My 1983 Mazda Cosmo (rotary injected turbo)

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Re: My 1983 Mazda Cosmo (rotary injected turbo)

Post by Fred »

sry_not4sale wrote:Next is to find the correct places to mount the required sensors for the megasquirt...
Ummm, OEM sensors should be sweet. You just have to know what they are. You have a jap setup, so your sensors are probably ND.
Where is the correct place to mount a map sensor on a vehicle with individual throttle bodies? On one of the inlet runners?
you need a Y fitting and to go to both runners (two throttles on a rotor box??)

This may give you a noisey map signal though... if so, get a bottle to smooth it out.

or build a dual map sensor circuit as seen in non-free or general ems or something.

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Re: My 1983 Mazda Cosmo (rotary injected turbo)

Post by sry_not4sale »

I have documentation... just not in english :)

The problem is I am trying to clean up the inlet tract as it has a hell of a lot of now-unused vacuum hoses.

Regarding the map sensor/individual throttle bodies. It doesn't actually have individual throttle bodies, it uses the standard rotary turbo style three throat throttle body. One large primary, two secondaries. The problem is, there is no "plenum" as such behind the throttle bodies, the air flow is divided into 4 runners post throttle body (2 primaries, 2 secondaries).

Standard, the secondaries are air only. The primaries have injectors right at the "block" end of the runners. If plan to mount injectors in the secondary runners quite high up (as there are no holes in the "block" to mount them like the primaries), is it a no-no to mount the injectors before the sensor - could it cause misreadings?

Going by the result of a quick google search, it sounds like people just mount the map sensors off any old boost line. Shouldn't it be reading the boost post throttle bodies to correctly read when the throttle bodies are not wide open/closed?

Hope that all makes sense...
Owner / Builder: 1983 Mazda Cosmo 12at (1200cc 2-rotor turbo) coupe [SPASTK]
165hp @ 6psi standard - fastest production car in japan Oct 82
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Re: My 1983 Mazda Cosmo (rotary injected turbo)

Post by Fred »

Yeah, map must be between throttle(s) and engine.

Can you post a pic of how the throttles and runners look?
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Re: My 1983 Mazda Cosmo (rotary injected turbo)

Post by sry_not4sale »

Yup will try grab some tonight.

Thanks for your help :)
Owner / Builder: 1983 Mazda Cosmo 12at (1200cc 2-rotor turbo) coupe [SPASTK]
165hp @ 6psi standard - fastest production car in japan Oct 82
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Re: My 1983 Mazda Cosmo (rotary injected turbo)

Post by sry_not4sale »

Finally got a pic of the intake lol

The t/b doesn't mount quite right as it is off a 13b and I am looking at getting some adaptors cut up for it, but you get the idea
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Owner / Builder: 1983 Mazda Cosmo 12at (1200cc 2-rotor turbo) coupe [SPASTK]
165hp @ 6psi standard - fastest production car in japan Oct 82
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Re: My 1983 Mazda Cosmo (rotary injected turbo)

Post by mk e »

sry_not4sale wrote:
Where is the correct place to mount a map sensor on a vehicle with individual throttle bodies? On one of the inlet runners?
The anwser unfortunately is there is no right spot, they generally all suck. All you can do is try but usually the signal bounces around too much to be usable....but it should be better on a rotary.

I was thinking of trying a SMALL hole in all the manifold....like 1.5mm. Then the tie them together and them to the MAP hoing the combination would damp the pulses enought to get a usable signal out of the MAP, but the standard answer is to use the TPS

-edit- Ahh, turbo, so you NEED to get that map sensor reading right. Then a combination of the small holes and some volume like Fred said. The problem is the more volume and the smaller the holes, the less responsive it will be so you end up need to add more fuel onthe acceleration enrichment map or whatever MS calls it.....which can dampen the responsiveness, but its' usually ok.

-edit more- I have a basic machine shop in my basement if you don't have somebody over there. Just give me a drawing a few days.
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Re: My 1983 Mazda Cosmo (rotary injected turbo)

Post by sry_not4sale »

Some pics from the weekend:
Image

Image

Image
Owner / Builder: 1983 Mazda Cosmo 12at (1200cc 2-rotor turbo) coupe [SPASTK]
165hp @ 6psi standard - fastest production car in japan Oct 82
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Re: My 1983 Mazda Cosmo (rotary injected turbo)

Post by Fred »

Why didn't you drive it in there? :-)

Edit: This explains it : http://www.carjam.co.nz/car/?plate=spastk

not street legal for 5 years :-)

My truck is worse at 8 or 9 years :-/ I reckon I'll have it officially legal again before you though! The race is on!

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Re: My 1983 Mazda Cosmo (rotary injected turbo)

Post by sry_not4sale »

OK, so regarding the MAP sensor. There are a couple of ~2mm holes just after the t/b linking one of the secondary runners and the primary runners - guess I'll run the map sensor off them.

What other sensors do I need?
- Intake temp (post turbo, pre t/b)
- MAP sensor (post t/b)
- TPS
- O2 (dump pipe)
- Coolant temp (engine side of thermostat)
Owner / Builder: 1983 Mazda Cosmo 12at (1200cc 2-rotor turbo) coupe [SPASTK]
165hp @ 6psi standard - fastest production car in japan Oct 82
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Re: My 1983 Mazda Cosmo (rotary injected turbo)

Post by Fred »

Photo of your holes please? ;-)

You'll need appropriate power and grounding which will likely be 5 cables of some sort (good ground, dirty ground, good power, dirty power, reference power), maybe more smaller parallelled. you'll also need some ignitors, external, in the engine bay.

you might want a second IAT/MAT one in the manifold and one out the front of the car where the air comes from away from the engine heat. But that's for advanced code, later.

Fred.
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