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High compression low boost VS low compression high boost
- Thread starter odie84
- Start date
I guess I should have stated. In my case I'm not wanting to go way high in boost. In wanting to run 15lbs and switch to the gt28.or a t3/t4. But I like having options to go more if need be. Car is and still will be a daily drivin car. I like to play as we all do and tax season is right around the corner :-D
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- 2003 Mazdaspeed Protege 1660, 2004 Winning Blue RX8, 2005 Mazda6
I've got the GT25 maxed out. I haven't dyno'd it and I'm not going to until I get my AFRs in the 11.5-12 range. I literally just finished rebuilding my built engine due to oil starvation that killed two K1 rods and a crankshaft.
Higher compression is going to give you a couple of things.
1. More power/better engine response when not on boost (same as an NA engine.)
2. Potentially more exhaust energy depending on cam timing (more energy in the cylinder, but if you're cam timing is too tight then it won't help spool the turbo.)
unfortunately
3. More cylinder pressure means more propensity to knock. Depending on quench design of the piston/head, port tuning, ect. higher compression may end up with a net power loss vs. low CR and more boost once you tune it rich and retarded to keep your rods in the block and the pistons from melting down.
It's been done before, but high CR with boost is harder on an engine all things being the same.
1. More power/better engine response when not on boost (same as an NA engine.)
2. Potentially more exhaust energy depending on cam timing (more energy in the cylinder, but if you're cam timing is too tight then it won't help spool the turbo.)
unfortunately
3. More cylinder pressure means more propensity to knock. Depending on quench design of the piston/head, port tuning, ect. higher compression may end up with a net power loss vs. low CR and more boost once you tune it rich and retarded to keep your rods in the block and the pistons from melting down.
It's been done before, but high CR with boost is harder on an engine all things being the same.
just read up on all the people who have or at least have talked about turbocharging the jdm fs-ze. its a n/a 10:1 compression version of the engine thats in your car.
theres been lots of discussion over the years. generally speaking its a waste of time. if you have a great cylinder head that can resist knock, or feel like paying for e85 or high octane pump gas it might be a different story.
IMO you would hardly even feel the difference and a stock compression motor running near same boost level is safer and has a better Intake vs Exhaust pressure ratio which also helps it make more power.
its not like the motor is a 7.5:1 slug for the 1970s. 9:1 is great. if your car feels sluggish it is probably just in a state of disrepair / poor tuning.
9:1 if more than enough in virtually every application. if you wanna go faster just turn up the boost on a built motor with supporting mods + good tuning.
theres been lots of discussion over the years. generally speaking its a waste of time. if you have a great cylinder head that can resist knock, or feel like paying for e85 or high octane pump gas it might be a different story.
IMO you would hardly even feel the difference and a stock compression motor running near same boost level is safer and has a better Intake vs Exhaust pressure ratio which also helps it make more power.
its not like the motor is a 7.5:1 slug for the 1970s. 9:1 is great. if your car feels sluggish it is probably just in a state of disrepair / poor tuning.
9:1 if more than enough in virtually every application. if you wanna go faster just turn up the boost on a built motor with supporting mods + good tuning.
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- :
- 2003 Mazdaspeed Protege 1660, 2004 Winning Blue RX8, 2005 Mazda6
OP, read this. If it doesn't sink in, read it again. That's the easiest and most straight forward way to look at this situation.just read up on all the people who have or at least have talked about turbocharging the jdm fs-ze. its a n/a 10:1 compression version of the engine thats in your car.
theres been lots of discussion over the years. generally speaking its a waste of time. if you have a great cylinder head that can resist knock, or feel like paying for e85 or high octane pump gas it might be a different story.
IMO you would hardly even feel the difference and a stock compression motor running near same boost level is safer and has a better Intake vs Exhaust pressure ratio which also helps it make more power.
its not like the motor is a 7.5:1 slug for the 1970s. 9:1 is great. if your car feels sluggish it is probably just in a state of disrepair / poor tuning.
9:1 if more than enough in virtually every application. if you wanna go faster just turn up the boost on a built motor with supporting mods + good tuning.
Back in the days 8.5 to 1 was the standard, today 9.5 to 1 is the "norm" even 10 to 1....I've personally seen 10.5 to 1 on a dd. higher compression = better response, and on 15 lbs your're very safe. I'm shooing for 400hp and i'm 9.5 to 1 no meth. The protg community is so small that sometimes we're out of touch, lots of ppl. here just wanna settle for 300hp, why?...... just keep doing your research, talk to experienced builders and come to your own conclusion. If it helps I was 8.5 to 1 now I'm 9.5 to 1 WHEN this engine goes kaboom I'm going 10 to 1....why not? When choosing compression you absolutely need to check your turbos' range and go from there...
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tweety2300
Member
- :
- 2001 mazda protege mp3
I've driven a 10:1 turbo car and own a 7.9:1 turbo car. Pros and cons to both
10:1 civic way better response even with a larger turbo but it detonated under boost once with a very conservative tune and cracked a piston. There is little room for error on tuning and issues
7.9:1 323 has held up to s*** tons of abuse tiny turbo runing 18 psi multiple 25 psi spikes from waste gate issues cause detonation and super lean conditions. Held up to years of rally abuse all stock cast internals with 200k miles on them and made with 25 year old technology. Absolutely no power till the turbo spooled up
Choose your demons a little less power till the turbo spools up with room for error. Or power when out of boost and less room for error
And people stop at 300-350hp because that's about the limit for the trans and that's about the limit for a street car unless you run with radials all the time
10:1 civic way better response even with a larger turbo but it detonated under boost once with a very conservative tune and cracked a piston. There is little room for error on tuning and issues
7.9:1 323 has held up to s*** tons of abuse tiny turbo runing 18 psi multiple 25 psi spikes from waste gate issues cause detonation and super lean conditions. Held up to years of rally abuse all stock cast internals with 200k miles on them and made with 25 year old technology. Absolutely no power till the turbo spooled up
Choose your demons a little less power till the turbo spools up with room for error. Or power when out of boost and less room for error
And people stop at 300-350hp because that's about the limit for the trans and that's about the limit for a street car unless you run with radials all the time
hornsfan10609
Certified Mazda Tech
- :
- 2003.5 Mazdaspeed Protege x2
300whp range is definitely the limit of the drivetrain not to mention that much power to a light FWD is just STUPID, you can't even put the power to the ground. Anyone that spends $10k+ on a $4k econobox just to burn up a set of front tires does it because they really want to, you can do that in a stock MSP. The protege platform was never meant to be a 500hp supercar, and anyone with a speck of common sense is painfully aware of that fact.
