|
Well hi; welcome to another stream of consciousness thread about people (me) doing stuff with rotaries. I'm a test engineer at a small engine company, and previously was at an R&D lab doing testing for fluid film bearings. Which sounds boring, except if you consider that "testing" means having machinery weighing a couple dozen tons putting up to a thousand horsepower into bearings (for stuff) and loading it up until you break it. I've also been doing roadracing with my dad since '02 with 1st gen RX-7s; pretty much devolved to me doing a lot of the work while he drives. Car was built for pretty much SCCA E-Production, which is fairly heavily modified as these things go; widebody, slicks, a lot of suspension changes allowed, etc. So, engine building and development, suspension work, wiring, blah blah blah. Unfortunately, we got behind the curve ball and never really caught up in terms of maintenance and preparation - took a step back last year to an NC MX-5 built for SCCA T-4, which is basically bone stock with a cage, Hoosiers, and a spec suspension package. So what else? Oh yeah, I make things. This year's project is to get started on an SCCA GT-3 class RX-7 for myself, which is tube chassis but relatively low powered. See, I've looked back over the last 14 years and come to the realization that a lot of the maintenance hog or bodged or workaround stuff is because we were forced by rules to maintain commonality with the stock car. Eff that. I'm also working on home foundry stuff - using a 3d printer to make stuff that gets investment cast. Eventually branching out to sand casting, but heck with it, got to start somewhere, and investment casting is easier in some ways. So here, have some pics.  The foundry itself. Why yes, it looks like a hot water heater tank filled with stuff with a furnace oil burner sticking in the side. That's exactly what it is, in fact. But it melts aluminum really well, thank you.  A test casting which turned out kinda crappy because I got too lazy to do correct spruing. The whole point though is that I measured all the dimensions before printing the cube and investing it, and now have an established shrinkage fudge factor for the metal I'm using.  Solidworks screenshot of the current project. It's an intake manifold to mate an E-Production street ported 13B (which is only a 'street' port in that it's not a bridge port) with an Arctic Cat snowmobile throttle body. Why? Ebayable 50mm ITBs for the win.  Test print of the intake manifold. I actually have a full scale (plus fudge factor) one printed, but I realize I need an aluminum melting crucible that isn't a $2 stainless steel pot from Goodwill if I'm going to be melting that much aluminum at once. So that's a start. I guess I'll update this approximately whenever I bother and or have anything interesting to say.
|
#
¿
Jan 28, 2016 21:34
|
|
|
|
| # ¿ Apr 27, 2024 22:32 |
|
|
Oh yeah, just remembered I had a video on youtube from one of the old race cars with the homebrew peripheral port 13B. Yes, everything is a bit ratty at this point. Oh well. And no, I never had dyno figures of that engine - I still have it kicking around though so I might at some point. https://www.youtube.com/watch?v=_RYZR5orxR8
|
|
#
¿
Jan 28, 2016 22:37
|
|
|
Oh god. If I had any inclination of trying to do a nationals level EProd car I'd be tempted as hell to pick up an RX-2 or several. See, EProd restricts to 42mm chokes on a Weber IDA on a street port to limit horsepower and so there shouldn't be much power difference between a 12A and 13B - torque difference sure, but if you built it to spin the horsepower limit should be driven by the venturi size. And all else being equal, a 12A RX-2 gets to run something like a hundred pounds less than a 12A FB. I had this idea of building an RX-2 and FB shell with a 13B for the FB, and just swapping suspension and driveline between the shells for different tracks - the 13B FB should have a top speed advantage. The problem with EProd though is that while the cars are widebodied on slicks and making good (naturally aspirated smallish car) horsepower, you have to stick with a bunch of annoying stock crap. Fun fact - EProd requires stock rotors and calipers, while at the same time making 200-260ish horsepower and running slicks with about 10" of full-slick Hoosier race rubber meeting the track, so you can imagine what the pad compounds and heat loads are like. And since the bearing carrier is integrated into the hub, cracked brake rotors, if not caught in time, can lead to wheels departing the car. Ooops. This is not theoretical, I've seen this happen at turn 5 at Road America. SCCA changed the rules to allow aftermarket solutions for safety (still keeping the same brake size but at least the hubs don't depart the car) but you still have to maintain the stock spindle, which on the FB is part of the strut housing. So before you can do anything with the struts you have to do machining... and you need to do something with struts, spring rates are pretty high, there are zero options that fit the stock housings that are even remotely appropriate, and the front running guys are running stuff that's Penske caliber. I actually started a strut development program before I said "eff this, I'm building a GT car" and it'll end up on a street GSL-SE once I get around to it. The big appeal of the GT car is actually that I can design 90% of all of it to be made out of circle track parts that are built for race use, durable enough to stand up to anything I'll do with the car (short of hitting things) and cheap / ebayable. For street use? I have a shell in mind to do an "ultimate FB build" on when I get around to it, and ... well, I should take a picture down my parent's field this weekend, we're at something like a dozen stored FB rollers. For more short term rotary street use, I'm on the lookout for a clean pre-95 Miata to do a 13B swap into (I have 3 sets of EProd ported 13B irons and housings sitting around, that should be enough power) and go bomb around in, mostly because I've always wanted to. That's still tempting though.
