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infernosg
infernosg New Reader
4/28/20 2:55 p.m.

Let's do late Summer/Fall 2019...

At the National Speed celebration I went to open the passenger's door and quickly realized something was wrong. The handle only lifted halfway and not far enough to disengage the latch. Since I rarely have passengers this wasn't a huge deal but it eventually bothered me enough to dig it out and figure out what was wrong. Problem found:

Apparently this is common in FCs and I've happened to be extremely lucky for this to only happen once in my 10+ years of ownership. A major downside of a non-OEM color is I can't just scour the internet for a drop-in replacement. There are some aftermarket billet replacements but I took a more GRM approach.

Some scrap aluminum, a couple M3 screws and some epoxy. It's held up so far. I'm told the best way to avoid this issue is to lock the car from the outside using the key insteading of holding the handle up.

Minor annoyance aside it was time to solve my filtration issue. I pushed my luck and drove ~100 miles without filters but I've always read just a little bit of grit can quickly kill these engines. I really wanted a custom air box but that was quickly becoming a Winter project so I opted for the easy button. I scored a K&N filter kit for a IDA carb for like $35. Thanks Amazon! Unfortunately, it meant my big, beautiful ram tubes had to put into storage.

Lots of fiddling to get everything to fit. Ended up having to modify the filter base and the filter is still streched over the ram tubes.

Not ideal but I figure this can't be any worse than my previous setup (filters clamped right onto the lip of the ram tubes). Ultimately I ended up with something somewhat presentable.

It doesn't have the wow-factor of the oversized black ram tubes. I was going to paint the chrome top black but figured this would be temporary so why bother. Spoiler, it's almost May 2020 and I'm still running this setup. It's not really noticeable but my IAT sensor is just run between the filter and the base and is zip-tied to the A-shaped bracket in the middle. As expected, IATs were just as bad as ever. It was time to do something about that.

First, drill a 4" hole into nice, shiny paint and a couple of those cheap, aluminum adapter plates found at many auto parts stores (Spectre Performance, I think):

Add a ridiculously large silicone elbow:

Hmm, not straight, but good enough. Damn headlight motor is in the way. On the other side, some more large silicone couplers and a random piece of Al tube.

It's not pretty but it works. Quickly verified with a leaf blower and later confirmed during drives that showed cruising IATs around 100F with ambient temperatures in the low 90s. The inlet has to share a hole with both the headlight motor and the passenger's side front brake duct. I'm sure there's a more elegant solution available. I've given some thought to making a fiberglass duct that fits around the headlight motor and doesn't block the brake duct while point more toward the front of the car. My ideal solution would be to ditch the pop-up headlights for a fixed setup but there isn't anything readily available off-the-shelf I like and I'm not ready to commit to modifying the front bumper just yet.

So that's really the state of the engine right now. I've got some other things in the works but by this time it was ~September and I really wanted to start tracking the car again. That meant doing a lot of deferred maintenance to make sure everything was track-ready. Oil changes all around, coolant flush, brake fluid flush and bleed, front wheel bearing adjustments, etc. Fall is a busy time of year in our house so it took me a few weekends to get through everything. I also decided to stop being stupid and finally addressed my naked roll bar.

SFI certified padding. If my helmet ever hit the bar something VERY bad happened but I figured it be some reassurance. Unfortunately, previous commitments and general laziness kept me from any NASA weekends or SCCA track nights. My only taste of the track last year was at the 2019 East Coast Rotary Classic at Dominion Raceway hosted by Angel Motorsports (yes, THOSE guys). We were promised hot laps but what we got is what I'll call "paced" laps. Basically, follow-the-leader with one of the track's Camrys. I think I did half a dozen or so sessions that day and against my better judgment I'll insert a video of what I consider to be the best session...

 

So let's cover some things...

1. Yes, it was slow. The first several laps painfully so. There was a lot of confusion throughout the day and it shows. This was the best session because I was immediately behind the pace car and he gradually picked up speed as we went on. 

2. I'm rusty. VERY rusty. I'll admit my last HPDE was in April 2011 and it shows. My hand ettiquite is awful and my shifts could have been smoother.

3. I generally drove pretty conservatively. I was usually shifting well below 8000 RPM and was lightly rolling onto the throttle. I'm still nervous about the durability of this car.

