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Triple Blowthrough Turbo


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@ZetsazYeah I couldn't figure out the best way around the trans mount. I basically ran it down from the downpipe then back up after the mount. All as close to the edge of the trans tunnel as that's the area with the most clearance. Half a finger gap or so around that area as to not melt the poly bushing lol. I did see a thread here on HBZ from years ago where people were running oval piping there for the most ground clearance.


I'll post up what I end up doing for the hangers and bracing. Everything is solid as-is but I know from experience if I don't at least brace the DP it'll crack out from the extreme heat cycles


Just realized you have a 75. I think the 280s have more clearance in that area due to the catalytic converter? I've only seen the underside for 240s and 260s so I'm not sure either

Edited by Dat73z
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So with the majority of the exhaust fabrication complete this afternoon I've started back in on finishing relooming the harness. 


I started off by unlooming and cleaning each wire with QD parts cleaner. I then replaced all of the aged and cracked connectors/terminals with new. I plan to integrate all of the add-on harnesses into one large harness and have a few rolls of tesa tape to reloom. 


Specific to the turbo cooler packaging I needed to reroute the wires in the rad support area below the intercooler. I got some grommets from mcmaster carr and am planning to reroute the wires through there. I also created custom brackets for the horns as I'm using that area for my intercooler mounts. 


One thing I'm still unsure of is how I'm going to do power and ground distribution. I have like 5 pos and neg leads for my MSD box, fuel pump, headlight relays, etc. If anyone has clean ideas for distribution please let me know






Edited by Dat73z
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For power and common distribution, consider these general guidelines:


1) + leads for controls (items that use very little amperage but require stable voltage, like electronics, ECU, etc) should be separated from major power consumers. Therefore you should have one common bus for your relay power, starter, incandescent lights etc. separate wire all the way to your battery for ECU and electronics. 

2) consider a dedicated negative lead from your battery to your starter. Another dedicated (much smaller) negative lead from your bat to your electronics/ECU stuff. The rest (lights, relays) can ground yo the body. 

Race car guys and others considering from-scratch wiring often used these. I have a set. They come with fuses and relays all ready to go, and the switch panel illuminates to indicate if on or off. You can also switch them from momentary to latching. Not cheap, but boy does it save space and time. 



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Thanks @AydinZ71. I'm not at the point where I'm rewiring the car yet but good resources for reference. 


Really just want to clean up all the accesories that somehow ended up on my battery terminals over the years. 


Got busy today making up for lost time with the wife. I went a bit overboard this last couple of days with the exhaust fabrication. Took it easy as started filling fluids. I'm going to try this Amsoil zrod 10w40. I don't recall if Rebello recommended any oil, I think he just told me to make sure I change it often and warm it up fully before beating on it. I'll probably dump all this out after a few hundred miles anyways as I shake the car down. 


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  • 3 weeks later...

It's been a busy month so far but I managed to squeeze a few hours into this build. Unfortunately most of the past couple weeks was spent wrapping up rust repair welding, bodywork, and paint. 


On the turbo build it sounds like my zinc coated parts are done, custom radiator is done, and some random brackets I had machined are done. So final assembly when those come in. 


Also welded on my o2 bung and will be sending the downpipe off for inconel shielding tomorrow. 


Little by little, day by day






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1 hour ago, AydinZ71 said:

Hey at least you only need one O2 bung 😂

My silly-ass needs two, one for each SU carb.  All this fancy tech to make a 50-year non-competition carburetor into a contender.

Great attention to detail.


Yeah I don't know why but I really struggled with drilling the o2 sensor hole so I definitely don't envy 2. The SS tube is ridiculous. I first tried a milwaukee hole saw and the blades flattened out and only scratched the surface within seconds. I ended up using a high quality carbide burr at high speed to wallow out the hole

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Yeah on stainless, that might be the ticket. That's what I would do, especially dealing with that curvature that tends to kink your jig or tear at the work surface. I would drill a 1/2" hole, trace the larger hole (3/4" bung?) then use a die grinder to make it bigger. it is much easier on a drill press but you already had everything assembled. 

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  • 2 weeks later...

Been a while since the last update but I had to take a 2 week break from the build for a nice vacation. 


Before heading out it was a frenzy of parts prep and fabrication before sending a bunch of parts and drawings off to have a few items machined and worked on while I was away. I've just received back my downpipe from inconel shielding and some parts from zinc coating.


At this point I'm just waiting for a few items for final assembly. Hopefully I'll be back on the road this month if nothing else gets delayed


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This evening I started unboxing and mocking up some of the parts that came in while I was gone. 


One large item was the custom 3" core Wizard Cooling radiator. It is definitely a quality piece. Test fitting in the car it barely clears everything, but it clears. I was also able to reuse my twin spal 12" fans. 


Unfortunately the mounting holes to the chassis are slightly off so I'll need to oval the holes in the rad brackets out slightly. Not a big deal, but another mini project for this weekend. 


