Yeah, I checked a couple times and it was a 0.3º difference. Unfortunately no CV joints, we couldn't find an adapter from the Super 8.8 flange to the 930cv and didn't have enough time to manufacture one. I'll check the angle once more since we made some changes to the gearbox mounting.

I'm running a 3.55 final drive. I've seen many numbers floating around for the max output shaft speeds... last I read 8500rpms was still "safe". I don't use 7th and 8th at all (unless coasting), which means my current top speed is 223km/h at 7300rpm, aka not enough. Next year we should be able to rev to 8500, which would already bring it up to 260km/h. We can still move to a 3.31 final drive, bringing it to 279km/h. On top of that, we might go straight to 18" wheels, which would bring it to 307km/h, which is way more than we realistically need, so if we go to 18s we probably don't need to change the final drive.

Oh man, so much has happened haha, I don't even know where to begin... but I just realized I didn't post any onboards here. For now I only have the onboard from the first test day in Sweden, VERY far from the limit and braking miles too early since we never really got the brakes working properly, but still, so much fun to drive this car.


This was my first lap pushing a little bit, and I matched my best time on a Porsche GT4. I still had to lift on the straights due to the vibrations and you can see how early I brake on the first corner, so after T1 I was already down 2.5s on the Porsche, just made up for it on the tight section. The one time I tried to stay in on the straight I was significantly faster than the Porsche, but then the gearbox let go. All in all, the car should have at least another 4s in it without any changes.

The parts for the new engine are already ordered, it'll be sleeved and dry sumped, fully built top and bottom ends, so hopefully we can push somewhere between 700 and 800whp, as originally planned. That should give us a little more time. The current class record is a 1:05.3, so we still have a ways to go, but I'm motivated.

Other items on the list for this winter are a proper ABS, probably going with a Bosch motorsport and never looking back, so more upgrades to the electronics packages (finally install those IR tire temp sensors and some other bits), and finish the aero package (still missing the flat floor, diffuser and other smaller details).

If there's anything specific that anyone wants to hear about let me know, happy to talk about any part of the car/development. I'll try to not let the thread die again, but be assured that the build is progressing.

 

That's impressive, really looking forward to you getting over the teething issues. On the ABS front, I have missed what are you currently running?

 

I'm running an mk60e5. I know lots of people run them successfully, and it seemed like it would work ok after the first shakedown, but the software is weird, and I found the information online to be scattered and confusing, so I decided that I don't want to make a project out of the brakes and would rather buy something that works out of the box and has proper documentation and software.

 

How fast were you going when the transmission broke? I have a similar setup in my car (K24 turbo, 400hp, 8hp50, 3.24 final drive) and I have had it up to 145mph in 6th, which is about 7100rpm output shaft speed. I also get some crazy vibrations at high speed, but I'm not sure where it's coming from yet.

 

I wasn't going very quick at all.. about 195km/h. My final drive is 3.55, weirdly when looking at the data it doesn't quite match my calculations, but looks like rpm was around 6800, which should have been ~10km/h faster. There's a little reel of the moment it let go here: , it wasn't very dramatic.

FWIW, I don't think the output shaft speed is what killed it, I think it was the vibration coming from the driveshaft. In the onboard I posted in the last post you can see the g-force going over 5Gs on the straight, the engine is on poly bushings and the gearbox mount was a bit too rigid although there were tiny bushings, so my hypothesis is that the engine movement split the gearbox. Not sure if I posted here, but it was a fairly clean break. The vibrations increase quite sharply in 6th gear, so I think it's something to do with the box.

On a different note, a couple people asked, so I convinced a friend and we started a little YouTube channel. We released an episode showing the prep for the Nurburgring and within the next few days we should have the Nurburgring video out. I'll probably try to record something about what's been done far, including the 3D modeling/CFD/Printing/Carbon process, but if anyone has any suggestions/requests let me know.
https://www.youtube.com/watch?v=08VqPuvQcgI

 

Subscribed!

