Weekend Racing a Rotary - LDRL 2022
Thursday Evening
After all the trials and tribulations of preparing the RX-7 we are finally here at the race track. So relieving to be here with it and the BMW, relaxing & setting up our paddock space for the weekend. If you want to see more about the paddock spot take a look at the E30’s post (it was less broken so I needed some filler material).
As with every race weekend, you must unpack the car and organize the spares. With the last minute engine pull, complete new set of gaskets and fluids I was concerned about the idle and warm up. At home it didn’t seem to like cold starting, but here in its home she just sprung to life and sat there idling ready for racing while we unpacked.
Tech Inspection Time (Friday Evening)
We always must be safe and ensure all the gear is prepared correctly by submitting to a higher power. The all powerful tech inspector. Because I was running two cars, this consisted of letting Kai drive the car while I watched temps and engine health of both cars via ASL. That and running between our paddock spot and the cars because of forgetfulness.
Speaking of forgetfulness… Thank you Greg for breaking into my house and stealing the tablet mount for our dash in the car which I forgot in the chaos of final packing.
It’s okay, its a good day. I’m surrounded by race cars and we got to chat with the best organizer ever! Cathy McCause Fuss
After the success of not failing tech we went into town for Casa Ramos and their awesome margaritas (again see E30 post for all the fun).
The rest of the evening consisted of basic checks on the cars and then a bit of relaxing while watching Abu Dhabi F1 practice in the new canopy. Projector + canopy + propane heater definitely provides a different feeling at the race track…
Calm before the storm of racing two cars that are both older than me.
Race Day (Saturday)
Kai is slated first for the fun. It started uneventful after the pre-race red flag. From that point forward the Brapmobile continued to have RX-7 problems aka gasoline and rotary’s don’t have the same priorities. But hey, look at these optimistic faces that didn’t know the entire day would be spent smelling like fuel!
Starting with his radio message about lean AFR and low fuel pressure we called him in to diagnose. Fuel starvation was an issue that should have been solved by the new Holley HydraMat fuel pickup. Apparently it wasn’t solved and we had no idea why. The fuel pump, filter and lines only had 1,000 miles on them both since my initial rebuild. Enter the recurring photo of the day for RX-7…At least Felix RotorHead was always happy to see us.
I don’t even know where to start with this car and fueling problems. My last race we were able to make it about 45 minutes from a full tank before getting starvation issues, but the car was already running lean with all its vacuum leaks. This race it was almost immediately, leading us to believe it might be a fuel pick-up or flow issue (<-correct). Starting with some general assumptions, like a fuel pump either works or it doesn’t and a brand new part from Holley isn’t going to fail, we proceeded to diagnose incorrectly all day long.
Solution 1
First thought was a clogged fuel filter, not entirely out of the question considering the car sits for months at a time. Our ‘solution’ was to bypass it with fuel hose. Zaid was sent out to find some 3/8” fuel hose since I was unprepared for this issue. Success. Post attempted fix we saw fuel pressures rise a couple psi, hopeful. At this point I don’t remember who we sent out, I believe it was Zaid to drive the car for a bit and very quickly realize we didn’t solve anything.
Solution 2
When he returned we noticed a significant fuel leak from the tank somewhere. So much for POR-015 (or my application of it). A bit of flashlight work and we might have found the culprit to be some old hoses and less than tight clamps. But it still doesn’t solve the startvation issue. At this point we are like maybe its the alignment of Pluto. Everyone tossing out ideas and ‘solutions’. Meanwhile the car idles happily in the pits so the fuel system works. Just not on track. Great for diagnosing.
Solution… just put me in the car, that might fix something???
Solution 3
After a lap on track I started troubleshooting. First of all it seemed to be related to corning or acceleration, no issues under braking. Cool that doesn’t help much, but still something. I couldn’t pin it down any further because the AFR was spiking to 17:1 at wide open and fuel psi falling to 25 psi, very dangerous for the engine’s health. Tried a few other things and nothing helped me out. But clearly there was a fuel pressure issue that needed to be resolved.
Not really a solution, but it clearly wasn’t an empty tank or bad fuel pick-up.
Everyone staring for the solution. We tried squeezing off the return fuel line to see if the regulator was doing its job. It wasn’t, but it also kinda was. It couldn’t hold 40 psi at idle, but would float around 36-40 psi. Leading to our next ‘idea’.
Search of the Evening
We decided it was clearly a fuel pressure regulation issue, I mean I did weld closed the fuel rail fuel regulator because it was leaking. Yeah I know I am a genius, but it was mostly fine last race. Perhaps it wasn’t fine last race and we didn’t know any better? So our search began for any aftermarket fuel pressure regulator. No local parts store within 50 miles had anything except a 5-8 psi carburetor regulator. We sent out Mark, the master of parts finding, and he came up empty. Zaid wandered around with no luck. Kai and Amanda drove around the local area looking in person with no success. Eventually we check our home local Concord hot rod shop and they actually had the part, but that was a full 2 hours each way. An option, but not great. So we started searching the paddock for broken competitors with anything that might work.
After an hour of pit walking we eventually found team GMW and their turbo charged car with an oil starved turbo. They asked if we had a turbo to which we clearly said “we wish”. They were on their way to leaving and graciously tore off their Aeromotive regulator for us to use. So many thanks to them!!!!
We were in business, we thought. We proceeded to make the AN fittings from their regulator adapt to our 5/15'“ fuel lines. Searching from Mark found a few AN-8 to 3/8” barb fittings, then a bunch of miles in town Zaid and Kai found lots of sketchy 3/8” to 5/16” hose barb adapters and clamps. The rest of the evening was spent making a masterpiece of hopefully not fire.
Day 2
Since there was all the hose clamps from this zip code and burning the car to the ground would be a bit harsh to put onto anyone else I opted to take the car out the first stint. It started out all great….
Then I noticed it was having problems while exiting corners or mid corner. So perhaps a fuel slosh issue even though it is very unlikely.
At that point I tried lifting off throttle mid corner in T8. Magically AFR’s came back to 12-13:1 and it stopped stumbling. Tried it again in a few other hard long corners and confirmed it was a WOT issue. Nothing to do with corners or fuel pick-up.
The fuel pump clearly wasn’t doing its job and was running out of flow. At this point we let the car cool down before pulling fuel lines again, I started working on putting in the new pump we bought yesterday (yes we should have installed yesterday).
I’m a bit tired of working on the fuel system and need to get out some frustrations. There is an open spot in the E30 so I jump into it and have some fun. Greg V buttons up the fuel system and takes the RX-7 out on track.
We had finally fixed it, Greg and Zaid got to enjoy long stints in the car. I also was able to follow the car on track while I was in the E30. Overall it was a good weekend.
One great piece of news was for Zaid’s final stint. We kept him out for over an hour and half, running very long even though he started with less than 3/4 tank. The Holly Hydramat really did it’s job, he coasted into our paddock stall just 4 laps from the end of the race. The tank ended up with just 1/2 gallon remaining. Meaning we are ready for the next race to run as long as we want.
