Laminar's M3 5.0 swap: Fünf-Null

[Laminar]

I've started a thread on the RX-8 forum but I haven't said anything about engine swaps yet. A few years ago they were EXTREMELY hostile to any engine swaps, though they've softened recently. Probably after seeing that most engine swaps add reliability, power, efficiency, and have little to no weight penalty.

I've been driving the car to work to get miles on it. It's 34 degrees outside so I let it warm up a bit this morning while I got the 3 year old ready to go. Got a text from my neighbor asking if the "thunder boomer exhaust warm up at 6:30am" was just a temporary thing or not. So...oops. Maybe I'll drive the truck tomorrow. The RX idles quietly but once it gets moving it's ear-splitting and something about the rotary exhaust note is like an unpiped sportbike - the sound travels for miles. I'm off to buy a resonator...

But the brakes seem to be bedding in, they're grabbing nicely once I reach the friction zone. I just wish the friction zone was right off the top of the pedal, and not two inches down. I'm wondering if I can shim the pedal/booster/MC linkage so that there's not so much dead space before the action.

[mrallande5020]

I like the updates man, I like when ppl keep posting on there new projects or just news about them in general.

[Laminar]

Got the car lifted back up last night and started on the nut-and-bolt check. The big finding was some grease "spray" above each axle.



I found three loose axle bolts on the driver's side and one or two on the passenger.

No leaks from the engine, a little weeping under the trans tailshaft. Nothing else from the diff, brakes still look great.

Even after fixing the busted spark plug wire, I was still seeing the driver's side bank running leaner by 1-2 full points. Took my 8yo to soccer practice and sat there on the laptop fiddling with the ECU while I waited. I finally decided to enable EGO correction, where the ECU actively uses the O2 readings to adjust fueling. I'm able to assign each cylinder to the O2 sensor on its bank (I could actually run an O2 sensor per cylinder if I had the inclination). I put in some preliminary guesses for the PID tuning and we drove home. Huuuge difference - both banks nailed their target AFR, I've never seen those graphs so smooth and centered. The big find there was occasional lean spikes on the driver's side bank at light throttle/steady cruise. The graph would be nice and steady at 14.7 and then spike-spike-spike-spike continuously. I could definitely feel it in the engine, too. The plugs are new, all four of those wires are new as well, I made those right at the end of last year. I went through and tightened up the high tension leads on each coil, some had slipped down by 1/4" or so. I could see how a weak connection would be fine with high spark energy but under light conditions produce a weaker spark. If I have the inclination tonight, I may just pull all four spark plugs and make sure I don't have any damaged ceramic (been there before) and that the electrodes all look good.

Then I'll throw on the race tires and we should be ready to have some fun tomorrow!

[Laminar]

Racing!! Had a great weekend, had to make the best of some bad tires.

I ordered some corner scales on Thursday and to my surprise, they showed up on Friday. So obviously I had to weigh the car.



Last time I weighed the car it was 3184 with a little more gas in the tank. Since then I've some some weight reduction on the front bumper bar and taken off the flat tow brackets.

That left front corner was way overloaded, but with very little time left in the evening I couldn't do anything about it.

Day 1 was a bit of an odd course, with several pure 180 degree turnarounds and some odd tight elements. My car liked to push hard at the limit and I struggled to get it to turn. The first time I hit the brakes almost nothing happened, which was disconcerting, though those got better throughout the weekend. My attempt to mitigate understeer by tightening up the front sway bar was unsuccessful. My tires were toast at the end of last season, and they certainly didn't gain any tread over the winter.



I started out running a 71.9 and then a 69.7. On my third run I pushed harder and ended up spinning, ending the first heat of the day. When I went back out for the second heat I decided to slow down and focus on setting up for a good line. With these slippery tires, I couldn't throw the car at a corner and hope it stuck like I usually do. My fourth run was a 70.4 - slower than the morning but I felt significantly better about picking a good line and smooth driving, and I knew where I could add speed. I followed that with a pair of 68.2 second runs to end the day.

Ended up at 17/74 raw, running a second or two behind the people I usually hang with.

On the way home, I felt a significant vibration on the highway, bad enough that I thought I may have corded my tires, though it would change significantly when I let off the gas. I had plenty of time for some doomsday scenarios to go through my mind about the engine and its health. To make things worse, I was a couple miles away from home and started smelling something bad. It wasn't coolant or oil, but kind of an acrid smell. I also saw a little smoke wafting up through the hood vent, and I was trying to remember if I had thrown my fire extinguisher back into the race bin in my trunk.

