SeR_Cyclops
Member
- :
- Mazdaspeed Protege
How did the bad tune feel with no ECU and the 28RS?
Boost Reduction
- Thread starter jjm86m
- Start date
2.0t03speed
Member
- :
- 08.5 CWP Speed 3
umm it felt awesome msp ecu's are designed for 505 manis and 28rs's lol. low 11 tip into boost and 12.3 afr in the top end. no lean spots no hesitation
SeR_Cyclops
Member
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- Mazdaspeed Protege
that is a bad picture I cant tell.
SeR_Cyclops
Member
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- Mazdaspeed Protege
Straight on. Why do you think it might be different? If its not stock it could only be the 626 manifold.....
SeR_Cyclops
Member
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- Mazdaspeed Protege
Its more than likely a 626 then.
2.0t03speed
Member
- :
- 08.5 CWP Speed 3
its definitely a 626 mani. I can tell because of its shape and 1 piece design
Last edited:
SeR_Cyclops
Member
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- Mazdaspeed Protege
I thought it was but I didnt want to say because I didnt know for sure since I had only seen them in pictures. The only other manifold I have seen in person is the 505 which everyone knows is the be all end all manifold hahaha! j.k
- :
- 2003.5 Mazdaspeed Protege
So i just had an off topic question lol what is the airflow rate of a 2871r ? Is it the same as the 28rs? And if ur worried about too much boost couldent u just set ur bypass or bov to full bypass?
2.0t03speed
Member
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- 08.5 CWP Speed 3
2871 flows more then the 2860. 2860 is a 350hp turbo 2871 is a 400hp turbo
- :
- 2003.5 Mazdaspeed Protege
Aww s*** lol sick i would mind 400 hp guess my transmission wont be to happy about it though
Ok I've read many posts over the years (pushing a couple decades now actually) that say a certain turbo is only safe at such and such psi because a "fill in the blank" turbo produces more power than a stock turbo at the same PSI.
I think this phenomenon is grossly exaggerated. The WGA is controlled by pressure from the manifold (unless you've wisely modified it to come from the compressor housing or IC pipes).
So an 8psi spring is 8psi at the manifold no matter what kind of turbo is pushing it in there. What a bigger turbo does is run cooler, so that 8psi of air on a big turbo has more mass than a little turbo would. PV=nRT for those that paid attention in class.
More mass means more fuel can be burnt and more power can be made. Engines typically do not blow from running more power, they break rods from detonating too early in the combustion cycle, a concept called pre-detonation. The fuel-air mixture explodes before that piston reaches top dead center and the explosion pushes down on the piston while it is still being forced up by the momentum of the rest of the car. Normally this isn't that big of a deal, and you get pinging "or knock" and the engine retards the timing to mitigate. It actually sounds like gravel is hitting the bottom of your car. I've had others tell me that is sounds like your engine is chewing rocks, but that was my impression in the MSP. However, if you are making enough power or put this kind of stress on the engine for a long enough period of time you will snap a rod and most likely send it shooting through the oil pan creating the metal soup we all fear.
The hotter the intake air the faster it will ignite and the more prone the car is to pre-detonation. A cooler charge from a bigger turbo is actually safer. The MAF and IAT sensor our car uses is inadequate since it doesn't account for the increase in air temperature that occurs from the MAF through the turbo to the manifold. The car thinks the air temp is lower than it actually is, which causes it to advance spark more than it should, and the "engineers" at Mazda decided to solve this problem by increasing the fuel maps to insanely low AFRs.
I believe most of the blown MSP engines are due to the closed loop operation of the stock PCM. The PCM is physically no different than that from a regular Protege. All Mazda/Callaway did was increase the fuel maps to safeguard against the manifold air temps that the turbo would cause and rely on the MAF to account for the extra airflow. When everyone complained about the hesitation (read my hesitation explained thread), all they did was advance the timing so that we'd get back some of the power lost by running stupidly rich. It didn't fix anything and actually made the tune much more dangerous.
Below 4200rpms on a stock PCM is in closed loop, our engine is trying to reach a 14.7 AFR. This is considered dangerous on an NA car let alone one running boost on crap internals. The PCM doesn't know what 14.7 AFR is, it just pulls fuel when it sees rich and adds it when it sees lean. So when you step on the throttle below 4200 it could be either be pulling or adding fuel depending on where in its cycle it is. If it is adding, you get a smooth transition into open loop. It is terribly rich and you are losing a bunch of power and MPG because of the extra fuel but at least you have the fuel to burn. If the PCM is pulling fuel you could be insanely lean and you just don't go anywhere until the PCM transitions to open loop and you get pushed in the back like you just shot nitrous. I remember reading the fourgasm C&D article when the MSP was released where they faulted the MSP for inconsistent throttle and I am sure this was the problem.
