Triple Blowthrough Turbo

[Dat73z]

A week and a half ago I attempted to source some 0.045 308L filler wire to finish the exhaust. It turns out the smallest quantity any local supplier around me sells is 10lbs. So I found a 1lb bundle on Amazon and I'm still without filler with a delivery date of next week due to trucking delays 🤬. Oh well. 

 

This past week I wrapped up the rest of the plumbing and cooler bracketry for the car. On the frontend the 10AN SS braided really does not like to bend. I decided to fabricate a bulkhead to ease the oil cooler routing. There is a small air gap between each component and my AC condenser fits in there nicely with all the fittings as well. The packaging is extremely tight. 

 

This weekend I'm going to start modifying the charge piping to fit. That is the last major component in the engine bay, then I can finish relooming the harness to ensure it clear everything and begin filling fluids. 

 

Edit: just realized after posting the photos I also pulled off a bunch of parts to have them zinc plated. Also refurbishing the JDM fairlady grille. Not really turbo related but I figured the inspection light, hood latch, etc. would brighten everything up a bit

 

Edited April 23, 2022 by Dat73z

[Dat73z]

Some rough measurements on the hot side I'll need to chop and shorten on two sides of the run. On the cold side into the surge tank I'm still not sure if I'll attempt to make some pie cuts or just two angle cuts to line it all up. The good thing is now I know everything will fit but it'll be tight. 

[Dat73z]

This morning I trimmed the hot side charge piping to fit. I'm happy with the clearances but need to purchase a bead roller to dimple the ends and prevent tube blowoff. I could also run some beads with the tig. 

 

For the cold side, I eyeballed that it'll take 2x 45s so I ordered the pipe and was promptly hit with a warning message for transportation delays/supply chain issues...hopefully I won't be waiting months for that 😂

 

I also fabricated a plate to hold the headlight relays and fan controller. I think I've probably made something like 20 random brackets for this build from bending to welding using scrap materials I had laying around the shed for house projects and my wife's garden. I now feel confident in my abilities to fabricate a bracket for any occasion LOL

 

Got some good news as well that my 308l filler should arrive today...so now I get to clean up my cutting, grinding and welding stations for stainless exhaust fabrication again since I switched to AL while waiting...

Edited April 23, 2022 by Dat73z

[Dat73z]

Had a bit of time to work some small items today. Kept welding and fabricating the exhaust. I have half of the midpipe tacked out and half of it welded but it's been hard to find solid blocks of time to make good progress. Slowly but surely it's getting there. 

 

Also got the cold side piping in so I profiled and chopped the tubing in preparation for welding. I still can't believe it came in so quick, I've been used to waiting weeks or months for parts lol. As I suspected I was able to get good angles and clearances with 2x 45s trimmed. Now to order a bead roller. 

 

The weather is improving too so time permitting this weekend I can paint my cowl section and get the windshield back in. 

[Dat73z]

Was cleaning up some albums on my phone and realized I never posted the turbo fuel system setup. Maybe someone can find this helpful.

 

I decided to do -6 feed and -8 return with an in-tank 255 pump bypassing through an aeromotive regulator. I had considered a 270 pump as well but didn't see it as necessary. Based on my research this should support 600whp on carbs which gives me some headroom. 

 

I fabricated the lines from basic SS tubing, AN flared connections, and limited braided SS softline use just at the small section by the tank and from the fuel logs to the carbs. Most of what I saw online for blowthrough/nitrous carb fuel setups were big v8 guys but maybe someone will be searching and find this in the future as well for sidedraft carbs on an inline 6. 

 

If I decide to go itbs later this setup will support that as well. If I was going to do the setup again I'd run the lines out of the tunnel for safety but I got to the point where everything pressure tested out good and I wanted to get the car back together by this summer. 

Edited April 29, 2022 by Dat73z

[rossman]

Your engine bay looks really clean! Is that a custom catch can?

[Dat73z]

Thanks @rossman. The catch can is an off the shelf Vibrant. I did cut and tig weld the bracket though. Originally I thought I could bend it but it turned out to be like 1/8" SS which was impossible to bend with my garage tools. I reused the firewall ground threaded hole and did a rivnut on the other side. 

[Dat73z]

Finally got a solid hour today and finished welding out the midpipe. It felt like a small victory after a crazy schedule this past few weeks. Tomorrow I have a few hours off so I'm hoping I can tack and start welding out the rear section.

 

Now that I have a bit more fabrication experience, fitup is getting a bit quicker but I think I need to pay more attention to making absolutely sure everything is "white glove" clean before welding

[Zetsaz]

Yours is looking much nicer than mine, i must say! Granted you have a much nicer workspace than what I have available to me

[Dat73z]

Thanks @Zetsaz! It's not perfect but I've learned a lot. 

