Jamo's RB25DET ''250Z''

[sco_aus]

Had that come from anyone else, flame suits would be required, but so far you seem to be pretty knowledgable, so I'm going to do some research on that.

[jamo240]

Turbochargers actually require stable and laminar airflow into the compressor, but anytime air is flowing at speed, odd dynamics can happen that upset it, which can upset flow into the turbo, as well as the measurement of air by the AFM. This could have been the case with dat240Z. I am not sure that will happen in my case, but we will see when it's all happening on the dyno.

 

Cheers

 

Jamo

[jamo240]

Well lads, she runs! After much rooting around to get the car on the trailer (my drive is steep), I got it down to the tuner to begin sorting out the no-start issue. After about.....ohhhhh......45 or maybe 50 seconds of looking, my tuner asked me why I had the fuel feed and return hoses round the wrong way. Have to say lads, I didn't have a very good answer. Anyway, I changed them around the right way, and it started right up.

 

The power steering is glorious...with 235/40R17's on the front, it turns.....well.....like it's got power steering!

 

I warmed it up, put coolant in it and cleaned up the basic fueling and timing which was way out from the last owner of the Apexi ProFC that is running it. Set the timing too, and now it will take it's turn on the dyno.

 

One little bug though, I don't seem to have enough travel on my clutch....it is the same 5/8 bore master cylinder that the R33 Skyline has, so that shouldn't be an issue. One of the mechanics at the workshop had seen this before on skylines, and said there are different clutches suited to different master cylinder/slave cylinder combos, so we are chasing that solution down (I may have the wrong cluch for my hydraulic setup). But, does anyone know if there is an 11/16 master cylinder available that will bolt into the 240Z bolt pattern??

 

Cheers

 

Jamo

[Zedman240®]

With the clutch issue, find a slave cylinder with a slightly smaller bore; that will give you more travel for the given pedal movement. Had that issue with the RB in my zed. Solved with a Skyline slave.

[KatoKid]

Happy days Jamo!

 

Ive done a few other conversions and in my experience clutch operation is a real pain and often the biggest disappointment of many conversions. Often you have to go up a size or two in master cylinder but this results in an overly heavy pedal, especially if people go for a strong clutch at the same time.

 

Pedal ratio, the available pedal stroke and how that compares with the pedal stroke of the skyline and the actual stroke delivered to the master cylinder (not the pedal) needs to be checked as this is where ratio impacts.

[Riceburner]

Jamo do we get a video of the Dyno run?

 

Also in previous pics is that an L series shifter in the RB box, was this a straight swap? Great way for regular shifter position in a modern box.

 

[jamo240]

Hey guys...here are a couple of pics of the car on the trailer.

 

Dimitri...do you know which Skyline the smaller slave is off?

 

Kato: Yes...I have fiddled with clutch ratios over the years myself and it can get tricky. The R33 Skyline actually has a spring assisted pedal, so that's how they dealt with high efforts. For that reason I am not wild about increasing the master or decreasing the slave, but I will have to do one or the other (or get a different pressure plate configuration) to deal with the issue. The clutch at present is not super heavy, but it will be at the heavier end if I have to move 1/16" on diameter...might have to see if i can integrate the spring assisted R33 pedal box?!

 

Gareth: I will do a video of the dyno run if I am there when they do it (we didn't do it today, just shook it down to get it ready to rumble!).  It is a L series shifter. It was not a straight swap...i actually took the RB shifter and cut if off then cut the piece left (that goes into the gearbox) longitudinally. I took the L series shifter and did the same, but with the bit you hang on to...picture the cut looking like an inch-long semi-circle in section. I then vise-gripped the two together and set up the angle to the shifter so that it was at the height and position i wanted it to be. I then TIG welded it together, and then linished and polished it until it looked like one-piece. Then I had it re-chromed so it looks like a standard L-series....Voila!!!

[Zedman240®]

Sorry can't remember as it was a few years ago but I remember getting a vernier caliper and measuring directly. I think it was only around 1-2mm smaller but it did the trick. Played with rod lengths at the clutch fork but it was either not letting me get into first or clutch partially engaged in neutral. Measure you current slave and find one a tad smaller. Try a R31 slave?

[jamo240]

THanks Dimitri...will measure and find what's out there. If all else fails, I will have it sleeved to 1-2mm smaller than what's there now.

 

Hey, on another note, I followed your advice from another forum on temp sensors for RB's that jive with the standard gauge, and settled on the RB20 sender. Works perfectly (81 degrees C = half gauge, which is the temp at which the thermostat started flowing an appreciable amount of coolant, so that's where it will run at most of the time...and the fans come on at 91C and go off at 86C), so saved me a bunch of trouble getting all that to work!

 

CHeers

 

Jamo

[RB30X]

Turbochargers actually require stable and laminar airflow into the compressor, but anytime air is flowing at speed, odd dynamics can happen that upset it, which can upset flow into the turbo, as well as the measurement of air by the AFM.

 

I totally agree about laminar airflow through the air flow meter which I'm hoping dat240z was on about, hence the reasons hey have screens and vains in the meters themselves.

 

The actual turbos requiring laminar airflow is a new one Turbos create their own uniform inflow. How many turbos do you see on big $$ engines sitting out in the open without any intake pipe or filter on them at all. Dont see the flow into those getting upset?

[jamo240]

Hey RB30X...it's quite ok to have the turbos sitting out in the open with no filtration etc (like on racing boats), provided the air is relatively clean and a very long life is not essential. The key to stablising the flow is the design of the smooth approach orifice (SAO) going into the turbo. The 'bell mouthed' ram tube on the front (a bit like the shape of the cowling on an aircraft engine) is designed to accelerate the air into the compressor while stabilising the shape of the incoming air column. The distance between the orifice and compressor is also significant in achieving stable flow (ie avoiding standing pressure waves ahead of the compressor).

 

 

Cheers

 

Jamo

[dat240z]

Umm what??

 

Ummm  yeah^^^^

 

When we did my build it ran OK, but once the turbo pipe holding the airfilter was extended it ran a dream apparently due to not enough turbulence???  Dunno but worked, and my guy is a Jap tuner

[RB30X]

So one reckons you need more turbulence and the other reckons you need none?

 

Maybe we should end this couch debate now.

[jamo240]

Good call RB30X....as an engineer I once worked with used to say in these situations "...without data, you're just another person with an opinion"!

 

We will know soon enough....it will be going on the dyno in the next few days.

 

Cheers men

 

Jamo

[Zedman240®]

I think any hole that has large amounts of air sucked into it needs a ram tube or bell mouth to help "correct" the air flowing into it. Steve Newing (A very smart man when it comes to anything turbo/injected) once explained it to me years ago the reasons why... If it wasn't a big deal, you wouldn't see it on virtually every performance engine on the planet. Even the early 240Z airbox has them!

[jamo240]

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

[d3c0y]

I had a '78 260Z 2+2 that worked with a 280ZX distributor too. Was yours modified to work on your L28ET set up already?

[luvemfast]

Awesome work 

 

I have a surplus K&N conical filter in the garage.

There's a pic on my build page. I imported 2 from the states as the postage was indifferent.

Let me know if it suits your needs.

[jamo240]

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

[jamo240]

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

[luvemfast]

No probs Grant.

Suprised though. As its pretty big.

RE-0810

 

[jamo240]

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?

[jamo240]

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

[luvemfast]

Great work.

Clearly, you're a genius and didn't even know it Grant 

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?

Pobs easiest to swing by my work, or I can drop by and have a looksy 

[jamo240]

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