[rusEfi] Hunchback 1991 Miata NA/NB2 rusEfi official racecar #20

What engine are you torturing? Is it inside some car?
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Re: 1991 Miata #20 Hunchback

Post by russian » Sat May 27, 2017 5:45 pm

It's hall, we can try routing signal via op-amps instead of MAX9926?
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Re: 1991 Miata #20 Hunchback

Post by kb1gtt » Sat May 27, 2017 6:27 pm

Max vs opto is not the problem. The problem is that 12V/470ohms = 25mA, but many sensors and probably this one can only handle around 5mA to 10mA. In this situation, it appears that the OEM sensor can not handle the 25mA that the MS unit was setup to use. The MS unit may or may not use 12V, and may or may not be the same as the OEM.
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Re: 1991 Miata #20 Hunchback

Post by stefanst » Sat May 27, 2017 7:48 pm

Good point on the 12V vs. 5V. So yes, 1k for 5V should be close enough to 3.3k for 12V. I believe we went through this already a while back when I was scoping those sensors. Standard circuit for MS3 also uses 1k resistor for 5V pullup.
I also just read that it's not really a hall sensor, but a VR sensor with integrated circuitry to emulate a hall sensor.

I like the MAX9926 for it's ability to change the reference voltage. Since it appears now that the Miata sensors have pretty crappy signal stability, I think this would be an advantage.

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Re: 1991 Miata #20 Hunchback

Post by kb1gtt » Sat May 27, 2017 8:18 pm

Do you have an extra sensor? If so,,, can you cut it apart? If you see coils inside, then it's VR if not then it's hall. If it's VR emulating hall, then I have no idea what current it can pass.

It appears the OEM was 12V, and if that was measured at 3.3k ohm, then 5V and 1k should be close enough. I suspect the MS was also 12V. So 3.3k ohm would be desirable for that setup. However Frankenso's default is 5V, so that should be 1k.
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Re: 1991 Miata #20 Hunchback

Post by stefanst » Sat May 27, 2017 9:40 pm

kb1gtt wrote:Do you have an extra sensor? If so,,, can you cut it apart? If you see coils inside, then it's VR if not then it's hall. If it's VR emulating hall, then I have no idea what current it can pass.

It appears the OEM was 12V, and if that was measured at 3.3k ohm, then 5V and 1k should be close enough. I suspect the MS was also 12V. So 3.3k ohm would be desirable for that setup. However Frankenso's default is 5V, so that should be 1k.
Unfortunately no extra sensor here. But I may have to get a new one anyway, so then we'd have a candidate to cut into pieces.

MS3 instructions have 1k pull-up to 5V and that's how I built mine. Just couldn't remember since that was 6 years ago...

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Re: 1991 Miata #20 Hunchback

Post by kb1gtt » Sun May 28, 2017 1:10 am

Hmmm, then it works with 5V and 3.3k. That seems odd to me, but perhaps that's the OEM specification. The OEM seems to show a 12V supply, so I guess I don't know were the 470 ohm comment came from.

Would you expect the Frankenso 5V with 1k to work? Or do you expect the Miata would benefit from a 3.3k and 5V?
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Re: 1991 Miata #20 Hunchback

Post by stefanst » Sun May 28, 2017 1:20 am

I think we got our wires crossed. The original quote with the 12V / 3.3K was from the ME221 ECU, not the Megasquirt. Megasquirt uses 5V 1.0K
So all is internally logical...

