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Miata scroll supercharger (homemade setup)

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Old 06-08-2012, 03:16 AM
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Do you suggest me to rescale the AFR table to 100kpa 135 170 200 like before ?

I'm located at 550meters or 1804 feet above sea level.

Here's the spark table, it's the original table gave by megasquirt, I didn't touch it yet. I prefer to finish the VE table first.



Nice, I will keep in mind your timing table and I will adapt it to my boost curve later.

Today it's rainning and the car is tricky on the road with the new big torque^^
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Old 06-08-2012, 04:56 AM
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I found this comment on msextra forum:

"i understand in a supercharger the elevetion has effect on the boost out put because it doesnt have a boost regulator (like a wastegate) a supercharger will give an engine less boost into an engine because now its trying to push thinner air.. but boost is boost it shouldnt remove fuel or have baro correction while on boost.."

I not sure to understand but I don't need to set 92kpa in my target table because MS is already correcting the barometric difference? So I put back 100kpa?
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Old 06-08-2012, 09:33 AM
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Originally Posted by phenixmt
I found this comment on msextra forum:

"i understand in a supercharger the elevetion has effect on the boost out put because it doesnt have a boost regulator (like a wastegate) a supercharger will give an engine less boost into an engine because now its trying to push thinner air.. but boost is boost it shouldnt remove fuel or have baro correction while on boost.."

I not sure to understand but I don't need to set 92kpa in my target table because MS is already correcting the barometric difference? So I put back 100kpa?
A superchager will pump a (roughly) fixed volume of air for every revolution. Its output is linked to the crank speed, so if the air is thinner it pumps less of it. A turbo, not being married to crank speed, will pump more air at higher elevations.

You dont need set your cell to local baro pressure IMHO. MS uses interpolation for lookup in the ve and spark table. This means that even if the read value is in between your cells it will calculate a value in between them.
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Old 06-08-2012, 03:50 PM
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^Yes what he said. If your engine is working halfway between two cells the computer will use halfway between the two values in the boxes. This makes it smooth. There is no reason to change the kpa numbers.

The spark table is good and safe which is what you want right now since the last engine blew up. It could make a little more power with more spark but it is more important to be safe right now. It is good not to need to be worried about it and just enjoy driving the car.
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Old 06-11-2012, 04:52 AM
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Ok thanks for your comment. It was what I needed to know.

Do you have some chrono on 0-60mph of your supercharged miatas?

1.6 Stock N/A is around 9.7 second from what I know.

I also notice my duty cycle is kind of high, at 5000rpm, I got 70%

Fuel pressure is only 30psi, I will raise it to 36psi and go further in rpm.

Last edited by phenixmt; 06-11-2012 at 05:37 AM.
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Old 06-11-2012, 09:03 AM
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Does your fuel pressure rise with boost? It should.
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Old 06-11-2012, 09:12 AM
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Originally Posted by sixshooter
Does your fuel pressure rise with boost? It should.
oh yes of course. I wanted to say, my FPR is set at 30psi.
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Old 06-11-2012, 04:37 PM
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Mais bien sur, lol.
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Old 08-01-2012, 10:26 AM
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I have no idea of the power and no idea how long my setup will last but, for the first track test, I had so much fun and no trouble with the car.

http://www.youtube.com/watch?v=YCmKK...ature=youtu.be
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Old 09-24-2012, 11:57 AM
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Update:

+
500miles done, 2 track days, no trouble.

-
injectors are out of flow approaching 6000rpm.


So New injectors + high flow fuel pump are comming


Attached Thumbnails Miata scroll supercharger (homemade setup)-di-h3ud.jpg  
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Old 09-24-2012, 01:42 PM
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Congrats man! How are the IAT's looking now?

For injectors, check out the Bosch EV14 units. They require adapters but they are pretty much superior to everything else on the market with regards to flow and deadtime. They are a bit pricey though. FIC (Fuel Injector Clinic) and ID (Injector Dynamics) are known good suppliers for the bigger EV14s. I would avoid FiveOhMotorsports though, their quality control seems to be a bit hit or miss as of late.

Good used RX8 yellow or blue Denso style injectors can also be good budget choice. They are direct drop-in IIRC, but be aware that there are really cheap chinese knockoffs out there now, especially on eBay.
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Old 09-24-2012, 02:36 PM
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Thanks!

My IAT's are around 85 F° on road and I never saw more than 120F° on a track day with 90F° outside temp

About injectors I have already ordered DW 800cc as I would like to avoid the use of adapters.

You have Bosch EV14 or RX8's on your car?


I plan to go E85. I guess 800cc will be enough, right?
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Old 09-24-2012, 03:23 PM
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Something about your map reading the wrong pressure with the engine off.. essentially this makes no difference as far as your tunning is based on that error. Just make sure you look at the numbers when you take psi into account. For example Map sees -1 psi when its atmo. You hook up your sc to push 10 psi but the map sensor should only show you 9 psi because of that calibration error.

As far as air temp goes, super chargers are fixed to the crank so any cooler intake charge will allow more air to be pushed into the engine because cooler air is more dense. Same thing as higher in altitude. Higher altitude, less pressure, less dense air.

For SC cold air intake makes a bigger difference, for turbo.. not so much. How many psi do you want to run on the 800cc injectors?

At 1800 feet you should be at 95kpa absolute air pressure.
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Old 09-24-2012, 04:04 PM
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You are right, I notice that air temp and altitude have a huge effect on the supercharger.

Exemple: on a warm summer track day, i have got 10psi at 5000rpm and last saturday night it was 10psi at 3700rpm (MAT was 77F°)

So, I planned to find or make a cold air intake stuff.

I'm a at 92-93kpa engine of.


PS: between 10-12 psi, it will depend how many the G-charger could supply

Last edited by phenixmt; 09-24-2012 at 04:20 PM.
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