The UHaul trailers have the stops and straps at the front of the trailer. Unless you were to strap up further back with your own straps, you are limited to what you can do.

Now, if you do strap the vehicle down on a UHaul trailer in a different manner than they provision for, they will not cover you under their insurance if something happens. The trailers are designed to have the front tires in the chocks and the web over the top, even if the design is not the best.

I used to work for UHaul and there were instances of corporate denying insurance claims for a variety of reasons. #1 was not hooking up the trailer in the way UHaul wanted you to. Worst case, the trailer hops off the truck or a wreck happens and they see the car in the middle of the trailer, they will instantly deny any liability.

You are better off buying your own trailer.

Yeah, you nailed it. The Uhaul was just to get it back to the house when I bought the car. Since the FD is fairly short, and the wheel straps are at the front of the trailer; the car was too far forward and I ended up with way too much tongue weight. It pitched the truck around like crazy with every bump. If I start towing in the future, yeah, I'll just buy my own trailer.

Thanks! Your build threads were the main thing that inspired me to get an FD and build it like this. Too many build threads on this forum focus on pointless dress-up parts and the owner doesn't end up using the car for anything exciting... Yours were like an R&D project; build it, take it to the track, improve what was lacking, repeat. It was awesome (and, spoiler alert, that's where my thread is going). Time for you to get another FD, btw.

kind words. thank you!

i will have my 5th FD this weekend, as a matter of fact :)

V-mount

Alright, cooling. I wanted a v-mount for obvious reasons; this being a track car, I needed to stuff as much heat exchanger surface area as I could between the grille opening and the engine. I'm not the type of person who pays the FD-tax for a pre-made v-mount kit, so I decided to make my own. CXracing's parts are too cheap to pass up, so I ordered a radiator from there (rad-016) with the intention of returning it if the quality wasn't up to my standards. Surprisingly, it's a really well-built radiator -- all of the welds are super nice, the fins are nice, and the pipe attachments are in a good place for the FD. After that, I went ahead and ordered one of their intercoolers too (IC0047-A).

The radiator came with two fans and "zip tie" mounts that go through the fins. I didn't like that mounting solution, so I opted to build a fan shroud. I used 3/4 angle aluminum to build a frame around the back of the radiator, welded aluminum sheet metal to the frame, cut out two fan-sized circles in the sheet metal, and bolted the fans to the shroud:

https://cimg6.ibsrv.net/gimg/www.rx7...1b837ca41e.jpg

Made some brackets to mount the front of the radiator to the frame rails (this is the driver's side):

https://cimg0.ibsrv.net/gimg/www.rx7...46abe3d8cc.jpg

I was too lazy to re-locate the battery to the rear of the car, so I decided to keep it up front. I've used a Deka ETX14 battery for my RX8, and it's been totally dependable for several years, despite its size. I used the same battery on the FD; I made a mount to located it on the driver's side of the engine bay, just beside the radiator:

https://cimg7.ibsrv.net/gimg/www.rx7...c54d603255.jpg

https://cimg3.ibsrv.net/gimg/www.rx7...46e7e3aa4d.jpg

In the process of adding the radiator, I had to ditch the stock s-shaped power steering cooler. I replaced it with a Derale 13249 heat sink that I mounted behind the radiator on a piece of tubing that goes between the frame-rails:

https://cimg4.ibsrv.net/gimg/www.rx7...43796f1fd4.jpg

I wanted to make an undertray that would do two things: 1. Protect the bottom edge of the radiator from bottoming and 2. Keep debris from bouncing up into the accessory belt area. To do this, I ended up making a "front subframe" of sorts:

https://cimg3.ibsrv.net/gimg/www.rx7...c682cd62b7.jpg

https://cimg6.ibsrv.net/gimg/www.rx7...098134b2d7.jpg

For the "anti-debris" part of the undertray: I found a cheap carbon fiber panel on ebay and riveted that to the undertray frame:

