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Help me prep a GSLSE for Endurance racing (Chump, Lucky Dog, Lemons)
Hi guys. Working on prep'ing a ratty GSL-SE for endurance racing and need you guys to share some knowledge with me. Some questions:
1. The cat is clogged so going to need to either gut it or cut/weld or... are there any cheap off the shelf cat deletes?
2. Any suggestions on headers? A teammate found the cheap one below on ebay. Anyone use it?
3. It doesn't seem like it's worth removing the air pump and emissions from what I've read. Is that correct?
Lol, I watch the Lemons videos on YouTube, I'm just joking with you.
You'll gain some power by removing the air pump. It doesn't cost anything to remove stuff, you'll have to pull the air control valve and block off that port on the manifold.
I'm currently building a 1985 GS for Lemons racing. We deleted the cats and replaced with a resonator to help keep noise down. You don't want to run a straight pipe because it will exceed decibel levels for most tracks and you won't pass tech. Damn rotaries are loud! Haha!
For headers, we found a used Pacesetter for dirt cheap. Obviously the Racing Beat header is better quality but for crap can racing you'll want to keep the costs down. The cheap Pacesetter with the paint that burns off can be found new for cheap on ebay and will work fine for track use. Can't speak for the one you posted, but I imagine it will do fine.
We also stripped out all of the emissions (air pump, ACV, rats nest) as well as all of the air conditioning parts. What's the old saying, "simplify then add lightness"
make sure your radiator and oil cooler get good airflow,
ditch the clutch fan and the rear sway bar
Stock brakes are fine on these with appropriate pads. I recommend carbotech.
If you have sound regs, be careful with your exhaust, its hard to quiet these down. A new muffler at the beginning of an event will probably be melted and loud at the end.
Don't solid mount it either, use some light chain so it can expand and move around a little
If you have to go off track keep in mind how hot these get. You will set grass on fire.
For additional context, we are all experienced, licensed racers so we have those knowledge areas covered. Just need specifics about the GSL-SE as it's new to all of us.
We have the gauges, brakes, rad, oil cooler, ducting and fan covered.
We plan on using the stock muffler for now since it's in decent shape.
The cats are clogged and rattling so we need to remove them. Probably will wind up with the Pacesetter header as recommended since it's cheap and I don't see any RB headers for the GSL-SE listed in the classifieds.
We will need to figure out what to do about opening the 5,6 ports... Which I think are impacted by the air pump as well. Still trying to make sense of that area specifically right now. ^Anyone have more insights on this?
I'm thinking we should install a 180* thermostat as well. ^Thoughts on this?
First off, the GSL-SE has the larger 1308cc fuel-injected 13B Wankel rotay vs. the smaller and less powerful 1186cc 12A. That Pacesetter header will not last long on the track, so I hope you're getting it cheap! The Pacesetter design is sub-par and not tuned, and being thin walled mild steel, it fails right at the 90deg bend, and quickly, due to the high exhaust temp of the rotary. If durability is important, Racing Beat is it - tuned, high grade steel construction, and designed for the engine to produce best power.
Also, the 6-ports are operated from exhaust backpressure on this model, which is fed from a special split-air pipe coming off of he Main Catalyst. This pipe carries 4-6psi back to the actuators which open the Auxilliary Ports at ~3800rpm under load, right where you need it. Wiring them open (*or closed) results in significant power loss at either the top end (closed) or the bottom end (open). Its worth getting them working correctly, especially on a track car, unless you plan to swap engines at some point, then go for a 13B 4-port motor for simplicity.
Racing Beat parts aren't that expensive for the durability and performance you get from them,
You know, I totally agree with you on the Pacesetter quality. I normally wouldn't suggest it except I bought it for $25 and it has lasted longer than most of the parts on the rest of our Lemons car. The only thing going for it is that it is a noticeable improvement over the stock exhaust manifold in performance and it's cheap. Otherwise it's not something I would use. But on a Lemons car that sees the track twice a year and usually for less than an entire race weekend before something else breaks, it has worked ok. I would not put it on any kind of real car that has greater value than something that probably should have been sent to a scrap yard 10 years ago, but for us it's probably one of the nicer parts on our car. I suppose the YMMV warning applies here. Proceed with caution.