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Re: 1991 Miata #20 Hunchback

Post by stefanst » Thu Jul 27, 2017 12:52 am

How are the turbo plans coming?
You have some TD04s I believe?
They can make decent power and awesome spool:
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(Done with a TD04L-13T)
Check the build on MT.net: https://www.miataturbo.net/build-thread ... 9-a-76499/

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Re: 1991 Miata #20 Hunchback

Post by russian » Thu Jul 27, 2017 2:11 pm

stefanst wrote:How are the turbo plans coming?
Turbo plans are pretty on hold to be honest - at the moment I am not comfortable even driving this car as is, a turbo would only make matters worse. What makes matters worse is that not only myself but my team also needs to get better at driving :(

At the moment I am hoping that we will weld at least one nascar-style passenger side bar this weekend. One way or another next race is Aug 11-12 weekend, one way or another car would hopefully have a legal cage again. If we do not wreck the car at that race I will have a vehicle with instructor's seat.
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Re: 1991 Miata #20 Hunchback

Post by russian » Sat Sep 02, 2017 9:10 pm

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Re: 1991 Miata #20 Hunchback

Post by kb1gtt » Sun Sep 03, 2017 12:26 am

Ah, I see you can now fit more car's in your garage. How long do you think it will be before you poke an antenna through the floor and get yelled at by the better half? Cool to see.
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Re: 1991 Miata #20 Hunchback

Post by puff » Sun Sep 03, 2017 12:22 pm

nice! how did you mount it? does it have some linkage beneath the floor? steel anchor plates in concrete? what's the maximum allowed weight?

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Re: 1991 Miata #20 Hunchback

Post by russian » Sun Sep 03, 2017 12:27 pm

You drill five 22mm holes in the floor and drop threaded anchors. Each post is bolted with five bolts to the floor, and there are tiny wheels so if you want to you can roll it from one set of holes to another set of holes. No linkage no nothing. 6000lbs they say but this car is closer to 2500lbs.

I want to get a longer hydralic hose and have it on the ceiling, not on the floor.
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Re: 1991 Miata #20 Hunchback

Post by NBytevenom » Fri Sep 08, 2017 3:39 pm

stefanst wrote:
kb1gtt wrote:Do you have an extra sensor? If so,,, can you cut it apart? If you see coils inside, then it's VR if not then it's hall. If it's VR emulating hall, then I have no idea what current it can pass.

It appears the OEM was 12V, and if that was measured at 3.3k ohm, then 5V and 1k should be close enough. I suspect the MS was also 12V. So 3.3k ohm would be desirable for that setup. However Frankenso's default is 5V, so that should be 1k.
Unfortunately no extra sensor here. But I may have to get a new one anyway, so then we'd have a candidate to cut into pieces.

MS3 instructions have 1k pull-up to 5V and that's how I built mine. Just couldn't remember since that was 6 years ago...
I have extra cam/crank NB1 sensors. Which one needs some surgery?

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Re: 1991 Miata #20 Hunchback

Post by russian » Sat Sep 09, 2017 2:14 pm

NBytevenom wrote:I have extra cam/crank NB1 sensors. Which one needs some surgery?
Not that we really need to cut any sensor open. I believe the story was that we are puzzled how does crank act as hall sensor on the wires while we suspect that it's a VR sensor by nature? There was a theory that maybe there is some electrnics inside the sensor?
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Re: 1991 Miata #20 Hunchback

Post by russian » Mon Oct 23, 2017 1:08 am

Fresh battle scars but everything was fixed fast and we kept racing. More details later :)
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Re: 1991 Miata #20 Hunchback

Post by Abricos » Mon Oct 23, 2017 2:38 am

OMG who give you a driver's license !!!

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Re: 1991 Miata #20 Hunchback

Post by kb1gtt » Mon Oct 23, 2017 9:43 am

I see you have customized your car. It's now a one of a kind work of art. Not just some every day industrial piece of metal.
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Re: 1991 Miata #20 Hunchback

Post by russian » Tue Oct 24, 2017 4:03 am

At this stage of life everything is on someone's camera

[video]https://www.youtube.com/watch?v=rzf4LYQyp_I[/video]
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Re: 1991 Miata #20 Hunchback

