Lower Compression???? Better or worster???

tommyg2b

Member
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2003 Mazdaspeed Protege
hey, guys, I was just wondering....I am planning on lowering my compression by swapping my stock pistons out and putting aftermarkets in....You guys think I can gain more power by doing that and how much PSI will be safe for me to run on....Planning on going atlease 8 for compression.
 
Going with an 8:1 compresion will make your car feel more sluggish off the line, and cause you to lose low end torque. BUT you can safely run more boost with lower compression pistons.
You won't gain any more power by swapping pistons, and staying at the same boost level. You may want to think about a complete engine build since the weak link in our motors isn't the pistons, its the rods...
 
^^^what he said, it's the rods that are the problem, and you won't gain any power with swapping pistons unless of course you raise the compression but then you'd risk detonation under boost. The thing with lower compression is that its easier to tune under boost add a little more boost maybe some timing and you can make more power. It's just easier than having to retard timing for adding boost, but there are sacrifices down low and when not boosting. Look into rods and pistons, there has to be a deal on both somewhere.
 
so, should I stay with stock pistons and just boost my turbo to somewhere 10 PSI?
 
it sounds like you should stay at stock boost and take the time to learn about these engines and turbocharging first. then make an informed decision.
 
tommyg2b said:
so, should I stay with stock pistons and just boost my turbo to somewhere 10 PSI?
NO, please list your mods and then we can help you make a decision on what steps you should take. 10psi+stock=BOOM. (I don't care to hear anyones stories about how you boosted 10 or moer stock for the time being thats just understood here.)
 
low_psi said:
it sounds like you should stay at stock boost and take the time to learn about these engines and turbocharging first. then make an informed decision.

good suggestion. (first)
 
wow everyone jumped on that one quick, good catch to all of you LOL. Listen to everyone, these cars don't last long at 10 psi stock.
 
okay, all I got so far are Denso IK20 plugs, FMIC, Injen intake, Greddy Type S BOV, and stock exhaust, cuz the pigs always get us here.
 
wow everyone jumped on that one quick, good catch to all of you LOL. Listen to everyone, these cars don't last long at 10 psi stock.

there has yet to be a properly setup car fail. Stop spreading this nonsense. Give me a link to one person that has blown a motor at 10psi and had fuel control and IC/exhaust. just cheap asses or people that didnt know what they were doing and now the MSP has a bad wrap.
 
Leave it at stock boost if you've got the stock exhaust. Or get an exhaust and deal with the "pigs" :rolleyes:
 
yeah right......I got busted so many times.....dealing with those pigs in the past......Well anyone else have any ideas for me....What PSI should Run at if I get a FMIC????
 
are you serious about building the motor or do you want power now? If you are building the motor right now talk to MAM or HiBoost. Both are great and can help you plan out your goals for the car. If your like me and just want good power on the stock motor, a afc, intercooler and exhaust should get you going low 14s on street tires and 91 octane @ 10psi, thats pretty much where I am. With good gas,more boost and a methenol injection kit you are laughing and still on the stock motor and are in the 13s on street tires. Pretty much the max the stock clutch and rods can take at that point,traction also starts becoming a bigger problen. then you give HiBoost or MAM a call for a built motor and look for a used Quiffe(or reweld your stock LSD) and really good tires.
 
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The number one mod before you up the boost should be your exhasut(thats if your only going to about 10psi). Go get something custom and keep the stock Axel back. That shouldn't be much louder then stock. I aslo suggest 1step colder plugs and a DSMAFC
 
that's right dominoy2k1. Damn pigs......hahhahaa.....Okay guys about my question......At what PSI should I run with a FMIC......
 
tommyg2b said:
that's right dominoy2k1. Damn pigs......hahhahaa.....Okay guys about my question......At what PSI should I run with a FMIC......

What don't you get a 2.5 exhaust? It is not loud. It will cost you 500 for exhast and midpipe.
You have all the bolt on and you could probably go to 8 10 psi safely with the AFC and sparkplugs.
Maybe 8 psi with no AFC.
 
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