 

I think I'm finally at the tail end of this project. I spent like an hour positioning the muffler and hangers. I think I'm going to tack the muffler hangers first to lock in that positioning then fit up the final tubes. I'll probably do one joint at a time and be super careful with the heat input so in case anything moves I can still do some fine tube profile adjustments. 

 

I'm planning to add 2 more hangers, one by the diff and one to brace the downpipe. Then the o2 sensor bung. Finally send the downpipe off to be inconel shielded. 

Edited April 29, 2022 by Dat73z

[Dat73z]

I tacked the rear muffler hanger in place and ended up spending the hour I was hoping to get the muffler final mounted instead looking at it from every angle. I was crawling all over the ground at different distances...my neighbors must think I'm crazy. 

 

I don't know why but each time I've been looking it seems the angle keeps changing so I keep repositioning the muffler. I think my eyes must be tired. It's pretty well centered but I want just a hair couple mm angle up. Definitely no downward angle. 

 

I'm going to tack in the front hanger and call it a day. I figure I can still bend the hangers a bit with the tacks, maybe it'll look different in the morning. 

[AydinZ71]

Dude did you TIG weld that yourself? It is beautiful! 

[Dat73z]

Thabks @AydinZ71! Yeah I've been doing all this myself and re-teaching myself how to tig on this project. Before this I was probably a decade away from the torch. Really it's like 5% welding and 95% fitup and cleaning fundamentals. My cleaning still isn't where it should be to get the quality of welds I want...but it's all part of the learning process

[Dat73z]

A couple of hrs more than I should've spent today but I finally figured out the issue. The front SS bracket I fabricated duplicated the OE mounting with a welded SS nut and uses an OE Nissan mounting strap. 

 

When I was mocking it up A couple mm of offset angle in the strap translated to the muffler moving a couple mm vertically in either direction. 

 

I ensured the strap was fully vertical and tacked the hanger in place. The result is the muffler sits as I measured and fabricated the bracketry. A couple mm slant up which follows the lines of the 240z gas tank and also centered out the back. I set the car down just to be sure. This weekend I'm going to try and finish the exhaust. 

[AydinZ71]

Looks super clean. I still think your welds look great despite your lack of recent practice. All I have been doing is sheet metal welding with a MIG. In comparison, it feels like slinging shit at a wall and using a squeegee to grind off the excess. I don’t have enough chassis welding left to justify prioritizing TIG, but maybe on the next build. 

[Dat73z]

Lol. Mig is pretty well suited for what you're doing. The annoying thing about tig is all of the prep work that goes into a single piece. It can easily be hours of prep for a 5 minute weld job. I definitely miss being able to just send it with the mig. 

 

The nice thing is there are a lot of affordable hobbyist tig options now. I remember looking like 10 or 15 years ago and the only "affordable" option was like the $10k+ miller dynasty

[Dat73z]

Today I managed to get the rear section welded out with the exception of the muffler. I was able to achieve perfect alignment to the muffler in position with the assistance on a paint stirring stick and a bunch of painters tape because I don't have 10 hands.

 

Unfortunately I'm running out of argon. I think I have just enough to tack the muffler, final hangers, and o2 sensor bung. I have been backpurging everything including the hangers so I've been going through argon like crazy. I've basically gone through an entire 145cuft tank just for this exhaust. Fortunately this will be the last fillup. 

 

Knowing what I know now, if I was going to do this again I'd go 4" or larger oval pipe as the 3" was easily able to be tucked under the car. Maybe on the next turbo build. 

 

 

[Dat73z]

So this morning I couldn't resist final welding out the muffler. I backpurged that rear section and I finished welding right as my regulator gauge hit 0 lol

 

The rear section was definitely the most challenging to weld due to the size of the piece and the angles so most of the welding was done completely out of position. The muffler I actually tacked on the car on my back holding it with my knee, filler and torch with my hands, and foot pedal on the ground actuated by rolling my other foot. I welded the muffler itself completely standing up which was good practice. 

 

With everything mounting and vbands tight it's actually really solid. I could've probably gained another 1/4" of clearance by tucking the pipes even higher than I did. 

 

I'm still thinking of bracing the downpipe/midpipe to account for thermal expansion/contraction off the turbo and one more by the rear diff just for full support. Any thoughts? 

[Dat73z]

And a final system shot. The lowest part of the car are the cooling fins for the oil pan. I probably could've gained 1/4" of clearance or more for a lot of the system with the exception on the trans mount area. I had to kick the pipe down then back up from there and only left about a finger gap. Not sure how I could gain more there, probably oval pipe would've worked...maybe someday in the future

[Zetsaz]

Looking goooooood. Not sure why you had to kick down at the trans mount though. But your 73 is a bit different than my 75.

 

Just saw your post on Facebook and started following so I could see other's ideas haha.