Dat73z

@Zetsaz Yeah, probably the most annoying thing is there's no good way to fix it without pulling everything apart again. Oh well, a problem for another day 😂

Over lunch I removed the block drain and installed the adapter fitting. I'm going to first attempt the block feed location before trying the water pump outlet. Mainly for convenience of routing. Hopefully I'll have some time later tonight to fabricate the hose. I'm curious how the coolant vacuum test/fill setup will work out. I'm pretty oldschool and have traditionally filled and burped cooling systems my entire life.

Make sure you add some provision for air to evacuate at speed be it louvers, rubber flaps, etc. That was just a mockup prototype and I ultimately went another direction. Good luck

It's turning into another crazy week so I had to break jacking the car up into 2 days lol. This morning I got up early and got the car in the air to prepare coolant draining. I also did an undercarriage inspection since I've covered a few hundred street miles. Everything looks good except the typical rear cap seal seepage. Pretty annoying but it's minor enough that I can live with it for now. Usually I replace those seals myself even if someone else did them as they're tricky to get right. In this case I sent it but as is tradition with that strategy I'll need to rework it at some point 😂. I snugged up the pan a bit more and will keep pressing forward.

Yes the L24 in your 240z is a 2.4 liter inline 6. I would recommend fabricating an actual shroud with an air space. The mishimoto has an inward ledge from the rear face to the actual core, something like 0.25" iirc. If you use a flat plate, consider how you would allow air to bypass at speed. Some people use a rubber flap such that when the car is sitting in traffic the flap gets sealed closed by the pressure of the fans on drawing air from the front of the rad. At speed the flaps open up for less air obstruction through the rad. I have fabricated a couple shrouds/iterations for the Mishimoto actually, here is an example I made using twin spal 12 pullers. If I ran it I would've added some flaps or louvers as I mentioned above. Either way start with a basic sketch and measurements, all of the items you linked had them then do some cardboard templating, all the basic fabrication stuff

Some good news, my 1/2 BSPT to -6an block fitting came in early today so tonight I'm going to install it and try out my new Harbor Freight vacuum bleeder. I think the strategy will be one change at a time. It will be another iterative and annoying development process, but hopefully one that gets me to a resolution.

If you mount a single 16 you may run into issues in terms of overall assembly thickness. The Mishimoto 2 core is a hair over 2.75" off the rad support. The fan you linked is a hair over 3.25" (~3.27"), and the shroud is 2 5/8" deep at the top. So your total assembly thickness would be 8.625" best case assuming all of the mounting is perfect, there are no dimensional tolerance issues, and your car isn't tweaked. The Water Pump pulley face is roughly 5.5" off the core support. You may be able to make it work, but the fan would not be mounted in the center of the rad. Edit: I assumed you had an L-series. I think the 8-9" measurement for the assembly is about right. If you are swapped, take a measurement from the core support and compare. I've seen SR20's and others which have much more room than the L6.

This morning I got up early and started taking some measurements for the AC system since it seems I may be waiting a while for parts...as is typical these days. I think I have most of the components for the AC so I can start cutting some shapes and welding up the compressor bracketry. I intentionally fabricated everything around where the AC components would go since I know my wife at least needs a heater and AC lol. The condensor I have fits perfectly between the intercoole/rad/oil cooler. I also already ran the integrated wiring for the AC when I reloomed the harness. I visited a friend this past week to borrow some OER jets and saw they had a really cool kick up/down solenoid on their triple Mikunis. I'm going to do some more research and see how I could implement this as my idle does drop a couple hundred rpms, esp with both efans going, probably more with an AC compressor running

Since I'm still waiting on cooling system parts and jets, I decided to try my hand at soldering and drilling jets. I successfully got the car to 11-12 afrs across the board. More tuning to be done but it's decently drivable now and at a baseline where I'm comfortable with boosting. Tomorrow I'm going to tune a bit more after work and put the surge tank on.

After a couple hundred miles of street driving it was time to check the torque on everything again since everything was redone. So far so good, only my vbands were loose due to thermal cycling/relaxation. I torqued them back up and will check again in another few hundred miles. At that point I'll safety wire them in along with installing the inconel vband shields. I should probably wipe the whole system down with acetone again too but I think that's just the ocd getting to me...it's an exhaust so it'll get banged up and stained.