Post by russian » Sat Dec 02, 2017 7:59 pm

Since the engine is out to address oil consumption it's a good time to upgrade trigger wheel from NB 4 tooth to ZM-DE 2000 protege 36/1 trigger wheel ZM 01-11-408
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Re: 1991 Miata #20 Hunchback

Post by russian » Thu Dec 07, 2017 5:34 am

We've found the reason of oil consumption - these grooves on cylinder wall should not be there :( And two more panels will now be garden green instead of original racing green :) Because racecar.
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Re: 1991 Miata #20 Hunchback

Post by kb1gtt » Thu Dec 07, 2017 11:08 am

Any ideas what caused the groovy piston wall? I don't see any dents in the top of the piston, so I don't think there was any debris from the top side. As well the carbon build up on the next cyl could indicate that cyl was consuming oil which resulted in the carbon build up. Did you have your blow by connected to the intake manifold? Could the blow by be dumping oil into the intake, when then caused the carbon build up? Did you have a catch can?
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Re: 1991 Miata #20 Hunchback

Post by Abricos » Thu Dec 07, 2017 1:48 pm

Maybe broke piston ? Over Heat ...
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Re: 1991 Miata #20 Hunchback

Post by russian » Thu Dec 07, 2017 4:32 pm

kb1gtt wrote:Did you have your blow by connected to the intake manifold? Could the blow by be dumping oil into the intake, when then caused the carbon build up? Did you have a catch can?
A hose dumps blow into intake. No catch can on this car.
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Re: 1991 Miata #20 Hunchback

Post by kb1gtt » Fri Dec 08, 2017 1:12 am

Generally as you increase the HP of your cyl, you grind the rings gap more than OEM suggests. This prevents issues while under load, and allows for more blow by, especially because you are typically much closer to detonation pressures. The oil in the blow by commonly causes carbon build up problem, and increases the need for a catch can. It might be good to add one if you don't have one yet. I see several videos on interwebs and they typically don't cost very much. If you take our your pistons, you might want to use the below gap chart to help ensure a good race day.
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Re: 1991 Miata #20 Hunchback

Post by Somebody » Wed Jan 24, 2018 9:41 am

@Russian I think it is time to put together...
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The Russian equivalent to redneck engineered catch cans ;-). I'm sure we could get this in the car running as a catch can or even better 2 of them :-)

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Re: 1991 Miata #20 Hunchback

Post by russian » Thu Apr 19, 2018 2:58 am

What is it, three and half weeks until the first race this year? We've started the rebuild engine! Now with 36-1 trigger wheel.
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Re: 1991 Miata #20 Hunchback

Post by puff » Thu Apr 19, 2018 9:42 am

This trigger wheel is not the stock one, is it? just wondering, what was the torque you applied to that pulley bolt?

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Re: 1991 Miata #20 Hunchback

Post by russian » Thu Apr 19, 2018 12:17 pm

Trigger wheel is not stock - it's from a later Mazda engine and happens to work. ZM-DE 2000 protege 36/1 trigger wheel part number ZM 01-11-408

My part is to set the ECU, my partner Ethan is the one applying the right amount of torque :)
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Re: 1991 Miata #20 Hunchback

Post by russian » Sun Apr 22, 2018 9:32 pm

This 1991 body has 2002 engine harness to run the 2002 engine. Over the winter I've started to cut "unneeded" wires.

So we've started the car and it smelled BAD, eye-etching rich. Troubleshooting pointed at VBATT=20.5 volts?! on the gauges?! Troubleshooting with a DMM has confirmed that in fact ECU power supply was 20.5v.

The car rans original-ish 1994 alternator with it's own field control, rusEfi is not touching the alternator. Also the body part of the electrical - there are few power supply connectors - was showing 14.4v

Question: how do I mess up the wires to increase the voltage from 14.4 to 20.5 assuming I am not contolling alternator field wire?

This post - viewtopic.php?f=3&t=906&p=25018#p25018 - is where I am recording the state of the mixed harness.
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