I also threw the downpipe back in with the o2 sensor so I could start back in on welding up the exhaust bracing. I found it interesting how the inconel shielding was done. Originally I thought they would stop at the flex, but they covered everything in multiple pieces which allows the flex to flex as it should. They also including vband shields that I'll safety wire on later. 


I also got a bunch of other mini projects wrapped up around the car but trying to keep this thread focused on the turbo blowthrough L setup





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So far this weekend I haven't done much on the Z due to being distracted on a bunch of house projects. I've actually been waking up at 4 or 5 AM on some days just to get an hour or so in on the build before the day takes over. 


I did manage to wrap up the clutch lines, fill, and bleed everything out. It's nice to have working brake, gas, and now clutch pedals again, feels like progress is actually being made.


First impressions of the OS Giken twin plate is the pedal is much stiffer than the Exedy 240mm I had before but definitely not as stuff as some of the clutches I've run on other cars. Definitely within range of what I'd consider streetable personally but driving and holding ability will tell the full story. 


If I can find a couple of hours today I'd like to at least final mount the radiator in position so I can move forward with the final looming of the wiring harness


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One item I installed earlier in the week for the turbo build were new engine mounts. 


I was searching for a moderate (e.g. non-solid) option for a while and couldn't find anything that I was satisfied with so I kept my good condition OE mounts and travel limiters originally. 


Recently Milkfab Engineering came out with a set of 40-50 shore D mounts which is a similar durometer to mounts I've run in my other street/track dual duty vehicles in the past that I've been happy with. I've run harder mounts in the past and personally don't care at all for all of the cabin vibrations for a street car. 


I was really impressed with the build quality and the alignment/installation was actually easier than the OE mounts due to the stud design. I like how the design takes into account the full stack height of the OE assembly (mount + travel limiter). They came with good instructions along with torque specs and Andrew @ Milkfab was also super quick to respond with any Qs. Pretty excited to see how these will perform


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Haven't had much time to work on the build this week but got a more few parts in for final fitup. 


For the hot side pipe I wasn't happy with the original routing so after some measuring I added an angled coupler to gain clearance and clean up the run. 


Just waiting for a few more parts to come in and mock up which is mainly the coolant overflow before I slot the radiator mounting holes and finalize the position.


Sounds crazy given how large the s30 engine bay is but things are really tight and since I work on my own car I've been trying to be thoughtful of how things are mounted as to be serviceable



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This past couple of days I've been busy working on some welding projects for other parts of the car but I managed to make some progress on the turbo build. 


The Wizard Cooling mounting tabs are off. After some test fitting I slotted the holes and bolted the rad in. I may raise it a couple of mm for additional clearance of the charge piping as well but I've been waiting on my radiator cap to come in to ensure it won't hit the hood with the additional height. Things are getting really tight. 


I found a 280z hose has the right bends but needs to be trimmed maybe 1" so I created a coupler from some scrap AL tube. It was good practice on cutting, grinding, annealing, and bead rolling. 


Hopefully I'll have enough time to fabricate a bracket for the coolant overflow can as well but we'll see how the weekend goes. 






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looks good! any particular reason you used a bulkhead fitting at the rad support? Nothing wrong with that, just curious what your take was. I thought about it on mine but realized it would just add weight and complexity. More fittings means more leak points, especially on oil which seems to weep through when its doing its job. I just drilled some 1.25" through holes and plan to use a rubber grommet 

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@AydinZ71 I agree less fittings, less chance for leaks. 


SS braided line really doesn't like tight radius bends, and it will eat through anything around it. 


I wanted to keep my cooler packaging as tight as possible along with my hood springs since this will also be a street car. I also couldn't move the oil cooler any further to the DS as I'm going to be running AC and my condenser barely fits in that spot, but it fits. I also wanted to run SS Braided and not nylon braided or pushlok. So it's a compromise from all perspectives. 


If I was building a turbo racecar I'd omit the hood springs entirely and move the intercooler forward and at an angle along with boxing on the entire frontend. Move the oil cooler further to the center and forward. That would gain the clearance to run some large swooping bends with the SS braided line and also make things easier to work on. 

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I should probably also mention eventially I want to do all stainless hardline in front of the rad support for the oil cooler and AC, like how I did my fuel lines. 


For now I ran the SS braided to get me back on the road as I already had the AN fittings and hose. The 10AN SS tube and bending tools I don't have and are quite expensive

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Started in on mounting the overflow tank. I've been going back and forth on where to mount it given everything is so tight but it seems next to the rad will have to do for now. 


I started with some scrap AL from the garden which I also used to fabricate all of the other brackets on the car. After some trimming I think I have something that will work. The charge piping will barely clear beside, and the AC lines should have just enough room to run below. 




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Looks good :) if anything looks to be less than 1/8” gap, I’d put on a little patch of 1/16” thk self-adhesive silicone. Better to have things rub on rubber than metal :) ask me how I know 😂


PS: don’t use silicone on any material that oxydizes. It attracts moisture in a way other synthetic rubbers like EPDM or urethane do not. It behaved almost like a rust catalyst on some parts of this car from the PO’s use, even on nuts a bolts. 

Edited by AydinZ71
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