Still waiting for parts so I continued tuning this AM. Things are finally looking up after all the new build drama. I was able to borrow a box of OER jets and the engine is running smooth at idle 11-12afrs and off idle but falls flat on it's face above 2-3k rpms pig rich 10afrs. A few years ago I put 36mm venturis into my 47 OERs thinking I was going to run it on my 2.5l turbo motor. When I moved, the 3.2 stroker was a last minute decision since I didn't want to put the spare engines and all of the stroker parts I had into storage. When I removed the main jet stack, the car cruised around at 12-13afrs. With the 36mm venturis on the pilots and my mains are coming online at 1.5krpms which is crazy but seems to make sense since the carbs are choked down to the lowest end of the range for 47s so the signal is much stronger. I'm going to borrow some mains jets from my other buddy today and if I can get the afrs at 11 across the board to start then I'll throw the surge tank on and start boosting/tuning from there. Really hoping I can get there this weekend 😁

It's really faint to hear but at 2 and 6s you can hear the movement of the coolant as it cools the turbo post shutdown. 20220729_190052.mp4

Did some more running and tuning today and I'm not sure what happened but on shutdown I can feel the coolant thermally siphoning/moving through the heater core branch from the lower rad hose. No more boiling, but faint gurgling as fluid is moving from the suction side through the turbo and to the tstat housing dumping at the upper hose. Maybe this entire time there was some airlock or something going on and the pressure testing multiple times dislodged it. I have no idea. Either way I feel better about it now and it's pretty cool to see thermodynamics in action. This weekend I'll continue tuning and shaking the car down.

It's been another crazy week but almost time to get back into the project. This morning I pressured the cooling system using an Autozone loaner tool. Unfortunately the tester cap didn't fit well enough to go beyond 15psi without leaking so I pressurized everything to 14psi and it's held steady for hours so I don't suspect a leak unless it's happening under very specific circumstances and allowing air in at the heater branch. I'll see if I can get it to 20psi and hold it there overnight. I also picked up a vacuum bleed/test tool from Harbor Freight. I think I'll try using this to test with vacuum then fill when I've reconfigured the system. I'm waiting for a new Borg Warner Tstat, fittings, and a Bossa Design water pump to come in beforeI drain and start reworking the system. I have been driving the car around a bit and I still get the gurgling/after boil at the heater branch on shutdown. After some further research this sounds like the convective cooling/thermal siphoning that's been discussed. Looking at other forums for subarus/miatas/etc. Both OE and aftermarket It seems like it's a mixed bag in terms of people who say it's not normal versus normal. It also varies by altitude e.g boiling point who experiences this. Some OEs apparently use a turbo coolant pump for circulation after shutdown to prevent this. Either way since I set up my system modularly with AN fittings I'm going to try a couple of different feed areas and can always go back if I like the original routing. Also I'm borrowing some jets later today from a friend to continue tuning.

Look great keep at it 👍

@AydinZ71 yep that was my understanding as well. To be honest I'm not even sure if localized boiling after shutdown is just a normal water cooled turbo thing but I'm under the impression it's not... Curiosity got the better of me and since I'm still waiting for parts I decided to drive the car a bit more and see. Interestingly enough the temps on the car today were overall much lower and much more stable at the middle of the 240z gauge instead of fluctuating between the middle and the M in Temp. The fans only kicked on once in 30 mins instead of like 10 times. Both the upper and lower hoses got pressurized but not crazy pressure where I was blowing hoses. The rad was uniformly hot top to bottom including the hoses instead of the top hose cooking and the bottom cold. I was still getting boiling after shutdown at the heater core branch but everything felt cooler. I have no idea what's going on and now I'm questioning if the system got air locked or something. I'm going to see if I can pick up a vacuum bleeder tomorrow to pressure test/vacuum bleed the system but my work schedule has been crazy this week.

@calZ I'm not sure how the stock was routed to be honest. I've seen a lot of factory and aftermarket cars routed from pump outlet to Tstat housing and block to Tstat housing. I think most of the cooling for the turbo is done by the oil, and in my car it hasn't gone over 180F yet...but with the way my setup is currently, my heater core line off the branch with the turbo return is boiling coolant on shutdown. Either way, I do want to try and set things up to thermally siphon so I'll need to be careful with the routing of the lines to ensure smooth flow up and towards the rad after shutdown. @rossmanGood point about running under the block, I had not considered that. I have a few days to mull things over while waiting for parts but that sounds like a fairly clean approach.

Thanks @JMortensen. Good to know I'm not alone here. I was considering getting another pedal and bending it up but was afraid to fatigue the metal and have my gas pedal possibly break off. Yeah I made a couple of the plates, I think they are 1/8" scrap and can be stacked. Will check that pedal stop at the bottom again for WOT.

