jamo240

One final thought to retain the standard instruments. For oil pressure, simply use your L series oil pressure sender unit screwed into the RB25 port in the aluminium oil filter body (it's the same thread), and for coolant temperature, use the sensor in the inlet manifold cooling jacket out of an RB20 engine (it is the same as the sensor in a number of other Nissan's built through that period). It is a direct replacement for the standard RB25 sensor, but has a response curve that jives with the 240Z gauge. If you follow these instructions, you can retain all of the standard 240Z instruments without modification. Cheers Jamo

Hey Scando...good to hear you had a good result with the full cage. You are absolutely right though...cages are in race cars mostly to stiffen up the shell for performance...protecting the driver in a crash is a byproduct! In the GTR's, we had a bar on each side running straight back from the front strut tower through the firewall which picked up the main bar that came off the floor and up the A-pillar and along the roof....this bar came through more-or-less horizontally and welded onto the A-pillar bar about where it bends up along the A-pillar. There was then a bar behind the dash board that had a bend in the middle in the centre of the car and was welded to the A-pillar bar where the longitudinal one came through from the strut tower. Then, there was a bar on each side that came back diagonally from each strut tower, went through the firewall and was welded to the bent one behind the dash board. Finally, there was a removable bar across the strut towers. In this way, the whole lot was triangulated and prevented any movement in the strut towers, and of course transfered the loads between the bars and right through the roll cage and body structure. The cars were very stiff...even driving them through the pits over spoon drains you could feel how unyielding the body was compared with a road car. Cheers Jamo

Not sure what Sticky is Mick, but hope the post is of service to you! Jamo

You're welcome ROady...good luck. Jamo

Hey Roady I had a look in my 280ZX workshop manual, and it shows the positive supply to the coil also being wired in parallel with the supply to the IC pickup on the distributor, as well as a supply to a 'thermo switch' (not sure what it does, nor whether you still have it in your system). Otherwise, it all looks pretty conventional...so I would just wire to the positive side of the coil as discussed. If it's any consolation, I had crank triggered ignition on my L28, and used a mercedes ignition coil, and that drove the tach just fine. CHeers Jamo

Hey Roady The green/white wire actually feeds the coil through the ballast resistor into the black/white wire. When the key is in the run position, the power comes through the green/white wire, and hence loses a bit of voltage through the ballast such that the voltage on the black/white is dropper to ~8V for normal running. WHen the key is in the crank position, there is still battery voltage applied to the green/white, but the ignition switch also supplie battery voltage directly to the black/white wire, hence the coil is at battery voltage while cranking to aid starting. With the ballast resistor no longer required (provided you are using a coil intended for full battery voltage all the time, such as a GT40, NOT GT40R, and you are using the 280ZX elec distributor that doesn't have points to wear out), then you can simply connect the green/white to the black/white where the ballast used to be, and the coil will be at battery voltage all the time....happy days. Don't get too confused by the tach operation...it is simply a part of the coil primary circuit...it doesn't matter how you fire the coil (ie points, elec dizzy or crank triggered)...provided the primary side of the coil is wired into the tach as designed and the coil is working properly then the tach should work. Cheers Jamo