Another modification I see some guys with FB cars do is to run two oil coolers in series to keep the oil temps down. I plan on trying this as soon as I come across another scrap yard oil cooler.
LongDuck, Thanks. I'm concerned about that too. Searching through the threads I've read on here make it seem like it will be good enough... Are you speaking from personal experience? How quickly is the failure?
I mostly understand how the 6 ports work. I definitely want to keep them and ensure they operate correctly. Right now they don't seem to but that may be because the cats are clogged.
The Pacesetter on my 12A 80LS lasted less than a year of street DD.
I didn't run it lean or drive it very hard in that years time, and being in the desert, it didn't see any undue moisture or salt from freezing roads, so I think my life from it was pretty typical. It burned a hole right through the steel at the rear rotor exhaust port, where the tubing makes the tightest turn leaving the port. For the $100 it cost me at the time, it wasn't bad but it was also very loud, even before the hole burned through! I hope it works out better for you,
With my 12a and 3.90 rear end, I spend virtually no time below 4,000 RPM on the two tracks in my area that hold Lemons events. Mine is too nice for lemons racing, but I have thought about building one with some friends to do those events.
With your SE and it's 4.10 rear end you'll be able to keep it out of the low RPMs all together. I'm thinking you can just remove the actuators, or fix them open and have the motor always run with open ports. That way you don't risk being down on power with your cobbled together exhaust.
I wouldn't mess with the thermostat, other than replacing it with a new one. Just make sure you have the belly pan and any air that enters the nose actually goes through the radiator.
On the Thermostat - resist the racer's urge to remove it; rotary engines need a working Thermostat to close off the lower bypass port on the water pump. if you run with out a Thermostat, it will cavitate and prevent coolant from moving at all, resulting in overheating constantly.
Also, get the Mazda (or aftermarket) Thermostat that has a 'jiggle-pin'. This Thermostat has a hole drilled in the top with a tiny dumb-bell shaped pin which has a bulb on one end and smashed crimp on the other side. Its function is to allow air to exit from under the Thermostat when you fill it, and also to allow a small amount of hot coolant to pass through the Thermostat in order to better control the operating range from slightly open to full open. Without the 'jiggle-pin' type Thermostat, it's hard to burp the system on filling it.
The aux ports are intended to promote low RPM torque. On a race track, you do not need to worry about that because you will not be going that slow. So my recommendation would be to remove the sleeves and actuators from the engine.
For gearing you want to be able to use the transmission gears that have the closest gear ratios to keep the engine in its power band. So you need to run a gear that lets you use 3rd, 4th and 5th. It would be best to have the car run out of steam at the end of the fastest straight in 4th. If you are running a 23" tire (205 50 15 or 225 45 15) a 4.78 would do the trick and give you decent speed. These things are readily available on eBay for cheap.
I have had good luck with Center Force DF clutches on stock engines in SCCA racing.
If you do a thermostat use a good name brand that is for a 84/85 13B that is designed to fail in the open position. I would also recommend drilling two 1/8" holes so it leaks all the time. You could also run a 3/4" Moroso restrictor but when you do this you need to block the bypass hole that the thermostat opens/closes
Radiator - get the biggest one you can fit and make sure it is sealed to the grill opening. I run a 26 x 19 dual pass aluminum stock car radiator but a believe a 28 x 19 will fit too. I bet you could find a big GM style brass 2-3 core radiator for cheap that wouldn't attract too much attention.
Oil Cooler - run at least 1 OEM cooler with -10 braided lines. Two OEM coolers plumbed in parallel works better. Stay away from the push lock hoses, they fail in rotary applications....ask me how I know. There are after market RX7 knock off coolers on eBay that are not very expensive but I don't think they are as good as the OEM pieces. The problem is that OEM coolers are getting hard to find.
