When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
I'm curious about your Weber setup. Is it the 13B 6-port intake? What did it take to make an adapter plate?
I know they aren't as efficient as EFI but I love those wrapover intakes, they just look so cool. That setup also aligns with the eventual goals for my FB, which is a more balanced car with around 175-200 hp with a carb setup that's more for weekend drives in the mountains and occasional longish drives to meets. I've been thinking about building a 13B hybrid with Renesis rotating gear but a carb'd Renesis sounds easier and possibly cheaper.
Chips Motorsports makes a Renesis RX-8 lower intake manifold flange that will allow you to create your own wrap around intake system.
Some updates:
1) Some of you might have seen a separate thread I started regarding some rear end noise. After some poking around, I figured out that when I torqued the rear pinion nut to set preload (after swapping to the small axle pinion flange to allow compatibility with my factory driveshaft), I failed to take into account the drag from the oil seal. Turns out, if you actually READ the factory service manual instead of assuming you know what you're doing, you can avoid mistakes like that. Don't be like me, lol. Anyways, after tightening up the pinion nut to approximately 110 ft-lbs, my noise has gone from very loud to about the volume I would expect of an older LSD.
2) I installed a really nice Mishimoto shift **** that matches my white grip royal steering wheel very well.
Very nice please ignore the horrendous AutoZone seat covers, they're relatively temporary. I also found this sweet cupholder designed to fit an NA Miata, that also happens to fit FBs. Sweet!
3) After much deliberation(with myself, of course) I decided that I do, in fact, like vacuum assisted brakes. This presented a small problem, my DCOE intake manifold has no provisions for such things. As such, it was removed, and provisions were made. By force.
I tried my best to hide it so that it wouldn't ruin the otherwise naked look of this intake setup. I used a factory RX-8 Brake booster hose and check valve, as well as some extra 3/8" hose to get the job done.
4) I have relocated the battery to behind the passenger seat. This was not only to clean up the engine bay, but also to improve weight distribution.
Such empty. Barely fits. Needless to say but I did install a hold down and secured the wires using some insulated hold downs. The positive to the alternator is run inside the car in the driver's side rocker. I would highly recommend using a smaller than factory battery if you're going to attempt this. I will be swapping to something smaller when this one goes out.
5) I finally got some decent in-cockpit footage of the car on the road. It's uploaded to my YouTube channel here:
6) Unrelated to the car, but check out these pictures of my FC!
Here's me with the car back in high school. Oakley Razorbacks, definitely one of my finest fashion choices lol. This one is more recent. My dad takes care of the car for me while I'm in the navy, he took this one a few weeks back. Not really related to the FB but it's fun to see where it all started.
Last edited by Eydes2Rotor; Jun 28, 2022 at 09:10 PM.
The car has been running pretty strong. My current jetting is: F9 60 Idles F2 emulsion tubes with Modifications 165 Mains/185 Air Correctors 60 pump jets 43mm venturis The car currently Idles around 1300 rpm. I can get it lower, but it seems happier at a higher rpm, with a much more consistent pulsation to the idle. This particular engine setup does have a subtle "brap" at idle, not as defined as a bridge port, but more than the average street port.
I blew out an axle seal. I'm going to go ahead and change the differential fluid even though it's basically brand new, as well as both axle bearings. I get to make the drive to Atkins tomorrow for parts.
2024 Update:
I've been pretty busy with work recently so I have a bunch of parts waiting to find their home on the car. There are some notable updates:
- I plan on running this car at a few NWRA RallyCross events this year, as my schedule allows. I'm unfortunately precluded from running a full season because my deployment and work up schedule is tight this year. Luckily, that means I'm only really doing it for fun!
- I recently sold my T3 rear coilover setup. There's nothing wrong with them inherently, but I figured that if I'm going to start using the car for RallyCross, I might be better off with the divorced shock/spring setup that the car was designed for. Yes, I'm sure there are solutions to this problem, but swapping back was simple and inexpensive. Got a couple 150 pound Eibach circle track springs, cut half a coil off, and they slid right into place on the factory perch. Very nice! I'm running Foxbody Mustang Koni red shocks, for those who are curious. I also removed the rear swaybar. I will be playing around with this, but so far I like it on the street.
-A friend and I are currently designing an airbox of sorts for my DCOE. We are using a 3D printer with Carbon Nylon filament to build it. We are toying around with a design which I haven't seen done before. I have no idea if it's going to work well or not, but I can't find much info on the subject, and seeing as how it is an obsolete technology, it may just be that nobody has had this idea in a long time. See below:
Very unconventional, I suspect it won't work well at all, but we figured it could be fun to play around with. Once we finalize a design I will be routing an intake hose in front of the radiator with a pod filter (I think)
If anybody wants to weigh in on this, feel free. I'm sorta diving into the unknown. Not many people left with an encyclopedic knowledge of Weber carbs.