https://cimg0.ibsrv.net/gimg/www.rx7...5c109d3341.jpg

https://cimg5.ibsrv.net/gimg/www.rx7...6014d3f073.jpg

Also, you probably noticed a couple of pictures ago, the stock oil cooler hard lines had to go to make room for the radiator. I replaced those with nylon braided AN hose. I zip-tied those hoses to my PS cooler mount:

https://cimg4.ibsrv.net/gimg/www.rx7...39344d7270.jpg

So, since it's hard to show everything in one picture, the V-mount setup looks like this diagram:

https://cimg6.ibsrv.net/gimg/www.rx7...338239a012.jpg

With my new discovery that carbon fiber sheet is pretty cheap on ebay, I made some ducting for the v-mount out of carbon fiber:

https://cimg7.ibsrv.net/gimg/www.rx7...7f7c17d3b5.jpg

I cut out the flat pieces, epoxied thin angle aluminum to the inside edges, and gaffer taped the outside edges just to keep it from fraying. It resulted in a really strong and lightweight piece. Also, CF is soft enough on the edges that it doesn't rattle like sheet metal would.

https://cimg7.ibsrv.net/gimg/www.rx7...362aacc88c.jpg

I also made a small catch can that mounts to the rear of the intercooler:

https://cimg4.ibsrv.net/gimg/www.rx7...fe000099aa.jpg

And a picture of everything together:

https://cimg8.ibsrv.net/gimg/www.rx7...b933f3b417.jpg

I had a temporary hot air intake on the car at this point. Eventual plans were to run it down into the passenger side duct.

So, it's coming together! My next update will go into details about my initial testing.

This is a great build, and I appreciate that you can do so much yourself. Can't want to see more results.

You might want to rethink that "hot air" intake... here's what I did with a similar set-up. I got two cast tight-radius 4" elbows (connected by shortened 4" silicone couplers so they touch each other and the turbo to maximize space) to get the filter into the opening next to the IC... it's pretty open, eventually I'll make a cold air box, but with your fab skills this would be easy and more effective.

Also, if you're tracking I wouldn't waste the passenger side bumper opening (if that's what you're thinking), get a 2nd oil cooler in there.

ALSO: Maybe mods can figure out why every photo I attach from my phone comes in upside down?!

Yeah, the hot air intake wasn't ideal, but it was just temporary at this point. My eventual plans were to run it down into V through my carbon fiber duct on the passenger side of the intercooler. I'll get into that in a future update. And I already have a second oil cooler since it's an R1.

Nice engine bay btw!

Mind pointing us in the direction of these carbon fiber sheets? The only thing I found on eBay (in great quantity) was small 200mm x 300mm sheet. I assume you were using something a bit larger than that.

Also where did you source the CXRacing parts? eBay as well?

Thanks!! looking great BTW

Search "carbon fiber cutoff panel" on ebay. There's a company called elitemotoring that sells defective or excess panels from their production runs. .04" thickness is pretty sturdy and can be cut with sheet metal cutters.

And I bought the CXracing parts directly from their website.

awesome, thanks!

I see you've copied my former FD's (red car) intercooler setup and mount. i'm flattered.
i like what you've done here, EDIT: I see you're planning to run the CAI through your new CF box. I am interested to see how you do it!

great work with that front end subframe! it looks very nice.

here are some more pics of what I did, for reference. this setup worked amazingly, btw.