4. I swear I can operate a manual transmission. I don't know what was going on but a few times I absolutely couldn't get the car into 3rd on the straight. It was generally an issue when shifting over 7500 RPM and I'm hoping it was because of my poor driving and not a bad synchro (the only things I didn't replace in the transmission, remember).

5. Ignore the rubber Ducky. I know I should have taken that out but since this wasn't an official trackday I didn't bother. It makes a decent visual accelerometer though...

So that, somewhat embarrassing, note was the end of the 2019 "season." I worked on some things over the Winter but we're largely caught up now. Next up: Winter-present...

infernosg
infernosg New Reader
6/15/20 3:04 p.m.

Having another go at updating this. Winter 2019/20 was admittedly a bust. The car did fairly well for its first time on track so I left well enough alone with the plan to tackle some things before the 2019 season started. I slowly accumulated parts with plans to start working in late February/early March so I'd be ready for the first events of the year. As everyone knows COVID-19 had other plans and everything was canceled. With no events for the foreseeable future and increasingly bleak news from work I was pretty unmotivated/depressed for the majority of March through April. Despite a single week of hope in late April/early May the work front has still been depressing but I've managed to get myself back out into the garage to keep my mind off things.

 

My intended goal for 2020 was to finish up the suspension. There were still a few original rubber bushings and boots floating (literally) around. First in my sights were the upper bushings in the rear hubs. Out went the 31 year-old rubber and in went brand new, shiny aluminum.

 

With the rear hubs solidly in place I moved slightly forward to the rear control arms. Many years ago (10?) I replaced the forward inner links with adjustable units from AWR. They were adjustable, which allowed me to dial the rear camber in separately for each side. While the adjustability was initially appreciated they are kind of set-it-and-forget-features. With ride height dialed in I haven't had to adjust camber in years. Also, the years haven't been kind to the AWR pieces. They were rusty, grease fittings had been broken off and they required frequent removal, cleaning and re-greasing to stay quiet. They were replaced with fixed-length, anodized aluminum and stainless steel units.

The company that makes these, Ronin Speedworks sells three different "stages" and my previous setup was somewhere between their Stages 2 and 3. I opted for the 3 so I have slightly less camber than before (around -1.75 degrees). In addition to being Al and SS these use spherical bearings so are less likely to bind (i.e. make noise) and Ronin sells the different length frames separately so I can always switch to a Stage 2 if I want to run around -2.25 degrees of camber. I figure I'll chalk the rear tires whenever events start again to see what the car wants.

 

Next I moved to the front control arms. My suspension is from a 89 RX7 so it has the control arms with the integrated ball joints. Previous years had replaceable/serviceable ball joints. Since my ball joints were 31 years old and the boots were starting to crack I figured it was time to replace them. I located some 86-88 control arms off Facebook and purchased some new, OEM ball joints. The rear and inner bushings were replaced with polyurethane units as well.

The rear bushings are supposed to increase caster by moving the pivot point outward; thus, rotating the ball joint slightly forward. I figured it couldn't hurt. While I was in there I replaced the 31 year-old sway bar end links with adjusted units with heim joints.

 

Next I got side-tracked on a non-performance upgrade. Factory non-AC cars came with a unique duct between the blower motor and air mixer. These are less bulky than the AC heat exchanger and are unfortunately NLA from Mazda. While they do pop up for sale periodically they're expensive and sell quickly. Fortunately an enterprising individual on one of the may Facebook RX7 pages came up with a cheap solution.

Some 3D-printed side pieces and some 4" dryer vent and for less than $50 I was able to ditch the bulky, gutted box on top. Weight savings? Small. The real benefit here is opening up space under the dash. I can now access entire wiring sub-harnesses that would have previously required the dash to be removed.

 

After that detour it was time to return to the chassis. Many years ago (2014?) I decided I was going to run a "de-powered" steering rack. The process is straightforward and well documented and I completed it with no issue. I've been driving the car for nearly 3 years now with no problems. However, the whole point of de-powering a power steering rack is for quicker steering. Manual racks have a ratio of 20:1 whereas power racks are either 15:1 or 17:1. My rack came from a 89 GXL so it had the "speed sensing" power steering, which has the 17:1 ratio. With the big 380 mm steering wheel I sometimes found myself in situations wishing I had the quicker rack. Fast forward to this Spring and I managed to procure a 15:1 "engine speed sensing" rack and I repeated the process all over again. This time I went a little further. I removed EVERY seal and even ground off the fittings on the pinion housing.

