LFX Engine Swap (GM V6) at GWR

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Re: LFX Engine Swap (GM V6) at GWR

Postby Ryan @ GWR » Wed Sep 27, 2017 8:48 pm

Mazfest 2017

Finally! Time to go stretch the car’s legs and see how it runs. This weekend was the first big shakedown. This is pretty much a completely fresh build at this point, and so you have to expect to discover issues and there's a long teething process as issues are sorted out, items fixed and improved, etc. once it’s being used at the race track. This weekend was all about getting the car out there and running it as much as possible to discover those issues and to take home a long but focused to-do list for how to improve the setup.

Saturday was Mazfest at Auto Club Speedway and I had a great time showing the car when I wasn’t on track.



On-track was special, after this much time building the car it was great to just feel the thing doing what it is built to do. There is a lot of power on tap and the engine is super smooth and worlds better than the old turbo setup. Torque is just always there if you want it. I'm delighted to find the car is still very "Miata" with great balance and drives just like it should just with much more motor attached to the right pedal. That was the biggest goal with going with this engine package over alternatives that might weigh a bit more.


Here’s a run-down of notes on each system and any issues that did spring up.

- Engine (max temp 225 water / 265° oil): no issues to report. Ran like a dream, makes power everywhere. Currently running with no oil cooler, just the factory filter housing. Oil cooler will bring oil temp down a good chunk once I have that in and working.

- Transmission (max temp 200°): Grinding on upshifts. I believe it’s a pedal/rod length issue. Bled the system after 1st session with no effect. Drove around it the rest of the weekend by trying to be VERY patient on shifts to let the rpms drop to where they needed to be on the next gear… which was somewhat successful. Gearing is good. Used 3-4-5 at this track which has a really low speed ~50mph tight right at the end. 3rd pulled right out of it, I won’t ever be using 2nd on a road course.

- Differential (max temp 180°): puking fluid out of the vent on top. V8R says running a breather line will fix this. Otherwise, the limited slip characteristics feel great.

- Power steering (max temp 190°): leaking fluid from the cap. We’re suspecting it’s from high-G right-hand turns which effectively submerges the left/lower side of the non-sealed cap. I’m implement a fix in the next couple days. Steering feel with the NB power rack is good and I’m much less worn out at the end of a session than with a manual rack. I think I’ll be keeping the power steering for a while.

- Ergonomics: new seating position and controls are all perfect. I did accidentally hit the fuel pump switch to off when shifting once. Might need to move the switches or add a guard.

- Display dash: I’ve already forgotten how I lived without one of these. The dash is set up to monitor all the temperatures and pressures without me having to do anything. If something is amiss, it lights up a warning light and lets me know. Otherwise, I just drive.

- Suspension: the spherical bearings and Feal 442 shocks are butter. I haven’t even begun making adjustments here yet, just set compression and rebound to dead center of the available range and left them there while I focused on everything else.

- Brakes: The V8R/ST four wheel kit has some serious stopping power and is easy to modulate.

- Powdercoat: powdercoating has a “squish” in the coating that prevents proper torque on bolts. I lost a spindle to caliper bracket bolt on track which prompted checking every bolt on the car that was in a powdercoated surface. Several had loosened. The rest of the weekend I re-torqued bolts after every 2 sessions. Will be adding split lock washers to most of those bolts this week since the lock washer will cut through the coating.

A great thing about the temps listed above for steering, diff and transmission is this confirms what we suspected - these items are all way under-stressed in a small lightweight Miata. Zero need for diff or transmission coolers.

Joe working the pedal while I bleed brakes:


Chatting with Sean about something. Probably about how something tried to fall off the car:


It was great fun to see so many friends at Mazfest who were there for the track day portion or who just came up to check things out. Being back out on track in my own car with fellow Roadster Cup guys felt great:


Spent all of Saturday with a passenger riding along and sorting out issues, and got absolutely no clean laps without traffic but I still ended up setting the fastest time by a Mazda at Mazfest with a 1:11.x.

Quite honestly surprised by how much pace the car had out of the box with zero time spent on dialing things in. Since it was still running well I signed up for the Redline Time Attack competition coming up the next day and grabbed a hotel for the night.

Redline Time Attack

Sunday morning first practice session in the cool air I went out with no passenger and did a 1:08.763. That is a new lap record for a Miata at this track (Auto Club Speedway Infield) by a gap of almost 3 seconds.

Time sheets after the practice session revealed that not only was it looking like I could take the win in my Limited Rear Wheel Drive class, I was actually within range of contention for the top overall time with the unlimited cars. There’s no way I could ignore that carrot dangling out in front of me so “I’m just testing things this weekend” went out the window at this point and it was game on. I did a little research around the paddock to scope out the cars that were at the top of the time sheets with me:

At the top of the sheets, this 500hp BMW M4 built for NASA ST1 competition running in Unlimited RWD:


Bulletproof Automotive's 750hp GTR in Limited AWD:


Time Attack veteran Amir with a 660hp aluminum V8 swapped E36 M3 in Unlimited RWD:


In true Time Attack fashion, Redline has just two Time Attack sessions where it all counts. Only three laps in the session, do or die time. Cars are pre-gridded by lap time from practice so I was third in line behind just the GTR and M4. Temps had climbed

That lap took 1st overall by a gap of just 0.08 seconds ahead of the M4.

