JCH13 - Turbo Miata Rehab Thread

[jlarsson]

*cough* In action! (Excuse the crappy, huge cell phone pic)

 

[JCH13]

Wut... other forum members are real people?! :biggrin:

Were you driving at the autox school? Or going to something else at NHMS?

Also, yes, my fiance and I went to an autox school yesterday. She drove (the shit out of) her MR2 and I thrashed on my Miata. Both cars held up quite well. I am totally blown away by how good the FM Stage 2 suspension is. AMSoil transmission oil was awesome, never missed a shift or had a rough shift all day. Oil cooler kept oil pressures good and the oil didn't toasted. Friction modifier in the diff made it a lot easier to get on the throttle in tight corner exits. Everything about the car felt better than the last time I did an autox event.

The only thing that was really painful is the car's relatively high-rpm boost threshold, especially in 2nd gear it can 'out run' boost. It felt like I wasn't getting full boost until 4krpm, maybe higher. I need to get a smaller turbo if I want to be faster in autox... waiting for it to spool up was positively painful.

There were some timed runs in the afternoon, I got the 2nd fastest time, just barely behind an MS3 with a very experienced driver. The two of us beat every single WRX and Evo there by a decent margin. Just goes to show that you can buy a fast car, but that doesn't make you a fast driver. Speaking of that, my fiance wound up middle-of-the-pack, beating a C5 (maybe C6?) Corvette and good number of the turbo awd guys. Only 2s back from a Gen3 1994 turbo Mr2 with 2x the hp of her car. Never even spun her MR2... Not bad for her very first time out!

 

[jlarsson]

Wut... other forum members are real people?! :biggrin:

Were you driving at the autox school? Or going to something else at NHMS?

I was helping out at the autocross school (picking up all those cones in the slalom!). During the mini event in the afternoon, I was out by the main road, preventing people from entering the parking lot from the front. When I saw your car out there, it took me a couple minutes to remember where I had seen it before ...

That guy in the MS3 beat me today at today's autocross event in PAX time (we are both in Novice class). So far this year, I've beat him twice, he's beat me twice.

 

[FuzzyDunlop]

Awww! I see new best friends potential! So cute!

 

[satyajitmenon]

I am totally blown away by how good the FM Stage 2 suspension is.

:awe:

What tires/wheels you running?

I've been "challenged" with oversteer the last few autox events. Ended up disconnecting the rear sway and that helped quite a bit. Although I do feel the rear sway (in middle setting) makes a pretty big difference in spirited street driving.

 

[Howard]

Finally got everything sorted out with the oil cooler. Found an STP filter that fit every requirement, and is a nice big filter upgrade to boot!

The kit:

I also added two 3/8 FIP/MIP elbows to turn the barbed fittings 90deg.

Sandwich plate clamped in place on the block with barbed elbows:

Maybe I'm not familiar with that type of thread, but how did you get both elbows pointed the same way with them being so close together?

EDIT: Oh, I see. Those are actually 2 pieces each. Wizardry not found.

 

[JCH13]

I was helping out at the autocross school (picking up all those cones in the slalom!). During the mini event in the afternoon, I was out by the main road, preventing people from entering the parking lot from the front. When I saw your car out there, it took me a couple minutes to remember where I had seen it before ...

That guy in the MS3 beat me today at today's autocross event in PAX time (we are both in Novice class). So far this year, I've beat him twice, he's beat me twice.

Cool! I'll probably see you around at the next autox then?

I don't think it was the owner of the MS3 who beat me, it was a friend of his (Leo?) that was co-driving with him. I beat the guy (Jeffry?) who actually owns it.

:awe:

What tires/wheels you running?

I've been "challenged" with oversteer the last few autox events. Ended up disconnecting the rear sway and that helped quite a bit. Although I do feel the rear sway (in middle setting) makes a pretty big difference in spirited street driving.

I was using 225/45-15 RS3s mounted on 15x7.5 TRM C1 wheels.

That's a lot narrower than most people like to run them. They have really smooth, predicable, breakaway mounted on a wheel that narrow, at the sacrifice of some ultimate grip. Very easy to drive, but not as fast as the tire can be on 15x8s or 15x9s. I believe the RS3 has been shown to be fastest mounted on 15x9s. Pushing them really hard I definitely got some slidey sideways bits, but nothing that caused me to lose control, or even hit cones. Though it did cost me some time... I didn't have a run that I was 100% happy with, unfortunately.

