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~73 Turbo L28 to N/A RB25 240z Project~

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Worked on your harness a good bit today. I will make a list of things that will need to be done on the car to get a complete install. The check engine light wire is there with the necessary power wire, all you need is a light from an auto store. Also, the "check" wire from the diagnostics port is labeled with the necessary power wire, which will allow the check engine light to blink the codes when connected. All you need for that is a momentary button to connect the two wires.


Things that are done:


1) removed all unnecessary wires (ABS, A/C, windshield wiper)

2) labeled all under dash wires (diagnostics, check engine light, tach, ign on, temp sensor, fuel pump, start signal)

3) separated knock sensor, backup light, and alternator connectors from lower harness


Things yet to do:


1) wire up 3 relays with fuses for power

2) change temp sensor connector to work with the L24/26/28 sensor

3) run a power wire for everything that connects to the battery lug on starter (hidden in harness)

4) re wrap some of the untouched harness for looks




pm sent  would like to get something done similar

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  • 2 weeks later...

So I've come to the conclusion the 3.9 ratio R200 isn't doing the job. The gears are still quite tall. In my previous Z I had a 4.11 r180 which suited the RB trans very nicely. Well I came across a differential that will be a little more wild that that.. a 4.375 R200 w/ LSD. Wasn't cheap but it should make a big difference. 


The diff comes from an HR31 which was the first skyline to be equipped with the RB motor (rb20). The n/a RB25 trannys are the same as rb20's so it should be a perfect match without having to worry about too high of RPMs on the highway. The added benefit of the CLSD will make powering out of corners a night and day difference as well.


Looks like the outer seals are new and original paint on the housing shows very little wear.






Come to find out an R34 with RB25DE motor has a 4.364 rear end, so with this new diff I'll be getting it back to normal. Here's some info I found online:


Final drive options ; /top speed / ft-lbs at wheel in 4th
3.357 ---------------- 385km-------68.5
3.538 ---------------- 365km-------72
3.692 ---------------- 350km-------75
3.917 ---------------- 330km-------80
4.083 ---------------- 317km-------83.35
4.111 ---------------- 314km-------83.91
4.364 ---------------- 296km-------89
4.375 ---------------- 295km-------89.3
4.636 ---------------- 279km-------94.6
4.900 ---------------- 264km-------100

Edited by ~KnuckleDuster~
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  • 3 weeks later...

ATI Damper is here. I wanted to replace the stock pulley mostly for the weight reduction benefits but the oem damper is also a part that can wear over time and if it fails can destroy your whole motor if out of balance. I've invested time and money into naturally aspirated sr20's in the past and reducing any rotational mass from the crank will result in better throttle response and a sense of a lighter car. In a turbo application you probably won't "feel" much of a difference with mods such as this but when n/a the change is quite noticeable. The ati damper is small in diameter so I'll need to run a small belt, and should be 5 to 8 lbs. lighter. I will weigh both and find out exactly.


You can contact ATI directly and they can make you a damper with only one accessory belt for even more weight loss but it will cost you more money for them to custom build one. I opted for the off the shelf model with 2 row pulley even though I'll just be using one belt. Model 918598.





Edited by ~KnuckleDuster~
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Edit: 2/29/2016


Did some routine maintenance today. To get some of the fluids that were left over in the engine out.  I changed the oil after the first few drives and it came out creamy brown. It was sitting for who knows how long so this was my second oil change within a hundred miles or so and it looks a lot better this time around. Coolant was looking a little brown as well so I flushed that out as well and put in some fresh coolant in.


There's a couple different OEM oil filters you can get for the RB series.. 15208-53J0A is what you will find when you look up what filter to use. 15208-55Y0A is what I prefer to run since the filter is twice the size.


I also replaced the fuel filter to a 16400-N7605-JP which is for the 300zx, 280zx ect.

Edited by ~KnuckleDuster~
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  • 1 month later...

Decided to get a proper seat. I like the oem look but I was sliding all over the place in the corners which doesn't exactly inspire confidence. I went with the Sparco R100 from the ease of install and oem like appearance. I used modified stock seat sliders and re drilled mounting points. The seating position is pretty much where the stock seats were, I was hoping to sit a little lower but this works just fine and I'm 6' 3". Ditched the 43 year old sun faded seat belt for a matching 3 point harness bolted to the stock locations.



Edited by ~KnuckleDuster~
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Straight from Japan, Nismo solid shifter. Had positive reviews and non of the downsides of a short shifter.


By hardening the inner rubber of a standard shift lever, the amount of deflection is decreased. At the same time, the lever length was reduced by about 7.5mm, providing a stroke 10% shorter. This changes the rather soft touch of a standard car to a much more precise, fast feeling. At the same time, while the goal is to change to a quicker shift, an overly short shift stroke will result in poor, heavy shifting. Unlike a quick shift, the lever ratio has not been changed, so the transmission synchro is not effected and a moderately faster degree of shifting is possible. Installation is easy because the solid shift has the same basic dimensions as a standard shift.




Update: Looks like I ordered the wrong part due to a poor description. I ordered the one for DET/DETT. I have the proper one ordered now.


I originally ordered 32839-RN595 and I needed 32839-RN40

Edited by ~KnuckleDuster~
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Is there a scaling on the pics? We can see the differential but actual temps would be nice.

Their isn't a temp scale but you can pinpoint an area for a temp reading. It's due for an update so I'll have to see whats new.


Your interior is so freaking clean!! That new seat is classy.

Thanks ^_^

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How much headroom do you have with the R100? I really like the look of those seats, but I'm taller than you are and worry about my headroom.

Like I said they sit pretty much where the stockers were but the padding isn't worn out so you feel a pinch higher, I just offset it by reclining the back one noch more. If your much taller than me I would suggest getting an aftermarket seat bracket, ( Planted makes one that looks decent) and bolt the seat directly to that.

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I guess I should have specified. My car didn't come with stock seats, so I don't have those as a comparison. Right now it has Cobra Imola ProFits in it, but they're pretty harsh for the street IMO.

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I guess I should have specified. My car didn't come with stock seats, so I don't have those as a comparison. Right now it has Cobra Imola ProFits in it, but they're pretty harsh for the street IMO.

This should help more than I can.. someone measured from the bottom of the seat to the roof.



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Nismo shifter update, got the right one in today. Not shorter by much at all but angled very different. The angle reminds me of the stock shift lever and it places the knob slightly closer to you which is nice. Feels more solid than the other one, it's raining so I can't go test it out right now but I'll update this post after a road test.
















Edit: Shifting feels great, notchy like it was with the old factory trans. Very happy with it!

Edited by ~KnuckleDuster~
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