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dannyp84
dannyp84 HalfDork
10/17/23 12:37 p.m.

A few years ago, I talked my way onto a local Champcar team, and since then the road racing bug has bitten hard. A couple months ago, I got my SCCA comp license, and about a month after that, I brought home this old SCCA ITS/EP RX-7, which I found for sale in New Jersey about 6 hrs from where I live in WV. The car had a decent logbook, lots of good parts including ceramic apex seals, and the owner sounded like a decent guy who was getting out because of health issues. It was more than I wanted to spend at the time, but the price for the car and all the extra parts it came with was something I felt I needed to jump on, so I hooked up the trailer and dragged the car home. A few weeks ago, I took it to a track day at Mid Ohio for a shakedown, and aside from having to replace a short fuel line, and eventually running out of fuel on the cool down lap of my last session, the car seems to run well and the chassis feels tight. I'd never been on racing slicks, so the Hoosiers were a new experience, and I need to learn to trust them to go properly fast. I was also very conservative in my braking zones, but being that it was the first time out in an unfamiliar car, I'm ok with that. I was loving the car's behavior in corners, it seems like whomever set up the corner balance and alignment knew their stuff.

Plans for the car over the winter are to replace the expired harness and window net, let my friend and rotary guru Logan from Defined Autoworks play around with the exhaust and the Haltech tuning (including adding another muffler), and maybe figure out some new livery. I'm hoping to enter my first SCCA race in either ITS or EP (currently the car would need more ballast to qualify for ITS) next spring. I'll have plenty of questions, including how the new harness needs to be secured, where to find 1 lap tires etc. Photos and in car video:

https://youtu.be/lKfNqQjaoXE?si=2j8VQoO_ASlpaSYr

jgrewe
jgrewe Dork
10/17/23 11:15 p.m.

Love it! There is a lot of weight on the car that doesn't need to be there for EP. You can lose the headlights and all their mechanical stuff.

I make a fiberglass hatch that weighs 13lbs and a hood that fills the headlight doors, let me know if you think about heading down that path.

myusdmcavalier
myusdmcavalier New Reader
10/18/23 9:14 a.m.

Finally an rx7 that isn't ls,or k swapped. Looks like a fun project.

dannyp84
dannyp84 HalfDork
10/18/23 9:44 a.m.

In reply to myusdmcavalier :

I'm happy to carry the rotary torch, I have 3 RX-7s and they all have the 13b.

dannyp84
dannyp84 HalfDork
10/24/23 10:41 a.m.
jgrewe said:

Love it! There is a lot of weight on the car that doesn't need to be there for EP. You can lose the headlights and all their mechanical stuff.

I make a fiberglass hatch that weighs 13lbs and a hood that fills the headlight doors, let me know if you think about heading down that path.

I think whether I run EP or ITS just depends on how many drivers show up for each class, I noticed that at Mid Ohio's last SCCA weekend, ITS wasn't listed. The car is  currently underweight for ITS, as I'm a bit smaller than the previous owner, but if I remove the balllast from the passenger floor it might be just over the EP weight minumum.

TVR Scott
TVR Scott GRM+ Memberand SuperDork
10/24/23 11:12 a.m.

Very cool! 

Back when I was fresh out of school I always drooled over the ITS RX-7's.  I had a street one that was my daily for a few years, and I just loved it.

 

jgrewe
jgrewe Dork
10/24/23 3:25 p.m.

Do yourself a quick favor and look at the bottom bushings in the rear shocks. Years ago there was a well respected race prep shop that was selling Bilsteins with delrin bushings installed in them. There was a few instances of the ring that holds the bushing breaking off.

There needs to be a few degrees of motion allowed because of camber gain.

TVR Scott
TVR Scott GRM+ Memberand SuperDork
10/24/23 4:14 p.m.

What's the parts availability nowadays on for the FC? 

wvumtnbkr
wvumtnbkr GRM+ Memberand PowerDork
10/24/23 7:53 p.m.
TVR Scott said:

What's the parts availability nowadays on for the FC? 

4 piston calipers are NLA.  The front hub bearing caps are worth money and NLA.

Regular performance shocks are unavailable. 

Anything to do with drifting is easy to find.

Interior parts are starting to be able to be found again due to additive manufacturing.

Engine parts are becoming harder to find.

WondrousBread
WondrousBread Reader
10/24/23 9:32 p.m.
wvumtnbkr said:

Regular performance shocks are unavailable.

AGXs are still available, but Illuminas are out of production. Even some of the common springs (Tanabe) are no longer available.

Interestingly, Rockauto now lists some Bilsteins for the FC. The rears look like a direct fit, but the fronts don't include the bracket for the knuckle and I'm not convinced they're the right part. They look more like they're designed for an FB knuckle

I'm told the price for new engines from Mazda just increased to $14k USD...

wvumtnbkr
wvumtnbkr GRM+ Memberand PowerDork
10/24/23 10:00 p.m.
WondrousBread said:
wvumtnbkr said:

Regular performance shocks are unavailable.

