codrus

Does it do 20Hz GPS and include sophisticated analysis software to integrate the GPS and accelerometer signals?

My frustrations with the DL1 stem from having bought a data logging system with a not-so-great user interface on the analysis software and one that nobody else I know uses. I probably should have bought an AIM.

--Ian

aidandj

iTrader: (5)

Brief googling tells me I might even be able to do 50hz if you asked nicely.

codrus

OK, back when I bought this system, 20Hz was fast, almost everything else maxed at 10.

The really important part of a data logging system is actually not the logging -- it's the analysis end. For example, this is comparing three different laps:



--Ian

Efini~FC3S

iTrader: (4)

Yes, the analysis software really is the most important bit, and where the phone apps really fall short.

The Race Technology software really is very powerful, once you can learn and get used to the software.

When I raced in Grand Am we used Race Technology stuff, and had some pretty awesome math channels set up for advanced super secret engineering analysis stuffs

codrus

Looks like it was a good thing I didn't take that last session, these pads were almost to the backing plates. A total of 3 days on these pads (DTC-60s), 1 at Thunderhill West, 2 at Laguna. Laguna is just brutal on brakes.





A small crack starting at the edge of the driver's side front rotor:



Found the brake caliper speculum:



--Ian

codrus

WTF, why is mt.net double-posting everything for me today?

--Ian

EO2K

iTrader: (37)

Its trying to help pad your post count

How many days on the rotors? I'm starting to see your thread as a cheat sheet of things I'll probably have to deal with in the future. Thank you for documenting and posting up as you go

codrus

The same 3 days. I switched to the 11.75s this spring, have 2 sets of rotors, one street, one track. The street ones are bedded with BP-20s, the track ones with DTC-60s.

--Ian

turbofan

iTrader: (1)

Wow. That's kinda shocking. I had much, much less wear on mine. Then again, I was running at a MUCH slower pace than you for the first few sessions saturday, then just a little slower sunday (but regularly held up by traffic, probably not as much of a problem in A group).

My brakes at the end of Day 2:

codrus

I brake too much.

In A, I was one of the slower cars on Saturday, which actually slowed me down quite a bit because I was spending a bunch of time watching my mirrors and being courteous. Sunday I was a ton faster than Saturday (mostly due to recent practice and gaining confidence), I was faster than most of the Spec Miatas and some of the SuperMiatas.

--Ian

turbofan

iTrader: (1)

I see. Do you have a map with speed breakdown like what we posted in gordon's thread?

codrus

My software doesn't generate a cool map like that, no. I've got this graph:



It won't label the mix/max, annoyingly. Manually grabbing them, I have:

- Max before 2: 109
- Min in 2: 43
- Max before 3: 80
- Min in 3: 56
- Max before 4: 88
- Min in 4: 64
- Max before 5: 111
- Min in 5: 56
- Max before 6: 90
- Min in 6: 60 (this hurts me)
- (7 is not a significant corner)
- Max before 8: 104
- Min in 8/8a: 43
- Max before 9: 77
- Min in 9: 63
- Max before 10: 91
- Min in 10: 60
- Max before 11: 95
- Min in 11: 37

--Ian

aidandj

iTrader: (5)

This hurts me too

You must care about your car/life more than we do

turbofan

iTrader: (1)

Holy smokes. Yes you do brake too much, lol! But damn, that power... Your minimum speed in 6 is 9 MPH slower than my minimum, but you're doing an additional 9 MPH at the top of the hill. You're also doing 11 MPH faster than me into turn 5.

woooo that thing is a rocket!

codrus

So yeah, higher top speeds + lower cornering speeds == a lot more brake load.

*must learn to resist voice telling me to brake*

There's another track day at Laguna this coming Saturday that I'd hoped to go to, but my daughter has a school thing I have to go to instead.

--Ian

codrus

So based on the dyno at Synergy, something is choking the flow at a bit over 300 rwhp. I was pretty sure it's wasn't the turbo (since Garrett specs them at 425 crank hp), but I was suspicious of the right-angle-in-a-cavity bend in the FM 3" muffler, so we set about to measure it.

We used two pressure sensors, one post-turbine (in the O2 bung that's available for narrowband use) and one pre-muffler. There's no O2 sensor bung after the cat, so we ran the copper tubing up the tailpipe, through the muffler, and out into the midpipe. Bend the end over 90 degrees so it's not acting like a pitot tube, put a length of silicone tubing on the end, and route it into the cabin through the trunk. Hook it up to the MS3, go out and do a 270 kpa acceleration run and we got this:



Conclusion: it ain't the muffler, there's about 5-6 kpa of back pressure coming from that. The vast majority of the back pressure is coming from the cat, about 55 kpa worth. That sucks.

Did some googling for the part numbers on the cat, "n/ic 54959 0913", and it appears to be a Magnaflow cat. 3" piping, 4" core, 9 inches long, check check, wait, it's a ceramic core?

So it turns out that the metal core cats that FM was selling were having a lot of warranty failures, and the supplier switched them to a ceramic core. My original metal core one failed last summer and I thought my replacement was another metal core, but apparently not. I never really ran the old motor on the new cat because the replacement arrived almost the same time as the throttle body screw broke.

So now I have to figure out the right answer. I trailer the car to the track so I can (and do) run a cat delete pipe there, but I'm not really willing to do that on the street.

This may go a long way towards explaining why my spool is significantly worse than I'd expected as well.

--Ian

JasonC SBB

Can you measure TIP?

codrus

i measured TIP back in June:

https://www.miataturbo.net/build-thr...4/#post1231551

TIP measurements were done at 230 kpa, the muffler measurements above are at 270. We also ran the muffler measurements at 230, it's about 10 kpa less back pressure through the cat for that.



--Ian

JasonC SBB

Metal cats are better than ceramic cats

codrus

Indeed they are.

So tonight we swapped in the test pipe and measured the back pressure again. At 265 kpa of MAP the pressure at the muffler inlet didn't change (107 kpa), but the pressure at what I'm calling the turbine outlet (actually about 6-8 inches downstream of the outlet, where the FM downpipe includes a bung for a narrowband sensor) goes from 160 kpa down to 115 kpa.

Also, between 230 and 265 kpa of MAP, the pressure through the cat goes up by 20 kpa, whereas with the test pipe it doesn't change. This is highly suggestive to me that it's the cat that's flow saturating and limiting power on the dyno to just over 300 at the wheels.

Butt-dyno says the car is making a bunch more power at 270 kpa without the cat, for one thing it's now spinning the wheels in 3rd when the boost comes on, which it hasn't done before (at least, not in the dry with Rivals, 6-speed, and 3.636). Strangely the logs don't show a big change in VE, though.

I'm trying to decide if it's worth taking it to the dyno with the test pipe or not. I don't plan to run it on the street that way, and the fueling differences don't appear to be big enough to need retuning that map for track days. I guess the question is how much it will have moved MBT, and whether or not there's a need to retune the timing map.

--Ian