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Old 01-08-2015, 12:17 PM   #1
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Default Tuning using an AFPR

I have a 1992 Miata with a t28 turbo going to run about 7psi! I will be running e85 on a walbro 430LPH. I am on a budget and the car starts and drives fine from what I can tell... I have a wideband but am only gonna drive it for a few months so I dpnt want to spend $700 on a Plug and play piggyback! I know everyone says different ("buy Megasquirt").

My question is could I run an AFPR and change the timing 6 degrees while running e85?
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Old 01-08-2015, 12:30 PM   #2
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The stock ECU is not going to play nice with E85 AT ALL. Save your shekels and get proper management and injectors.

or

Do what you want and blow your **** up, then later buy management, injectors and new engine.
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Old 01-08-2015, 12:51 PM   #3
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Short answer: No.

Long Answer. Nooooooo.
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Old 01-08-2015, 01:03 PM   #4
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The truth is that with E85, you may get away with it. I've tuned a car with stock ECU, slightly larger injectors, and an SAFC that ran great on E85. And we did not mess with base timing. That whole fuel system was setup for 91 octane gasoline. We logged knock and it just did not have any issues. No wideband because cheap so all we know is that we saw about .91V on the ghetto old narrowband 02 sensor. This was a 7.8:1 compression 2L at 18PSIG with a decent intercooler.

Keep in mind though we only made small tweaks with the SAFC, and let the larger injector put in significantly more fuel than stock. We are talking about going from stock 450CCs in this application to 550s. And we ran a Walbro 255HP. So a lot more fuel volume than stock, even though the ECU was running a mostly stock tune. And that application had a 1:1 rising FPR stock.

E85 is incredibly forgiving of AFR screw-ups because it runs very cool and does not detonate easily. Lots of E-wisdom online saying that you cant run it without a dedicated fuel system and that's just not true. I would bet you will not blow up given good boost control, good spark with proper plugs, and good cooling.

If this is a car you really don't care much about and just want to have some cheap fun, I say do it. And report back. The risk is that even with the cool burning properties of E85, you will just be too damned lean and either get spark knock (detonation) of get enough heat in the #4 to get pre-ignition, which you probably wont hear and will definitely kill power and your engine.
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Old 01-08-2015, 02:39 PM   #5
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Originally Posted by Sparetire View Post
The truth is that with E85, you may get away with it. I've tuned a car with stock ECU, slightly larger injectors, and an SAFC that ran great on E85. And we did not mess with base timing. That whole fuel system was setup for 91 octane gasoline. We logged knock and it just did not have any issues. No wideband because cheap so all we know is that we saw about .91V on the ghetto old narrowband 02 sensor. This was a 7.8:1 compression 2L at 18PSIG with a decent intercooler.

Keep in mind though we only made small tweaks with the SAFC, and let the larger injector put in significantly more fuel than stock. We are talking about going from stock 450CCs in this application to 550s. And we ran a Walbro 255HP. So a lot more fuel volume than stock, even though the ECU was running a mostly stock tune. And that application had a 1:1 rising FPR stock.

E85 is incredibly forgiving of AFR screw-ups because it runs very cool and does not detonate easily. Lots of E-wisdom online saying that you cant run it without a dedicated fuel system and that's just not true. I would bet you will not blow up given good boost control, good spark with proper plugs, and good cooling.

If this is a car you really don't care much about and just want to have some cheap fun, I say do it. And report back. The risk is that even with the cool burning properties of E85, you will just be too damned lean and either get spark knock (detonation) of get enough heat in the #4 to get pre-ignition, which you probably wont hear and will definitely kill power and your engine.
So just get the AFPR, run e85, and get bigger injectors and it should run fine? I daily drive a Infiniti g35 so I don't care that much for the Miata I just wanted to challenge myself with a custom turbo kit
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Old 01-08-2015, 02:49 PM   #6
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Quote:
Originally Posted by bmkpriest View Post
So just get the AFPR, run e85, and get bigger injectors and it should run fine?
In theory, yes. Upsizing the injectors by a multiple of 1.47 will get you into the ballpark of correct operation for E85. For a 1.6 car, that'd be around 330 cc / min, presuming that the dynamic characteristics are identical to the stock injectors.

Obviously this isn't the same thing as flex-fuel capability, so it'll only ever be "correct" on actual 85% Ethanol fuel. Depending on what data you believe, the actual Ethanol concentration of fuel branded as E85 can be as low as 51% (Source, pages 5, 7).

I guess more than anything I'm curious as to why you'd want to undertake this project on a car that you have no intention of keeping.
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Old 01-08-2015, 02:53 PM   #7
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By "Tuning" in your title, you meant "Not tuning at all," right?
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Old 01-08-2015, 02:59 PM   #8
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In theory, yes. Upsizing the injectors by a multiple of 1.47 will get you into the ballpark of correct operation for E85. For a 1.6 car, that'd be around 330 cc / min, presuming that the dynamic characteristics are identical to the stock injectors.