I like having the rear sway bar in there. Being able to get the rear end to rotate around with the gas OR the brakes let me crank through some really tight corners that the AWD kids were slogging through.

I'm planning on going to an autox on September 8th. This time I won't be man-handled in modified class by r-comps... I'll either be on Toyo RA1s, or possibly the infamous purple crack.

Speaking of that, I mounted my 205/50-15 RA1s on Konig Helium wheels. That dropped several pounds of weight per corner of rotating, unpsrung, mass. Took it for a spin... wow, what a difference. I am very much looking forward to seeing what these wheels and tires can do on the auto x course.

 

[JCH13]

When I got home I found that my front passenger wheel was sporting a very sad -.5 deg of camber, nowhere near the target -1.9deg of the drivers side. I might have slipped a camber bolt I corrected the camber and re-adjusted toe last night. Steering wheel isn't quite dead-on center though... I'll need to redo my front-end alignment soon.

Maybe I'm not familiar with that type of thread, but how did you get both elbows pointed the same way with them being so close together?

EDIT: Oh, I see. Those are actually 2 pieces each. Wizardry not found.

Damn... I've been found out...

 

[jlarsson]

Cool! I'll probably see you around at the next autox then?

Yep, I'll be there (I'll be the noob in the white Audi S4).

 

[JCH13]

New area of interest: optimizing turbo spool-up.

So, at the autox school I recently attended I noticed a couple of things about my car that I'd like to improve:

Issue 1:
When the turbo spools up it hits HARD. While entertaining on the street, it leads to some frustrating throttle modulation on the track.

Solutions:
-Smooth out spool-up to full-boost timing (not sure if this is an issue)
-Soften spool-up through timing/fuel adjustments (negative impact on issue #2)
-Upgrade MBC to EBC (espensive!)
-Adjust wastegate preload


Issue 2:
It takes longer than I'd like to build, and rebuild, boost. I hit peak boost (10psi) around 3500rpm (or so it feels) I'd like that to be 3,000rpm at least, overly-optimistically 2500rpm would be awesome.

Solutions:
-Increase BOV open pressure. More springs/shims? This might help spool-up if the BOV is leaking, and will definitely help off-throttle boost response.
-Make larger diameter downpipe. Currently 2.25in, could remake at 2.5in.
-Advance spool-up timing, a little scary because of knock.
-Lean out spool-up fueling, aim for 13-13.5:1 AFR vs 12.0:1. Less scary because AFRs are a lot easier to measure reliably than knock events in a Miata engine.

In the event that I just can't make my T3 turbo work acceptably, here's the backup plan: TD04-13G from a WRX. This is a plot of spool-ups from a number of different Miatas from Miataturbo.net, Pipefather is a user with a similar setup to mine, 1.6L, 2.25in ehxaust, etc, as well as similar performance goals: excellent response for autox, up to 210whp. He is use a TD04-13T and gets peak boost by 2600-2700rpm, which is insane.

Any thoughts, comments, suggestions, and the like would be great. I've never attempted to change a car's behavior like this before, so any discussion is welcome!

 

[Howard]

anti-lag system

 

[JCH13]

anti-lag system

There is some appeal in that... :awe:

http://www.youtube.com/watch?v=fb5vJRQ8WXM

 

[jlee]

Can your Megasquirt do boost control? If so, it's fairly cheap. I'll post a vid of first gear with my GT3071 -- well worth the investment.

 

[JCH13]

Can your Megasquirt do boost control? If so, it's fairly cheap. I'll post a vid of first gear with my GT3071 -- well worth the investment.

I think it can (and has)... but I think the wiring got fried (or maybe a diode in the wiring got fried?). I have two GM boost control solenoids, so it'd just be a matter of finding out what's wrong and fixing it, assuming either of the BC solenoids works!

Obvious idea is now obvious... no idea why it didn't occur to me before.

 

[satyajitmenon]

This thread makes me want to drop my plans of header/exhaust and go straight to turbo

*sigh*

 

[exdeath]

This thread makes me want to drop my plans of header/exhaust and go straight to turbo

*sigh*

 

[JCH13]

This thread makes me want to drop my plans of header/exhaust and go straight to turbo

*sigh*

FM turbo kit w/o electronics for $3k, MegaSquirt PNP for $800 from DIYAutoTune, upgraded clutch and a better exhaust and you're off to the races :awe:

Do it.