By the second afternoon time attack session temperature had climbed a lot and some teams didn’t run because they knew they wouldn’t go faster. The GTR and M4 both went out to try to take the top spot. They both went slower. I did a 1:08.8 again, so that lap would have been even faster in the cool morning.

SO... first shakedown weekend with the car… fastest Mazda at Mazfest, 1st place Limited RWD and Top Time overall at Redline Time Attack, and a new Miata Lap Record.

We’re on the right track here. With some more track and tuning time this car is going to rip.


Ryan @ GWR
Posts: 242
Joined: Fri Oct 17, 2014 11:37 pm

Re: LFX Engine Swap (GM V6) at GWR

Postby Ryan @ GWR » Tue Oct 10, 2017 9:40 pm

Great Miatas @ MRLS event! I'm working on gettings some pics/vid together from that. In the mean time, there were a couple things that sprang up at ACS that I needed to solve, and now after running MRLS I can confirm the fixes worked so I'll cover those..

First up, the differential fluid was exiting the vent cap on the top of the diff, leaving a very traceable mess on the underside of the rear subframe and down the side of the diff. A quick check with V8R confirmed they've seen this happen and fixed it by replacing the vent cap with a hose barb fitting and running a vent line up higher.

Vent cap (right) is just removed with pliers. It's being replaced with the 1/4" NPT to 3/8" barb fitting on the left:


Tapping the hole for the fitting is a treat when the diff is up in the car. I'd call changing the vent config on the getrag a must-do item so if you haven't installed your diff yet, just do this now before installing everything:


Fitting and hose installed with a loop in the hose:


If the vent tube mod works, we can just run the hose to the open air. But since we didn't know yet if it would work, I wanted to run the line to a reservoir to catch the fluid in the event that it was still losing any. I repurposed a Wilwood brake fluid remote reservoir for the task, with a barb fitting installed in the cap and a hole drilled in the top of the reservoir to vent pressure:


After 3 days at MRLS, the reservoir is still dry so that's confirmed that the vent hose is working perfectly.

The second fluid that was trying to exit the vehicle was the power steering fluid. This one was a bit trickier to diagnose but I came to the conclusion that because the reservoir cap was a vented/non-sealed design, in high-G right hand turns the fluid was being pushed against the side of the tank and effectively submerging the side of the cap, and thus exiting via the cap's vent.

The cap needed to be sealed. I didn't take a pic of this but sealing the cap involved drilling out the spot welds that held the three pieces of the cap together, removing the vent ring, welding the two remaining pieces of the cap back together and then ordering a second cap to scavenge a second O-ring from and doubling up the O-rings under the cap to take up the height of the missing vent ring and seal to the reservoir neck.

With the cap sealed, the tank still needs a way to vent pressure. Drilled/tapped a small 1/16 MPT hole in the upper left hand corner of the tank and ran a vent line off that, with a loop to stop fluid from passing down the line:


Same as the diff vent line, to confirm the modifications were working as intended, I repurposed another brake fluid remote reservoir to serve as a catch can:


Same story, 3 days at MRLS and the reservoir remained dry. Fix worked.
Ryan @ GWR
Posts: 242
Joined: Fri Oct 17, 2014 11:37 pm

Re: LFX Engine Swap (GM V6) at GWR

Postby Ryan @ GWR » Wed Oct 11, 2017 8:28 pm

2017 Miatas @ MRLS! The final week of prep before the event there was a lot of crunching to get things done in time. Lots of little details here and there, and finished it up with completing the color scheme on the car which included wrapping the new hood and adding details on some other panels.

Made the pilgrimage up to Laguna Seca and had an awesome three days up there. In short, more confirmation that the car has lots of potential.. this isn't the type of event for putting down fast laps, we're mostly giving rides and making sure to play nice with all the traffic out there, but Sunday morning I did get one fun clear lap. I wasn't pushing things, just having fun chasing Jess Heitman in his V8 Prod car, waiting a month between upshifts (because we're still chasing the shifting issue) and still that lap was good for a 1:38.6. On street tires. I wasn't even thinking it would be a quick lap until I crossed the start/finish and saw it come up on the AIM.







Holy tire deflection batman!


And footage of a fun lap! The sound of that motor echoing off the pit wall going down the front straight is just rock and roll. But the best part was getting my dad in the car for a couple laps and his reaction at the end:

I did have a sound issue over the weekend. Car hit 107db in the cool morning air XD so a track-side fix was needed. Brian had the great idea to rotate the passenger side muffler on the V-band so the outlet was pointed at the ground instead of straight at the sound booth (which is located at right side of the track between turn 6 and 7). A little Macguyver action with a coat hanger and things were adequately suspended from the mounting points. Sound check confirmed this dropped output to 101-102 db at the booth and I ran it this way the rest of the weekend:

Ryan @ GWR
Posts: 242
Joined: Fri Oct 17, 2014 11:37 pm

Re: LFX Engine Swap (GM V6) at GWR

Postby Ryan @ GWR » Thu Oct 12, 2017 11:56 am

A couple clips friend Greg took from trackside:

Ryan @ GWR
Posts: 242
Joined: Fri Oct 17, 2014 11:37 pm


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