Every oz counts, right? Here's it installed with new polyurethane rack bushings as well:

I'm not a fan of the blue but it's the only color they come in and OEM bushings are NLA. I also took this time to install new outer tie rods that move the pivot point downward in an attempt at reducing bump steer.

Only slightly lower than before but probably can't hurt. I know my car is probably too low but I don't compete so there's some compromise between performance and appearance. If anyone needs a de-powered 17:1 RX7 steering rack with all the brackets and bushings let me know!

 

Obviously after this my alignment was entirely screwed up. I bought a camber gauge and mount from Longacre and made a simple alignment jig out of some metal pipe and string. No pictures, but I was surprised how easy it was to get everything squared up. While not perfect I know front and rear toe is somewhere in the +/- 1/16" range.

That's all for the suspension work. Next post I'll cover how I finally intend to solve my IAT issues once and for all.

Arosa14tdi
Arosa14tdi New Reader
6/16/20 4:35 a.m.

Love the Colour and the build .Always like the 7 over 8 shape

infernosg
infernosg New Reader
6/16/20 11:54 a.m.

In reply to Arosa14tdi :

Thanks! 80s cars are very "in" right now so the older RX7s are getting popular. I still wish I had the better suspension geometry from the FDs and RX8s though. I wouldn't mind a later model RX8 R3 as a DD either.

stylngle2003
stylngle2003 Reader
6/16/20 2:52 p.m.

cool to see you're in Midlothian as well.  Maybe I'll see the car around town or at Dominion some time.

 

infernosg
infernosg New Reader
6/16/20 4:55 p.m.

In reply to stylngle2003 :

Yeah, I'm down nearer to Chesterfield off Hull St. Every now and then I buzz around but generally I try to avoid causing a scene. It looks like there's a SCCA event at Dominion next weekend (6/27-28) but I probably won't be able to attend. My employment situation is still up in the air for at least another week and if I do find myself without a job I probably shouldn't be dropping $300-400 on track day weekends. I do hope to do at least one HPDE at both VIR and Dominion this year.

infernosg
infernosg New Reader
6/19/20 2:48 p.m.

Alright guys, time to bring this thread back up to the here and now. I've been holding off posting this next section until this particular project was completed. One issue I've had since getting the car running in August 2017 is high intake air temperatures (IAT). Stuffing filters directly onto velocity stacks and sucking in hot engine bay air will do that. At DGRR 2019 I was seeing IATs as high as 150 degF. The car ran but it wasn't as happy. My ECU pulls both fuel and timing at those temperatures. I came up with a half-assed fix for last Summer that was basically a pipe pointed at my air filter that took air from the former fog light location. I knew I could do better...

Initially, I thought I could make my own air box. I've worked with fiberglass before and that seemed like the logical approach. I was fully prepared to make a buck out of cardboard and expanding foam and have at it. There was another approach, though. For a while I've known about these "Group C" fiberglass air boxes designed around rotary engines with IDA carbs. The design is attributed to Australian driver Allan Moffat. I always assumed they wouldn't fit my car because they were designed around earlier generation RX7s with carburetors. After some discussion with EFI Hardware, the current owners of the molds, I determined the box would physically fit under my hood but my fuel rail and water pump neck would be in the way. I figured I could solve these issues more easily than building my own air box so I placed the order. After an unusually short shipping period, even by pre-COVID-19 terms, I had this:

The base comes un-cut and un-drilled. This is not quite a drop in affair even for the intended applications. My main issue is one side of the air box interferes with my injectors and fuel rails. The base and box needed to be modified to remove the interference. The easiest solution is to angle the base on one side so it clears the fuel rail and then modify the box to accomodate that modification. I toyed with the idea of doing more fiberglass work but ultimately decided it would be easier to just make a new base out of aluminum. I ordered some 0.100" thick 6061-T6 aluminum sheet, used the old base as a template to get an approximate shape and drilled the holes for the intake and mounting bolts. The next trick was bending the plate to avoid the fuel rail. Two problems here: (1) I don't have a metal brake and (2) 6061-T6 doesn't like to bend. I resolved #2 from randomly reading another build thread here. Apparently marking the area to be bent with permanent marker then heating it until the ink disappears is a good approximate method to return the aluminum to T0 temper. As for #1 that was solved with a random email (or was it a Facebook ad?) from Eastwood. They sell this neat setup that turns your bench top vise into a small sheet metal brake.