Hey Lars That's ok. Why I am not a big believer in strut tower braces for road cars is two fold. Road cars don't generate the sort of cornering forces required to create substantial body deflection to the point where it is effecting performance. To get that happening, you need sticky tyres up to working temperature and the sort of conditions where you are going around on two wheels. That is not a common occurance on a road car. Why carry around weight and compromise (a rear strut tower brace stops you carrying luggage around in the back as conveniently when on a trip for example) in anticipation of the mother of all corners where you think it might help? The second thing is function. A straight bar across the strut towers is of some use when both wheels are in bump together...in that case, it acts in compression and prevents the two strut towers getting closer together...this is the reason we put one on the Holden Adventra's when we built them...it was in anticipation of people bumping along rough corrugated roads (such as the Gunbarrel Hwy) where such loading would occur, and was included to increase the life of the body shell, not improve handling. Not many Z's are going down corrugated roads! A bar across the strut towers does almost nothing to reduce movement of the strut tower from a torsional rigidity perspective (ie transferring load from one 'flimsy' structure to the other when you're cornering). To increase that component, you need to triangulate the strut tower bar back to the firewall, which in turn needs to be reinforced to prevent it moving (this way you create structures that transfer cornering force deflection into tubes in compression/tension that cannot deflect because of the triangulation). When I was at Nissan Motor Sport in the 90's building the GTR race cars, we had barwork behind the dash board that picked up the triangulation beams that complemented the front strut tower braces. The dash bars in turn were welded to the main cage, which was welded to the body shell, and went through to the rear strut towers. All the tubes were designed to carry loads in tension/compression, never in bending, and that is how the stiffness is achieved. All in all, a very stiff structure torsionally, as well as there to protect the driver in the event of a crash. In my view, a single bar connecting the front and rear strut towers in isolation will offer no discernable value. If your aim is to increase the impression ratio though, then go for it along with those earls braided steel hose fittings that have the hose clamp in them, as race car parts on road cars always have their fans....but, if you are building a road car, be clear about what it needs to do and what it doesn't, and build it accordingly! Cheers Jamo

Hey Lars. If it's a road car, I wouldn't even worry about the strut braces, but that's up to you. I haven't had a lot of public reaction thus far, but people do look at it as it goes by! The boys at the tuning shop loved it though. They have all sorts of cars through there, and one of them has a 370Z, but they all love the 240Z...as one said, some shapes just never go out of style, and this is one of them! Cheers Jamo

Here is a cct diagram of how it works. Cheers Jamo

Hey Lars Glad you like the thread...they're fun to write, and hopefully help and inspire other members with their projects. I did seam weld my car, but I don't imagine it has had a major effect on stiffness. I never did any barwork....to make a substantial difference to stiffness, it has to be integrated right through the car (ie from front strut towers through to the rear), and I did not want to take the car in the direction of being like a race car. On the road, the car does not feel flimsy. I have CV joints in the rear, and the power delivery is very smooth (big prop shaft joints help with this too). The power comes on at about 2,400RPM, and builds quickly such that by 4,500RPM in, say 3rd gear, it will really start to get going and will wheelspin while it's at it right through to redline (7,700 in my case). Cheers Jamo

Hey Roady You've certainly tried a lot of reasonable things to fix the problem. One thing i did notice is you are running a GT40R coil...why the R model? This is intended to be run with a ballast resistor, and as you don't need one now because of the electronic distributor, you would be over-saturating the R model at the full B+ supply...perhaps this is contributing to the problem. While I accept the problem didn't used to be there and has develped, have you got a conventional coil you could try? You may have had some form of degradation occur in the coil over time that is causing the tach to fall over at 4,500 RPM that wasn't there when the coil was new. Good luck Jamo