Obviously this isn't the same thing as flex-fuel capability, so it'll only ever be "correct" on actual 85% Ethanol fuel. Depending on what data you believe, the actual Ethanol concentration of fuel branded as E85 can be as low as 51% (Source, pages 5, 7).

I guess more than anything I'm curious as to why you'd want to undertake this project on a car that you have no intention of keeping.
Alright thank you! I've always wanted to build a turbo car and I'll have some fun with it this summer and trade it for something new probably another project car
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Old 01-08-2015, 03:03 PM   #9
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If you could pick between piggybacks the Bipes ACU or the AEM FIC6? I know the FIC is more expensive but is it necessary or will the Bipes ACU work fine?
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Old 01-08-2015, 03:07 PM   #10
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Quote:
Originally Posted by bmkpriest View Post
If you could pick between piggybacks the Bipes ACU or the AEM FIC6? I know the FIC is more expensive but is it necessary or will the Bipes ACU work fine?

If there's no Option 3: Eat a gun, i'd have to go with the FIC6 if there were no other option.

Seems like the best way to spend some money to have no support on this forum after you attempt to install and tune it, because nobody here is using that.

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Alright thank you! I've always wanted to build a turbo car and I'll have some fun with it this summer and trade it for something new probably another project car


I've never had much luck trading a car with a blown motor.
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Old 01-08-2015, 03:08 PM   #11
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Seriously you can build a MS1 for how much you will spend on an afpr and other random piggybacks you are talking about.
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Old 01-08-2015, 03:09 PM   #12
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Seriously you can build a MS1 for how much you will spend on an afpr and other random piggybacks you are talking about.

He could buy a PNP for the money he's talking about, honestly.
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Old 01-08-2015, 03:23 PM   #13
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He could buy a PNP for the money he's talking about, honestly.
The PNP AEM FIC6 is around $550-$600 and the Megasquirt PNP is over $800
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Old 01-08-2015, 03:27 PM   #14
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Originally Posted by bmkpriest View Post
The PNP AEM FIC6 is around $550-$600 and the Megasquirt PNP is over $800
MS1 is mid 2000's tech, but will be so much better they any piggy back you think of. For $600 you can almost build an MS3x yourself. I had less then $400 into my MS1/wideband/engine harness back in 2007 when I first installed MS in my car. Ran fine with the MS1 until 2010 when MS3 came out and I upgraded.
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Old 01-08-2015, 03:28 PM   #15
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Quote:
Originally Posted by bmkpriest View Post
The PNP AEM FIC6 is around $550-$600 and the Megasquirt PNP is over $800

How much is an AFPR worth buying? Have you bothered to shop around for the MSPNP at all?

Are you really hell-bent on "saving" $50 in the name of creating an inferior setup?
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Old 01-08-2015, 04:03 PM   #16
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I built my MS3+MS3x for $519 + shipping. Add a wideband for another 160$.

$679...tell me again why you want the AEM?
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Old 01-08-2015, 04:07 PM   #17
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I have researched this into the ground literally for years. There are two* options that might make sense for anyone doing anything forced induction Miata*:

Super ghettochearged idea rising AFPR and mess with base timing.

MS of some kind.

One is super cheap fun, the other is super competent.

Everything theoretically 'in-between' actually isn't. Bandaids end up costing more than MS, with vastly inferior results. So you pay more for less performance and possibly a grenade engine. Which you could have gotten with the ideas already discussed.

* The only exceptions to this are full-on racers running something super trick who are very very particular about how they want to tune. Think 949 and other shop cars. The other is Califailia, where you are living with your neck under a bunch of jackbooted thugs and will be sent to the gulag for daring to make your engine run properly. So unless you live on the wrong coast and/or plan to tangle with Theseus, Bbundy or Crusher, ignore these exceptions.
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Old 01-08-2015, 04:11 PM   #18
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I was about to flame a newb for bumping a 2001 thread.

then I realized he's even worse than that.

then I lol'd. then I read some of the responses and lol'd some more.

OP - just turn the timing up to 99 and run an eggplant AFPR disk, you'll be fine.

Over the years I learned that the smart people do it right the 1st time. The dumb people do it wrong, then fix it later. Some are poor because they're too dumb to be rich. I guess not everyone is fit to have a fun, sorted, proper turbo miata.....There's gotta be the molsted tubs of crap driven by cletus and his stepbrother/wife.
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Old 01-08-2015, 04:33 PM   #19
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There's gotta be the molsted tubs of crap driven by cletus and his stepbrother/wife.
I initially read this as "molested tub of crabs."

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Old 01-08-2015, 04:39 PM   #20
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Cheaper than an FIC:
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