- I'm slowly working out some minor gremlins. I finally have a working coolant temperature gage, after much trial and error. I know, I should've had one the whole time, I'm stupid. I believe I've successfully isolated my oil pressure gage issues to a faulty sending unit, unless the motor is making 0 psi after a few seconds, in which case I'm already screwed. I am relatively certain I would've popped the motor by now if I had actual oil pressure issues. I finally sourced a new speedometer drive gear, as I somehow lost mine in the course of 2 moves cross-country. I know I could solve a lot of these issues by swapping to aftermarket gages, but frankly I love the stock gage cluster on these cars. It reminds me of my FC, of which I have many fond memories, so for now it stays.
- I have installed a psychotically over-kill fuel system into the car, after experiencing some vapor lock issues at an autocross. I now have a massive external Aeromotive EFI fuel pump moving fuel up to a really neat Fuelab regulator that drops me into weber friendly pressures. It is a return-style system. I don't have vapor lock issues anymore, no matter what, ever. I also think there might be some premix-mixing advantages to recirculating so much fuel. Everything is done with -6AN stainless/PTFE hose. Very nice stuff, I could probably run E85 if I wanted to, haven't looked into doing that with a weber yet.
- Yes the car is... Quick. Still haven't gotten it dyno-d yet, I want to finalize my intake design before I do. The ol' butt dyno tells me it's a decent bit faster than my Hyundai Genesis 2.0T w/ Bolt-Ons. That is just about enough power for me, for now. It is certainly faster than my FC, and lays waste to a stock 12A car. I actually think I might be making more peak power than an RX-8, but that is probably my mind playing tricks on me. To anyone who is interested in doing this, don't listen to the renesis hate squad. These are good motors, they just need some extra love. Get rid of the OMP, premix, profit. If you go the carbureted route you'll also be gifted with a very unique idle noise. It may not be efficient, but it's a lot of fun. I still love the confused expressions rotary heads give me when they see 3 exhaust runners right below a weber DCOE, always leads to fun conversation.
I will try and be more active with updates as the weather warms up and I get back to grinding away at this project.
I'm curious about your Weber setup. Is it the 13B 6-port intake? What did it take to make an adapter plate?
I know they aren't as efficient as EFI but I love those wrapover intakes, they just look so cool. That setup also aligns with the eventual goals for my FB, which is a more balanced car with around 175-200 hp with a carb setup that's more for weekend drives in the mountains and occasional longish drives to meets. I've been thinking about building a 13B hybrid with Renesis rotating gear but a carb'd Renesis sounds easier and possibly cheaper.
Racing beat sells an adapter that converts renesis intake pattern to s5 6 port. I have no clue WHY they make this, as I don't know a single person using it besides myself, but it exists. https://www.racingbeat.com/RX8/Intak...nts/16480.html https://www.atkinsrotary.com/86-92-r...are705k48.html
Unbolt Renesis LIM, bolt this thing on, bolt FC carb manifold to it, profit. Absolutely painless installation on my car, took about 20 minutes. The only odd thing is you have to modify the stock Renesis intake manifold gasket to fit. Can't remember now if that was difficult. Atkins sells a 6 port LIM gasket for FCs, requires a little bit of arts and crafts to match the ports up. The hardest part of this swap is fabricating an oil pan, and swapping the front cover (If you want to use a dizzy and stock mounts, like mine.)
Sorry for the mild thread revive. Just curious about a few things.
With the carb setup, you lose the 8's fancy multi port system. So would this mean you won't get the same HP as the Renesis, or would it be like wiring the ports on a 6port FC open, in that you still get the same peak power but lose out on low end torque?
What does the RX8's PCM do in this setup? Spark, gauges, anything else? Could it be left out and a 12a distributor used instead?
I'm considering possibilites for what I want to do with my FC and I think a carbed Renesis swap might be a good, potentially lower cost option vs 6 port turbo.
I am using a 12A Dizzy. The RX-8 PCM is sitting in some dudes garage somewhere, you won't need it if you emulate my setup. As far as power: My understanding is that it doesn't get much better than a weber for peak power (in the carb world anyway.) What you do lose is power in the low-mid range, and a LOT of drivability. Maybe I just suck at tuning carbs, but I have yet to find a jetting combination that yields EFI-like smoothness throughout the power band. What you gain is a neat intake noise that you just can't get with EFI, a lot of serviceability (my engine bay is ROOMY, I can do oil changes without getting under the car now), and a lot less moving parts. I would argue that my setup is significantly more serviceable than the RX8 splatter disaster of vacuum hoses and wires. I also weighed the stuff I took off the engine, and in total I dropped about 20ish pounds off the motor by switching to the setup I have now. A lot of that weight was in the RX-8 front cover and accessories. I am not certain, but I think that unless you go through the effort to jerry-rig the stock PCM into working in this chassis (it can be done), this is the cheapest way to put a 13B into an FB with this amount of power. If you have a stock 12A car, you can rob everything you need for the swap off your original engine except the flywheel, counterbalance, clutch, and intake bits. After that, you just have to build an oil pan, and extend your factory engine mount bracket by about 1/2". If I could go back and start over with what I know now, this swap could be done in a couple weekends. A lot of the modifications I made are wholly unnecessary to make the car move.
