So far the car has been running on V8R's '93 octane' tune. Since we only have 91 at the pump here in CA I have been mixing Torco octane booster to bring it up to ~95, or using 100 from the pump at the track. I've been looking forward to changing over to E85 for all the benefits that fuel provides; far better knock resistance, the car runs cooler, and it should make more power.
As cool as E85 is, the really cool thing is that instead of having to change injectors, do a permanent change over to E85 and a ground-up tune for that fuel, GM already did the hard work for us. Even though the Camaro never sold with a flex fuel feature, some of the other cars that the LFX came in did, and so the engine was designed from the beginning to run E85 and there is a full ethanol tune just laying dormant in the Camaro's ECU waiting to be turned on. That means smooth driveability and reliability pf a factory tune, AND with flex fuel the ECU is always monitoring the ethanol content of the fuel and adjusting the tune accordingly, so in a pinch if you can't find E85 you can pour regular fuel right in and the car with sort things out on its own.
To enable flex fuel, there is one missing puzzle piece; we need to add a flex fuel sensor in-line with the main fuel supply line. I took this opportunity to replace my stainless fuel line with a pair of fancier - and lighter weight - kevlar braided lines with crimped hose ends. These lines saved a half pound over the stainless line:
The flex fuel sensor is an OEM part number 13577394. You also need a wiring pigtail which can be found all over eBay.
Wire colors on the eBay pigtails may vary, so here are the factory colors at the sensor connector:
pin 1 (Pink/Black): +12v power pin 2 (Black): Ground to chassis pin 3 (White): Signal to ECU
1 and 2 are very straightforward. Remember to fuse the power wire. The signal wire is straightforward but takes a bit of time. This goes directly to the ECU at pin 38 of the X1 connector. Because the Camaro didn't had a flex sensor, that pin is vacant in the Camaro's wiring harness. So, you need a factory pin with a wire tail to add to the connector. If you modified your own engine harness and eliminated some wires, you may have a spare to use here, but I didn't. My overkill approach to this was to buy a second full engine wiring harness from a junk yard and from that I pulled one donor pin and wire from that harness' ECU connector to use on mine. Now I have a spare but incomplete harness I can scavenge anything from if I need it. If anyone else is doing this same thing and needs an ECU pin/wire to add flex fuel, just shoot me an email and I can pull one from my donor harness for you.
With sensor installed, all that's left is to turn on the flex fuel sensor in the ECU. This is done in HPTuners or similar tuning software. Since the software side isn't my area of expertise, I took the car to Church Automotive Testing in Los Angeles. They're familiar with tuning these high feature GM motors, and using their dyno would enable us to monitor everything to make sure it was working right before I get out to the race track.
For the dyno tuning, I added a pair of AEM UEGO wideband sensors - one for each bank of the exhaust. This allows us to precisely monitor the air/fuel ratio and make sure everything is running correctly.
As the final step of preparation, I drained the tank and then re-filled it with just 1 gallon of 100 octane; just enough to do a baseline run on before switching to E85. At the dyno, we began with the baseline run on the existing fuel and then poured 5 gallons of E85 in. Then the tuner switched on the flex fuel sensor in the software and ran the engine at low rpm waiting for the new fuel to work its way down the line until we began to see the ethanol content rising on the sensor's signal. Once there was a good 75% ethanol at the sensor he did a few more pulls which showed an immediate jump in power. He made a couple minor adjustments to fuel and timing which pulled a couple more hp out of it and improved the low-end torque. More timing beyond that didn't make any more power so we backed it down to the previous timing values and called it great. The good news there is that the E85 tune from GM was already 98% there to max power, we only made tiny refinements. If I was doing it again I'd be confident in just switching on the flex fuel sensor and pouring E85 in the tank. After verifying that the sensor is operating correctly and reading the ethanol, it's good to go drive - no need for dyno tuning or air/fuel ratio monitoring.
So what did we gain? From baseline to final run on E85, +18 whp and +20 ft-lbs at the wheels. And E85 costs ~$2.20 per gallon compared to $9/gal for 100. Works for me.
This past weekend we went out to Streets of Willow Raceway to support our sponsored Roadster Cup series. I took the HyperMiata for demo laps and to get some test/tune time in, but hanging in the background was another carrot; the Miata lap record for the track might be within reach.
Conditions weren’t perfect, with 30+ mph winds getting worse through the day but I managed a 1:19.488, which just happens to be an EXACT match to the standing record. A return to Streets may be in our near future, there is some unfinished business here.
The extra power from the recent flex fuel conversion felt great ripping up the back straight. The winter changes to suspension need dialing in but are already showing a lot of promise. Transmission shifts much better thanks to the shifter fix, but clutch is improved but still not quite right. Still, shifts are quicker than before. Overall a very successful test/tune day.
The sound and fun of this car is not getting old at all. In the moment I'm focused on the driving and feeling what the car is doing and how to improve it, etc. but then there are times after a session I replay things in my head and just can't get enough of much the car rips.
Carguy123 wrote:A quick question on your oil pan. After the modifications did your oil pan still hang down below the bell housing?
Have you or anyone found a ready made road race oil pan? Everyone laughs at me when I call around and ask for one for this engine.