Once I got home, I popped the hood and sniffed around, when I spotted it. The 20-pin connector I had loosened up from its spot to cycle the ABS, I had neglected to re-secure. Throughout the day, it had worked itself loose and ended up touching the heat-wrapped header tube.



With that mystery solved, it was time to grab dinner and take care of the family, no more time to look at the car.

First thing Sunday morning I got the car jacked up and chipped all of the now-hardened melted plastic off of the header tubes. Then I inspected the tires to make sure nothing was corded. That all checked out, so I went ahead and swapped the front sway bar from full tight to full soft. I also lowered the front left coilover by two turns, and centered each adjustment on the front shocks. Nothing like making a billion random changes right before a race. The one thing I forgot to look at was the rear diff bolt. I knew that it was screwed all the way in from my pre-race inspection on Thursday, but it has backed out before and given me some odd driveline characteristics as it allows the front diff to move up and down, which throws off the u-joint angles.

I headed back out and immediately could feel the diff THUNK at every gear change and throttle on/off. I was gentle on it and as soon as I got parked in the paddock, jacked the car up and took a look.



Yep, backed right back out. This is probably a consequence of me using anti-seize in that bolt hole to ensure that I can get the threads out if that bolt ever breaks. But based on the last few years of abuse, the bigger bolt seems pretty immune to busting. I tightened that up and dropped the car back down, time to race.



Waaaaaaaaaay different. Where the car refused to turn yesterday, it couldn't help but turn today. The rear end was VERY reactive to the throttle and the car felt like it would actually follow where the front tires were pointed. This course was set up by a Corvette driver, so it was much more flowy and had some wider, higher-speed sections. The first couple of runs I stayed in first, but ended up preferring 2nd just so that I didn't spend the whole run fighting the inevitable power oversteer. I continued to focus on picking a good line, knowing that my tires couldn't save me from sloppy driving.

I started the day by missing a gate to the finish, so that run was thrown out. Then I ran a 51.5. All of the fast guys were sub-50, so that's where I wanted to be. My next run was a 50.2 but with a cone. I knew that if I tightened things up I could get sub-50 in the afternoon. Right out of the gate in the second heat I did a 49.899, putting me ahead of the turbo Miata in my class and the C5 Corvette that set up this course. Unfortunately, they both managed to find another second on their later runs, while I followed my time up with a 49.910 and 49.906. Nothing like being consistent - three runs within 0.011 seconds! Now if only I wasn't consistently slow...

The end was fairly exciting due to my car's power oversteer and my propensity for getting on the gas early.



Ended the day at 19/95 raw. I felt much better about my showing on day 2 than day 1. Overall it was a great weekend, but my lack of tires (and subsequent lack of competitiveness) is killing me. I'll need to see if I can figure something out before next month's event.

[computiNATEor]

Nicely done. Based on my time fiddling in iRacing setups, tightening the FSB will only make understeer worse, haha. Those are some clean and consistent runs; great to practice driving in. If you’re learning, and having fun, does all out time matter?

[Laminar]

I suppose if I had a healthy outlook on life and myself, I wouldn't be so worried about comparing myself to others. But here I am...

Oh, and I forgot the best part of the day. I was pulling into a gas station on my way home and spotted a new Audi R8 with paper plates. I figured I wouldn't give him too much attention. But as soon as I got out of my car, he came over and asked what I had done to it. I told him about the swap and popped the hood, and he offered to buy it from me on the spot . He liked that it was a sedan and a stick and he wants a fun track rat. He gave me his card and said to call him if I ever think of selling it...

If that wasn't enough, once I finished filling up and went to leave, I heard someone yelling, "Hey you in the BMW!" I got back out and it was a couple in a brand new Audi Q7...the dude ALSO WANTED TO BUY MY CAR. Then he asked if I had any cats to sell as he deals in used catalytic converters. I told him about the RX-8 and he was disappointed to find out that its cat was already gone, too.

Apparently everyone's flush with cash right now. Looking at Bring A Trailer, every M3 sedan sold this year has gone for over $15k. Not that mine is in BaT shape, but man prices seem crazy. Maybe it's worth some rust repair and a repaint...