Attachment 752525

Attachment 752526

Attachment 752527

Attachment 752528

Initial Testing

With the physical build mostly together, it was time to start it up and and do some tuning. For starters I made a timing map based on some historical knowledge from the forums. My map is a combination of the arghx timing maps from the Rtek subforum and the standard PowerFC timing map. I made some educated guesses, used bits and pieces from those two maps, and tried to make the map as smooth as possible. This is the result:

https://cimg3.ibsrv.net/gimg/www.rx7...2a61a2667c.jpg

For fuel; I used some more of arghx's advice from the PowerFC forums as a starting point for my target AFR map. Also, much of the low-load stuff came from AaronCake's Megasquirt write-up:

https://cimg9.ibsrv.net/gimg/www.rx7...91153117f3.jpg

Then, I set the VE table to arbitrary values that I know to be too rich, turned on VE analyze (autotune), and started driving the car around. I would drive up and down my road and try to drive in as many different load/rpm situations as possible, take a quick look at the changes VE analyze wanted to make to the VE map, apply the changes, and repeat. Within ~30 minutes, the car was running almost perfectly. The nice thing about Megasquirt is; once the VE map is dialed in, changes to the AFR can be made directly from the target AFR table. So, for example, if I'm at the track and decide I want to lower my WOT AFR from 11.5 to 11.0; I just go to the target AFR table and change the 175 kPa row from 11.5 to 11.0. No other re-tuning necessary.

To continue fine tuning, I took the car to a local road (hwy 151) to generate more high-load/high-rpm data points:

https://cimg5.ibsrv.net/gimg/www.rx7...77869235a1.jpg

Sadly, I never took any video of this part. But don't worry, plenty of track videos to come in future updates.

So at this point, the car was running really well tuning-wise. However, I had a few lingering hardware issues I needed to fix; I had an oil pan leak, the clutch slipped at anything beyond 10 psi (I could run 8psi all the way to redline with the 7670, for reference), I wanted some stiffer motor mounts, and I wouldn't mind refreshing the 22 year-old engine before doing some hard track time. So I decided to go ahead and pull the engine to fix all of those issues.

https://cimg5.ibsrv.net/gimg/www.rx7...42a4e757e4.jpg

Still had the stock clutch with plenty of life left, just not enough for my power-level:
https://cimg6.ibsrv.net/gimg/www.rx7...67b011acb5.jpg

Exedy stage 1 HD:
https://cimg7.ibsrv.net/gimg/www.rx7...aae47a51b0.jpg

I replaced all of the soft seals, used RA super seals and new apex seal springs. The everything in this engine is super nice being a 35k mile engine, but it was nice to go through it to confirm that and put some fresh rubber in it. The RA super seals were just for a bit more safety on the track, as I trust the 2pc seals more than the stock 3pc seals. I didn't do any porting in the interest of keeping as much torque as possible. Also, my 7670 turbo is a better match for a non-ported engine.

https://cimg0.ibsrv.net/gimg/www.rx7...6830b79651.jpg

Banzai oil pan brace and Himni engine mounts. I used "the right stuff" to seal that pan and was really satisfied with it, seems much more durable than RTV.
https://cimg8.ibsrv.net/gimg/www.rx7...da72177a67.jpg

https://cimg1.ibsrv.net/gimg/www.rx7...0f7a88d674.jpg

So, the car was tuned really well and had a fresh engine rebuild. A little bit of suspension work on the next update and we'll get into some track updates!

Be careful with the right stuff. Their newer formula isn't able to come in contact with gasoline, which gets in our oil pans sadly. I learned the hard way, it only lasted 1500 miles for me. Read your tube, it will say if it's the newer formula

I am a huge fan of Toyota FIPG black. That stuff is resistant to damn near everything.

I have put FIPG on a oil pan, stuck it on the crankcase, let it hold there by stickiness, then installed the bolts. It's that good.

Do you have any links to more information about NASA TT1-3? I could only find general information on what time trial is and then the rules for for how TT 1-3 are classified.

Also correct me if I'm wrong, but the TT1-3 classes are pretty much open in terms of aero/braking/engine mods, it just really comes down to tire size and power to weight right? I read the rules, but they don't even mention any of those things.

