3rd Generation Specific Talk about 3rd gen RX-7's here.

Post-3 Mod Rule

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Old 04-05-2005, 11:20 AM
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Your fourth performance mod should be an ECU.



But what does that mean? An ECU won't do too much without a boost controller and a wideband fa ratio sensor, will it? And even then, one would need to tune for each new mod.



If I wanted a marginal increase in performance with no degrading in reliability, should I save up until I can buy a PFC, boost controller, wideband, and a SMIC?



Or would just the PFC and SMIC be safe to buy together, and download a map for?



The above is my specific concern, but general enumeration of the steps one takes after passing the three mod rule might be helpful to others.
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Old 04-05-2005, 12:28 PM
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The only rule that you need to follow is the air/fuel ratio theroem.



The air/fuel ratio theorem states: one's rotary engine must not lean out at any time during a WOT run. In the case that it does lean out it will cause the owner's wallet to feel lighter almost instantaneously, nausea and headache typically come soon after.



A proper aftermarket ECU keeps the car from leaning out due to modding and higher than stock boost levels.



The stock ECU has runs enough fuel to keep the car safe at no more than 10 psi (stock boost). So you can go ahead and mod your car and still be safe as long as you stay below 10 psi. That means no spiking, no creeping no nothing. NEVER pass 10 psi until you have an aftermarket ECU.





I am currently running:

mild streetport

DP

MP

M2 CAI

PFS SMIC

Stock ECU

9.5 psi of boost controlled via a profec spec II



I'm ready to buy a PFC now.
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Old 04-05-2005, 12:39 PM
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[quote name='montego' date='Apr 5 2005, 09:27 AM']The only rule that you need to follow is the air/fuel ratio theroem.



The air/fuel ratio theorem states: one's rotary engine must not lean out at any time during a WOT run. In the case that it does lean out it will cause the owner's wallet to feel lighter almost instantaneously, nausea and headache typically come soon after.



A proper aftermarket ECU keeps the car from leaning out due to modding and higher than stock boost levels.



The stock ECU has runs enough fuel to keep the car safe at no more than 10 psi (stock boost). So you can go ahead and mod your car and still be safe as long as you stay below 10 psi. That means no spiking, no creeping no nothing. NEVER pass 10 psi until you have an aftermarket ECU.

I am currently running:

mild streetport

DP

MP

M2 CAI

PFS SMIC

Stock ECU

9.5 psi of boost controlled via a profec spec II



I'm ready to buy a PFC now.

[snapback]695598[/snapback]

[/quote]



So the three mod rule should really state: Your first mod should be a boost gauge. Watch it, and if you notice spikes or creep above 10 psi buy a boost controller.



After you have a boost controller, then you can buy mods that'll put you above 10 psi as long as you have an aftermarket ECU and the parts to push enough fuel, if needed.
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Old 04-05-2005, 12:56 PM
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first mod should be a boost gauge.... definately. Even if you get an aftermarket ECU, you're still limited on what boost you can run due to the fuel system being lacking. 13 psi is about all that i'd trust the stock fuel system to support.
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Old 04-05-2005, 12:59 PM
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[quote name='Orochinoyamato' date='Apr 5 2005, 09:38 AM']So the three mod rule should really state: Your first mod should be a boost gauge. Watch it, and if you notice spikes or creep above 10 psi buy a boost controller.



After you have a boost controller, then you can buy mods that'll put you above 10 psi as long as you have an aftermarket ECU and the parts to push enough fuel, if needed.

[snapback]695608[/snapback]

[/quote]





Yeah pretty much.
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Old 04-05-2005, 01:01 PM
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[quote name='GreyGT-C' date='Apr 5 2005, 09:56 AM']first mod should be a boost gauge.... definately. Even if you get an aftermarket ECU, you're still limited on what boost you can run due to the fuel system being lacking. 13 psi is about all that i'd trust the stock fuel system to support.

[snapback]695619[/snapback]

[/quote]



But with a boost controller, even if you dont have an aftermarket ECU, you'll be safe with any amount of mods, right? You just won't be getting full performance because you're not unleashing the boost potential of your mods--for instance, cooler air at 10 psi is the only benefit you'd get from an upgraded intercooler, until you got an ECU and raised your boost.



//

And thanks for vastly simplifying the complex world of beginning performance modification, montego.
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Old 04-05-2005, 01:04 PM
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depending on how far you go with the mods.... you may have trouble keeping the boost down to 10 psi. easpecially during the colder months.
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Old 04-05-2005, 01:40 PM
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Orochinoyamato,



No problem . And oh yeah a boost controller will set your boost (obviously) and fix boost spikes but it won't do jack $hit for creep. If you ever get boost creep the fix is porting the wastegate.
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Old 04-05-2005, 05:07 PM
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what is boost creep? ive heard alot about it but never payd any attention
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Old 04-06-2005, 01:09 PM
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Boost Creep = where the boost reaches set boost level then continues to climb with an increase in RPM. Associated with an undersized/underflowing wastegate.



Boost spike = Uncontrolled exceedance of set boost levels for a brief period, followed by pressure settling to controlled levels. Associated with the wastegate not opening fast enough because of mechanical or electronic deficiencies.
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