The only way to lower boost pressure is to use a weaker spring on the WG or a larger WGA, but IMHO this is unnecessary. The bigger turbo is only a good thing for the car. The only thing I worry about is the closed loop operation and pulling fuel and running too lean below 4200 rpm. The only way to fix that is an EMS of some kind and your options are limited, inadequate and expensive. My car has been running the stock tune for 76k miles without a problem. The hesitation sucks, but I don't think the lean AFR is dangerous at stock boost levels and a lower manifold temp will only make the stock tune safer.
I think this phenomenon is grossly exaggerated. The WGA is controlled by pressure from the manifold (unless you've wisely modified it to come from the compressor housing or IC pipes).
So an 8psi spring is 8psi at the manifold no matter what kind of turbo is pushing it in there. What a bigger turbo does is run cooler, so that 8psi of air on a big turbo has more mass than a little turbo would. PV=nRT for those that paid attention in class.
More mass means more fuel can be burnt and more power can be made. Engines typically do not blow from running more power, they break rods from detonating too early in the combustion cycle, a concept called pre-detonation. The fuel-air mixture explodes before that piston reaches top dead center and the explosion pushes down on the piston while it is still being forced up by the momentum of the rest of the car. Normally this isn't that big of a deal, and you get pinging "or knock" and the engine retards the timing to mitigate. It actually sounds like gravel is hitting the bottom of your car. I've had others tell me that is sounds like your engine is chewing rocks, but that was my impression in the MSP. However, if you are making enough power or put this kind of stress on the engine for a long enough period of time you will snap a rod and most likely send it shooting through the oil pan creating the metal soup we all fear.
The hotter the intake air the faster it will ignite and the more prone the car is to pre-detonation. A cooler charge from a bigger turbo is actually safer. The MAF and IAT sensor our car uses is inadequate since it doesn't account for the increase in air temperature that occurs from the MAF through the turbo to the manifold. The car thinks the air temp is lower than it actually is, which causes it to advance spark more than it should, and the "engineers" at Mazda decided to solve this problem by increasing the fuel maps to insanely low AFRs.
I believe most of the blown MSP engines are due to the closed loop operation of the stock PCM. The PCM is physically no different than that from a regular Protege. All Mazda/Callaway did was increase the fuel maps to safeguard against the manifold air temps that the turbo would cause and rely on the MAF to account for the extra airflow. When everyone complained about the hesitation (read my hesitation explained thread), all they did was advance the timing so that we'd get back some of the power lost by running stupidly rich. It didn't fix anything and actually made the tune much more dangerous.
Below 4200rpms on a stock PCM is in closed loop, our engine is trying to reach a 14.7 AFR. This is considered dangerous on an NA car let alone one running boost on crap internals. The PCM doesn't know what 14.7 AFR is, it just pulls fuel when it sees rich and adds it when it sees lean. So when you step on the throttle below 4200 it could be either be pulling or adding fuel depending on where in its cycle it is. If it is adding, you get a smooth transition into open loop. It is terribly rich and you are losing a bunch of power and MPG because of the extra fuel but at least you have the fuel to burn. If the PCM is pulling fuel you could be insanely lean and you just don't go anywhere until the PCM transitions to open loop and you get pushed in the back like you just shot nitrous. I remember reading the fourgasm C&D article when the MSP was released where they faulted the MSP for inconsistent throttle and I am sure this was the problem.
The only way to lower boost pressure is to use a weaker spring on the WG or a larger WGA, but IMHO this is unnecessary. The bigger turbo is only a good thing for the car. The only thing I worry about is the closed loop operation and pulling fuel and running too lean below 4200 rpm. The only way to fix that is an EMS of some kind and your options are limited, inadequate and expensive. My car has been running the stock tune for 76k miles without a problem. The hesitation sucks, but I don't think the lean AFR is dangerous at stock boost levels and a lower manifold temp will only make the stock tune safer.
^^ This post is [/THREAD] ^^
I don't know why people said I was wrong when I simply stated that 7 psi is 7 psi and that the gt28 would actually be safer than a gt25. I agree with you that most proteges blow up from the terrible closed loop operation that gives you 14.7 AFR at full boost. Anyone with a MSP should immediately buy a wideband o2 and a SS-AFC as a minimum for fuel management.
I don't know why people said I was wrong when I simply stated that 7 psi is 7 psi and that the gt28 would actually be safer than a gt25. I agree with you that most proteges blow up from the terrible closed loop operation that gives you 14.7 AFR at full boost. Anyone with a MSP should immediately buy a wideband o2 and a SS-AFC as a minimum for fuel management.