|
|
#
¿
Jan 29, 2016 15:35
|
|
|
Was at my folks to borrow their truck, took some pictures wandering around. So I'll call this the "this is the race shop" and "this is why I need my own drat shop". I only had my Fuji X100 with me so I think the 35mm (equivalent) lens makes everything look that much more claustrophobic and hoarderey than it might otherwise. Not to say that my dad isn't kind of a hoarder, because wow. Enjoy! Main part of the barn. Visible is... a lot of stuff.  Mill and lathe. Old bridgeport mill with a homebrew rotary converter to turn 1 phase into 3 phase. Lathe is an old South Bend we got from a National Guard ammo depot selling it on ebay, of all things.  The engine build area, if I cleaned it off again. Some ported 12A and GSL-SE irons up on one of the upper shelves, and that's a closed deck EJ20 block on the shelf. Because who doesn't need to do a built engine for their daily driver?  Locost project in the foreground, lots of stuff in the background. Locost is Miata based, but we're using rotary running gear because... well, god knows we have it and have experience with it.  More... storage. There's the welding table under there somewhere in the foreground. But yeesh.  The new race car. Coolant hose came off at the last race last year and blew the engine. Oooooops.  It's amazing what gets easier with a lift. New engine on the right, old engine on the left. Horay for Mazda Motorsports new longblocks.  More "storage". A lot of this is stuff that's already rusted, or is less vulnerable to rust.  A little different angle showing the formula car chassis. One on the left is an old Formula Mazda chassis, one on the right is an '84 Van Diemen Formula Ford chassis. Long story that basically boils down to "oops, we didn't realize what it would cost to get the rest of the parts to get them on track."  One of the RX-7 race cars. This one is in pretty bad shape, honestly, but we got it for cheap.  I call this one "why I don't need any more FB shells". There's 11 back there (well, one or two are SA22C shells) plus a Porsche 924 shell, an FC shell, an NA Miata shell, a TR7, a GC Impreza with no engine and suspension, and my brother in law's Torino and spare Celica All-trac. Yeesh. Now for some of the actually cool stuff.  More storage, and a late 40s vintage US Navy copy of an Argus pulsejet, as used in the WW2 V-1 flying bomb. See, this dates back to the vintage when we copied everything the krauts did, and only later tried to figure out what to do with it, so among them the US Navy copied the V-1 flying bomb and decided to use it for a target drone. My grandpa was head of the engineering faculty at his college and managed to score this from somewhere; they used to run it at engineering open houses in the 60s. Well, it disappeared for a while and finally turned up in another family friend's storage facility. One of those things I need to put back together because it's kinda cool.  EProd "street ported" iron; this is for a GSL-SE. Note how it's no longer separate intake runners? Yeah. Dave at Mazdatrix claims he got about 270hp out of an FC version when he was running competitively. Yes, naturally aspirated.  The peripheral port engine from that youtube video. The shell it was in at the time got wrecked, but the engine is still fine. Just waiting. I turn it over every few months and it's all full of Boeshield.
|
|
#
¿
Jan 30, 2016 19:34
|
|
|
SlimManFat posted:Details on the All-Trac? That one he got as a parts car, so I think it's partially stripped. Had an ARC intercooler and some other rare bits that he sold off to recoup the price of the car. We may do something stupid with it at some point because it's basically a free car at this point. His main car is one of those studies in escalation of project cars... started off as a JDM engine swap at the same time as doing a replacement trans, and at the point it's at now he's doing a built 5S block and so on and so forth. There's another Alltrac guy locally with a GT40R (or one of FPs reworked versions) built car making over 800whp that he made friends with, so if he doesn't get bored a lot of that might get copied. You know how it is with your first major project car. I dunno, from helping him (my brother in law, not the high power car) work on it, it killed any desire I have to deal with one of those things in any sort of stock capacity; too much crap underhood and I hate 90s wiring. Some part of me wants to take the spare Alltrac chassis and do something like hack it up enough to have wishbones on all 4 corners with an Evo driveline bolted to a modified 2GR-FE with ITBs or something, but it's not my car and I've got better uses for my time and money.
