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A tale of two Z's - NA vs Turbo


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Hello everyone,

    It's been well over 10 years since I last participated in this community. I'm excited to share that I still have both of my 240s and have recently started working on them again. In the past, I faced some obstacles due to limitations in my home garage and other life commitments like family, job, and finances. Thankfully, I stored the cars instead of selling them, knowing that one day I would return to them. It would have been disappointing to lose them.

 

    A few years ago, I left my previous industry after 30 years and ventured into my own business, but it wasn't as enjoyable as I had hoped. Dealing with the day-to-day operations and working alone didn't suit me well. Fortunately, I found a great position in the Aerospace industry with a company that I enjoy working for. This new job allows me more personal time for my hobbies. I was able to keep my shop and equipment from my business venture, transforming it into an amazing man cave, fully equipped for building custom cars and motorcycles.

 

     Around six months ago, I started working on my cars again, with the goal of getting them on the road within a few years. Both cars are 1972 240s, one being my old autocross/track day car with its original Safari white paint that I've owned for 20 years. The other one, which I bought back in 1984 when I was 15 years old, has been stripped down to the shell and will be converted to a turbo configuration. Both cars have solid shells, with the turbo car in particularly great condition considering its garage storage and origins from Atlanta. The NA car has some minor rust starting on the lower doglegs, which I plan to replace and repaint from the lower body line down, while preserving the original paint and its nice patina.

I thought it would be fun again to document and share my progress on both cars with the community, as well as seek suggestions and ideas from all of you. It's been a while since I've been involved, so I'm sure a lot has changed over the years. I appreciate any help and guidance you can offer.

Thank you all for your support.

 

monZter

 

 

 

 

 

 

Edited by MONZTER
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This is both cars as they currently sit.  The Turbo car is the black shell.  All apart and ready to be put back together.  The white one on the lift will be the NA car and its just starting to come apart.

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Edited by MONZTER
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I've owned what will be the turbo car since 1984 (black shell now), which is pretty cool. I bought it in Atlanta, Georgia, so it was in great shape with its original paint and no rust.

I still remember the first time I laid eyes on a 240z. I was 14 and working at a bike shop. One of my co-worker's friends had a shiny black one, and I instantly fell in love with it. I saved up around $1,500 over the course of a year. Living in Ohio meant finding a clean, rust-free 240z was a challenge due to all the salt on the roads during winter.

Luckily, my dad knew someone who bought cars down south and sold them in the rust belt. I asked him to keep an eye out for an original and clean car for me, and after a few months, he found one. My dad and I flew to Atlanta together, and I even got to drive it back home on my learner's permit. Those were some really great memories.

 

Here are some old pics I found digging throug boxes

 

Me ripping out the engine as soon as I got it.  I had a shop class in high school where we re-built a lawn mower engine.  This this was my first car engine I ever built.  I remember reading the "How to Modify" book over and over.  Who did not want that engine on the cover in their dream car?  Drove it like this throughout High School.

 

 

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I only ran simulations (CFD) on the Turbo Plenum. As for the NA Plenum, I used a stock version and modified it myself. Personally, I don't think it's as necessary for an NA car since it pulls in air instead of being pushed like a Turbo. But hey, that's just my initial thinking. The dual plenum design might help reduce turbulence in an NA car, but we'd need to put it on a dyno to know for sure. Unfortunately, CFD would be tricky for that. I could try some ideas, but I don't have access to the software anymore. Right now, I only have access to basic fluid software in Solidworks, and it's not great for modeling air and other compressible fluids.

 

Ill dig up some old photos and post them up of both of them since it sounds like many of the original photosd are gone.

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This is the NA Plenum.  I found a OEM verion that did not have the EGR and proceeded to cut it up.  Cut the plenum down the middle to open up and blend in the runners.  Added about an inch to the width to increase the volume.  I then added about 1.5 inches to theh length of it where the throttle body attaches.  I added this at an angle to better align it with the front cowl for a straight pipe, as well as allow for a large radius.  I think the angle and the large radius going into #1 was a good way to go.  Ill try to find more pics of it before it was done showing the work.

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Here are some pics of the Turbo Plenum showing the inside details of the slot and the flow straightening vanes to prevent swirl as the air changes direction.  These vanes gave the air more of a tumble into the runners for even flow.  I see if I can find some of the old CFD pics on a back-up drive somewhere.

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5 hours ago, Dat73z said:

That plenum is a work of art. Have you seen the Milkfab engineering plenum? It looks like they're working on something similar, but I think your design looks much cleaner. 

I thought I heard about them going out of business?  Who else make a plenum that is available to purchase for the L-Series motor?

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39 minutes ago, MONZTER said:

I thought I heard about them going out of business?  Who else make a plenum that is available to purchase for the L-Series motor?

 

Apparently you can pre-order them here: https://milkfab-engineering.com/shop/ols/products/milkfab-l6-ultimate-intake-manifold?fbclid=IwAR2QU6NWyno4bkaHjMeclJE8GjibiUpXNflrK7zKtNn78XIMtKwqNsuRALg

 

It would've been cool if they had a standard dcoe style pattern for the runners to open up itb options. 

 

Also I just realized in the description you inspired the design so I suppose that makes sense 😅

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2 hours ago, MONZTER said:

I thought I heard about them going out of business?  Who else make a plenum that is available to purchase for the L-Series motor?

 

ProTunerz makes one, but it's just a simple plenum. Looks nicer than the stock intake, though. 

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4 hours ago, Dat73z said:

 

Apparently you can pre-order them here: https://milkfab-engineering.com/shop/ols/products/milkfab-l6-ultimate-intake-manifold?fbclid=IwAR2QU6NWyno4bkaHjMeclJE8GjibiUpXNflrK7zKtNn78XIMtKwqNsuRALg

 

It would've been cool if they had a standard dcoe style pattern for the runners to open up itb options. 

 

Also I just realized in the description you inspired the design so I suppose that makes sense 😅

Thats looks pretty cool, seems to pretty much capture the design intent.  It will be interesting if they finish it up and see some results of how it runs vs a stock system.

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Mine has been sitting here in my office as a display with the rest of the engine.  About 6 months ago the first part I started on completing was the long tube headers for the turbo car.  I always liked the "bag of snakes" look from the old Gurney car, so this is what I ended up with.  It’s all 321 stainless.  Probably about 6 hours of sanding and smoothing on each primary, then I sent it out to polish which cost a small fortune to polish.

 

Its a 6-2-1 design with 28" primaries in 1-5/8 diameter.  Obviously the down pipe is just a mock up but its 3.5" diameter.  I will run the wastegate parallel along the down pipe and connect it in downstream 

 

Some more pics

 

 

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I just stumbled on this thread! Happy to have you back on the forums!

 

The turbo car and the plenum really inspired me and thus why the Milkfab Manifold came to fruition. Its great to see you back in the swing of things! I cant wait to see your progress on both cars.

 

Also, that exhaust manifold is a piece of art!

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