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

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AndreyB
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Hunchback 1991 Miata NA/NB2 rusEfi official racecar #20

Post by AndreyB »

Because I need my own race car.

Image

"was in accident, run when parked"

http://rusefi.com/wiki/index.php?title=Vehicle:Mazda_Miata_1990

==========================================
base tune as engine config code https://svn.code.sf.net/p/rusefi/code/trunk/firmware/config/engines/mazda_miata_1_6.cpp
Frankenso 0.4 board
http://rusefi.com/images/Frankenso/frankenso_0_4_1991_miata_hunchback_front.jpg
http://rusefi.com/images/Frankenso/frankenso_0_4_1991_miata_hunchback_back.jpg
==========================================
dashboard/logging ECU:
max9926 input no pull-downs and no pull-ups
MAF/VAF 3O W53 no pull-down and no pull-up
IAT 3P W54 no pull-down and no pull-up (stock ECU R421 2.7K pull-up to +5v)
CLT 3Q W55 no pull-down and no pull-up (stock ECU R431 2.7K pull-up to +5v)
TPS 3M W50 no pull-down and no pull-up

Wiring info - https://rusefi.com/forum/viewtopic.php?f=3&t=906&p=25018#p25018
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kb1gtt
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Re: 1991 Miata

Post by kb1gtt »

Cool, let me know if you need help with it electrically. Does this have that valve that needs to be activated for high RPM?
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Re: 1991 Miata

Post by AndreyB »

kb1gtt wrote:Does this have that valve that needs to be activated for high RPM?
I believe it does not have VICS yet - not the 99+ 1.8 engine

[video][/video]
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Re: 1991 Miata

Post by Abricos »

Wow congratulations ...
Good luck with the recovery engine ...)))
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Re: 1991 Miata

Post by AndreyB »

That's a $10 'Mini 5M 4LED USB Waterproof Endoscope Borescope Snake Inspection Video Camera'

[video][/video]
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Re: 1991 Miata

Post by kb1gtt »

That looks like mostly good news on the inside. Doesn't seem to have much for carbon build up. Is that an oily residue? Does it have good compression? Did you get to see the side walls? Any how how could you post such a boring video :)
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Re: 1991 Miata

Post by AndreyB »



Image

Wonder how low they want idle? this is stock ECU obviously.

Note how idle was lower when I started it, but would not go down after I rev the car a bit:

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Re: 1991 Miata

Post by AndreyB »

Plot twist: I've got an AUTO miata with a light hit in the rear quarter for engine donor and now I am hesitating if I want to swap the engine into the red car and scrap the perfectly fine green body, or if I want to convert the perfectly fine green car to manual.

Both cars are pretty much rust free.
Arguments for red car:
it's already registered
alignment is fine & suspension is tight
manual swap is extra effort, who knows what crazy auto heritage would bite me when
I like red color more then this dark depressing green

Arguments for green car:
front is perfectly straight

Image

I will be busy parting one of these cars out for a couple of weeks - I need to junk on of these shells to get the test mule neon back into my tiny garage.
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Re: 1991 Miata

Post by AndreyB »

Still has not decide which shell I go with

Image
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Re: 1991 Miata

Post by AndreyB »

Green car is now manual, red car is gone. rusEfi promo car is coming along!

Image

Image
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Re: 1991 Miata

Post by RasPL »

about 1000bhp promo car ? :mrgreen:
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Re: 1991 Miata

Post by AndreyB »

RasPL wrote:about 1000bhp promo car ? :mrgreen:
Closer to 100 to begin with...
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Re: 1991 Miata

Post by kb1gtt »

100,000mbhp sounds cooler :)
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Re: 1991 Miata

Post by Abricos »

power by pedal ...
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Re: 1991 Miata

Post by AndreyB »

Next step: finding what kind of flange it is so that I can try welding a maniforl. Flange pattern is about 75mm by 57mm. I believe I've removed it from a 2nd generation Eclipse couple years ago.