Fan - I run an electric pusher fan on my race car and use it all the time on track.
Brakes - if you are going to run GSL/SE brakes you need to run NEW front rotors and keep an eye on them. GSL/SE front rotors will fail in racing applications. They crack around the lug studs. So get NEW ones from a brand you recognize and change them often.
Definitely not removing the thermostat. I know it's needed on a rotary w/o the corresponding 'fix'. Mazdatrix and Pettit sell a 180* thermostat that should help maintain a lower operating temp - along with the radiator and ducting. We'll also be doing some hood venting.
We may get an underdrive pulley for the water pump.
Gearing changes won't happen right now.
Thanks for the input on the oil coolers and brakes. Adding brake ducting to the list of to-dos.
For about the same price as the Pacesetter, you can get SS headers on ebay. One of my buddies has been using one of those in LDRL/Champ/Lemons on his 13B first gen for several years with no issues. My enduro/ITA car has a 12A and I have been using the racing beat header, because it plugs into the rest of the exhaust system and it fails every couple of years. Through some business contacts, I got a free ceramic coating on the last replacement and am interested to see how it works out in the long term.
As noted above, make sure the radiator is up-to-snuff and have the OEM oil cooler. Also the undertray in place and air flow around the radiator as sealed as possible. With that you should not have overheating problems. We have not had any, including running at Willow Springs in June and Texas in July. Underdrive pulley for water pump ensures no cavitation, although I am not positive it is needed (I have one anyway). Running without thermostat on a cool day can result in not reaching engine temp. I had a Feb day at Buttonwillow where I could not get water temp over 125 degF without putting cardboard over the radiator. Ran at Willow Springs this May (95 degF) with thermostat installed and never got over 200 degF (although it was clear that the thermostat was fully open and not going to help control the temp any more).
Agree with advice on the aux ports. Remove them. As I remember there is something else that needs to be installed when they are removed, but I can't remember what it was (since it was my buddie's car).
Have you had your Spec Miata out on track lately? I am heading up to Laguna for Labor Day weekend race if you are going to be there.
@Carl , got a link to the SS headers? Does SS mean stainless steel like I think it does?
I actually have an RB header for a 12a but that is another stalled project...
As a data point, I did ceramic coating on my FD's downpipe 7 years ago / 40k miles ago and it's holding up well. Jet Hot I think it was
Interesting advice on the aux ports... If I can get them working with minimal effort we'll run them as is and take it from there.
I'm surprised you never got over 200* F in 95* temps! My Miata with a 180* thermostat will run around 200* at that ambient temp in race conditions. I expected the rotary to run hotter.
Yeah, I expect to be at the Laguna race in the SM. Hope to see you there! What car will you be racing? Mine is #05 white with red and blue stripes.
The SS seems to be much more durable than carbon steel, even the thick RB header. The attached pic shows my RB header after 3-4 years of racing. That is the 2nd time it has happened. The SS header shows no signs of oxidation after a similar length of time.
If any of you who are converting a GSL SE to a race Car are relocating the Battery I would LOVE to buy your original factory battery hold down parts !
I have a one owner original GSL SE that is missing those parts and I want to keep the car original.
Please Call me at 510-825-2737 if you have those parts and want to sell them!
Darrell 510-825-2737
The header was unwrapped. It was on an enduro car that is basically running nearly WOT for 7-8 hours at a time, two times per weekend. The first failure occurred with a combination of sprint racing and enduros. I don't know what the exhaust gas temp is, but the A/F ratio is rich, in the range of 12.5-13 so should not be crazy hot. I had a temp gauge on for a while and if I remember right, the temperature was in the high 1500 degF, which is pretty normal when racing an RX7. RB was surprised when I pointed out the failures to them.
I killed a RB header on my ITA Rx7. Not as bad as Carl but the steel started to crystalize on the top side of the bends. Took a few years to make it fail but it did. I have been using an ISC Stainless header ever since.
08-02-19, 04:51 PM
Help me prep a GSLSE for Endurance racing (Chump, Lucky Dog, Lemons)