@Eydes2Rotor
First, want to say I love what you did here. Really look forward to any dyno numbers you come up with.
This is exactly what I want to do to my SA. My 12A is getting tired and I have been gifted with a rebuildable Renesis. So I have a series 1 RX-8 Renesis 6 port short block, RB Dellorto 48 with the intake and lots of 12a front covers and oil pans. My biggest question is how to do the exhaust. I've seen where the stock RX-8 exhaust manifold doesn't clear the transmission tunnel and I suspect a aftermarket header would have the same issue. How did you do you exhaust and can you post pics of it? I would be very grateful. My thoughts on exhaust was to use the RB RX-8 mid pipe and then either go out to the side or over the axle with some custom piping. I prefer to keep it out back so the car looks OEM from the outside.
My biggest question is how to do the exhaust. I've seen where the stock RX-8 exhaust manifold doesn't clear the transmission tunnel and I suspect a aftermarket header would have the same issue. How did you do you exhaust and can you post pics of it?
You are correct. A stock RX-8 exhaust manifold won't clear the transmission tunnel. Neither will an aftermarket RX-8 header. Your best solution is to modify an aftermarket RX-8 header to help everything line up, and to clear the transmission tunnel.
Did you use the FB starter with the RX-8 flywheel or opt for an auto counter weight and light flywheel setup?
Did you have custom oil lines for the front mount oil cooler or get some already made that work? I noticed when I was just tearing down the renny block I have that the rear oil line attaches at the bottom of the oil filter pedestal and not at the bottom of the rear plate like it does on the 12A.
Originally Posted by t_g_farrell;[url=tel:12594803
12594803[/url]]@Eydes2Rotor Sorry, two more questions.
Did you use the FB starter with the RX-8 flywheel or opt for an auto counter weight and light flywheel setup?
Did you have custom oil lines for the front mount oil cooler or get some already made that work? I noticed when I was just tearing down the renny block I have that the rear oil line attaches at the bottom of the oil filter pedestal and not at the bottom of the rear plate like it does on the 12A.
I’m using an RX8 counterweight with an FB flywheel and clutch. You cannot use the RX8 flywheel with an FB trans because the RX8 uses the larger 225mm flywheel vs the FB 215mm flywheel.
Oil lines are custom on my car. I love AN-ing all the things so that didn’t bother me. Exhaust was accomplished by cutting off the rx8 header flange off and welding on a vband. I’m using a stainless set of headers.
Did you have custom oil lines for the front mount oil cooler or get some already made that work? I noticed when I was just tearing down the renny block I have that the rear oil line attaches at the bottom of the oil filter pedestal and not at the bottom of the rear plate like it does on the 12A.
the oil cooler lines might be easy actually. the FD engines also have the oil cooler line going right to the pedestal, and Banzai racing sells a set for the FD engine in the FC, FC3s Oil Cooler Lines its in the drop down menu. its for an FC, so it might be a little long, and maybe you need to shorten it a bit.
also there exist fittings that go from the FD/Rx8 clip on fitting to AN, although i have no clue what they are called, so you could actually run the stock Rx8 hoses and short AN lines with these things.
12594890[/url]]the oil cooler lines might be easy actually. the FD engines also have the oil cooler line going right to the pedestal, and Banzai racing sells a set for the FD engine in the FC, FC3s Oil Cooler Lines its in the drop down menu. its for an FC, so it might be a little long, and maybe you need to shorten it a bit.
also there exist fittings that go from the FD/Rx8 clip on fitting to AN, although i have no clue what they are called, so you could actually run the stock Rx8 hoses and short AN lines with these things.
this sounds like a good solution if you don’t wanna make your own from scratch. That said, AN lines can be assembled very inexpensive with some basic tooling. Don’t be afraid of doing them yourself!
Part 3 of the intake design. Ironically. it's starting to look a lot like a renesis manifold. 2 steps backward, 1 step forward... Say what you want but I think it's pretty cool. Hopefully it doesn't let me down performance wise.
So some updates:
My differential pinion gear ate itself Dog says hi y’all
After much deliberation, I decided to take my LSD diff and swap it into a Kia Sportage carrier. This gives me 4.77 rear gears. Fair warning to anyone thinking about this, this is NOT street friendly. I am a glutton for punishment, so i will continue to drive this thing to work occasionally. The good news is that my differential noise is gone.