Out of the box it works great on thinner metal. However, I knew right away the near knife-edge would was no good for my 0.100" thick sheet. Improvisation time!

Some angle iron and 3/16" flat stock from the local home improvement store. The internal radius of the flat stock was a nearly perfect fit for the 3/16" flat stock and would give me a larger radius to avoid fracture. Moving 0.100" plate, even just aluminum, is still hard in a <6" vise though...

I ended up having to alternate sides and use "percussive persuasion" to get the metal to move. In the end, I was triumphant.

Fits good

As you can see I left one side long to account for the angle. Here you can also see how I resolved the coolant neck issue. An enterprising individual on Facebook makes various CNC-machined parts for RX7s of all year (JDL Manufacturing). He recently had released this low profile coolant neck and I immediately ordered one. Neat piece.

It does necessitate a non-OEM upper radiator hose but after trips to several auto parts stores I found one that worked after some trimming. It's close, but everything clears.

With the angle of the base set it was time to trim the box itself. After days of trimming and sanding I got the fitment to where I was happy and I could finally finish cutting out the base.

Add some 1/4" Viton foam to act as a seal and latches to the top and I have an air box!

The original fiberglass base has depressions in it for the latches to grab. I initially tried to grind similar grooves into my base plate but that wasn't working; especially on the angled side. I ended up pop-riveting little catches on three sides. Here it is from the bottom:

The extra hole in the middle is the fresh air source for my PCV system. Another benefit: I finally mounted my IAT sensor in an actual intake!

With the box mounted the next step was to make the rest of the intake. My initial plan was to make a sealed cold air box behind the passenger's side headlight. The idea was my silicone elbow in the fog light area would force cool air up into the box, which would then be drawn through a large 5" base filer into the air box. However, after getting the air box in I realized I had less space to work with than I had thought. I tried a couple 5" base K&N filters I could find and they were all too big to really fit in the intended area. The resulting cold air box would have required a more complex shape than I was confident I could build. After staring at my setup for a while I had a brain fart. I remembered the old AEM/K&N cold air intake kits that put the filter down in the bumper. I should be able to do something similar. After some trial and error with several 4" base filters I found one that fit perfectly where the silicone elbow had been.

View from the top

Now, I know this leaves the air filter fully exposed. On one hand, perfect! On the other, it's a risk. It appears that frequent cleaning will be in my future. As for water, I avoid driving in the run/wet if I can avoid it. I understand track days can be wet so I'll probably pick up one of those water resistant sock covers. Worst case, I can make a little shield in front of the filter but I'm concerned that could choke airflow.

So, filter mounted. Just need to connect filter to air box. It's a pretty tight bend so hard tube wasn't really an option. Enter neoprene ducting. I splurged for the more expensive wire-reinforced, double walled stuff. I found this amusing on the box:

I've never worked with this stuff before but my God is it a pain in the ass. It was hard to get a clean, square cut at the ends and the support wire always wanted to do it's own thing. Eventually I prevailed and got something that looked passable.

And here's the setup in its entire glory:

The hole in my car is 4" so I had to use 4" neoprene duct whereas the air box inlet is ~5" (it's fiberglass, after all), which necessitates the use of a 4-5" reducer on the front of the air box. Since the duct and coupler both have 4" IDs I had to use a short span of 4" OD aluminum tube, which I had leftover from my previous setup to join the two (hence all the worm gear clamps).

I wrapped all this up on Wednesday and due to rain I've only taken the car out once yesterday. It doesn't really feel like it's driving any differently, which is good. Maybe the air-fuel rations are a little richer. I am slightly concerned the filter size and duct diameter will hurt airflow and reduce power. A quick area calculation shows the new filter area is a little more than that I had before with the carb air filter kit but it's also tucked into a hole and air has to pass through a series of tubes before it hits the velocity stacks. K&N does advertise a somewhat generic equation for calculating air filter size: Area = (displacement in cu. in. x max horsepower RPM)/20839. My 13B is listed as 1.3L (~80 cu. in.) but I don't think that's a reasonable number to use. I've seen some people claim rotaries are more comparable to engines twice their "size" so let's assume 2.6L or ~160 cu. in. If my maximum power occurs at 9000 RPM that gives (160 x 9000)/20839 ~69 sq. in. My filter has an area of about 78 sq. in. so according to that I'm good. I've also seen someone quote maximum power potential = filter area x 4.53 for rotaries. This would suggest my 78 sq. in. filter would be good for around 350 hp. Factor 25% loss results in around 260 hp to the wheels, which is more than I am making. I need to schedule another dyno session so time will tell.

