I forgot to get back to you. The Vitours are about 25.25" diameter.

I bet I know who you've been talking to lol.

 

I promise you it isn't who you think it is!

Looks like we'll both probably be doing a similar amount of clearancing as the height of a 285/650r18 comes out to about 25.6.

 

Car is looking awesome!

Do you have any idea on what the cage weighs (since it was pre-fabbed from CAD)?

 

Thanks Peter!
No idea on the weight at the moment. I'll let you know when I hear back from them. I can't imagine it weighing much over 140 lbs (it is still way underweight for most competitive power to weight stuff!) I hope I can get it to about 2650-2750 with me in it and a full load of fuel and water and just add ballast as needed.

 

Texted these over to you, but putting these on the Club for posterity for any other badasses like you










Best of luck kicking off and getting through the semester!

 

Oh alright, I thought there was only one person pushing Emtrons lol.

Damn. Not looking forward to that.

 

You could try raising the ride height and seeing if that's something you'd be alright with. I know you can fit tires that tall without cutting anything, but I am fairly certain that it does involve riding the car higher than you might want.

If you're inclined, reach out to the folks at Bad Cat Engineering (the same people who I have doing my fabrication) They do a lot of Emtron and the guy that handles the engine calibration does a really good job of explaining what certain ECUs do well and not so well. They all do the same thing at the end of the day, but how they calculate stuff and the degree to which they function for what you are trying to do are all different. As I am learning, it is a little more nuanced than initially thought.

 

@ptrhahn I just heard back from the fabricator. The cage weighs exactly 140 lbs (there's a mathematical model in the CAD program he used to calculate tubing weight or we could have just determined the overall length of tubing in feet and got it that way). Pleasantly surprised as I figured we would be somewhere between 130 lbs and 150 lbs with how much tubing was used.

 

Nice, that's pretty good considering the completeness of it! And I love that you did it in CAD.

 

That cage is gorgeous!

 

The only thing I don't like is the bar going over the driver's head. Having suffered a concussion when I wrecked my race car, I do my best to keep hard bars away from my head.

 

Yes, that is definitely something to think about. I'll be padding it regardless. Would you happen to recall how much those harnesses are supposed to stretch? I have such a short torso that with a helmet on that my head probably wouldn't be any higher than the top of the seat, but if the belts end up stretching enough for my head to contact it that would definitely be a problem.

 

You'll def want that double density padding on that. Though it might have been better as a "t" bar down the middle vs. crossing over you're head.

 

Hey guys. Back with more exciting photos and slightly less exciting news.

The dashboard showed up. I just need to get it to the fabricator this weekend. The roll cage is also pretty much in place. All that is left is the forward section that goes to the strut towers.







In other news, I was advised by my academic advisor that if I ran off to the Westminster show in New York, I might be paddled so I ended up sitting this year out. One of the poodles I previously showed and put points on when we still had her won select (4th place iirc) out of an entry of 24 or so other poodles, so that was neat.

 

Hey folks. I was able to get the transmission and some other parts to the shop yesterday and we test-fitted them.

I am using an HGT bell housing. It looks like I am going to either have to clearance one of the mounting ears on the transmission (would rather not, as it is magnesium and costs monies) and/or a smaller starter. (I saw somewhere that someone suggested that one from a first gen may work?)

We're going to need to adjust the shifter setback, but that's also part of the reason I went with the A431 and not the GSR, as it is much easier to adjust yourself. (will need to adjust mounting distance and get longer shift rods)

We are also fairly certain that the driveshaft will be more than long enough to do what we need it to do once we have the 8.8 installed (still need to get on that...)






That's what's going on at the moment. We also came up with using quik-latch fasteners with springs for the dash because quite simply, it's easier to work with when you want to remove it.

Thanks for reading.

 

Hey guys. Not much going on at the moment aside from the 8.8 conversion stuff showing up last week. Still waiting on the differential to get here, but we have everything else on hand.

At the moment, I am thinking about differential options, as I would like to go with one of the clutch-type offerings (due to me wanting to run hill climbs with the car and how frequently one of the driven wheels are likely to lift in some of the turns (ergo: no torsen one-tire-fire action)) which leaves me with two options. An OS-Giken super lock (costs bigly and has more things to adjust than I know what to do with at the moment with my understanding of differential setup) or the Ford traction-lock, which might be in the differential that shows up (I'd probably have to dismantle it to see...) and rebuild it adjust as needed.



Thanks for reading. No dog-showing this weekend so I can probably help some of the local guys dismantle their stuff and put it back together.

 

Very cool, looking forward to seeing progress on this.

 

Hey folks.
Haven't updated in a while (I was in poodle purgatory and have to go back on Wednesday), but I am still very much alive and still making questionable RX-7 related decisions. I have devised a most novel (and equally unwise) solution that should (in theory) make the car cheaper to operate and less likely to break whilst also having the unintended consequence of making it 10x more obnoxious (there are no free lunches, I am told...)

I have an early production 20b that will be run sans forced induction on the way. (We will make the case for this below...)