|
|
#
¿
Jan 30, 2016 22:29
|
|
|
One more quick one. Full size 3d printed intake manifold on my coffee table. Beer bottle for scale. Still have to cast it, and like I said, I want to use a real crucible rather than a halfassed stainless pot. Seriously, watching that pot glow yellow where the oil burner flame is hitting it scares the hell out of me; I don't want to dump a couple pounds of molten aluminum on my leg.
|
|
#
¿
Jan 31, 2016 05:12
|
|
|
The pulsejet honestly scares me a bit. I have the technical manual and spare parts, but the fuel and ignition was something my grandpa breadboarded together back in the 60s out of god knows what, and considering that the end result is spraying gasoline into the thing under high pressure I want to be a little bit cautious. I think I found a place to stick a flowbench in my house's garage; I honestly think that most rotary streetports could stand to be improved in terms of using the ports efficiently and I have ideas to do it... but it's going to take making a lot of specialized crap. I'm sure my wife will love the noise.
|
|
#
¿
Jan 31, 2016 19:14
|
|
|
Quick reply to my own drat thread. Heh heh. I feel like a slacker for posting without pics, but oh well. Been working on the tube chassis design for the GT3 car. Got dimensions for the cage stuff from scaling a scanned 3-view from some model kit - I'm sure that'll be totally accurate, right? Yeah, I'll be taking measurements from one of my shells to confirm. The whole idea on the GT3 car is to eliminate all the production based compromises on the suspension geometry and eliminate all the reliance on weird parts or parts that aren't built for the task. So the suspension is going to be built around late model parts - unequal length wishbones with a Coleman Wide 5 upright with Wilwood or PF calipers, quick change rear end with Wide 5 hubs, etc. Nice off the shelf shocks instead of having to fab struts. Molds for all of the bodywork so I can just make replacement parts if it gets dinged up (though this will be fun - I've got a set of molds I can borrow but there's a lot of stuff about them I don't like and will have to fix - yay fiberglass work) Probably something like a Jerico 5 speed as they're surprisingly cheap and will actually last (at rotary engine torque, probably pretty much forever) unlike all of the other race transmission solutions we've tried. For example, the last "ultimate" transmission we got should have been great, and probably would be if we got it fully sorted, but it was built in the 80s for some IMSA series by a guy who apparently died a couple years ago, which hampers the spare parts situation.
|
|
#
¿
Feb 8, 2016 15:19
|
|
|
Was wandering around the barn last night. Had forgotten about this. Penske triple. Funny what you can find on ebay when the seller doesn't know what they have.
|
|
#
¿
Feb 9, 2016 16:27
|
|
|
Well, nothing new, per se, but I got to thinking. I'm wanting to do a rotary Miata for a backroads summer bomber thing and I have a bunch of EProd streetported housings sitting around... unfortunately right now I only have one good set of internals around and it's earmarked for my dad's Lotus 7 clone project. And I'm kinda broke right now so don't want to go buying more internals. Except... I do have another set of internals in the peripheral port motor, with good seals, new bearings, etc. Iron seals too. And if I'm using those internals, why don't I go and finally fix the water leaks and just use it? And I also just found where there are pics of it including all the weird crap I did.  Custom exhaust inserts. See, the Mazda Factory Race housings, which are different castings, actually use fairly small exhaust ports because they don't have the sudden expansion in area to kill velocity. I reasoned what if I made my own inserts that did the same sort of thing? In theory it should have good flow because the velocity's kept up. And no, this engine never saw a dyno, I don't know for sure how well it worked.  Finished (not clean) housing. Intake ports are, IIRC, 47mm. I think I used the wrong epoxy or something because it always dribbled a little water into the engine after shutdown. Need to redo that.  Crazy attempt at determining balance weights of front counterweight; this is the one that was balance with the rotors I was using. That's a junk eccentric shaft with a bolt screwed in, pressing on the center of the scale. The unit is completely arbitrary.  12A front counterweight that I took a little mass off with a grinder. Same force on the scale means that the static imbalance should be the same as the 13B counterweight. Why did I bother? Look at the two counterweights - the difference in weight was about half a pound.  Front iron - note the plugs in all the oil passages that go to the front cover. This is deliberate.  Flushing it by driving the pump with a drill and using the screen. Note the external loop lines - oil pump has a straight shot out of the front iron with no drilled turns, front bearing is fed by a straight shot from the external fitting with no drilled turns.  I always liked this - the oil pumps have a little jet that sprays the inside of the drive pulley, which lubes the chain. Don't do this without blocking off the holes that feed the front cover, btw. So that's the engine that was idling in that youtube clip a bit back. My thinking is to bore out the existing ports, put in new tubes, and make a manifold going pretty much straight to a 55mm DCOE throttle body. It'll be a bit rowdy on the street, but it's a rotary Miata - I'm going to have to fab an exhaust and mufflers anyway.