AGXs are still available, but Illuminas are out of production. Even some of the common springs (Tanabe) are no longer available.

Interestingly, Rockauto now lists some Bilsteins for the FC. The rears look like a direct fit, but the fronts don't include the bracket for the knuckle and I'm not convinced they're the right part. They look more like they're designed for an FB knuckle

I'm told the price for new engines from Mazda just increased to $14k USD...

Bilstein never made direct replacements.  They are inserts.  You need to cur the tip off your stock strut body and drill a hole in the bottom then these bolt in.

The bilsteins are usually special order.  The ones I just got took 11 months to show up from tire rack.  They were direct shipped from bilstein.

infernosg
infernosg Reader
10/26/23 4:00 p.m.

The front 4 piston calipers aren't too hard to find. Especially considering they're nearly identical to the later FD front calipers and are a direct swap. The rear calipers are pretty much unobtainium now. I've got a spare set that I rebuild and swap in when the current set needs rebuilding. As far as suspension goes a lot of the old-style performance shocks/struts and springs are NLA. There are plenty of BC/Fortune Auto/etc. style coilover systems out there with a good amount of customization options. I think Ground Control still offers a kit, which can allow the use of aftermarket Koni inserts and Eibach springs.

The car looks pretty good. If you ever come eastward maybe we'll run into eachother at Summit Point. I've always wanted to poke around and study the cooling system of an ITS/EP car.

dannyp84
dannyp84 HalfDork
10/26/23 4:03 p.m.

In reply to infernosg :

I'd like to drive Summit Point and VIR eventually, the radiator on this car seems massive but I noticed my coolant temps got up to around 212 or so during the track day, it might need to be improved somehow. Oil however never got past 160, so the oil cooler is doing its job well. 

TVR Scott
TVR Scott GRM+ Memberand SuperDork
10/26/23 4:04 p.m.

I looked at Ground Control, and they do list a coilover kit with Koni shocks.  Street-performance grade.

infernosg
infernosg Reader
10/26/23 5:25 p.m.

In reply to dannyp84 :

I'm in VA so I hit up Summit Point and VIR at least once a year for HPDE. Not sure if I'll ever work my way into wheel-to-wheel. The car would need so much done to it...

Going off the pictures the radiator seems nice and thick but it looks like a down-flow type. A cross flow (will require custom radiator hoses) would be better. Another option is a double-pass like the Koyo n-Flo, which is what I have. Oil at 160F is low. I'm guessing this car runs an aftermarket or double stock coolers. Mine is the opposite. Coolant is usually 200-210F but oil can reach 240F with the stock cooler. I have one more event this year then I plan on tweaking the setup over Winter. The plan is to do what I can with the stock components for 2024 then look to bigger/better aftermarket stuff if that's not sufficient for 2025+.

dannyp84
dannyp84 HalfDork
10/26/23 8:48 p.m.

In reply to infernosg :

It has a fairly large oil cooler but it's still not a whole lot bigger than a stock fc cooler, I'm not sure where it's from. Based on your dyno numbers I'd say your car would be a good bit faster than this one in a straight line at least, though mine has the 5:12 ratio diff.

I think the Haltech needs some tuning and the exhaust can definitely be improved. The intake also still has that trap door thing behind the filter, I wonder how restrictive it might be..

Where is your last event for the year?

infernosg
infernosg Reader
10/27/23 12:49 p.m.

In reply to dannyp84 :

The stock oil cooler isn't as great as a lot of people claim it to be. It just has a lot of volume. Otherwise, it's a standard double pass type with 7 rows. I haven't been able to determine how many tubes it's made of. I'm going to mess with its position this Winter to see if I can't make it more efficient. If not, I'll just go with one of the biggest Setrab Series 1 coolers I can find. Cooling would be about the same based on area/volume but the Setrab would have a much lower pressure drop.

That 5.12 rear end is probably worth as much as the entire car at this point. Too short for me. I have the 4.30 but I think something like a 4:44 would be better for the tracks I drive to stay out of 5th gear. Who knows, maybe as I get better/faster the 4.30 will be fine.

My exhaust needs to change as well. The loudness has been fun but I'm realizing it's drowning out everything else and I'm forced to rely on "feel" a lot more than I'd like. Maybe I'll swap the Burn's muffler for a Racing Beat one this Winter.

My last event is at Summit Point Main with NASA Mid-Atlantic for their "Fall Finale." It's usually pretty laid back since it's only TT and HPDE. Just hoping for decent weather.

dannyp84
dannyp84 HalfDork
10/27/23 1:45 p.m.