Hey gang...I thought I would do a separate post so it's easy to find in future for people installing RB25 engines (or in fact any 6 cyclinder engine using multiple coils), and wanting to get their standard 240Z tacho to work (may work for 260Z too...not sure if they trigger off the positive side of the coil). From what I read on the web before I did my installation, I could not find any solution to driving the 240Z tach from a modern engine management system (such as Nissan ECCS or Apexi FC), as those systems have a dedicated tach driver output that operates a tach designed to pick up the pulses it outputs. A 240Z tach cannot recognise these pulses, and is designed to pickup the activity on the positive side of the ignition coil. In the standard 240Z, the coil feed either goes through a ballast resistor if fitted (when key is in the run position), and then through the tach, or in the crank position it bypasses the ballast resistor but still goes through the tach so that the coil gets full battery voltage for starting. In both cases, the coil supply goes through the tach and that's how it picks up the number of sparks and displays that to you in RPM via the needle on the tach. Most solutions I saw involved replacing the tach with one that works with the Engine Control Module (ECM) output, or attempting to convert the 240Z tach to accept the ECM output. While this all works, it is unnecessary, and assumes the only way to get a tach signal is to work with the ECM output. The other way is to supply the six ignition coils via the standard 240Z coil supply. The way this is done, is via the standard RB25 ignition relay. When you wire up an RB25 engine, you will find in the R33 skyline engine harness that there are two relays near the ECM that are often referred to as the 'relay twins'. They are identical in configuration, and one of them (the ECCS relay) supplies power to the ECM, while the other one (the Ignition relay), provides power to the ignition coils. That is it's only function. Both relays are energised, and in turn grounded by the ECM so they turn on, when the ignition key is turned on (an 'ignition on' feed to the ECM is the reference it uses to 'wake up', and ground the ECCS and IGN relays). The relevant circuits are: AF04: Red wire - power to IGN relay switching coil when key is on AF49: Orange wire - grounds IGN relay switching coil and 'turns it on' when ECM is powered up via circuit AF36 DA31: Black/red wire - power to relay switching circuit when key is on (this is the 'normally open' circuit in the relay) AF50: White wire - power output to ignition coils once relay is energised/switched on If you take your black/white coil feed wire from the standard 240Z, and feed circuits AF04 and DA31 (you can supply them both off the same wire), then effectively you are powering the 6 coils via the original 240Z coil feed (in effect a series circuit from 240Z B/W coil feed to DA31 then to AF50), and are replicating the standard 240Z condition, only you are powering 6 individual coils firing one cylinder each, instead of one coil firing six cylinders....electrically, it's the same thing. When you fire up your RB25 (or any other six cylinder engine using this configuration), your 240Z tacho will work, and hence you can retain the look and feel of the original. If you combine this with the VL turbo vehicle speedo cable output (from the gearbox), you can retain the look and function of the original 240Z instruments for both tach and speedo. I will attach a circut diagram once I figure out how to compress the pdf scan I did of the circuit diagram described in these words. Cheers Jamo

You don't need big noisy pumps as lift/surge tank pumps lads. Because they are filling the surge tank at no pressure (compared with feeding fuel to the injectors under pressure), you only need a relatively small pump...the inline roller cell or turbine walbro or similar pumps are quiet and do a fine job without all the in-cab noise. I double isolate mine (pump is isolated onto the bracket, and then the bracket is isolated onto the body, (using the rubber bushes that mount the ABS module on the R33 skyline). If you follow that sort of approach, there should be minimal noise in the cabin. Cheers Jamo

Hey Mick...I run an 044 on my RB25 installation. It also has a little walbro that feeds the surge tank. It works fine feeding through a 3/8 fuel pipe. I would also recommend isolating the mount for the pumps...I did it to mine (they used to be solid mounted via a mounting plate), and it is a lot quieter with the isolation. CHeers Jamo

Hey dj...R31 and Commodore won't fit (front bowl). Patrol and ZR200 are the only ones that fit. Jamo

Thanks boys...I'm happy with where she's at at this stage. I have to get the interior and such cleaned up now in time for the Xmas party. I have decided to do an E85 calibration to see if we can make 300 rwKw, so I will take a full power video of that so you can see it at full noise. Interesting note I meant to point out to other RB'ers too. With my first air cleaner (the one that was losing 15kW at full power), I was getting quite a bit of oil pull over into the turbo inducer from the crank case ventilation. The idea of this pipe is that it is meant to take clean air from after the air cleaner to go through the crankcase and then into the engine inlet manifold (when under vacuum of course...cruise conditions). I imagine I had sufficient vacuum in my inlet duct due to the air cleaner being restrictive that I was pulling crank case air in the wrong direction leading to oil in this duct. I know it doesn't have much blow by, as I took the rubber hose off on one of the full power runs and there is barely any blow by coming out of the pipe on top of the LH rocker cover...something to consider when you design your air filtration... turbos need a lot of air! For reference, my tuner guy says they would expect to lose no more than 8-10rwKw on cars producing 450-500rwKw, so to lose 15 in 256rwKw is definitely considered restrictive. Cheers Jamo

Here you go lads...not a very long vid, and early on in the tuning process, but you get the idea...