|
|
#
¿
Feb 18, 2016 15:24
|
|
|
 More crap off my hard drive - the old race car, RIP. Basing the bodywork for the new one off of it, but with some changes in addition to being based off a tube chassis instead of a unibody.
|
|
#
¿
Feb 18, 2016 23:47
|
|
|
Always depends on how you define "competitive". I still think they're great race engines, though emissions is not easy, and the modern fuel consumption based racing (LeMans that is) isn't kind to them. I actually got a possible commission to make some peripheral port housings the other day, and think I'll pull apart the old peripheral port at the same time and redo it - talked about that before. Been looking for Miata shells to swap and probably going to get a real crucible so I can get back to casting stuff without worrying about dumping molten aluminum on my feet. Have been stalled a bit by having to get something paid off, but now that that's done, some-speed-ahead!
|
|
#
¿
Mar 23, 2016 16:50
|
|
|
As a quickie update, finally ordered a proper crucible - should be good for a 15-20 pound pour. For bonus points, a lot of the early stuff I'm casting will probably be melted down FC intake manifolds and those awful 4-spoke FB wheels. Also got a toolbox and work bench for my barn, so moving the engine building stuff over there. Oh, and got some RX-8 rotors inbound too. Hey, they're far cheaper than S5 NA ones.
|
|
#
¿
Apr 12, 2016 21:44
|
|
|
RX-8 rotors are lightest from the factory, but S5 rotors can be lightened further. RX-8 rotors need some modification to use earlier style apex seals that will survive going over a peripheral exhaust port though - fortunately I have a milling machine. Most importantly though, right now they're cheaper and more available than S5 rotors.
|
|
#
¿
Apr 13, 2016 01:06
|
|
|
Rotors are usually fine, minus carbon buildup and worn out seal springs. Actually, I really would like to get a hold of an early RX-8 transmission (for very cheap) too - swap bellhousings with NB miata 6 speed, drop into NA/NB miata. But we'll see. Almost bought a couple more engines worth of internals, but then realized that I don't really have much money this month. Oh well.
|
|
#
¿
Apr 13, 2016 19:23
|
|
|
*edit* WTF forum, why you doublepost?
|
|
#
¿
Apr 13, 2016 19:23
|
|
|
This first one? I might take a sanding roll to the inside of the runners afterwards, and there's a few surfaces that are getting machined, but otherwise nah.
|
|
#
¿
Apr 13, 2016 20:55
|
|
|
Yup; did a couple test pieces, and measured their shrinkage, and adjusted the print to scale. It may be wrong but hey, it's not like I can't melt it and try again. Actually doing investment casting to start, just to avoid dealing with cores, getting the pattern back out of the sand, etc. No, not the most efficient route, but first things first, you know?
|
|
#
¿
Apr 13, 2016 21:48
|
|
|
ShittyPostmakerPro posted:I think you need to swap the input shafts as well, and the swap all the gears between transmissions onto each others shafts. I remember reading about the woes of putting a mx5 transmission in a rx8. Also the rx8 6 speed is made of glass. I'd be surprised if I couldn't just cut down the Miata input shaft a bit like you do to fit the Miata 5 speeds to rotaries. Might have to find an RX-8 diameter clutch with a smaller spline count but that's just parts bin engineering. And strengthwise, it can't be worse than the drat Mazda smoothcase 5 speeds - the turbo Miata guys seem to be using the 6 speed as the default trans. All I really want is a 6 speed Miata trans, in a Miata, bolted to a rotary. Not something I'd do behind a turbo 13B, mind.
|
|
#
¿
Apr 14, 2016 00:08
|
|
|
Repost from tools thread mostly... but also extra stuff specific to rotaries, because screw it! So, I had a pretty awesome couple of weeks around my birthday. 72" Montezuma workbench/toolbox, plus ended up burning gift cards to end up with an SK 3/8ths set, Wera Zyklop ratchet, another little gearless ratchet, and some other stuff. Then at a swap meet yesterday, picked up a 1/2 drive Blackhawk socket set for all of $80, plus a pile of taps and some other stuff from one of my wife's uncles. Box next to my nice new (to me) steel workbench. Last seen holding up a Lotus 7 clone, now holding a couple Briggs engines that will turn into one working one.  The SK set and ratchets. So nice to have actual nice tools.  Blackhawk set; still need metric ones but oh well, couldn't beat the price.  2 pairs of RX-8 rotors, one pair from Kyle Mohan Racing and race clearanced. Nice to be able to check my work. Need to mill them for non-renesis apex seals, but hey, I have a mill.  1 RX-8 rotating assembly, plus stationary gears and bearings. Leaves one and a half sets of internals (well, okay, and seals and machining, blah blah shut up) before I can build all my EProd ported 13B housings into race engines. Yeaaaah, I'm pretty pleased.
