240Z EgoBoost by Boben

[Boben]

As you can gather from my previous posts, I made a 3D model of the 180 degree exhaust manifolds. From that model, I produced manufacturing documentation for a CNC pipe bending machine. In the documentation, pipes for each cylinder are defined as a series of the following information: straight pipe to be feeded before next bend, rotation of the pipe in respect to the previous bend and angle to be bend. The bending radius is the same for all bends because of the tooling. The material used was 42mm pipe with a bending radius of 70mm. Due to the limitations of the machine, certain consecutive bends are not possible and some extra straight pipe feed is added. This ment that I got a pile of pipes requiring some extensive cutting to the correct lenght and welding. Still much more straight forward since you have a paln to work with. So this is what I got:

The pile includes all pipe work as per 3D model and some extra pipe in the places where two consecutive bends are too close to each other (all extra pipe was marked by the manufacturing shop to ease my work), materials for the collectors along with retaining springs and holders.

 

I made a jig to locate the pipes on the collector.

 

Jig in place.

 

 

I started with the center cylinders since those are the ones with exhaust pipes running to the other side of the block to combine with their 180 degree counter parts. I now have 6 out of 8 all tach welded in place. I've been working at a "two cylinders per evening" pace.

 

 

 

This is the money shot:

[74_5.0L_Z]

Cool! That is exactly how defined the bends for my exhaust. Except, I made everything from j-bends.

Who did you use to do the CNC bending? How much did they charge.

 

That looks really good. How long are the primary tubes?

[Boben]

Cool! That is exactly how defined the bends for my exhaust. Except, I made everything from j-bends.

Who did you use to do the CNC bending? How much did they charge.

That looks really good. How long are the primary tubes?

I used a local shop here in town called Martelius Exhausts. Cost was 340€.

The primaries are not equal length, but vary between 800mm-950mm. With the exhaust valve opening angle at 20 degrees before bottom dead center, the tuning of the primaries is roughly between 4000RPM-5000RPM. This is also the area where the engine produces the most torque and this is why I chose to aim for these lengths. Primaries not being equal length is actually beneficial since the torque curve will be more flat as different cylinders have their resonance at slightly different RPM. Better for street anyway.

[74_5.0L_Z]

Packaging drove the primary lengths for my exhaust. My primaries vary from 25 to 27 inches (measured from the exhaust flange to the beginning of the merge collectors). Being as short as they are, I expected to lose some bottom end torque. Unexpectedly, I gained 38 lb-ft of torque.

[Boben]

I continued on the Audi diffuser fitment. Managed to get the passenger side pretty much ready.

 

 

 

 

 

[ConvertibleZ]

Amazing attention to detail. Love the body work and the effort to maintain such a civilized car!

[Boben]

Amazing attention to detail. Love the body work and the effort to maintain such a civilized car!

Thanks, the progress is slow and I do find myself fiddling around with the little details time and time again.

[Boben]

I have been contemplating the rising of the center tunnel almost from the get go. After installing the exhaust manifolds I was faced with the fact that the steering shaft just was not going to fit. I had decided not to include the rubber joint of the shaft to the model and sure enough one of the primaries hit that. Also there was quite little clearance from the exhaust to the longitudinals. I knew the engine was sitting low with the oil pan bottom surface level hanging below the bottom of the x-member. With so many problems to be solved by lifting the engine and transmission, I decided to cut out the center tunnel and see if I was able to lift them. I raised the tunnel 45mm from the front and a little less from the rear. The engine and trans was lifted 35mm. Clearance between the modified steering axle, motor mount and the exhaust basically defined the new engine position. The tunnel height was defined by clearance to the bell housing, clearance between the drive shaft and shifter mechanism and the parking brake mechanism.

 

 

 

 

 

 

 

 

 

I received the billet adapter for my drive shaft from the machining shop. The transmission side was done according to measurements from the original rubber joint.

 

The drive shaft side was done according to the measurements taken from the CV-joint sealing cap.

 

And here is the drive shaft. At this point only tack welded for initial fitment.

 

Here is the extension shaft which connects to the rack.

 

 

This is the new height position of the tunnel.

 

 

 

Some pictures of the exhaust manifolds in place.

 

 

 

 

 

Here is the extension to the steering rack axle.

 

 

[Boben]

I cut the custom steering axle extension rod to the correct length along with shortening the original steering axle and preparing a new fitting for the joint on the lathe. After test fitment, welded the stuff back together. I am quite happy with the outcome since the angles of the joints did not increase too much. The steering seems to be turning smoothly. I still need to modify the primary from cylinder number 5 to clear the rubber booth on the steering axle and also make a bracket for the support bearing, but I guess I am on the winning side regarding the steering.

 

 

 

 

 

 

 

 

 

 

[disepyon]

Dude that Rear diffuser is sexy.  Awesome jig for the collector area of the headers.  Are you able to weld everything with all the headers tacked like that?