[computiNATEor]

That’s awesome

[Laminar]

Two more shots from this weekend's event:

[Laminar]

I just ordered tires. I've been running a 245/40R17 Bridgestone. I just ordered the 255/40R17 Falken RT660. It was in stock and only $160 each, then DiscountTireDirect had an instant $100 off and free shipping, so I have the whole set coming for about $570. Apparently they run wide, the listed tread width is about 1/2" wider than the 245s I've been running, so I may have to revisit the fender roll and/or play with ride height to prevent rubbing. I was looking back through past events and saw some top 10 raw finishes on fresh Bridgestones, I won't stand for this top 20 nonsense.



I had considered a set of 245/40R17s or even just doing a 245/40R18 for the RX-8, but both of those sizes were on backorder, so the decision was made for me - the M3 will continue to be fast.

[Tim Mc]

Laminar: great stories, race experiences, and tire selection! I prefer the Rivals, but they are a good bit more $. Thanks for posting...

[95maxrider]

Hell, I kinda want to buy your car, and I already have a silver M3/4/5!

[Laminar]

Came home to a package yesterday.



These things are MEATS.



I'm going from a 245/40R17 to just a 255/40R17 but according to everyone these things run wiiide. The specs say the Bridgestone 245s have a tread width of 9.8", these 255s are 10.4", which is 15mm wider, not just 10mm like the 245 to 255 tire spec would imply. These will push out a quarter inch on each side, which is going to put me veeery close to rubbing. I'm going to try and borrow a fender roller and see if I can push these out even more.

[Laminar]

Old tires were definitely toast.



Got the new ones mounted up yesterday. I didn't really get a good pic comparing the two, but the 255s are SIGNIFICANTLY meatier. The 245s are definitely stretched onto the 9" wheel. The new 255s are square or maybe even slightly pinched...they're wide.





Did an initial fit up to see where they'll rub. I'll have to roll the rears for sure, especially near the back of the fender







I have a 5mm spacer up front, and I'm probably less than 5mm away from the coil spring/seat, but I'm also right at the fender lip. I'll more than likely have to some some massaging there as well.

[Tim Mc]

Look great - definitely fill the fenderwell!

[95maxrider]

Looks like you need to graft on some E46 fenders!

[computiNATEor]

Subtlety flared fenders are the bees knees. Should look sweet.

[Laminar]

Oh boy.

Some things happened.

I set out Friday night to get the car corner balanced. I picked up 210lb worth of sand bags to simulate me in the driver's seat.





I did a whole bunch of iterations of adjust and check, adjust and check, trying to get everything as even as I could.



I ended up at about 49.7% left to right, 52.6% front to rear, and 51% left front to right rear corner balance.

Then I hooked up the sway bars and messed it all up. I quit for the night to get my lawn mowed before it got too dark.

Started back in on Saturday and adjusted the front sway bar to get me back to where I should be. With that done, I turned to the alignment.



The front was at 1/4" toe out, which is a bit aggressive for the street and is probably causing some excessive wear, but it's nice on course. I went to the back and measured about 1/4" toe in. That's about what it was the last time I checked, but I wondered if too much rear toe in was causing too much rear stability and contributing to my mid-corner understeer. So I decided to adjust a tiny bit of that out. I went under the driver's side to loosen the RCA bolts when...



Uh...is that bolt missing? And wait...is that other bolt even doing anything?



The answer is no, it was not. Only one bolt was holding that arm in place. I've been hearing a pop from the rear when I back up and I could never locate the cause - sway bar, end links, control arms, axles, diff mounts, everything seemed to check out. Looks like I found what was causing it, and it's probably been like this for at least a year, which is impressive for that one bolt still holding it in place.

So the M3 was definitely not getting raced Sunday. I could take my backup race car, but it was on old, junk all seasons, it was 3PM on Saturday so my time was running out. I wanted to run the new tires, but they're on 17" 5x120 wheels, and the RX-8 has 18" 5x4.5 wheels, so I couldn't swap the tires and I couldn't bolt up my wheels. I put out some feelers to see if anyone knew where I could get some wheel adapters locally, and somebody piped up and mentioned they had some wheel adapters he had used to run M3 wheels on his Mazda. I swung by and picked them up, and the M3 wheels bolted right up.



The offset on these wheels was already low, but with an extra inch of wheel spacer, it ended up being a LOT of poke.





Not my desired fitment, but beggars can't be choosers, and I was just glad to get some good tires on this car. I loaded it on the trailer and got all packed up for Sunday.





I don't know if anyone has ever discovered this before, but the RX-8 is actually a really good autocross car. While I'm afraid to wring the car out on the street due to the horrendously loud exhaust, it was a blast on course. The throttle is incredibly responsive and the dearth of torque and plethora of traction let me use the throttle like an on/off switch without upsetting the chassis or having the rear end get wild on me. And the brakes were fantastic, no excessive travel like the E36.