|
|
#
¿
Apr 26, 2016 00:57
|
|
|
They're both very incomplete too; the Van Diemen had the rear hacked up a bit to make a (poorly done) bike engined car, and the Formula Mazda we never had all the parts.
|
|
#
¿
Apr 26, 2016 11:06
|
|
|
All right, figure I'll mumble a bit since I finally had one of those epiphanies. Basic thing - I was thinking of doing a rotary Miata build because the suspension on the Miata is basically right, so all I'd have to do is make the rotary fit, put oil coolers in, revalve Bilsteins, and wire the whole thing, as opposed to an FB where I'd have to do a lot of fabrication to fix everything that needs fixing on the suspension. But then three things hit me. Number 1, I have a bunch of FBs (like, literally about a dozen) many of which are rust free. Number 2, I really like how FBs look and they're a lot more unique than an NA Miata chassis. And most importantly, number 3... duh, I *like* fabricating things. So basic plan is to do a sorta bucket list FB - you know, every hair-brained idea I've had for the things over the last 15 years. Suspension-wise, looking at a 3-link rear without any rubber. Found out about these Lemforder sealed spherical bearing things that are a Mercedes part that look too interesting not to try. I am not completely sure that the normal style Panhard I've always done on the race cars will fit with a stock gas tank, needs investigation. Front suspension is going to be moving to FC knuckles and new control arms with a new subframe - I want to fit something like an (aftermarket) MGB rack. Bilstein based dampers on all 4 corners; either the 36mm universal motorsports struts for the front or if I get really ambitious a linear/roller bearing guided setup. The big trick is I really want to tub it, though more in a "European Escort for rally" style than ye standard "US drag car" style. Actually, I'm thinking of moving the wheel tubs up by about an inch to compensate for taller tires and make the proportions not look dumb with it lowered (actually first saw this on an ALMS BMW) so new wheel tubs, rear shock turrets, and the front strut towers moved upwards as far as possible. And ZG flares. Hey, a man's gotta keep busy somehow, right? Plan on hauling one of the shells out to my barn next week or so.
|
|
#
¿
May 25, 2016 14:47
|
|
|
SCCA regionals this weekend at Blackhawk Farms. First race of the year with the MX-5's new engine (that I broke in by driving the gutted, caged, topless race car with numbers on the side to work for a couple weeks) and so far so good. I'll post a couple pics once I'm not so drat tired, which may be Monday because it's a double weekend. Not much there on Saturday, but here were a few funny things, like a Honda J32 swapped Miata. Yes, I took pictures. It got me thinking though, and I'm waffling here. Basically, one way or another I want to build a rotary powered car for an SCCA Nationals class - which is to say, not some weird oddball catch all class. I'm sorta down between GT-3 or STU. GT-3 would be a scratch built tube chassis car - which means a lot of development and all, but the ultimate versions of various driveline parts are basically circle track bits. But it's literally fabbing everything. I think I mentioned the idea before. The alternative is a Miata in STU. This would have the shell be not too far from an IT or Spec Miata, but with better brakes and a rotary (there's other engine options in STU but gently caress that) So most of the stuff is already solved problems, but it's the standard unibody thing where stuff's in the way and denting stuff means doing bodywork or writing off the tub... and gearbox solutions are a pain in the rear end. Help me decide, AI!
|
|
#
¿
Jun 12, 2016 02:09
|
|
|
Well, after that resounding response, decided to proceed with the STU Miata build. Been researching wing profiles and front aero solutions on MT.net and have a baseline idea, but first let's figure out brakes! So, I don't really like power brakes much, and ported rotaries (and this will be at the bleeding edge of what you can call a 'street port') don't really make much vacuum. So, some calculations later, and I'm looking at an OBP floor mount pedal box with around 0.7/0.75-0.825 masters, and 1.75" front and 1.375" rear Dynalites. Well, actually Afco Dynalite clones but nevermind, close enough. This also means that pads can be shared front to rear, which seems like a nice thing to me. Only thing is, does anyone make a bracket to put a Dynalite on the rear of a Miata? Oh however would I figure out how to design one!?  ^^ ... pretty much by doing that. Bonus vented rear discs too... which may be unnecessary but should last forever. Nice thing about this is that there's room to do things incrementally. Like, I know OS Giken diffs and stuff are the greatest thing since sliced bread... but I *have* a bunch of RX-7 clutchpack limited slips. So good enough to start with. Also figuring out transmission. To start with, planning on trying to find an extension housing from a dead NB Miata 6-speed and put that on an RX-8 6-speed. The next idea after that is hybridizing things. See, I know the AZ-6 is also used in some other cars... I don't know for sure if the internal bearings are the same sizes though, but I made a spreadsheet to figure out tooth counts. If the gears can be persuaded to fit, some junkyard mixing and matching (FR-S 3rd and 4th in an RX-8 box) gives 3.761:1, 2.270:1, 1.598:1, 1.258:1, 1.000:1, 0.844:1 for a nice tight 3rd-6th - given a 9000rpm shift point, call it a 2700rpm drop 2nd-3rd, and 1900-1500rpm after that. And a JDM Altezza 1st and 2nd, or a Cusco aftermarket 1st and 2nd for an FR-S tightens 2nd-3rd to around a 2100rpm drop. It sounds reasonable to me. Just dropped a line to Jim Drago about an RX-8 transmission and inquired as to cost for a stripped Miata shell, as I've heard he has been known to supply them. Also on the burner is a DIY data system. After tinkering around with AIM's Race Studio setup, I am pretty sure that I could reproduce the functions I need (not as user friendly as AIM but good enough for me - I do data aq for a living FFS) and the hardware is conceptually simple enough. Predictive lap timing not so simple, but hey, AIM Solos are cheap. And finally, working on the spare Subaru transmission. Turns out the 5-speed DCCD diff *almost* fits in the Phase 2 trans housings. I don't know that anyone has ever tried before, but all it needs is a little metal removed and should be perfectly fine. I'll take pics of that and my Afco Dynalite clones when I get home and or remember.