Suspension

Alright, I’ve been slacking on this thread lately, so it’s time to get this up to date. Reading Smokey the Talon’s thread inspired me to get back to it. This update takes place in January 2016.

https://cimg9.ibsrv.net/gimg/www.rx7...2832de5d36.jpg

I decided to ditch the CX Racing coilovers in favor of some quality suspension before my first track day. I’ve always been an Ohlins fan, and I live 30 minutes from their US headquarters, so I decided to go with a set of Ohlins DFV’s.

While setting the alignment with the new suspension, this is the best I could manage on the front (initially):
Front camber: -1.8 degrees
Front caster: 4.5 degrees

The caster was much lower than I wanted/expected. Upon further investigation, I found that the front upper control arm bushings had slipped, reducing the caster.

https://cimg4.ibsrv.net/gimg/www.rx7...24c363725a.jpg

As you can see above, there is a gap between the rubber “flange” on the bushing and the edge of the UCA. Braking forces had caused the bushings to slip and the UCA had moved further forward than it should have been; reducing caster. It’s really a crappy design – there’s no positive axial retention of the bushing, aside from the friction of the bushing within the bore.

So with that, I decided to make my own delrin offset upper control arm bushings. I wanted more caster obviously, a bit more camber, and a more reliable retention method for the UCA bushings. The lower compliance of a delrin bushing would be a welcome plus too.

I took most of the bushing design information from this thread: https://www.rx7club.com/suspension-w...shings-941277/

https://cimg2.ibsrv.net/gimg/www.rx7...8655fc215d.jpg

https://cimg8.ibsrv.net/gimg/www.rx7...96ce7bca86.jpg

https://cimg3.ibsrv.net/gimg/www.rx7...034106a62d.jpg

The bushing axes are offset to move the UCA inboard to allow for more camber. There is also a slight offset rearward to increase caster.

https://cimg9.ibsrv.net/gimg/www.rx7...49e130ff7a.jpg

I added my own twist on the design and turned some o-ring grooves into the aluminum sleeve. This allowed me to seal the edges of the sleeve to keep the grease in and keep water/dirt out.

So, the alignment I ended up at with the offset UCA bushings:
Front camber: -2.5 degrees
Front caster: 6.75 degrees
Front toe: 0
Rear camber: -2 degrees
Rear toe: 2mm in per side

https://cimg1.ibsrv.net/gimg/www.rx7...0e57702b8c.jpg

A friend and I found a set of Intercomp race scales and went in 50/50 on them. I made a set of ramps in order to drive up on them.

https://cimg5.ibsrv.net/gimg/www.rx7...180f320d1f.jpg

https://cimg8.ibsrv.net/gimg/www.rx7...7651ce4626.jpg

The car weighs 2815 lbs with me in it (I weigh 190 lbs) and ~5 gallons of gas. Weight distribution is 50.4% front.

More Suspension

I like to develop a good understanding of my cars, especially when it comes to the suspension system. There’s nothing wrong with trial and error, but track days are expensive, so I would like to limit the “errors” in the suspension tuning process to maximize my enjoyment of the car at each track day.

https://cimg1.ibsrv.net/gimg/www.rx7...9cf8b8cd01.jpg

I decided to reverse engineer the suspension kinematics to build a suspension model and quantify some key parameters. I’ve gone through this same process on my RX-8 a couple of years ago, and it’s been helpful to understand the camber curves, roll center heights, and spring/damper motion ratios when choosing alignment settings and spring/ARB rates. To measure the suspension points, I used a plumb bob to mark the X and Y position of each suspension point on my garage floor. I pinched the string of the plumb bob and held it up to a ruler to find the Z position of each point.

https://cimg2.ibsrv.net/gimg/www.rx7...8ccbb619ed.png

This shows the right-side suspension of the FD in Solidworks, along with the ARBs. My Solidworks license is up, so I had to use eDrawings for this screenshot, that’s why the aliasing is so bad.

https://cimg4.ibsrv.net/gimg/www.rx7...d04ae4be42.jpg

Above is my RX-8 suspension model. I went through a little more effort to make this one look pretty.