And we're all caught up! I don't envision anything major changing any time soon. I need to dedicate some time to optimizing the tune and do some more general maintenance and it's ready for track time. The next track day event is apparently next weekend (6/27-28) at Dominion but that's a little too soon for me. I really want to start slow with a single track day or night before working up to a full weekend.

crankwalk (Forum Supporter)
crankwalk (Forum Supporter) GRM+ Memberand SuperDork
6/19/20 5:35 p.m.

Airbox solution looks outstanding. Great work with the whole build.

 

I ran a Supertrapp on a turbo streetport  13b and it was the loudest car Ive ever heard in my life. I drove from El Paso to Atlanta in it and my brain was buzzing for weeks. Props for driving this thing long distances. 

infernosg
infernosg New Reader
6/22/20 8:50 a.m.

In reply to crankwalk (Forum Supporter) :

Thanks! This past weekend was the first in a very long time (ever?) that I realized I have no more parts to install. My "to be installed" parts box is empty and it's a weird feeling...

DGRR 2019 was the last time I drove this thing for more than ~2 hours at a time. I'm not old by any means but my body is starting to make it very clear what it does and doesn't like. I hear ya (pun intended) on the brain buzzing though. Any events more than 2 hrs away and it'll be trailered going forward. I do need to address the noise though. I did a little pull behind our house and afterwards my neighbors made it very clear they heard me. From inside their houses no less. At the very least my exhaust needs a turn down but I'm hoping I can squeeze another muffler in somewhere.

fidelity101 (Forum Supporter)
fidelity101 (Forum Supporter) UltraDork
6/22/20 1:28 p.m.

this is like reading my build thread if it ended up being an on track car, I have had a lot of similar experiences and setups! I have been eying that EFI hardware stuff for the rally car myself, I'm curious to know your feedback on them!

 

If you were struggling with low end issues and idle, why didnt you keep the primary fuel injectors on the block and save the large IDs for as far upstream as possible?

I would look into rx8 S2 gearbox if I were you, after tracking it you might want the tighter gearing for better acceleration and general shift quality with the newer components but you will have to go to a turbo style clutch and get an rx8 starter...

 

I literally can feel these photos as having gone through or done the same things you have but I'm still curious on why you went studded route for NA. I always make my engines a little looser so when they heat up they dont break and swell to spec as I estimate...

stylngle2003
stylngle2003 Reader
6/22/20 2:16 p.m.
infernosg said:

In reply to stylngle2003 :

Yeah, I'm down nearer to Chesterfield off Hull St. Every now and then I buzz around but generally I try to avoid causing a scene. It looks like there's a SCCA event at Dominion next weekend (6/27-28) but I probably won't be able to attend. My employment situation is still up in the air for at least another week and if I do find myself without a job I probably shouldn't be dropping $300-400 on track day weekends. I do hope to do at least one HPDE at both VIR and Dominion this year.

We have friends that live off Bailey Bridge, so we're down that way pretty often.  We are over right near the Wegman's.  We'll be doing the track day at Dominion 7/12 with our 350Z.  Good luck with the job, this is a crazy time.

infernosg
infernosg New Reader
6/22/20 2:52 p.m.

In reply to fidelity101 (Forum Supporter) :

Regarding EFI Hardware I've got nothing but good things to say. Their parts are reasonably priced although shipping from Australia hurts. Quality-wise I'd put them between Borla and Jenvey with Jenvey being slightly better but more complicated. Steve and Mark at EFI have been really helpful and responsive to my questions, which is big in my book.