|
|
#
¿
Jun 30, 2016 16:59
|
|
|
th vwls hv scpd posted:I like this thread killjoy, I just don't have much to add because I don't have a clue about most of your stuff. Sorry no one told you to build a tube chassis car. That would be a neat thing to see over the internet. Well, there's another aspect to it too that weighed it towards "rotary Miata" - I'm kinda also planning in terms of "what can I still finish if I have kids". It's not like they're going to un-invent steel tubes or fiberglass so I can always go back later and make the tube car. Also, the STU Miata would be towards the pointy end of its run groups while the GT-3 car would be towards the slow end of its run groups... so why not go with something where I'll have more competitors on track at once, and not have to watch the mirrors constantly? CAT INTERCEPTOR posted:Actually the rear brakes will get more of a workout than you expect... because you will be going faster than you expect. I've never seen a slow rotary MX-5 Well, maybe? I'm cribbing brake guidelines from guys who are running turbos or V8 swaps, but I figure going from solid to vented rotors never hurt anyone. Ok, pictures!  Rear Afco Dynalite clones. Got them because Speeway Motorsports had a sale and I wanted to check out the quality. I think I like them a lot more than the Wilwoods. Will wait on the front calipers because *those* aren't on sale.  Opened up the Subaru transaxle that will be going into the WRX. For those of you keeping score, it's a TY754VBAAA, which means it's the V5/V6 STI box. Or another way, it's got closer ratios than the lovely USDM WRX ratios and a 4.44 final drive instead of the lovely 3.90 USDM WRX ratio. Why this instead of an STI 6-speed? This is my DD and I don't have very grandiose power goals, so saving a couple grand by not overbuying is nice to me. Still viscous center diff too and open front. Don't worry, that'll be fixed.  New hotness on left, old shittyness on right. Did not get the extension housing though, which turns out would be important. See how the old lovely viscous center diff on the right narrows down next to the bearing on "top"? Keep that in mind.  Extension housing. You can see the inwards extension on the casting with a barely visible scrape. Turns out they did change that between the Phase 1 and Phase 2 extension housings. Now, I could get all panicked about this and go searching for a Phase 1 extension housing because it doesn't fit... ...except wait, I have a milling machine. gently caress it, I'll *make* it fit.  While I'm opening everything else up anyway, Chinese Torsen style front diff rebuilt with better hardware and belleville washers. The quality seems "OK" on these once you get rid of the hardware and stuff - let's be honest, Quaife is probably made out of the same factory - and working for a company that makes engines in China, usually they don't gently caress steel up too much.
|
|
#
¿
Jul 1, 2016 14:13
|
|
|
No pictures, but woooo, found a rust free shell for a couple hundred bucks. I mean, no interior or ... lots of things... and it's got front end damage, but I have a rustbucket donor car in my parent's field to supply that stuff. And starting with an empty shell gets over the urge to leave anything extra in out of laziness.
|
|
#
¿
Jul 13, 2016 00:58
|
|
|
Yeah, everyone in the US pretty much just goes to the 6 speeds nowadays. But I have all of about a third of what that would cost into this box even with the trick diffs, which means more money for the race car. I'm not even sure what the timeline is on bothering to do a built engine on the WRX; I have a lot of the parts but have to machine the case for rear thrust and there's no real signs of the EJ205 wearing out yet. It really would be nice to have a real rear LSD too, but I figure I can come back to that one easily enough. Oh yeah, leaving in about an hour to pick up the Miata shell. I'm not excited about that whatsoever. 