 

Found some more photos of the car at the Nurburgring. The editing for the video isn't quite done yet, but should be soon.

The fenders look so far off with the small wheels, but hopefully we can get the 18s in this winter and that should look a little better. The project list for the winter is already getting pretty long again... 😅

 

I really want that bit on the front drivers turn signal to be an RPM gauge that lights up as the car is driving. Glad to see more of this car. I stumbled upon your YouTube channel the other day so I'll have to start watching those as well.

In 4 wider wheels.

 

A couple people actually suggested that haha, it's a neat idea, but unfortunately right now it's just a simple flexible LED light that we threw in there last minute as it's required by the rules.

Pretty much all the parts for the engine build have arrived, just missing the dry sump and a couple small bits, but the build will start soon:

 

Are you sleeving due to boring out the cylinders a great deal, or just to cover all your bases? I went back and forth on having mine sleeved when I built it, but ultimately decided to skip it as I was only doing .5mm over.

 

Just for extra safety. I would like to be able to run somewhat consistently at 800whp, and chatting with my tuner/engine builder we also had a bit of a back and forth, but the consensus seems to be that that's right about the limit of what the stock sleeves could take, so we figured we might as well just go for it.

The original plan was to build everything for 1000whp and run it at 800whp, but there were significant extra costs and challenges with that, so this was our halfway solution. It seems like to hold more power than this we'd need a closed deck/mid sleeves, but then cooling becomes a challenge, so this engine should allow us to run a good amount of power for the next season while we figure out how to take it even further 😬

 

Do you have any drawings / models for the Super 8.8 differential in the Miata subframe? I am thinking about going that route with my current project since it has the perfect gearing for my Ecoboost Mustang based build.

 

I'm afraid I don't... I started 3d scanning the subframe and diff, but once you actually put them together it's a pretty tight fit, so there was only possible way for it to go together. I have some pictures of the process, maybe that helps a bit:

 

Thanks for posting those pictures.

 

 

This thread makes me want to do cool ****. I love it.

 

This is like the fast-forward version of my current build, like really fast-forward, amazing progress. I have a race prepped NB1 with a LS swap and aero that I am currently converting to forced induction.

So how far below the rails is the 8HP70 pan? I am also adding an undertray and it could/will be a bit below the frame rails.

I'll be watching to see how things are resolved with the transmission output RPM and the driveshaft balancing.

 

I also like this brace right here. Makes me think I will do the same.

 

It does't stick very far at all, probably even or just a few mm lower. In my case that's really not a problem, because I don't want to run the car too low and compromise the suspension geometry too much, specially next year if we manage to get the 18" wheels ready. The plan is to run the car at ~6" ride height (from the pinch welds), but the flat floor and splitter will be 3" from the ground. That should allow making the floor more efficient, since we can have a gentle slope starting from much further forward. This gives the same gain as adding rake to the car, which was huge when I tested it in CFD, without compromising mechanical grip on the slow corners. 3" also feels like a reasonable ride height, should allow for most of the ground effect benefits while still being able to run reasonably soft springs and not scrape everywhere (although it still scrapes a fair amount in elevation changes).

I'm still waiting for the OLH video to come out, but in the mean time the car made a small appearance in Misha Charoudin's video from European Time Attack Masters (link to the timestamp where my car comes up):
As for actually working on the car, I've been a bit lazy to get started on the winter upgrades and been just planning at the moment. I can't even walk into my garage at the moment... the weather will get a bit warmer this weekend, so hopefully I can organize things a bit, and then the plan is to finally weigh the car and immediately start disassembling it for the winter. The engine needs to come out, this one will go into storage as a backup, since we know it at least works 450whp. I have 2 other engines in storage, one of which we'll be taking up to the engine builder in the next few weeks.

 

Good luck on the winter work/mods. Great build, seriously cool.

FWIW I am using 5th gear in a T56 on fast tracks like CoTA; it has 15" wheels and a 3.55 rear end ratio. With more power, if I switch to a 8HP, I am going to need to use 7th, maybe 8th, and/or lower the rear end ratio.