 

My reason for not running stock primary injectors is simplicity. I didn't want to deal plumbing two fuel rails and dealing with injector staging. No doubt it would improve idle stability and transient throttle at lower engine speeds. I have a break-out harness for the injectors so it would be easy to add them. I actually had a pair of ID725s and a FFE primary fuel rail kit for a while and I was -that- close to installing them. I've gotten it to idle better. I switched my O2 control to the rear rotor, which has always run leaner, and some better closed loop control settings seems to have helped significantly. I also pulled timing quite. It'll happily idle at 1000 RPM all day. It still drops a bit after coming to a stop but it won't stall out. The shorter intake manifold has helped with transient throttle to an extent and I'm sure I could optimize the transient throttle settings better. For now, I just know it'll hesitate for a bit if I stomp on it below 3000 RPM. I rarely cruise around below 2500 RPM anyway (to the annoyance of other drivers, I'm sure).

 

I had to go look at the S2 RX8 ratios. Compared to the Miata it looks like their actually a -little- further apart but overall are shorter, which would be a good thing. I've also heard they're stronger, which may be a point in the future since I've heard people have issues with the NA transmissions over 200 hp. I just haven't looked into it that much. I understand the clutch/flywheel/starter differences but shifter placement, mounting and driveshaft options are unknown to me.

 

When you say "looser" are you referring to the torque in the tension bolts? IIRC, my studs are torqued to 30 ft-lb, which isn't much more than the OEM range of 23-29 ft-lb. I honestly can't remember why I bought the studs. Younger me (this was c.a. 2012) thought it was a good idea for some reason. Honestly, the OEM bolts would have been less of a headache, too... But here I am almost three years later and no issues so far. The real test will be later this Summer when I start doing track days again.

fidelity101 (Forum Supporter)
fidelity101 (Forum Supporter) UltraDork
6/22/20 3:34 p.m.

Good to know! I have been eyeballing their stuff but other issues keep popping up that need more attention sooner. 

 

For the transmission Its a bolt in swap, you just need to fabricate a transmission mount which isn't terrible either, there are some meaty attachment points on the gearbox. use an integra slave cylinder and some AN adapters and you can run a hose between the stock master and slave with ease. An automatic non turbo car driveshaft will be a direct swap, it has the same output splines as the turbo FC/FD/Rx8 the NA output yoke won't work. If you want to keep your interior nice it will take some shifter re-work which could be the hard part.  The s1 lasted in my rally car about 5 years but it would grind 2nd and 4th gear a lot, nothing like gear stripping teeth power because an NA rotary is barely going to make 150 torque to the wheels. Im around 190whp currently with a stock S5 intake and a haltech with 4 port irons.  I would worry about the transmission once it fails, until then just send it! whats it gonna do, break? 

 

I torque them incrementally to 26ft lbs so when they get warm they can swell with the engine, its my theory anyways... 

bruceman
bruceman Reader
6/23/20 8:05 a.m.

I have a FB which was an IT7 car ran with the stock 12A but this year installed a 13B 6 port full BP.

I've been using the same brand throttle body injection for the past few years with a RB IDA manifold. The problems I've had with it are minor throttle sticking when coming off track causing the idle to be around 2000 rpm and the velocity stacks coming loose as they are only bonded on to the base.

I like your air box which I had considered but want to do a much larger airbox like the Rx7's racing in the Australian IPRA use. Right now I use a small Home Depot airbox attached to the hood using air from in front of the radiator that looks pretty crappy. I like that when the hood is opened the air box is up out of the way and the TB is accessible.

A heat shield over the exhaust has fixed the throttle sticking at idle. 

infernosg
infernosg New Reader
6/23/20 1:31 p.m.

In reply to bruceman :

Oh, I bet that thing screams! The only issue I've ever had with the EFI Hardware throttle bodies is the off-the-shelf return springs are too weak. With any amount of heat/run time the throttle would take a long time to close down or in some cases never would. I could upshift without any throttle input because it would hang long enough to engage the next gear. I've been able to fix this on both my setups by adding a couple external springs. This is where I think Jenvey is superior but my God are some of their throttle setups complicated looking.

I think the SAs/FBs are easier to duct. I know lots of people who duct off the radiator like you and they all have 1st Gens. The low-sloped nose and radiator of the FC doesn't help in that respect. I also have no where near the hood clearance. The top of my air box is <10 mm from the bottom of the hood. At one point I thought about trying to make a hood-mounted intake like you have. It would have involved adding a scoop to the hood and in the end I assumed it was beyond my capabilities. What kind of IATs are you seeing? I've driven the car a handful of times now and unless I'm stationary they don't seem to get more than 10 degF above ambient.