I'm using the V8Roadsters oil pan. It's a shortened factory pan and the bottom sits 9/16" below the lowest point of the bellhousing. Working great, haven't had any issues with oil pressure under pretty high G's on the track.
We left off with heading out for the first test day of the year at Streets of Willow CCW. This was a Roadster Cup event so the plan was to have equal parts fun hanging out with friends in that series and doing demo laps in their run group and also to work on initial setup and testing of the changes made during the winter.
On the testing side, I did one shake-down session Saturday afternoon. The car felt stronger than ever on the E85. However, it was showing some issues in the chassis and handling; brakes were touchy and quick to lock up, the car wouldn't rotate the way I wanted, and it was skipping over bumps (particularly problematic on such a bumpy track). This resulted in quickly flat spotting the set of tires I was on, and here is where my first BIG "thank you" comes along because Saturday night I left the racetrack and drove to Northridge where Moti met me and generously loaned me the wheels and tires right off Creampuff so I could have something to run the car on on Sunday.
Sunday was more of the same struggles. I had to drive very patiently, give myself extra braking distance, reduce corner entry speed until the car would be willing to turn, etc. Tip-toeing around these issues resulted in a best time of 1:19.488, an exact match to the thousandth with the standard Miata lap record.
I left the event feeling like I have some unfinished business with this track. I didn't even post an update here because I put the car on the rack and immediately started crawling around on it to figure out what was wrong. My second big "thank you" goes to 949Racing/Supermiata who provided a ton of input to help pinpoint the issues and then work through them.
We uncovered several surprises. The largest one was that the new V8R tubular front lower control arms interfered significantly with the downpipes during suspension compression. Easy to see why the car was skipping over bumps and the shocks couldn't do their job - the suspension was going effectively solid. Not the fault of the arms, obviously I'm the one who put downpipes in the wheel wells, and I had factory arms when I made them. One item or the other had to be altered, and for several reasons I decided it was the arms that had to be reworked. The arms were cut, reshaped, reinforced with extra gusseting, and then capped. With the revisions, the suspension could finally do its thing:
Along with the major interference of the front lower arms, once that item was sorted I launched into a week of examining the suspension and wheel/tire travel. Even though my previous shocks had the same total stroke as these, the XIDAs use more of that stoke for bump travel. As a result, I found several other areas that had more minor interference issues at close to full compression, and we dealt with each item as I found it until suspension range of motion was maximized.
Finally, I've been chasing a pad knockback issue caused by significant flexing in the front uprights. Stoptech has been superb in their ongoing support, and to establish whether a floating rotor can solve this issue I've switched to Stoptech's 11" floating rotors in front.
With things sorted out much better at this point, I went to West End to get re-aligned and properly corner balanced. They got the cross weights exact to the pound.
The Streets of Willow test was invaluable in that it uncovered some big issues to address, but because the suspension wasn’t working right there was zero progress on learning and setting up the new pieces in the system. The second test at Chuckwalla Valley Raceway would be the first opportunity for this.
This turned out to be an excellent two days out in the desert. I had a chance to begin tweaking shock settings, the brakes were rock solid with the knockback gone, and I got a ton of laps in. Very refreshing after the last test to have the car feeling right now.
My best from December at this track was a 1:51.4. Returning this time on test tires I wasn’t expecting to be much faster, just focus on setup. However, to my pleasant surprise I set a new best of 1:49.777. I was really stoked to see a sub-1:50 on the AIM at the time, but it was only later when I started looking around at other lap times that I realized there was more significance to it. This is a new track record for a modified production car!
With the car running well at Chuckwalla, I've entered GTA's ProAm Round 1 at Buttonwillow coming up this Saturday. Made a couple little tweaks and repairs on the car this past weekend and tires are on the way. Limited class overall looks like a fun group, time to party:
Fantastic build thread!!! Update on the clutch situation? I’m starting my lfx swap for my autocross car and am trying to decide what to do for a clutch setup. Shandelle actually suggested I use the stock flywheel and clutch setup. I’d certainly like to eliminate the rotation mass, but this journey is one of getting back to actually having fun racing, instead of constantly chasing problems.
guttedmiata wrote:Fantastic build thread!!! Update on the clutch situation? I’m starting my lfx swap for my autocross car and am trying to decide what to do for a clutch setup. Shandelle actually suggested I use the stock flywheel and clutch setup. I’d certainly like to eliminate the rotation mass, but this journey is one of getting back to actually having fun racing, instead of constantly chasing problems.
I'm still fighting the clutch issues. I just ordered a factory clutch/flywheel after a missed down-shift cost me a good lap last weekend. I've been very resistant to adding the 20 lbs back in with the factory parts but have finally decided that the benefits of having a clutch that just works right is far more valuable than those 20 lbs for now.
Late update, it's the busy season here at GWR so as soon as I got back from Buttonwillow I dove back in to work straight away.
The day went exactly how you want every race to go: used my setup notes from previous times here to best-guess the morning setup and that got it 90% there right out of the gate. Minor adjustments in a few areas after first session and the car was strong. Increased the gap from the rest of the field through the day and finished 5 seconds up from 2nd place. New PB of 1:47.5 (1 sec improvement on my time from SLB).
Not only 1st place in class, also fastest overall in Limited across drivetrain categories. Really can't ask for more than that! Here are some tasty pics and vid from the weekend!