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300whp range is definitely the limit of the drivetrain not to mention that much power to a light FWD is just STUPID, you can't even put the power to the ground. Anyone that spends $10k+ on a $4k econobox just to burn up a set of front tires does it because they really want to, you can do that in a stock MSP. The protege platform was never meant to be a 500hp supercar, and anyone with a speck of common sense is painfully aware of that fact.
We ALL know the protege is an econobox ....so why even buy rims,or put a system in? Point being to each his own,I want 400+hp why? Cause I want it. Lots of high HP FWD cars running around. And the only ppl burning up tires is the ones running light to light or crap like that...I have a 58mm turbo and it only pulls u back in the seat around 3800rpm where I already have enough momentum,all depends on the tune..stop being narrow minded
tweety2300
Member
- :
- 2001 mazda protege mp3
I was breaking traction in 2nd making less than 200 whp with street tires. And that's not 1st to 2nd burn outs that's just laying into it while in 2nd. I can't say much because I'll be making 300+ whp in a older lighter car. But I'm just seeing how much my motor will take before it pops
hornsfan10609
Certified Mazda Tech
- :
- 2003.5 Mazdaspeed Protege x2
We ALL know the protege is an econobox ....so why even buy rims,or put a system in? Point being to each his own,I want 400+hp why? Cause I want it. Lots of high HP FWD cars running around. And the only ppl burning up tires is the ones running light to light or crap like that...I have a 58mm turbo and it only pulls u back in the seat around 3800rpm where I already have enough momentum,all depends on the tune..stop being narrow minded
Call it narrow minded all you want, it is simply being realistic. Personally 250+hp in a FWD car isn't even fun, a 500whp Mazda Protege defies logic
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call it narrow minded all you want, it is simply being realistic. Personally 250+hp in a fwd car isn't even fun, a 500whp mazda protege defies logic
lmfao!!!!!!......So please tell me, what the HP # for "fun".....your glass is always half empty huh?
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hornsfan10609
Certified Mazda Tech
- :
- 2003.5 Mazdaspeed Protege x2
It's not how much power it's the drivetrain, 250hp to the front wheels in a 2800lb car is nothing but wheel spin.
It's not how much power it's the drivetrain, 250hp to the front wheels in a 2800lb car is nothing but wheel spin.
Not necessarily dude.....I guess you never heard of BOOST BY GEAR??and if I wanted I could wheel spin a 150hp car.(which is what the Protg comes with stock to the wheels..or pretty close) and STOP limiting yourself....That's why I said to each his own, If you wanna stay at 175hp then cool...but it's kinda small minded to put out there that "that much power to a light FWD is just STUPID".....when ppl. been doin this before u got pubic hair....I'm done with this post.
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tweety2300
Member
- :
- 2001 mazda protege mp3
Not necessarily dude.....I guess you never heard of BOOST BY GEAR??and if I wanted I could wheel spin a 150hp car.(which is what the Protg comes with stock to the wheels..or pretty close) and STOP limiting yourself....That's why I said to each his own, If you wanna stay at 175hp then cool...but it's kinda small minded to put out there that "that much power to a light FWD is just STUPID".....when ppl. been doin this before u got pubic hair....I'm done with this post.
I'm going to say this. The 10:1 turbo civic I drove went 8.1 in the 1/8 on slicks making 200ish whp. There's another civic in my area making 600+whp that couldn't get lower than 9s on slicks due to spinning all the way down the track. And then there's 2 kswapped civics one supercharged making 300 or so whp and a turbo one making supposedly 600. Supercharged one won with them both on street tires because it hooked up
Just using these as examples to show that more hp does not mean faster just more money. Having 500 whp in a fwd street car is like living in NYC working in an office and driving a jacked up big ass diesel. It's not small minded it's common sense
hornsfan10609
Certified Mazda Tech
- :
- 2003.5 Mazdaspeed Protege x2
Not necessarily dude.....I guess you never heard of BOOST BY GEAR??and if I wanted I could wheel spin a 150hp car.(which is what the Protg comes with stock to the wheels..or pretty close) and STOP limiting yourself....That's why I said to each his own, If you wanna stay at 175hp then cool...but it's kinda small minded to put out there that "that much power to a light FWD is just STUPID".....when ppl. been doin this before u got pubic hair....I'm done with this post.
Damn you are really passionate about high HP FWD cars! Stock Protege makes about 100whp, MSP is about 150/150 at the wheels. My car hopefully makes about 200 and when I turn the boost up a little and it's cold I have trouble getting traction. I pull on a lot of cars that I wouldn't expect to once I get moving but I love stop light racing from a dig and if your car can't perform on the street because it can't put the power down I don't see the point of building it. I do see the point of starting with the right platform rather than trying to make a Protege a Skyline. Nothing against anyone else's opinions, this is just what I think.
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