 

fidelity101 (Forum Supporter)
fidelity101 (Forum Supporter) UltraDork
6/23/20 2:12 p.m.

In reply to bruceman :

its not going to be too quiet at the dream cruise this year then either! very cool!

cafcwest
cafcwest HalfDork
6/23/20 4:25 p.m.

Great build, great read!

I am also here in the Richmond area but am a recovering rotard (fifteen years sober!) -  I believe it was nine FCs in total during my stretch.  I hope that I see you at a meet-up or at the track sometime soon as I'd love to meet/chat/see the car in person.

-Jay

 

infernosg
infernosg New Reader
6/23/20 6:52 p.m.

In reply to cafcwest :

There sure are a lot of GRM'ers in the RVA area. I guess I need to get out more. The plan is to regularly hit up Dominion, Summit Point and VIR. I might try autox but this car really isn't set up for that. Whenever stuff starts to open back up I'm usually at C&C as well Saturday mornings although I'm usually in my 1st Gen.

infernosg
infernosg New Reader
7/1/20 7:56 a.m.

In reply to stylngle2003 :

I just realized I completely missed this post. That's right in my area. Your friends have probably heard me then. I frequently drive up/down Bailey Bridge.

Not much new to report. I had been taking the car out on weekends to smooth out the tune. Switched O2 control from the front rotor to the rear rotor since it likes to run leaner. This seems to have made the car run a little better. I'm still not sure why the rear runs so much leaner at certain points. It's always been this way, even with the old intake and exhaust, although maybe not as severe as it is now. I have a -4% fuel trim on the front to balance things out but there can still be a 0.5-1:1 difference in AFRs between the two. I've also been playing more with the closed loop control. Trying to find that happy medium between being fast enough to react to changing situations and over-correcting and oscillating all the time. Lately it's been so hot I find myself not wanting to drive the car when I have the time. The first Cars & Coffee in months is this Saturday so that'll give me a reason to take it out.

fidelity101 has me thinking about S2 RX8 transmission swaps now. While I just rebuilt mine last year I opted to leave the synchronizers, which I'm thinking may have been a mistake. The issue I seem to have is getting into 3rd gear at higher RPM. It seems to be the worst above 7500 RPM or so. It's generally not an issue on the street but as you saw in my video from Dominion it is issue on track so I'm wondering if heat is a factor. I changed my transmission fluid from Redline MT90 to Ford XT-M5-QS, which the Miata guys seems to like, but I haven't been back on track since. I suppose it's possible it's all just bad shift etiquette. Because of the long shift lever combined with the short-throw shifter any side deflection may be causing me to miss the gate for 3rd. Other than that, no grinds or other abnormal noises other than those that come with a solid-mounted engine and transmission.

infernosg
infernosg New Reader
8/10/20 3:23 p.m.

Figured I'd pop in for a small update. I'm still alive and more importantly, still employed, which means I still get to play with cars. Despite current events my employer decided to send me to Indiana twice in July, each for a week at a time. Combine that with a family trip to PA makes for a quick, busy Summer. I really haven't been driving the RX7 too much. Honestly, it's just too hot. Here in Central VA we're hitting mid-90s just about every day with 60%+ humidity. Just walking outside generally turns me into a sweaty mess...

 

I managed to attend a SCCA TNiA last Thursday at Dominion Raceway. Unfortunately we only got 2/4 runs in due to weather. The good news is the car didn't break and generally performed well. As a driver I need to catch up to it. I also didn't get black flagged for noise either even though I know I'm over 100 dB at WOT from 50 ft. The bad news is it still occasionally has trouble shifting into 3rd over 8000 RPM. I still haven't quite figured out if it's a synchro/heat issue or me simply missing the gate. I was also seeing peak oil temperatures around 210F at the filter with ambient temperatures around 90F. Internet wisdom says this is fine but knowing I'm not running the car at 10/10ths I'm slightly concerned. Water temperatures generally stayed below 190F so maybe I need to adjust the split in my ducting to increase airflow to the oil cooler. Only one pic from the paddock and no video because I forgot to turn on the GoPro before both runs.

Yes, that's my Silverado with the UHaul trailer. More expensive but definitely the right decision given the weather (oppressive heat on the way up and a monsoon on the way home). For any curious locals I'll likely be back at it for the next TNiA at Dominion on Sept. 3 if you feel like saying "hi."