 

[JCH13]

Dug into the wiring harness and found out why the EBC wiring wasn't working. It had never been hooked back up when I changed out the ECU pigtail. So I wired it back in and played with it a little last night.

I confirmed a really slow spool-up in 2nd gear - I hit ~10psi around 4400rpm :\

With the EBC I was able to get spool around 3500rpm in 3rd gear, but I'm not sure how much of that is the EBC and how much is being in 3rd vs 2nd. I will need to do more tests.

Progress!

I also figured out that my BOV seems to be a non-adjustable BPV... so I am going to look into options for that. Keeping some pressure in the intake between shifts will help a lot I think.

 

[FuzzyDunlop]

are there any turno miata guys not running a BOV?

 

[JCH13]

Been following this guide to tuning the MS EBC: http://www.miataturbo.net/megasquirt-18/how-ms-1-mspnp-ebc-62711/

Been getting good results so far. Took several datalogs and I'm going to compare them soon.

Stay tuned.

 

[FuzzyDunlop]

hmmm... Ill have to redo my boost control once (if) I get my car rolling again. That seems like a great way to set it up properly. Thanks for posting that.

 

[JCH13]

Great success!

Ran my first auto-x in something like 2 years today. The EBC setup worked wonderfully, the car was immensely more controllable at part-throttle. My 10 year old RA1 tires were total dogshit, but managed let me beat 4 other cars (my previous best was 2!) A local guy with a V8 Miata, who has always been one step ahead of me: he had a turbo Miata when I got my first one, then got a V8 the same time I got my turbo... basically every race he was 10-12s faster than me. Well, I figured I'd have an okay shot at him this time with my mediocre slicks... turns out he got brand new shiny slicks this year! However, either I got to be a better driver, or the mods to my car worked out (or both) but I finally beat him, both in raw time and PAX adjusted time. Goddamn did that feel good. All of the time, energy, and money I've put in over the last two or three years and resulted in a hell of a better car in a very measurable way.

JLarsson was also there, maybe he has more pictures? Either way it was cool to meet up with a fellow ATG'er. *lifts beer*

Here is a video of my fastest (and last) run.

 

[satyajitmenon]

 

[PseudoSport]

Have you noticed any boost pressure fluctuation based on outside temperature? I use to vary 2-3 psi from afternoon to evening depending on the temp swing and eventually went with a manual controller. Also did they ever fix the coding in MS so that you can actually tune for a set psi instead of setting duty cycle for the EBC? Reading about your success makes me want to try running it again on the Jeep XJ-R

 

[JCH13]

Have you noticed any boost pressure fluctuation based on outside temperature? I use to vary 2-3 psi from afternoon to evening depending on the temp swing and eventually went with a manual controller. Also did they ever fix the coding in MS so that you can actually tune for a set psi instead of setting duty cycle for the EBC? Reading about your success makes me want to try running it again on the Jeep XJ-R

I do notice that fluctuation, though generally not nearly so bad over the course of a single day (different turbo perhaps?) I also had the same issue with two different MBCs.

I've been trying to tune the PI controls, though something doesn't seem quite right about it yet. About half the time it does what I expect it to.

I need to go through and re-do my waste gate duty cycle table, I did it a bit quickly and not as well as I could have. The proper procedure is to set your boost cut just a little bit above where you want your boost to wind up, set the whole duty-cycle table to 100%, and then see where you start bumping into the boost limit at WOT (in 4th or 5th gear, ideally). Then, adjust that cell/row down until you don't hit boost cut. Lather, rinse, and repeat until you've adjusted all your WOT cells to hold target boost until redline. Then you can scale or tune the rest of the map to hit partial boost at partial throttle.

I gather than a well-tuned duty cycle table makes the PID tuning considerably easier. I also found out that not all of the adjustments make sense... increasing the P gain tends to make the control more stable (and slower to respond), not less stable and faster to respond. Very weird.

Hopefully I can get someone to be a test pilot for a bit while I redo all of this tuning!

Also, FWIW, one of the instructors who saw me at the atuox school, and then at the autox, commented that the controller work appears to have made the car smoother and easier to control. Particularly when the ass-end got loose it didn't get twitchy and I could recover more smoothly. That's going from a MBC to EBC.