I work with a few teams running similar V6 platforms (Nissan VQ30DE & Toyota 3mz/1mz). We had several cars on the ETX20L battery and moved to the Battery Tender BTL35A480C. We gained a little power while dropping from 15.5lbs to 3.75lbs.

We recommend the LiFePO4 chemistry heavily over standard lithium ion to avoid the lithium ion fires & thermal runaway scenarios. You should also get a good charger for the LiFePO4 such as a Battery Tender 022-0209-DL-WH . The instructions for the battery ask that you not dump more than 10amps at a time into it and that you don't use desulfating chargers.

 

You run that charger between the battery and alternator?

 

No. Battery Tender 022-0209-DL-WH is a wall charger. The alternator charges the battery normally in car.

 

Thats what infigured, so unless I mess up the battery and kill it, just run the battery in the car off the alternator just like stock. Gotcha. Thx

 

Yes. You want to give it a good initial charge. The manual also recommends not fully discharging the battery as it shortens the battery life as an FYI.

 

I'm using the Battery Tender BTL18A300CL. LiFePO4, 2.2lbs, 300CCA. I'd go slightly larger for a street car. The important bit is to make sure you have nearly zero draw on the battery when the car is off so it doesn't drain when sitting. Easy to accomplish in a race car with a battery kill switch, less so for a street car with other items that need to retain memory, etc. so YMMV.

 

I run that battery in my street car. If its below 40 out overnight, forget about starting it. Good for a summer car or one that is garaged.

 

Yes the BTL35A480C that vtjballeng recommended is probably a much better choice for a street car.

 

Wow suddenly a month's gone by!

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.



Hard to be unhappy with matching the Miata record, but I left the event feeling like I have some unfinished business with this track knowing the car wasn't right. 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!

 

Did stoptech provide you a new caliper bracket to match the new smaller rotor diameter?

Also, do you have an issue with the upper billet arm contacting the frame rail during full compression in the front??

 

Yes

I did. I don't any more. Grinder fixed that one.

 

 

What an accomplishment! Congrats!

 

So, if I am following right, every time this car has been out it has either won an event, matched a record, or set a new record? That is amazing for a new build, can't wait to see what you do with it all dialed in.

 

Now that you mention it, with the exception of doing demo laps and ride-alongs at Laguna Seca, yes every event from the first shakedown to now has been a win or record. Doing something right.

 

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:

 

Good luck! Can't wait to see some videos from the event!

 

Thank you for posting all of this. Been binge reading this thread and it is epic.

I didn't see much mentioned about the LGX. Have you looked at upgrading at all? Is it worth the hassle for a few extra hp?

I have read the LGX is quite a bit different internally, but any idea if it will mount up to an MV7? I don't think there was a manual transmission (with better gearing) offered on the Cadillacs with the LGX.

 

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!

 

Haven't looked into the LGX much, I'm pretty committed on the LFX and I imagine it's more work than it's worth to try to swap in my case. If I was doing it all over again now I might consider the LGX but I don't know about trans fitment, etc. since I'm not using that engine.