I struggled with hitting a lot of cones at first - still figuring out where the corners of the car are, and having to account for an inch or two of tire sticking out trying to nibble at the cones took some time. My best clean run of the day was a 58.0 (I did have a 57.8 but coned that one out), good for 8th overall in raw, only 0.2 seconds behind the turbo Miata in my class that beat me by a full second at the last event on the M3 with old tires. I'd venture to say that the RX-8 even on what appears to be the factory original 130,000 mile suspension and wheezing rotary engine is just as fast as the M3. There's a lot of compliance there and it feels like the tires have grip for days.

Of course, during my last run the oil light started blinking, which apparently means there's a fault in the oil injection pump. And then this morning on the way to work the check engine light started blinking at me, indicating a misfire, so it's still doing the normal rotary things.

And also once I got home with the truck after dropping off the trailer, I could feel heat radiating off of the front left rotor from about two feet away, so that will need a new caliper.



I'm hoping the RX-8 keeps working at least until I can get the truck fixed. The M3 was supposed to be my backup car for the unreliable rotary, but it's also out of commission. Maybe I shouldn't have gotten rid of my one reliable car

I have a new RCA pocket and three bolts in my cart at FCPEuro. I'll need to figure out what those threads are so I can get some nuts and weld up a new plate to attach to the body.

[95maxrider]

Wow, that's scary. You're lucky the pocket/arm didn't rip out and flip your car over. Now is definitely the time to weld on a set of RTAB pocket reinforcements.

[Laminar]

Wow, that's scary. You're lucky the pocket/arm didn't rip out and flip your car over. Now is definitely the time to weld on a set of RTAB pocket reinforcements.

Well, 5 years ago was probably the right time to do it before this thing ripped up and fired out an entire bolt/nut assembly. It's funny, because I thought with the front strut plates, rear strut reinforcement plates, rear swaybar mounts, and rear diff bolt I thought I had reinforced everything. Now I'm seeing some subframe reinforcement stuff that I don't have...

I think the RTAB reinforcement plates will help locate where the nuts are supposed to go since I have to correctly locate the two that pulled out. I've ordered up the AKG plates. I have to decide if I want to weld nuts to the back of those plates or go for some sort of tapped sleeve/spacer to get more thread engagement for the bolt to bite into.

[Tim Mc]

Two race cars now...oh boy!

:-)

[Laminar]

Got the video uploaded. The way the exhaust sound echos off of the walls is ridiculous.

[Laminar]

Parts arrived so I started prepping for pocket reinforcement.



Here's my pocket:



I mocked up the bracket and traced its edges:



And ground down to a clean weld surface:



Old and new:





Since I still have one of the nuts, I'll be able to weld it back in place. The other I'll have to make up. I cut out some 1/8" plate and have a 12x1.5 nut I'll weld to the back of it, then I'll tie that into the new reinforcement bracket and also the chassis.





I also picked up some 1/8" plate steel and some longer 100mm M12x1.5 bolts so that I can reinforce the RTAB bracket itself. Don't want to do all of this work and then leave a bunch of weak points in there.

Hopefully I get a chance this week to break out the welder and zap it all in. I bought a new welding apron to wrap around the gas tank since I'll be welding 1/2" away from it. If you hear about Des Moines getting leveled by a gasoline explosion, check on me, okay?

[95maxrider]

Hopefully I get a chance this week to break out the welder and zap it all in. I bought a new welding apron to wrap around the gas tank since I'll be welding 1/2" away from it. If you hear about Des Moines getting leveled by a gasoline explosion, check on me, okay?

Let me know if you're still alive after all that, I need to re-do some welding around my pockets and I was planning on removing the gas tank to do it properly and without fear of blowing myself up.

[Laminar]

After working all Memorial Day weekend, I took a couple of days off to get some stuff done, and that included the M3. First things first - wrap the gas tank in a leather welding apron.



Then I cut out some plate and reinforced the RTAB brackets.





I welded up the plate little by little, trying not to start too many fires.





Cleaned up.



Painted.



Plopped everything back in place.





Now I need to drop it back down and check out the alignment. I didn't do the other side yet so that I can make sure I can still get this side back to where it was before all of these shenanigans. Next race is this coming Sunday, so I may not get to the other side before then.

[95maxrider]

Nice job! Glad to see you're still alive