In other news, I got a new set of wheels on the way for the car. Very cool NOS in box Sparco Gravel Rallys
So here’s your daily, “This guy is an idiot” moment: I’m pretty sure I’m running the wrong front oil regulator spring. I have had the stock oil pressure gage showing between 15-25 psi since the engine was first running. Finally i decided to stop ignoring what i thought was a faulty indication, and I hooked up a mechanical gage. Turns out, the stock gage works! The less cool part is that I’ve been running the car with low oil pressure for a while. I went ahead and dropped the oil on discovering this, luckily no metal that i could see in it. That said, now that i know I’m an idiot the car will be down until i install the correct RX-8 front regulator spring. I don’t know how i didn’t think that would be a problem. I’m pretty sure the cause of my issue is that the front pressure regulator is relieving all the time because the rear regulator is rated to 85ish psi, while the stock 13B spring in my front cover is rated to 65ish. Glad i caught this before the engine grenaded. Hopefully this won’t result in an abnormally early rebuild. Luckily i haven’t been super hard on the engine because the car has been on jack-stands so much. I think i caught it early enough, we’ll see. I might cut open my oil filter as well, or i might just ignore it and hope for the best.
Feel free to let me know how stupid i am for doing that, i can’t describe how bad I felt when i realized what i had done.
Not sure where to go from here. The engine sounds healthy and doesn’t run any better/worse than it was before, but oil pressure is back where it should be. I think the best course of action is to give it an easy 2-300 miles and then do another oil change, cut open the filter, and take a good look for any bearing material. Any thoughts?
EDIT: I guess i should’ve mentioned what the fix was. I was correct that I was using the wrong front pressure regulator spring, which i adjudicated with some help from Atkins. I’m not sure if the one i had was a 12a spring, as I sourced the front cover from a race shop that i used to work at. I never even opened up that regulator before putting it in the car, unfortunately. The old spring seemed quite worn and compressed, probably from years of abuse in whatever race car that front cover came from. Bonehead move not to check it before, on my part. I replaced it with the correct spring from an RX-8, and also installed a couple shims from Atkins, per their recommendation.
Last edited by Eydes2Rotor; Mar 22, 2024 at 09:57 PM.
Good news, i think my motor is okay. Drove it a couple hours the other day and no metal in the oil when i drained it afterwards. No symptoms of a spun bearing or anything like that. Oil pressure has been steady since the fix so I’m sure i found my issue.
In other news, my fuel filter clogged and killed the car on the side of the road. Luckily, i tried to build the vast majority of the car to be serviceable with an adjustable wrench and a pair of pliers… Breaking your car does allow for some nice photo ops
After superficially mutilating some of my nice AN fittings, the filter became a clean, empty tube and I limped the car home. It’s since been replaced with a much nicer unit with a lot more surface area. My friend has this sweet turbo 1.6 Miata, which is now my “support vehicle”
Additionally, I did some more work with my timing and got the car to settle into a nice idle with a bit more conservative timing. The car starts much nicer now.
My new wheels arrived from Canada! Searching for a decent set of all weather tires to put on these.
Currently, I’m working through the final stages of setting up this custom intake The latest iteration. I’ll be running some airaid piping from the end of the pipe to a filter mounted in front of the radiator.
I will continue to do early oil changes and keep my eyes/ears out for any signs of bearing damage, at least for a while. I think i got really lucky here, but only time will tell. Worst case scenario, I’ll be going to rx8club to find a new motor, lol.
We’re on to the final tweaks with this intake. This version was printed with the carbon nylon filament. The intake is routed to an AEM filter in front of the radiator. Following install, all of my jetting is too lean, so i think this design genuinely improved airflow.
Project's turning out beautifully! I especially love how the air box turned out. Do you have any intention of releasing a cad file, or even selling these if you're happy with the results? (I don't think my brother has invested in an enclosure for his printer yet.)
Project's turning out beautifully! I especially love how the air box turned out. Do you have any intention of releasing a cad file, or even selling these if you're happy with the results? (I don't think my brother has invested in an enclosure for his printer yet.)
I will ask my buddy for the CAD file and send it to anyone interested. So far the intake works well, seems to do what i expected it to do, increased airflow with better filtration.
Minor update, I’ve been OCONUS for a bit, but before i left, I found an old Ford performance MSD 6AL. This is the older analogue style, which in my experience are far more resilient than the newer digital models. I will be doing some serious work to my ignition with this soon.
I cleaned up the splatter disaster behind my radio.
What did you do for the oil pickup tube since you fabbed up a pan that doesn't have much of the 12A pan as part of it?
Would you happen to have a pic of your oil pan?
I'm diving into this again this winter and about to do my own oil pan and wanted see how you did it. Thanks and I hope your car is still running great.
please ignore the horrendous AutoZone seat covers, they're relatively temporary.