Gday DevZed....how does $120 plus freight sound. I am actually coming to Newcastle in a couple of weeks, so could probably bring it with me. Cheers Jamo

Hey Simon...yes...clearly I am an unidentified genius!! If you can, throw the cleaner in and I'll either pop by your work or you could swing by here after work. Let me know which suits best!! Jamo

Lads it hit me out of the blue....i figured out why my unmodified 240Z tacho is working with the RB25DET engine. Here's why: When I was wiring it up, I used the old coil supply to both supply the switched side of the ignition relay on the R33 ECCS system, as well as power the relay switching coil (because this is effectively an 'ignition on' output). So if you can picture this, when you turn the key on, you power up the coil on a 240Z ordinarily. Well on my RB installation, that wire both supplies the ignition relay (which powers the 6 coils though the igniter), and also 'wakes up' the ECM. When the ECM is woken up, it grounds the ignition relay switching coil, and supplies 12V from my 'old' coil supply to the new coils. So, in effect, instead of powering one coil that fires 6 cylinders, I am powering 6 coils that each fire one cylinder...the result is the same in terms of how many sparks are delivered per rev, so it all works! Presto! Now if I had used the tach drive wire off the ECM, this would not be the case, as that will not jive with the standard 240Z tach. So there you have it boys...a perfectly easy and effective way to get your tach to work when installing an RB in a S30! Jamo

Hey Simon...I checked out RE-0810 on the K&N site....that might work...I am pretty sure my filter is not 9" long, so let's give it a go....how's the best way for me to pick it up?

Hey Simon...that pod filter looks about the size of the one I have....I will rock on down the filter shop and see what they have on offer first, and decide what to go with. Cheers Jamo

THanks Simon...I will try to find it and if it's the right size, I will take you up on that! d3coy: I had crank triggered ignition on the L28, so it used a bosch high energy coil (off a mercedes from memory) and I set the distributor up so all it did was distribute the sparks (basically just has a rotor in it)...the reference angle comes from the crank sensor and the ECM does the timing. I never modified the tach in that set up...i just plugged the positive lead onto the benz coil and it all worked. So....I'm buggered if I know why the tach works, but it does! Jamo

OK boys...the two-fitty ran in anger today! It took a good part of the day to tune, and in the finish, we made 256rwKw. That's about 420 engine HP, so I am pretty happy with that. To do that, we were running 16PSI boost and about 15 degrees of spark at peak power, so there was little point chasing more by pumping in more boost with not much spark to pull out to compensate. I reckon the exhaust housing is probably limiting it, but if I want more, there's always E85 fuel...I reckon I'll make the 500HP I was after no problem with an E85 calibration. Anyway..enough of that...how does it drive you ask? Well, first up, the power steering works a treat. You may recall it's got a subaru rack being fed by the R33 skyline pump. It is nicely weighted and really transforms the driving experience...much nicer! Otherwise, the CV joint rear end and bigger propeller shaft are a lot smoother, and you can really put the power down a lot more smoothly than how the L28T was. The VVT RB25T engine is very progressive with this turbo, hence my satisfaction with the lower outright power figure, but to have 5PSI boost at 2300RPM gives it a really progressive curve. As the power comes on, the tyres lose traction, so you kind of have to chase the throttle so you don't just step it sidways...it just lights em up if you hold it flat and let the turbo pump as much as it wants. All in all it's got the refinement i am after with more than enough performance. I took a punt on the smaller turbine housing when I set it up, and i can say it's worked out how i wanted it....I could chase more power, but it just doesn't need it. Only thing I do need to do is reconfigure for a bigger air cleaner...the one I have is holding it back a bit, so I am going to graft a bigger one in. One thing I absolutely can't explain is that the tacho works! I cant even remember hooking it up....but it is bog standard 240Z, and it is working fine! If I figure that little miracle out I will write it in a post for other would-be RB installers! Oh...for those who wanted a video, I did do one on my phone, but i don't know how to get it off and put it on youtube, so if I can figure that out, I'll do a link. Cheers boys Jamo

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