RobPhoboS

Greetings from the UK!
Such a clean and fantastic, Germanic attention to detail!!
I think Mr GT4 is the same friend of mine too (B), the oil pan spacer with the cooling fins is superb. How on earth did he do it? (I know you said 3d printed) perhaps he should take it to a factory to have a run of them made.
I hope to see you in the future at the 'ring 😎

Marcel Roehrl

Thanks, if you're his friend then we'll probably see each other at the ring
Yes the pan is great, he also designed it that way to eliminate his oil cooler and to save some weight (not a track only car).
To print these cost way too much, he was thinking about casting a batch, but I don't know if that's going to happen.

260DET

Hi from Australia I'm blown away, lots of reading to do here but one thing is for sure, yours is the best Z33 chassis in the world! By far!!

Marcel Roehrl

Hey, thank you. Yeah it's a great chassis and probably worth the ridiculous long waiting and build time.
I drove it on the streets two weeks ago and it felt great so far. I'll drive two trackdays next month and will probably do an update afterwards.

Marcel Roehrl

Took a while but now I've time for an update.
Last month after a lot of work I finally had my shakedown on the small Spreewaldring. The car felt really good considering that it spend the last years in several workshops. Of course there's a lot of tuning to do but it's already pretty good and so fun and exciting to drive, definitely brought some big smiles
The brakes felt great, but of course it I had to get used to the lack of brake booster and ABS. Learned in the end that I had to give it much more pressure in the hard braking zones. I also had some problems to get the slicks on temperature, but overall I'm pretty happy how the car performed and that everything worked and stayed together.
Here are some pictures and a video of the shakedown




Two weeks later I organized my own trackday with the german 350z forum. Was a really fun day with lots of Z enthusiasts, friends and nice people.
Because it felt a bit soft I hardened the dampers and got hotchkis swaybars, SPL endlinks, stronger inner tie rods and tweeked toe and camber.
These changes felt really good along with the faster track, much more direct and balanced. I also got very comfortable with the car on the limit.
Surprisingly the rear slicks (30/65) were more than dead after the first two stints, but luckily I had some 27/65 slicks with me which I could put on the rear rims at a local shop.
I wanted to try them anyways so I had the direct comparison. The car felt a bit better with these and the offer enough grip, so I'll go with them in the future. Smaller tires are also easier to get to temperature so that's a plus as well. The 30/65 slicks were medium Michelin slicks for a LMP3 car, the 27/65 all around are from the Michelin Porsche Cup. Along with the changes and the faster and warmer track the tires got much warmer than at the Spreewaldring, but still not warm enough. Less pressure and more toe should get me there though. After some more small changes and maybe a splitter I'll go to a faster track like Zandvoort soon. After that I'll go back to the nordschleife.
Heres are some pictures and a video

260DET

She looks solid in the video with no body roll so that's a great start to tune from, as it should be with that chassis. When the chassis work was being done was there any particular part of the car that was identified as needing extra strengthening? Keep the updates coming, I for one would like to follow your changes and results. My 350Z was bought as a caged race car and while the DE engine is great I'm in the middle of sorting out the suspension.

Marcel Roehrl

Not really, the Z isn't the stiffest chassis, especially if you take out all the welded and bolted sheets. So a good cage helps a lot. Reinforcing the rear strut tower was crucial because I removed the strut brace, but also when you go for true coilovers, which I'll do too.

Blurvision

iTrader: (4)

Looking real good!

doyle4281

Beautiful car, very high end build. If you don’t mind me asking, what we’re you able to get the weight down to? I assume composite panels are on the list, but I’m interested in what it’s at now and what you anticipate it getting down to with composites. Have you done any inquiring on composite body work. Much of what I’m seeing is more cosmetic carbon, so it would be nice to hear if you found anyone offering motorsports composites panels for the Z33. Thanks again man, your effort is very impressive.

Marcel Roehrl

Thanks, the weight is about 1290kg without fuel.
Yes panels are on the list. There isn't really a good aero kit for the Z so I'm planning to build one myself.
Besides Garage Mak and maybe this one:
Besides from that I could only find some good carbon doors:
https://www.exact-performance.com/pr...ht-4-5lbs-each (they were much cheaper a few months ago)
At the moment I'm building a full underbody with splitter and diffusor from wood.
That will be replaced in about 1 year with self build parts out of carbon with a foam core.