I also bought a program called Dynatune XL. It’s an Excel-based suspension kinematics solver, it’s much cheaper than similar programs and serves my needs nicely.

https://cimg9.ibsrv.net/gimg/www.rx7...b58ef981ed.png

Some specs:
https://cimg0.ibsrv.net/gimg/www.rx7...243c889595.jpg

So, what are the key takeaways?

-The front roll center height is really high compared to the rear, most cars are the opposite. This means that some roll stiffness is baked into the suspension kinematics and the front can be run a little bit softer. It also means the front of the car is really quick to respond (I think we’ve all felt this) since the high roll center generates immediate jacking force upon turn in.

-The front camber curve is ~twice as aggressive as the rear. So, be careful about running less static camber in the rear, because the dynamic camber in the rear will be a lot less. It’s probably beneficial to run close to equal camber front and rear (and it could be better to run more rear camber than front).

-The rear motion ratio is higher than the front. So, equal front and rear spring rates mean that the rear wheel rates are ~28% stiffer than the front.

Completely awesome you're able to get and share that suspension info with the community. Thank you for that. Keep up the good work. So did you get on track in 2016 at all?

Final Setup Tweaks

The Ohlins came with 11kg/mm springs on both the front and rear. As I mentioned earlier, the rear motion ratio on the FD is higher than the front; so the standard Ohlins spring rates would result in a higher rear stiffness. My go-to calculation for a car setup (at least for spring & ARB rates) has always been the Tire Lateral Load Transfer Distribution (TLLTD). Formulas for this calculation can be found in Race Car Vehicle Dynamics by Milliken – I highly recommend this book for anyone interested in car setup or vehicle dynamics.

Overview of TLLTD:

- The axle which has more load transfer will have less grip (tires reduce their friction coefficient, or “saturate,” when heavily loaded)

- As an example, a car that’s really stiff in the front and has a large front ARB compared to the rear will have a TLLTD that is biased toward the front. Most RWD production cars have a TLLTD of ~60% front, so the car is biased toward understeer.

- If the TLLTD is 50% front, the car will be “neutral” on the skidpad

- For rear-wheel drive cars, we need some extra grip “left-over” in the rear to accelerate the car out of the corner. I usually shoot for a TLLTD of 55-60% front to make the car feel stable.

I’ve been developing this car setup spreadsheet since my FSAE days:

https://cimg4.ibsrv.net/gimg/www.rx7...1585e1e2f9.jpg

So with the standard 11kg/mm F&R springs on the Ohlins and the stock ARBs, the TLLTD comes to 51.8% front and a roll stiffness of 1.88 degrees per g. That’s low of a TLLTD for my tastes, that setup would have trouble accelerating out of corners without breaking rear traction.

I had some 13 kg/mm springs laying around that I swapped onto the front coilovers. That brought the TLLTD to 54.4% front, which was much closer to my 55-60% target. Roll stiffness ended up at 1.77 degrees per g.

So, confident in my setup and ready to hit the track, the car got its final dose of preparation; a bath.

https://cimg4.ibsrv.net/gimg/www.rx7...6584ea1912.jpg

I put some new tires on the RPF1's: Hankook R-S3 - 245/40-17 front, 255/40-17 rear. I also installed new brake pads, Carbotech XP-10 fronts and XP-8 rears.

March 2016 – VIR Trackday with Chin Motorsports

My first trackday this year was at a track that I had never driven before (VIR North & Full), with a group I had never run with before (Chin), in a car I had never tracked before (FD). Sounds like a great plan! The first day of the weekend was on VIR North, and the second day was on VIR full. I ran in the intermediate group – I just had to get a quick check ride in the first session and I was all set.

