Question about stock 1.8 injectors - Miata Turbo Forum - Boost cars, acquire cats.

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Old 10-06-2009, 02:51 PM   #1
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Default Question about stock 1.8 injectors

This may seem silly, but I want to be sure. I have a 1997 w/ a Begi S3 kit with the GT2560 turbo, MSPNP, FM clutch, Koyo rad, enthuza 2.5" exhaust. It is being put together now and we will be running lower boost. The DIY FAQ says the stock 1.8's run about 7-9psi of boost (170-180rwhp).

The Begi kit advertises power at about 189hp at 6 psi. So I was wondering if this proves to be true and I make more than 180whp at 6-8 psi, is it ok?
In other words, if I can make 180-200whp with 6-8 psi and stock injectors, how safe is it?
OR should I be looking at the injector duty cycle while tuning and make sure it doesn't go over 85% or something like that?

The reason for not wanting to upgrade inj. yet is because the car is a 97 and will need the stock computer hooked back up once a year for obd2 emissions.

Thanks!
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Old 10-06-2009, 02:56 PM   #2
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its a rough estimate. watch your duty cycles in your logs. you could get away with an FMU to bump the fuel pressures and still use the MS.
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Old 10-06-2009, 03:05 PM   #3
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Do you mean FPR? Isn't the MSPNP a FMU? So, if the duty cycles are maxing out when not under full boost, it's an issue? What exactly should I be looking for in the logs? Thanks
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Old 10-06-2009, 03:11 PM   #4
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Quote:
Originally Posted by miatata View Post
do you mean fpr? Isn't the mspnp a fmu? So, if the duty cycles are maxing out when not under full boost, it's an issue? What exactly should i be looking for in the logs? Thanks
fpr=fmu
mspnp=ecu
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Old 10-06-2009, 04:51 PM   #5
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IF your going FPR or fmu, I wouldn't run ms.
If your running ms, I would run larger injectors.

The ms is only better for the ability to run larger injectors and tweak timing.

If you are not going to run larger injectors, I would save that money for the ecu (MS).

But with that setup you can easily have 200+hp with the ecu, larger injectors and a good tune.

If you suck at tuning. Let a shop do it.

As far as emissions....... for that day. I would have a extra 02 sensor bung welded onto the dp. And on the day for emmissions. I would plug back up the stock ecu. Screw the stock O2 sensor back into the extra bung. Install the maf on the intake side of the turbo. WIRE WASTEGATE OPEN!


Or if you just have to have boost, install a afpr for the way ther and home with boost turned all the way down. and timing at 9*
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Old 10-06-2009, 04:57 PM   #6
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I mean, really, there's nothing 'wrong' with stock injectors and a FMU coupled with a MS unit. You'll still have full control over the fuel, your map will just look funny in boost with VE% numbers equal to that of cruise.

A $30 used Vortech FMU unit with a 2:1 or 3:1 ratio is cheaper than $120 on good injectors.

small injectors + FMU + MS = perfectly spot on AFRs

small injectors + FMU + stock ecu = AFRs are 'okay' and **** during open loop.


would I do it myself? already have.
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Old 11-16-2009, 06:33 PM   #7
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Resurrecting.
What ratio does the vortech FMU from the greddy kit come with? If it's something like 10:1 then by the time I reach 8psi, wouldn't I have gone over 100psi at the rail?
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Old 11-16-2009, 06:56 PM   #8
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your stock pump won't let you get over about 70-75 psi. just dump larger injectors, rx7 460's are cheap. i got rx8 420's for $60 shipped to my door
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Old 11-16-2009, 09:00 PM   #9
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your stock pump won't let you get over about 70-75 psi. just dump larger injectors, rx7 460's are cheap. i got rx8 420's for $60 shipped to my door
Wow, nice. Where did you get them? rx8club forums?
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Old 11-17-2009, 10:38 AM   #10
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ebay actually. there is a rather large list of plug and play injectors in the diy section of this forum.
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