|
|
#
¿
Jul 17, 2016 14:17
|
|
|
  Why hello there. No rust! Also got a front bumper cover and dashboard plus an extra door. Does have front end damage, but it just so happens I have a parts car with rust but no front end damage. So, a bit of welding, followed by a lot of seam welding and caging, plus all the other stuff. Great thing about starting off this bare of a chassis is that there's no temptation to leave in extra crap, simply because it's already stripped out.
|
|
#
¿
Jul 18, 2016 15:18
|
|
|
I've done, am doing, and will be doing a lot of research... and have a general principle behind this build. "Unless something is absolutely perfect for my purposes or there's no reasonable alternative, make the car accept commodity race parts instead of special snowflake Miata parts". This may have consequences that make this build not look like most other builds I've seen online. Oh yeah, in the mean time, almost have the T4 NC MX-5 back and ready to rock. Need to weld up a flange to make the NC MX-5 Cup muffler fit the Racing Beat midpipe and, if it comes in time, fit the Tomei LSD. No more one tire fire! Also working on the CAD design of control arms since it'll be a while before I can spend any more big bucks.
|
|
#
¿
Jul 18, 2016 19:45
|
|
|
I'm... not completely sure! I haven't figured out how far back it's crooked and where a good place to start is. I half had the thought of drilling out spot welds and then stitch welding to replace them, but like I said, not sure if that would work right.
|
|
#
¿
Jul 18, 2016 21:59
|
|
|
What am I doing today (when I should be working)? Why, I'm figuring out shock valving! See, there's this great suspension calculator spreadsheet that is the result of someone going to the trouble of doing maths for a lot of basic handling stuff. Fun thing is that fairly accurate data for Miata suspension geometry is available so I stuck that in to come across what is at least a first cut of spring rates and bar selection (ok, in truth, it''s pretty close to what 949 Racing recommends; go figure they recommend a pretty solid starting point) I've added a bunch of sections to it, including data reverse engineered from published graphs for a lot of Miata shocks. I have a lot of those that I've found. Some interesting trends emerge.  Here's a graph of ... well, okay, the axes are labelled. It's two commercially available dampers that I went and picked vaguely approximately correct clicker settings (nobody provides a full sweep for obvious reasons, so stuff's a little off from perfect) for my given spring rates. No, I won't tell you which ones but I will say that I came up with all of this stuff without any proprietary information or disassembling anything so it's not too hard to do the same. I'd actually be really impressed if someone figured out which is which here, though.  Part of the fun part with analysis like this is figuring out which aspects are intended and which are a consequence of compromises in valving or the need to fit in the rear shock of a Miata. Why don't I just buy something? A couple reasons. The cheapest off the shelf solutions that I'm confident are good enough to be a good starting point run about $400/corner. If I convert to something that takes 1/2" rod ends on both sides though (which I can do) there are so so many options that it boggles the mind, I can upgrade the internals, tailor them to suit, and so on. And the big thing is that I want to learn this stuff anyway. Let it never be said I'm lacking for ambition on this project...
|
|
#
¿
Jul 19, 2016 18:47
|
|
|
Oh yeah, here, have another graph. That's from the old shock dyno before I did any smoothing or anything of the raw data. I think it was a Koni wet converted strut for the RX-7. Sucker worked with an electrically controlled proportional regulator driving a directional valve and then a pneumatic cylinder. So stroke the shock in and out at a given force and measure velocity. Had all of a hundred bucks into it and really wish I had video of it going as banging back and forth at full speed was pretty impressive. New version I'm doing will be using a pneumatic servovalve so I can try to duplicate the results of the classic crank style dynos, in addition to doing all sorts of other inputs instead of just a sine wave. One cool part is that you can separate hysteresis from valving stuff from that caused by gas force.
|
|
#
¿
Jul 20, 2016 15:21
|
|
|
No pictures right now, but status report. Got the NA shell into the barn and started drilling spot welds. Plan is to follow the FSM guidelines for where to cut and weld to replace the bits that are damaged because... well, look, why not? And then add stitch welding. Last race for a while on the NC was yesterday, which went OK - ABS wasn't working and one of the tires got flatspotted. Oh well. New Tomei diff seems to be working well though. Fun thing though is we paddocked next to some old friends of ours who used to run an FB in SCCA E-Production at national championships levels of preparation, and are now building a Miata. "Oh yeah, we have a couple OS Giken diffs we picked up used, and could sell on the Prather coilover setup after we move up..."  What was cool too is he gave me some tips about interpreting some rules, including that probably I can get away with doing the new Spec Miata-style seat floor modification to drop the seat down under the clause of "safety reasons". Which is nice because I'm right on the edge of too big for the car. He also confirmed that it really does seem like a pretty affordable way to do things, but neither of us are sure that it'll be a "potential to win national championships" level of competitiveness. Which doesn't matter too much because neither am I.