It says A/R.48 M24 internet says it's T25 or T28

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Re: 1991 Miata

Post by AndreyB »

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Re: 1991 Miata

Post by Abricos »

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Re: 1991 Miata

Post by AndreyB »

Hood/trunk pins installed - it's a true race car now :)

Just dropped it to be caged, I would not see it again until mid-Feb probably.

Image
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Re: 1991 Miata

Post by kb1gtt »

It's about time you caged that beast. As we know people get hurt when beasts like that aren't caged :)
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Re: 1991 Miata

Post by AndreyB »

Not complete but you get the idea.
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Re: 1991 Miata

Post by AndreyB »

And that's the plan for the lemons theme.
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Re: 1991 Miata

Post by AndreyB »

12 things done / 28 things on the TODO list. Building this car would consume a portion of my time between now and first race in May.
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Re: 1991 Miata

Post by stefanst »

Any progress reports/pictures?
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Re: 1991 Miata

Post by AndreyB »

New engine runs, need to convert auto harness to use manual ECU with manual TB since we are using OEM manual ECU for the first race.
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Re: 1991 Miata

Post by tomiata »

What engine did you end up with, a 1.6 or 1.8?
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Re: 1991 Miata

Post by AndreyB »

The green car is now made of two 1991 cars so it's a 1.6

[video][/video]

Would anyone by any chance know how do I decode the signal on the oil pressure gauge wire? does the sender change resistance, like a thermistor? gauge pull-up resistor value? is anything linear here? is there a magic table somewhere maybe?

Image

Some info on 1999+ later oil pressure gauge (mine is 1991, better OEM design with true sensor, not just a switch):

http://wiki.miata.net/tiki-index.php?page=Turning+the+NB+Oil+Pressure+gauge+into+a+real+gauge
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Re: 1991 Miata

Post by stefanst »

It's a real pressure transducer- meaning it changes resistance with pressure. This behavior will not be linear. I have never seen a calibration curve for it though.
I assume you want to read it with the Rusefi. Just hook up a series resistor - something between 10Ohm and 330Ohm would probably be OK. Make it at least 1/4W. Run it off stabilized 5V, not 12V: 5V/100Ohm = 50mA. 50mA x 5V = 250mW. So a 1/4W should do fine. Make sure it gets some airflow though!

Read the signal with an analog input. Value without the engine running is 0bar. Value with engine running, cold oil and rpm>>idle is maybe 5bar? Absolute values don't really matter. All you need to keep an eye on is values significantly below what is expected.
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Re: 1991 Miata

Post by AndreyB »

Yes I want to read the value by rusEfi but I also want too keep the OEM gauge working! The gauge is pulling to +12v and I can only read up to +5v.Would it be possible to add a divider into the OEM circuitry without messing it up, or is it only possible if I use an op-amp to isolate?
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Re: 1991 Miata

Post by stefanst »

You can use a divider. Go fairly high resistance, maybe 2.2K and 1K, and you won't distort the signal to the OEM gauge much.
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Re: 1991 Miata

Post by kb1gtt »

Because your 12V will be changing, to get accurate readings, you'll need to reference the 12V signal and keep in mind the signals are ratio-metric. If your base line voltage is say 14.4V, and your actual voltage is 12V, your 83% of the full signal. Then your 5V signal will also be 83% of the real signal. You'll have to compensate by multiplying your measured pressure by 1.20 too get the real pressure. Probably best to consider something like 18V to be the base line, such that you have some room if you go over voltage for a short bit of time. Or perhaps with floating point it doesn't matter. I'm thinking that if your base line is 14.4, and you alternator over shoots to 15.0, you could have some potential math problems. However with floating point perhaps it wouldn't care. Any how, key point I'm trying to make is that you'll need to consider the 12V signal as part of your algo for determining the pressure.
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