@rossman are you returning to the lower rad hose inlet direct at that location? Or as I currently have it routed by the heater core branch? In the vid above you can see the AN fitting I welded onto the heater core branch and that is the return area. I was conferring with Dave/Brian Rebello and Richard Boyk on this routing specifically, and some concerns were raised there with low pressure or backflow in that area after shutdown (e.g. pump pressure gone) which seems to jive with the boiling I've been getting there. I wish I had an IR thermometer but those turbo coolant lines get HOT. I think the consensus is right at the lower rad inlet shouldn't have issues but I'm still considering the block drain as it's just in a more convenient location + will have a constant and gradual slope up instead of wrapping the hose all the way around the block with all of those elevation changes, etc. In conferring with Tony D it seems the block drain would work too but would be warmer (e.g. setup for thermal siphon trickier) and have higher pressure (e.g. flow more through the turbo when running). Hopefully I got that all right. I'm a bit out of my league when it comes to coolant flow/temp characteristics in the L. Just trying to get something that works 😁

@calZ it is currently like this: heater core branch on suction side > turbo > lower tstat housing. After some deliberation I ordered a 1/2 BSPT to 37 JIC fitting to go: Block drain > turbo > lower tstat housing. Mainly because I didn't like the idea of wrapping a hose all the way around the block.

So after some further review/discussions and help from the community, it seems the turbo coolant line routing I have won't work. What I thought were air pockets boiling out at the heater core branch area is likely flow reversing from the hot turbo causing localized boiling in that area after shutdown aka nucleate boiling/after boil. For the heater core branch I'll block off the current feed there with a standard -6 cap. Now I'm trying to decide whether to feed the turbo from the lower coolant neck by the water pump, or the drain at the side of the block. I think either would work but the lower coolant neck would have lower temps/larger delta T but require me to wrap a hose all the way around the block. The block drain location may have slightly higher temps/pressure but would allow a more continuous gradual rise in the line run for thermal siphoning. It would also be a shorter hose run and hidden by the turbo.

Yesterday evening I managed to get the cooling system back together and bled out. I'm still getting nucleate boiling/after boil at the back of the head and around the heater core/branch feeding the turbo. Not sure what's going on but at the suggestion of some seasoned and super helpful Z people on the FB groups I'm going to run down the list this next few days to really drill down and diagnose: 1. Remove tstat and check for strong flow at the top of the rad across the fins (preliminar test for flow, even new water pumps can be bad) 2. Test and replace tstat (they can be bad brand new, have a new 160 in there now) 3. Check for flow through radiator, ensure not blocked (new builds can have sediment etc. flow out and block even a new rad) 4. Check water pump (not sure what's in there as Rebello had installed it) On one hand I'm glad I'm catching this now before boosting and blowing up. On the other hand, the teething issues are fairly annoying. I just want to go out and drive! 20220723_160542.mp4

Btw huge shoutout to my buddy Josel @ sidedraft specialties. And Craig @ Simtec Motorsports. So many people to thank over the years let alone a very understanding spouse lol. I definitely couldn't be where I am today on this build without the Z community. It's kind of crazy I've known a lot of these people and met so many more along the way over the past decades but I'm glad even with the way things are in the world now we can still get together and share the same passions and keep helping each other build our dreams👍

So after rebuilding the cooling system I put in the jets my buddy lent me. I suspect Rebello tuned the engine for straight dyno power pulls 4k+ rpms as the drilled/soldered jets in there responded crazy going into insane rich levels on tip in with 0 pump volume and still lean popping at idle an 10 afrs so a definite fuel metering issue. With the new virgin jets, the engine is responding now like any other sidedraft setup I've tuned which is going slightly lean on tip in with 0 pump volume and much more responsive. 20220724_205157.mp4 Unfortunately it was getting late and most of my neighbors have young kids so I shut it all down before 9pm. But at least now I can start re-baselining and actually tuning for a super responsive NA later this week. Hopefully I won't be pulling straight 12-14+ hr days at work again but we'll see tom evening.

Today some friends came over and we were checking out the car when the lower rad hose blew. Not sure what's going on but I've been struggling through some cooling system pressure and boiling issues. I bled the car for over 1 hour 2 times elevated with a spillproof funnel and kept getting more air out. Before the lower coolant hose blew I was seeing maybe 190 at the tstat housing and 180 oil temps with a 16lb rad cap. Nothing is burning or mixing so far as I can tell. I bead rolled the ends of the coupler I made a bit more (it blew out on the side which was "factory" rolled) and hopefully I can shake it down more tonight, and it was just a tightening issue. I mentioned earlier in the build I wasn't too confident in the factory hose clamps for a high performance app but I've been working with what I have. It was a bit of a bummer that I basically dumped 50$ of coolant on the ground but fortunate it happened right in front of my house so I was able to wash it out and animals didn't get to it. Another positive note is my buddy lent me some OER jets when he stopped by and another friend has a bunch they can lend me. Just another day of shakedown I guess but it was good to see friends that I haven't seen for years