|
|
#
¿
Aug 22, 2016 16:05
|
|
|
 Progress! Got sawhorses made and the car up on them. Now I can actually get at all the spot welds. Next up is taking off the crunched passenger side structure.
|
|
#
¿
Sep 4, 2016 02:26
|
|
|
No new pictures yet because pictures of drilled out spot welds are boring until I have something to show for it, but on a "continued accumulation of parts" topic, have a Miata 6-speed tailshaft housing dealie showing up Friday, and an RX-8 6-speed showing up Monday. By their powers combined, I should have a reasonably-close-ratio 6-speed that bolts to both a 13B and a Miata PPF! All of which means I just have to make mounts to bolt to the subframe; no goofy adapter plates or any such crap. ...well, and I have to put a front end on the car, so I can test fit it, but you know. May just do a quick test fit into the rustbucket parts donor before I cut it up, so I can get an idea what idiocy I've gotten myself into. Speaking of getting myself into idiocy, started delving into the Speeduino code. I basically want a 36-1 wheel that runs a box to do a real timing map with 4 smart coils, and lo and behold someone did most of the heavy lifting. "All" I have to do is make it do rotary split timing and the no-lift-shift poo poo I want to do. Well, and ideally migrate it to a Teensy or something and roll my own little board to cut down on the space it takes up. You know, easy. (cue 2 years from now when I get fed up and throw a distributor into the thing)
|
|
#
¿
Sep 15, 2016 21:47
|
|
|
I thought the S2 RX-8 gearbox was a Mazda in-house design and the same as the NC MX-5? We're both talking about the toploading one, right? Either way, problem is it'll be harder to adapt into an NA MX-5, and the RX-8 box solution is kind of an interim until-I-can-afford-a-real-box thing anyway. Though I wonder if there's some other version of the Aisin box I can raid for better forks. I'm hoping to do better than 9k RPM - a builder over here for a circuit class with similar engine rules but with requirements to use the 6-port irons was making power into the 10s on an extend port (that's what you call "not yet a bridgeport but lots of metal removed" down there, right?) And I'm intending to use a mix of S5 or S6 turbo (whatever the flowbench says works better) and 12A irons plus some carby tricks not allowed in the other class... and I'm all-of-a-sudden thinking I should maybe stockpile a few extra RX-8 boxes.
|
|
#
¿
Sep 16, 2016 13:22
|
|
|
I think the NC got it first, actually. S2 RX-8 starts in 09, right? The 06 MX-5 my dad and I built for SCCA T4 has one. There's actually an update for the plastic thingy, and an updated shift fork too. Apropos of nothing, what's up with the RADL thing? </newbie>
|
|
#
¿
Sep 16, 2016 23:38
|
|
|
Progress some more. So Friday, an NB 6-speed tailshaft housing showed up - thanks to a kind member of the Miataturbo forum who has gone through a few 6-speeds. And then today my RX-8 6-speed showed up. 61k miles on it, paid all of $170. Thanks car-part.com! So a half hour ago I went outside to take pictures to prove that stuff is happening. Like so. But then... I had to know. I had to. It should work, oh god it should, but I had to try it. A few bolts here and there and the RX-8 tailshaft housing was off.  And then... ... then...  MOTHER loving YES! It fits and shifts! Cheap 6-speed that bolts to a rotary *and* a Miata PPF! I KNEW IT! So yeah, that was my day. Now I just have to cut more spot welds. Still. Well, and then strip the parts shell, cut the replacement sheetmetal off of it, put the seat lowering pan and trans tunnel notch panel in, design, bend and weld a cage, modify the unibody if necessary to make the exhaust and stuff fit, fab or buy control arms... and you know, stuff like that. .. oh, and also, thank you whoever tagged me.
|
|
#
¿
Sep 20, 2016 02:56
|
|
|
Kaptainballistik posted:I would like to know where this plastic bush is on the s2 box! http://www.miata.net/garage/Mazda%20P66M%20Transmission%203-4%20ADJUSTMENT%20MANUAL.pdf Page 11 or so and then on. They mention that S2 RX-8 should have the stuff corrected already, though.
|
|
#
¿
Sep 20, 2016 03:32
|
|
|
|
| # ¿ Apr 27, 2024 22:32 |
|
|
kastein posted:Wait a minute. Aisin built all or some of the boxes we are talking about? Can you get me a decent quality pic looking into the bellhousing? Curious about something. Into the bellhousing from the engine side? Sure. Any particular thing to try to capture?
|
|
#
¿
Sep 20, 2016 11:31
|
|