I didn't want to have to try to package a turbo setup on one of these engines and they kind of weigh a lot in that configuration for how "little" power I wanted out of it.
Less monies spent on fabrication on account of no longer needing a water injection or turbo system.
Significantly lower fuel system requirements. (I only need 3 injectors)
Runs on 87 unleaded.
Less I/O needed on ECU.
We will be 3d printing the exhaust (and most likely also the intake) manifolds because it costs way less than fabricating it and the finished product is more consistent.

I initially wanted to run this as a side port engine and it seemed like a full cut bridge could have worked, but it involves removing material from the thick plate, so I refrained. It also would have been just as obnoxious, so we are going to do a peripheral port. Now please hear me out, as long as I can get this thing muffled down to 100 db, I'll be happy. I think I can fit at least two larger mufflers under the car if I am creative enough and I can just stick on an additional one with a v band on the back so it can be moved around without the neighbors wanting to shoot me.

I had some knowledge gaps on naturally aspirated engines, so I had to read up on the relationship between the intake length, exhaust length, and the power band. Before this the solution was to just put more air and fuel into the engine.

I will also be retaining the turbo rotors because unless I can find S5 NA rotors for like $3, $1800+ is a lot of money for maybe 4 hp and a little more midrange power.
The assembly will be balanced, and clearanced. I may also have them lightened. They will have ceramic apex seals (NRS).
RPM will be limited to 9500. I'd have preferred 9000 but my transmission doesn't have an overdrive gear.
I'll also be using a dry sump (not the MFR one or the similar offerings, way out of my price range) I'll find one from a stock car and just have a pan made for it.
I'm working on moving out my 13b and a few other things, so I can offset the cost of this engine. For now, it is just going into the car for mockup purposes as I think it can go back three inches before the bellhousing hits the firewall, and we'll deal with it later. (Ergo not anytime soon)

If anyone has any information on sizing of the peripheral ports or anything you think might be of help, let me know (I have read somewhere that the MFR ones were 43mm in diameter?)

Thanks for reading.

 

hello! i' from brazil and i'm currently building a 3d printed fd3s to make it in fiberglass for drift. do you mind selling the 3d file please? thanks in advance!

 

For quieting the exhaust, I've heard the rebuildable resonators from Burns Stainless are really good. They're a little pricey, at $700ish, but worth it from what I hear. I might add one to my system when I change it again. Years ago there was an FD that did autocross and I believe he had a 4" exhaust and one of these muted it enough to be able to hear the turbo spool. This is all from memory though, so I could be getting it wrong, but I remember it was a ridiculous feat.

https://burnsstainless.com/products/...=8112387162203

 

Hey there. Unfortunately, I don't have a full scan of the exterior of the car and probably won't for quite a while. You might be able to find one of the people with an SCCA GT3 or 2 car that uses a third generation RX-7 body shell and see if they might be able to help. I can get the inside of the car, but we only used it to design the cage, so I'm not sure how much help that would be.

Hey speedjunkie. I had been looking at their mufflers. I read somewhere that the ones they were using on the grand am RX-8's that were running around a while ago at some point had a muffler that was about 3 feet long and got them down to 105 db and were limited to 8800 rpm iirc, which seems to be a good starting point.

I could probably ask and see if they'd make one that is about that length and then fill it with lava rock like the old mazda competition mufflers and ceramic refractory insulation and see how far that gets me. It would probably weigh a ton, but I am going to need to add weight back into the car later anyway.

 

Back when I was running an SCCA Formula Continental racecar with the SOHC Pinto engine, the only way one could get good HP out of that was to run it really lean, i.e., EGT's 1400-1450F. Doing that and using a Burns-SS muffler, the SS scrubble fill would last at most 1 race weekend before it burned up, less than 2 hours of running on track. IIRC, a rotary's EGT's can be more than 200F higher. So, IMO, it likely wouldn't last long there either.

The Lava rock, etc, fill might as you mentioned, be more durable.

 

ive tried a bunch of stuff, and i can summarize.
TLR, the RB muffler does pretty well, its quiet, flows enough for like ~450hp

basically, the bigger the piping the lower the pitch. the bigger the muffler the quieter it will be
i've also found that two small tips are quieter than one big one, my peripheral port with a 3" tip is as loud as you'd expect. but i have a set of tips, and that makes it stock FD-ish
it also seems like a big pipe helps keep heat down, although i can't say i've done proper testing.

ive currently got a FEED exhaust, and its pretty quiet for what it is. the piping is 94mm, its got a center muffler that is about the same size as the cat, and then the rear muffler is as big as will fit the car. with the 100mm tip, its really low pitched
since its like a medium sized dog barking in your ear, i put a silencer in it, and its like someone took the EQ and zeroed out every bass frequency. its a 2" silencer, so it is limiting me after like 5000rpm, which is ok for a street car that is quiet.

 

Hey j9, thanks for the information. I'll consider adding a second exhaust tip (sort of like the defined fd or gmonsen's). Which racing beat muffler are you referring to?

 

i'm not 100% sure, but Howard Coleman is using one at like 600hp, which is plenty, lol