In reply to infernosg :

I was getting to about 118 mph in 5th gear at Mid Ohio with the 5.12 rear, but I probably had another 1200 rpm to use if I wanted it. Since it was my first time out in the car, I wanted to be somewhat gentle and just make sure everything worked. This car has a dyno sheet that claims 190 hp, which really makes me wonder how much power the Civic we race in Champcar makes. I went 4 seconds faster around Mid O in the Civic on street tires, compared to the FC on Hoosiers, with a top speed on that track of around 123-126 mph. It's not an apples to apples comparison, especially because I was being so conservative in braking zones with the FC, but the Civic certainly pulls a lot harder on the straights despite lower corner speeds than the FC. 

My favorite exhaust setup so far on my FB when it was stock port 12a was to have a universal borla about midway back (underneath the passenger seat roughly) and another one at the tail pipe, the car had a nice sound that way without being too loud. Unfortunately, with how low the FB is that first muffler became a wear item, so I currently only have the tail muffler which is insufficient. This year's off season will give me time to add a second muffler to both the FB and the ITS FC. In my opinion, too many racers equate loudness with power. You can make good power without damaging your eardrums if the exhaust is well-designed.

NASA TT is the class where Logan runs his 4 rotor car, it looks like fun, though in his class he gets very few clean laps in a session before encountering lap traffic, so it's not very cost effective for seat time. I only raced once with Champcar this year, and did one track day in the FC, so I really want to catch up on track time in the spring..

infernosg
infernosg Reader
10/27/23 5:03 p.m.

In reply to dannyp84 :

It's been so long since I've been to Mid-Ohio and back then I was in a mostly stock FC. I don't know what kind of speeds I'd expect there anymore. I'm hitting 130 in 4th at VIR and Summit Point and I have about 1000 RPM to spare. I know there's more speed to be had as well. 190 hp sounds about right for a ITS/EP car. Not knowing any details about the Civic, it's certainly possible it's faster. If it's a K series engine it easily makes more torque then the 13B in ITS/EP configuration (probably like 120 ft-lb).

My previous exhaust setup combined Racing Beat's presilencer and muffler. It was silly quiet for a rotary. I currently run two Burn's Stainless single stage race mufflers and it's stupid loud. I'd like it somewhere in between. Maybe a single Racing Beat muffler would be enough or swapping one of the Burn's single stages for a double.

I'm enjoying HPDE for the meantime. I'm pretty firmly in the HPDE2/3/intermediate/advanced group depending on which organization I'm with. Maybe next year I'll venture far enough out west to run Mid-Ohio again. I can only run 5-6  events a year, which leaves 1 or 2 spaces for something outside my usual VIR, Summit Point or Dominion track days. This year it was Pitt Race.

Pete. (l33t FS)
Pete. (l33t FS) GRM+ Memberand MegaDork
10/28/23 1:31 p.m.

My '81 only has a Racing Beat rear muffler and it is just about perfect.  It is quieter than the old Street Port exhaust system but not by much.  

It only has a stock 12A to quiet down, though, and I have yet to test backpressure.  The SP exhaust system has 1psi backpressure at 9000rpm on any 13B that I have tried.  It is more or less two 2" pipes through to a 2 1/4" collector that splits to 2" again inside the rear muffler, no baffles anywhere in the system.

jgrewe
jgrewe Dork
10/28/23 2:02 p.m.

I see the pulley on the alternator is larger, is the water pump pulley bigger than stock too? I'm assuming the e shaft pulley is smaller, that is one of the first things you do.

Be sure you are spinning the water pump as slow as you can with the alternative pulleys available. I remember watching dyno numbers drop when the pump would cavitate around 6200 rpm with stock pulleys.

We ran a dual cross flow radiator on a few cars. I forget what we started with but it was a universal radiator that we modified.

Make sure your intake hose on the water pump can't collapse.

Pete. (l33t FS)
Pete. (l33t FS) GRM+ Memberand MegaDork
10/28/23 2:31 p.m.

In reply to jgrewe :

I have the Racing Beat water pump chart somewhere.  The FC pump was a little better than the SA/FB pump but not by much.  6200 sounds right for the SA/FB pump.  The 3" crank pulley solved all of my overheating problems.

A big thing also is using a water pump with a cast impeller, and smoothing them out some.  Porting is good for more than just intake ports smiley.  The parts store grade pumps with the sheetmetal impellers are real coolant beaters.

Pete. (l33t FS)
Pete. (l33t FS) GRM+ Memberand MegaDork
10/28/23 3:36 p.m.

 

This and more is in the 2016 RB catalog.  There is a lot of good tech tips in it that did not make it into their website.

jgrewe
jgrewe Dork
10/28/23 11:19 p.m.

In reply to Pete. (l33t FS) :

Dang, my brain still retains old data! I dug that out from about 1992

wvumtnbkr
wvumtnbkr GRM+ Memberand PowerDork
10/30/23 10:02 a.m.

How is the ducting to the radiator? 

My car would run hot on track without the undertray keeping the air directed through the rad instead of allowing it to go under the car 

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