to OEM standards with a much cheaper/smaller/easier to mass produce plain pulley, in my opinion, it would have. It is far cheaper to stamp a pulley out of sheet steel in a press or cast one out of aluminium than it is to make a two or more piece steel device with a rubber insert. Something else has undeniably been considered here. My opinion on the other questions by Steve/GTS-t VSPEC/R31Nismoid regarding lighter pulleys on the other accessories is thus. Consider first the alternator. You could make a lighter pulley for it......but. Dont forget the rotating inertia of the alternator rotor. Being a big iron/copper component it outweighs its standard drive pulley by orders of magnitude and is of considerably larger radius. A lighter pulley here would have negligible effect. The water pump pulley doesn't weigh much at all. The power steering pulley is similarly light weight, and I would argue the same for that as the alternator. The AC compressor is probably too hard for anyone to consider modifying a pulley to suit, and for performance use one simply has to turn of the AC and remove all load. What about making the pulleys larger so as to reduce the drive ratio and hence the load? Well doing that will also reduce your power steering pressure and your water pump and alternator speed. Water pump cavitation issues I believe will become significant enough at super high RPM to warrant consideration, but thats about it. Consider the following example which I believe will suprise and hopefully enlighten a few people: Calculate the power required to accelerate a rotating mass from 650 rpm to 7000 rpm in 2 seconds. Assume that the mass is all concentrated at the circumference, i.e a circular ring (pretty much equivalent to a pulley/damper, and worst case scenario, a solid disk has half the inertia), and that it weighs 5 kg, and has a diameter of 150mm. The equation of power in watts for this is: Power P = I x A x W ( "Power P = I times A times W") where: I = moment of inertia = MxR^^2 (mass times radius squared) = 5 x 0.075 x 0.075 = 0.028125 A = angular acceleration in radians/second/second = (7000- 650)/2 = 3175rpm per second = 53 revs/second/second = 53 x 2 x Pi = 333 radians/second/second W= angular speed in radians/second = (650rpm / 60) x 2 x Pi = 68 radians per second inserting into the first equation..... P = 0.028125 x 333 x 68 = 637 Watts = 0.6 kW !!!!! Not much to worry about is it. And this is for the heaviest part being the crank damper. Its probably not even measurable unless your in a lab on a very good engine dyno. If you spend the money to lighten it all how much would you expect to gain...if your really really good you might gain 0.4 kW during your acceleration!!! IMHO there are better and smarter ways to spend your performance dollar.

Hey rev210, I disagree with you on a number of points. The sole source of the torsional excitation is from the impulses of combustion. The haramonic balancer is a driven device, and through its inertia is only a store of rotational energy delivered by the crank. As such it can not generate any excitation whatsoever, unless of course it is in a state of dynamic imbalance, which it is not. Weight of the balancer has nothing to do with excitation. Simply put a lighter balancer will have a lower ability to attenuate torsional vibration. The OEM type balancer is significantly more expensive to manufacture than alternatives with its multiple sections/compositions and assembly. In many circumstances the balancer itself needs to be dynamically balanced as the outer ring cannot be positioned with total accuracy over the flexible rubber hub interface. Yes the S2000 has no balancer. But it is an inline 4. One cant compare this with an I6. A inline 4 has a significantly higher crank resonant frequency to an I6. This is a direct result of a significantly shorter and therfore stiffer crank, and this is the major factor in torsional vibration susceptability. In addition the I4 recieves 2 excitation impulse per revolution whilst the I6 receives three. What I do agree with is that a lighter balancer will posses less inertia and allow the engine to build revs significantly quicker. However one must balance this with crank/bearing lifetime which may be significantly reduced.

Hey all, Harmonic balancer operation appears to be a very missunderstood subject. Its actually quite scientific in detail, with entire volumes of theory for those that way inclined. Unfortunately very few are exposed to this and all sorts of interpretations and missconceptions come along. Firstly, harmonic balancers have nothing at all to do with engine balance. For this breif intro assume that the crank is 'perfectly' balanced, and that all the pistons/rods are 'perfectly' weight matched. When a cylinder fires it causes a massive shock on the crank pin. So much so in fact that the crank pin physically deflects a measurable amount every power stroke. The crank shaft then acts like a spring and the crank pin deflection bounces back and forth until it comes to rest in its natural position. This happens AS THE CRANK IS ROTATING, and results in the crank twisting back and forth along its axis producing what is known as torsional vibration. This bouncing back and forth is akin to a tuning fork tuned to a certain 'note'. Similarly the crank has a given 'note' that happens to be a function of its manufacture. This is determined primarily by it weight, shape and material stiffness. Just as a tuning fork will ring its note if placed next to say a piano playing the same note, so too will the crank vibrate if the power pulse frequency happens to match its particular 'note'. This phenomenon is called resonance, and results in a build up of amplitude rather than it just dying away quickly before the next wack of the crank by the firing pulse. This ultimately leads to hammered bearings or a snapped crank. Usually the actual resonance frequency is beyond the redline of an engine, but what complicates things is that multiples of the resonance frequency still cause significant vibratory excursions. Remember this is a simple explanation in order for the point to be made. In reality the multitude of firing strokes and other complex interactions results in the crank 'ringing' uncontrollably at various RPM's determined by multiples of the resonance frequency throughout the RPM range. Lots of peaks and troughs in torsional vibration occur throughout the RPM range. The harmonic balancers job is to dampen out and reduce the amplitude of the torsional vibrations. The flywheel can be considered as a solid fixed point that supports the crank at one end. This is also as a result of the rest of the drivetrain acting against that end of the crank. Therfore the effect of the torsional vibrations end up at the 'free' end of the crank, so this is where the balancer is placed. Now for an explanation of how a standard harmonic balancer does its job. Recall that a OEM type job has a hub that attaches to the crank, with a heavy circular ring surrounding it. Between these components is a rubber material. Contrary to popular belief, it is the large inertia of this ring that dampens vibrations. The large inertia tends to oppose sudden changes in rotational speed. When the crank snout starts to twist as a result of the aformentioned power pulses, the large heavy damper ring doesn't want to change its speed due to its inertia. With the rubber seperating it and the crank, the shearing action tends to limit the extent which the crank snout can move torsionally and so the extent of the excursion (and vibration) is reduced. The energy of the vibration is instead dissipated as heat within the balancer rubber. So the moral of the story is that a heavy damper DOES NOT increase the stresses on the crank due to vibration, but in fact reduces them. (ever noticed the size of the GTR700 balancer compared to the stock one ???) Additionally the balancer itself is tuned to match the vibratory tendencies of the crank itself. Making matters worse is the long crank of the inline 6 cylinder engine, making it more prone to torsional twisting. This is why some 4 cylinder engines can live without a balancer, as the crank is physically stiffer due to its shorter length. Note however that even so, lots of 4's still have them. SO DONT MESS WITH YOUR BALANCER!!! Do you think that the factory wouldn't replace this bulky heavy and consequently expensive device with something cheap and nasty if it was beneficial. Dont underestimate the work of hundreds of engineers...they do know what they are doing. Another interesting point is the so called power saving of underdriving engine accessories. You can actually work this out mathematically, and in reality does not amount to any more than a handfull of KW at best. phantom

look here for more info on this issue.... http://forums.skylinesdownunder.co.nz/show...?threadid=24664 yeah I know its the other site!!!