Mazdarian
Mazdarian None
8/20/20 1:46 a.m.

@OP Hey man! just wanted to say i'm a massive fan of ur build, you've been a huge inspiration for me for a while!

I've been keeping tabs ever since you first started posting your N/A build thread on RX7Club back in what, 2016?
The first picture you posted of that ITB'd 13B sitting in a freshly painted bay had me hooked man. You're the guy
that set the bar for my build, I've shown your stuff to so many friends when asked what my end goal was lol. It's all
coming together now, I'm just about to fire it up for the first time! Since your thread on the Club dried up a 
bit I'm glad I found this place and see you've been posting on here more recently. 

Hope you'll read this man, I'd love to get in touch laugh

- Bart

infernosg
infernosg New Reader
9/14/20 1:53 p.m.

In reply to Mazdarian :

Thanks for the kind words! Glad to hear your build is coming along. Hopefully it didn't take 6+ years like mine did. I've got build threads spread out across a half-dozen different forums. With Facebook most of the forums are dying so I only frequent a few and even then I don't post much (as evidenced by the nearly 4 weeks it's been since your post). I'm in central VA, near Richmond and now that the car is running and doing well I'm trying to get it out more. It was always intended to be a track day car so I'm starting those again. So far I've done two TNiAs at Dominion Raceway and I'm hoping to do at least one more event there or at VIR this year. The ultimate goal is to regularly hit up Dominion, VIR and Summit Point with occasional tracks to other great tracks like Watkins Glen, Road Atlanta, Daytona, Mid-Ohio and more.

Speaking of track days, the Sept. 3 iteration of TNiA was more successful. It was still ungodly hot (95F+) but at least there was no rain in sight. The car took all four runs like a champ despite somewhat worrying oil temperatures. I definitely saw 220F+ a few times, which necessitated a couple cool down laps during each run. I'm hoping this is just a duct sizing issue and not something indicative of a larger problem. I've got some plans for this off-season to improve flow to the oil cooler. Other than that everything else looked good. The tune could still stand to be improved a little and the car is just a little too loud. I'm definitely over 100 dB at WOT and I've been fortunate no one has been measuring sound at these events so far. Here's a 20 minute video of what I think was my best run. Still working on improving as a driver.

 

Lastly, a shot from nearer to the end of the night cooling down after a run. Feels good to finally be putting this car to its intended use!

wvumtnbkr
wvumtnbkr PowerDork
9/14/20 2:14 p.m.

Why does 220 oil temps worry you?  My champcar runs about 240 or so all day long.  No issues.

I just googled this.  Racing beat says 205 is bad.  Mazda competition says 220 is bad.  Huh.  

 

infernosg
infernosg New Reader
9/14/20 2:46 p.m.

In reply to wvumtnbkr :

I've been using this as a guide: http://fc3spro.com/TECH/MODS/EL/GAUGES/otemp.htm. Going off that I'm still technically okay but I'm definitely in the "beware" area. Ambient temperature was 95F+ so I'm sure that wasn't helping. The front of my car is completely ducted and it's split between the radiator and oil cooler. I'm going to increase the inlet area to the oil cooler at the expense of the radiator. Water temperatures were around 200F max so I've got some room to spare. The split ends at the oil cooler so airflow through it exits out in front of the radiator. I'm curious if this is somehow back-pressuring the oil cooler at higher speeds. I'm thinking about closing off this area all the way to the radiator. The risk there is the heated air that passed through the oil cooler now has to go through the radiator. I've thought about cutting a hole in the bottom of the duct and sending this hot air under the car but I'm not sure what that would do.

Don49 (Forum Supporter)
Don49 (Forum Supporter) Dork
9/14/20 6:08 p.m.

On my RX7 I run the oil cooler mounted horizontally and the ducting is completely separated from the radiator, flowing down under the car. I normally see oil temps no higher than 205. Water temps run 185-195. I use Redline lightweight shock proof gear oil in the trans (although I have a PBS dog box). 

In watching your shifts to 3rd gear it looks like you are controlling the shifter and moving it over when you shift from 2nd to 3rd. If the springs in the shifter aren't worn out it should center between 3rd and 4th on its own. Therefore you should only have to push it forward and it will center itself, lining up correctly to 3rd gear. I see you doing this on downshifts from 4th. I could be off, but it's worth looking at.

By the way, the car looks and sounds great. 

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