The car made the 3hr trip to Virginia without any issues:

https://cimg9.ibsrv.net/gimg/www.rx7...4e88f1eeb8.jpg

https://cimg2.ibsrv.net/gimg/www.rx7...4c3fa0dc3c.jpg

For day 1, I ran on my lowest boost setting (8-9psi) so I could get used to the car and make sure everything stayed in once piece. Within the first session I could already tell how much more fun this car was going to be compared to my RX-8. It’s much more lively, easy to toss around, actually has some torque to play with, and it turns in much quicker. After the first session, I realized that I had filled my small catch can halfway (welcome to trackdays with an FD). I emptied it and added a second catch can (Dasani) for some more capacity.

https://cimg3.ibsrv.net/gimg/www.rx7...da582736b5.jpg

The car held up well for the entire first day, I just had to empty the catch can(s) periodically. Also, I learned that I couldn’t run the car below half a tank of fuel or it would fuel starve. VIR has a long left-turning section (NASCAR & left hook) that sloshes fuel away from the pickup.

That evening, I had a chance to look over my data logs to make sure things were behaving as I expected. Everything looked great; temperatures were cool, AFR was safe and consistent, fuel pressure never dipped, and nothing looked unusual.

I neglected to turn on “spot meter” for this video, so excuse the horrible exposure:


Stats from VIR North
Lap time: 1:44.7
Boost map: 8-9 psi
Weather: High 56F
Max coolant temp: 188F
Max oil temp: 205F
Max IAT: 102F
Top speed: 132 mph

Day 2 was on VIR full, and I decided to turn the boost up to 12 psi based on the success of the previous day.

Anybody who hasn’t driven VIR and lives close enough to do so… do it. VIR is such an awesome track to drive, the snake and the uphill esses are some of the best sections of racetrack in the country.

After during the 2nd session of the day, my brakes started to develop a huge vibration that I could feel through the pedal and steering wheel. The full course configuration added a much faster braking zone to the track, so I think I was just overheating the XP-10 brakes on the front and either warping the rotors or transferring excess brake pad material to the rotors. The vibration got so bad that I could hardly hold on to the steering wheel in the braking zones, and the pads would knock back on the straights to the point that I would have to double pump the brakes at the beginning of braking zones. I spent the rest of the day taking it easier than I would have wanted in the braking zones.

Otherwise the car ran fairly well. The setup was pretty neutral, some understeer, some oversteer, but it was easy to manage. I was getting some bottoming on the left-front through hog pen, and it was starting to wear through the inner fender liner and had chunked the tire in a few places. Also, I think my steering rack bushings were allowing the rack to move around a bit, because the steering wheel would be off center on some straights on the track.

I was much more agressive on day 2, except for in the braking zones. Also I fixed the settings on my Gopro, so this video is much better to watch:


Stats from VIR Full
Lap time: 2:12.0
Boost map: 12 psi
Weather: High 57F
Max coolant temp: 189F
Max oil temp: 205F
Max IAT: 117F
Top speed: 143 mph

https://cimg7.ibsrv.net/gimg/www.rx7...a8c09297ca.png

https://cimg2.ibsrv.net/gimg/www.rx7...6642c0eb81.png

https://cimg7.ibsrv.net/gimg/www.rx7...b84a644de5.jpg

Overall it was a successful first trackday for the car. Tons of fun and only a few issues that will be easy enough to fix in the future. I'm sure the car has a 2:10 in it at VIR with working brakes and more seat time.

To-fix list:
- Brakes: The overheating and vibration were the biggest issues I needed to deal with. Also, I went through an entire set of front pads in the weekend... brand new on Saturday morning, 1mm of pad thickness Sunday evening.
- Bottoming: Rubbing the inner fender liner was getting annoying
- Catch can: Yeah... I needed a bigger catch can

Awesome update!

that 7670 response sounds as good as the primary turbo on the stock twins... crazy.

with that wheel setup did you have to roll or pull and fenders ? it looks good. not too aggressive and mild !! +45 front and 38rear ?

Man... Kind of sad to hear the Carbotech's wearing down that quickly. They're pretty pricey pads and I was thinking of going to those over the HP+ on my rig too.

nice work!