[Boben]

Dude that Rear diffuser is sexy.  Awesome jig for the collector area of the headers.  Are you able to weld everything with all the headers tacked like that?

Thanks, I am quite pleased with the little more modern appearance that the diffuser brings to the rear.

 

As for the design of the exhaust manifold. The primary for each cylinder is a separate piece which connects to the detachable collector by slipping under a sleeve on the collector. Each primary is then secured to the collector with a retaining spring and holder. Even with this arrangement, the assembly of the exhaust manifold is a real pain, but what can you do.

When I finally get to the full seam welding part, I'll probably try and TIG weld as much as possible on the engine stand with the collector jig in place and then finnish off with the rest of the welding with primaries separated from the stand and jig.

[Boben]

The clearance between the valve cover and the brake booster was tight to begin with and the situation got worse when I lifted the engine. However, this did not come as a surprise and yesterday it was time to execute my plan to increase the clearance.

 

Here is how things looked after rising the engine with the brake booster in the original position.

 

Here is the unmodified pedal box with the brake booster and clutch master cylinder inplace.

 

I forgot to take pictures during the modification, but basically all I did was drill some new holes 15mm aside the original ones and cut some more space to the center to enable assembly of the booster 15mm aside from its original location. The displacement is big enough for the fork to clear the pedal axle and at the same time small enough for the booster to not hit the clutch master cylinder.

 

Here is how things looked like inside the cabin before cutting the fire wall. This is how I marked where to make the cuts and drills on the fire wall.

 

And finally the end result with increased clearance. Sweet!

 

[Boben]

It has been too long since I've updated on this build. Sorry for that. Well, here comes.

I got the tunnel finally welded back. With the new position, the HVAC unit was obviously not going to fit without modification so that went under the knife along with the original fixing points on the tunnel. The new mounts are not entirely ready yet, but at least I have proof now that the HVAC fits inside the dash. The lower fixing points on the dash also needed some cutting to make the dash fit. Here is some pics.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

[grannyknot]

Very impressed, some seriously talented fabrication going on here.  With the transmission tunnel kicked up like that will you have room for the stock console to fit in or are you making one?

[Ryan Merrill]

The raise transmission tunnel would be appreciated when trying to.reach the back bolts on my 4L80E bellhousing. I'm sure it creates a whole new set of set of issues with the interior. Loving the build, keep posting.

[Boben]

The stock console on top of the tunnel will not fit from the front so it will have to go under the knife as well. Other then that, no known major issues.

[Boben]

One of my friends at the garage dismantled an Alfa Romeo 156 V6 for parts. At the same time I was looking out for an A/C condenser for my 240Z and luckily enough, the Alfa unit has the perfect fit and refrigerant connections at a convenient location. I used the beaten old unit for fitment and fabricated some fixing points for it. I found some nice rubber grommets with thread inserts on them to use in the fixing. I have no idea for which car they are for and what they where meant to fix in the first place as I found them from a box we have at the garage that has all kinds of rubber grommets, seals and plugs everybody has just thrown in over the years. Anyway, worked quite nicely for me.

 

 

 

 

 

 

After fixing the condenser in place, I was finally able to weld the lower radiator mounts on the rails and fabricate the upper mounts. The BMW Z3 M Coupe radiator sits nicely between BMW OEM rubber bushings.

 

 

 

 

 

 

 

 

 

[Boben]

With the condenser and radiator mounts finished, it was time to modify the opening in the front to accept the Alfa Romeo 156 V6 dual fan bracket / shroud. I removed the original fixing flanges from the bracket by drilling through the spot welds and finishing off with an angle grinder. Then I cut the opening. around 2mm from the top all the way and cutting into the corners of the opening on the bottom did the job and the bracket slipped right in place. I applied some weather stripping around the shroud edge and mounted the shroud firmly agains the condenser. Should work quite nicely. After a light sand blast along with the rest of the body and some epoxy primer, the bracket should blend right in.

 

 

 

 

 

 

[74_5.0L_Z]

I hope those fans are intended to be mounted in front of the radiator (intended to push the air).  Most fans are mounted behind the radiator and pull the air through the radiator.

[Boben]

I hope those fans are intended to be mounted in front of the radiator (intended to push the air).  Most fans are mounted behind the radiator and pull the air through the radiator.

You are right. This is how most of the fans are mounted. The bracket was already removed from the Alfa when I got my hands on it so I am not entirely sure of the OEM installation. Based on a quick google search, might have been assembled in the back and meant to pull air through the radiator.

Quite many after market fans have the blade geometry symmetrical (straight) so that the direction of the rotation can be changed by switching the supply polarity, hence enabling the use of the fan both in a push and pull configuration. The Alfa fan geometry looks also suitable for both applications so I think it is going to work. Also, a fan can produce a much bigger volumetric air flow in a push configuration compared to a pull configuration.