doyle4281

Thanks alot. You have gotten the weight down very well. Sorry for being lazy, but does your car still have glass? I think the biggest weight saving as far as the panels will be the doors and hatch, as the fenders, hood, and bumpers are pretty light from the factory. But, I know exactly what your saying about the lack of motorsport aero for the Z33, especially composite. There is plenty of cosmetic aero, which I am sure is partially functional in some conditions, but I think your right about having to do it yourself. I am at a bit of crossroads now, as I am deciding whether to turn my S14 or my DE Z33 into a dedicated time trials (Time Attack) car. The 350z has the edge in suspension geometry, chassis rigidity, and likely the initial shape is more conducive to a race car than the S14. However, the S14 has the edge with weight, engine options, aftermarket support and again aftermarket support. Sounds like a "first world problem", but im still unsure which path to go down. The fabrication will be the same for either car, most of the parts will likely be the same as well, for some reason, I just cant get over the macpherson strut setup on the S14. I think the S14 will be easier, spatially, but the Z33 is so much more modern. Thanks for sharing your build.

260DET

What sort of aero improvements are you fellas thinking of? Because stock is not too bad at all, it's worth reading up on what Nissan did originally before changing too much I think eg they went to a lot of trouble to reduce under car drag and lift. There are also of course NISMO add on's and hat Japanese racing series 350's competed in. Another stock advantage is the space available to fit wide wheels with no significant modifications necessary, flares just add drag.

My priorities would be light weight panels,a OS.Giken LSD and a sequential shift.

260DET

Video of Japanese GT500 cars.

Marcel Roehrl

@260DET
First I'll go with a front splitter, rear diffusor and maybe the whole underbody. The Z underbody isn't particularly flat. My engine bay is open on the bottom so a splitter will reduce drag massively. Same with the rear diffusor, because I don't run the OEM exhaust which improves the rear aero.
Later I'll go with a bigger diffusor (need a new custom exhaust), add a rear spoiler and add a bigger splitter with diffusors in front of the wheels and fender vents to even out the aero balance. Maybe even some hood vents.
I'm craving for that gt500 kit for a long time, but it's impossible to get and maybe too wide. But this taiwan knock off comes pretty close to the real deal.
Lsd is also on top of the list, because I'm from germany I'll probably go for a drexler.

@doyle4281
I still have glass windows, I'll go for lighter one's when I build carbon doors with a good frame for the makrolon windows. There are no carbon doors with a frame which you can buy. But it's true that you can save a lot of weight there and on the rear hatch, but I'll wait with replacing the hatch because it doesn't help the weight distribution. A sequential transmission also saves a lot of weight and allows you to move the engine to the back. I was also thinking about a transaxle one with build in differential. That would save much more weight (it was about 50kg) and would even out the distribution.
I'm not into the s14 aftermarket but I think it's much easier to reach a very low weight with that car. Of course both cars have their advantages and I think that the aftermarket for the z is still growing in contrast to the s14s.

260DET

Definately bonnet vents, big ones. They help cooling by reducing engine bay air pressure and reduce drag too I think by reducing the amount of air pushed under the car which will exit the vents instead. Just one thing with under car panelling, depending on the length of your races it may lead to over heating by restricting air from reaching the differential and gearbox.

A GT500 kit would be 'wow', love your car, keep us up to date.

Marcel Roehrl

Yes, best would be a system to channel the air from the radiator the the hood vents. Would be easier if the engine would be further back.
Because I removed the first firewall and the plastic between the windscreen and hood I currently have some kind of a hood vent.

That's true, I'll go for a diff cooling system with a pump and maybe one for the transmission too. The engine temps should be fine.

260DET

Suggest you have a look at some air flow diagrams because the gap between the windscreen and bonnet is usually a high pressure area that should be blocked off.

Marcel Roehrl

Yes that's true, but some also think that removing that has no negative influence and could even suck out the air from the engine bay. I'll test that with some cameras and some wool threads.

guitman32

iTrader: (15)

Most race cars end up going full circle after theyve stripped anything and everything they can off the car, adding in more weight to correct many of the problems created by removing things like the second firewalls and all the associated rubber trim. If you pay attention, one realizes that the OEM airflow management from bumper inlet on has been very well thought out on our platform...eg. hood topside is completely sealed, a "virtual" rad box created by the plastic side trim pieces which contour around the crash bar, foam impact core which also serves to seal/route airflow, plastic side trim to seal off the underhood area from the wheel wells, cold air induction from the factory, etc etc.

Nice car, thanks for the updates.

260DET

Certainly any body mods to the 350 should be carefully thought through considering what the original designers had in mind, including for styling, legal or functional purposes. For example they are not going to go with big bonnet vents if only to avoid rain flooding the engine. Race car engine bay air flow is a topic all on it's own and can get quite technical but basically venting the engine bay reduces drag and lift by reducing air flow under the car. It also helps air flow through the radiator by reducing engine bay air pressure.