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What do you think about my mods list

7K views 41 replies 6 participants last post by  rickkari 
#1 ·
Hi everyone, so I have a 2008 5speed 2.0 Mazda 3. The only thing done to it is a 3" exhaust after stock manifold + cat with a pro series flowmaster. I'm about to add a glass pack resonator to get rid of some of that high end drone. I have some iridium plugs and aftermarket coils on the way. Within the month I want to add a ispeedytech aluminum intake manifold + cai, 255LPH Fuel pump, obx headers with a cat delete. I'm hoping that I can get a dummy o2 sensor to still pass obd port emissions, will that work (I'm aware it's illegal)? I'm also looking at the kelford 220 degree cam with a tune following shortly. I'm still confused about tunes on our cars. I don't want to go stand alone and I can't find a piggy back. I've heard of accessport for mazdaspeed, will that work for mine too? I've also heard that our cars constantly learn so your tune will be slowly worked back to factory a/f ratio, if that true, how do you work around it? Once I get that figured out I'm hoping all that together will give me around 200+bhp.
If everything goes smoothly up to that point I'm considering either skimming the head .080 inches to increase comp ratio to 12:1 and run premium pump gas. Or, boring the cylinders to 2.3l maybe even 2.5l but I'm not sure how that will affect compression.
At the end of the day I want this to be a reliable daily, I want to keep it N/A, hoping for 270bhp 250whp on stock pistons and rods, 10-12:1 comp ratio, basically I want to drive it around town and occasionally square off with a wrx. XD
Another concern I have is I've heard that N/A 4cyls when upgraded trade all their low end torque for high end, can anyone explain this a little more?
If anyone has any feed back or some answers it is greatly appreciated 😄
 
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#2 · (Edited)
Hi everyone, so I have a 2008 5speed 2.0 Mazda 3.......Once I get that figured out I'm hoping all that together will give me around 200+bhp.......
At the end of the day I want this to be a reliable daily, I want to keep it N/A, hoping for 270bhp 250whp on stock pistons and rods, 10-12:1 comp ratio,
Your stock specs:
2.0L I-4 Engine
5-spd man w/OD Transmission
148 @ 6,500 rpm Horsepower
135 @ 4,500 rpm Torque

This will not happen. Maybe N/A with nitrous will get 200 bhp, but will likely blow it trying. You won't see 270 bhp. If anything, swap in a Fusion or Mazda 2.5 and build from there to get the best chance of getting HP gain with the various mods suggested. But unless you run Nitrous, no N/A will give you 270 and will not give that without cooking first. You will be doing good to get a 2.5 to 200 with your mods.

Correct me if I'm wrong.

Buy a STI and then play with a WRX. LOL
 
#3 · (Edited)
Some general comments in no particular order:
  • Your car is not some video game where you can throw some parts at it and bump the output of the engine by dozens of horsepower per mod; believe it or not, your engine is about as well optimized from the factory as it's going to get.
  • The changes you've made so far are pretty much worthless from a power perspective.
  • The near-term changes you're talking about might account for for an additional twenty horsepower at redline at wide open throttle, but your low and mid-range torque will suffer greatly.
  • Your comment about modifying your air to fuel ratio suggests you think by increasing the ratio of fuel to air, you will get more power. If that's so, sorry, nothing could be further from the truth; increasing the fuel relative to the air will gradually reduce power the further away from stoichiometric you get.
  • To get even 200 horsepower out of a 2.0 liter engine, you're going to need to resort to a turbocharging application ala the GTI.
  • To bore your block out to 2.3 liters you'd need slice 0.15" of cylinder wall off your liners which would make then very thin and highly prone to deformation and/or cracking. To bore your block out to 2.5 liters you'd need to take 0.20" of metal out of the liners; I rather doubt there would be much liner left after such a radical bore out.
  • If you want to pick on WRXs and don't want to buy a WRX, then you should put your car back to stock (that will increase it's resale value), sell it, and buy something which is worthy of competing against a WRX, say a MazdaSpeed3 of the same year as your car.
  • As for low to mid-range torque versus high-end horse power; it is all about volumetric efficiency and an even mixing of the available air and fuel. Opening up intake and exhaust systems to allow higher flow rates virtually always reduces resonance and turbulence in the low to mid RPM ranges, and the reduction in turbulence and resonance reduces available power down low.
  • If you stay with your car then your best bet would be to drop in a 2.5 liter Ford Duratec, but even then, unless you resort to nitrous or forced induction, it is highly unlikely you'll get over 200 horsepower much less the 270 your looking for.
  • One final thought; if you really want a project car to terrorize WRXs, sell your car, buy an early 2000s vintage Honda Civic and drop a J35 in it (of course the car won't be a total sleeper as part of the hood will need to get cut away so it will clear the engine).
 
#4 ·
I understand it not a video game lol, I got 270bhp from the forums, I've seen people people saying our stock internals can handle up to 300base and our tranny can handle 350base. I've also read that the 2.0 and the 2.3 from 2008 are built on the same block, maybe I'm wrong but wouldn't boring the block to 2.3 leave me with the same wall clearance as a factory 2.3? I'm not wanting to run rich, however after I install headers/intake/cam shouldn't I adjust the a/f ratio because I'm taking in more air? Run a little richer maybe advance timing? Raising my compression ratio should net gains too across the whole powerband right?
I have concidered forced induction but I gave up when I learned our cars are already 10:1, I couldn't find any good low compression pistons or shorter rods, would a decomp plate be a good idea?
If I can get compression to safe number like 7:1 maybe 8:1 I'd go ahead and turbo it and run around 7 pounds of boost.
I don't really want to do an engine swap as the 5speed mz3 2.0 is the only 3 from that generation with a Japanese motor (sorry I hate Ford, always an issue with something).
I want to make a sleeper daily.
I also heard that our cars factory run pretty lean, so wouldn't a stock a/f tune get at least 10-15 hp increase WITHOUT all the breathing mods?
As far as my mods go right now, I'm not trying to get gains, I'm basically prepping for the cam so I can tune right after install to get the most out of it.
Will a accessport work for a mz3? How should I go about tuning?
Please correct me if I'm wrong in any of this
 
#6 · (Edited)
Anyone on a forum that told you they got 270hp from this 2.0L without forced induction or nitrous is full of it.
Yes, the 2.0 and 2.3 are built on the same block but the bore size is also the same, that extra .3L is all from using a different stroke, not a larger bore.
If you do all that work then to get the most gains you need to get it tuned. The Accessport is only for the MazdaSpeed version, Mazdaedit is the only software that can tune the 2.0L and you should have the tuning done professionally, you can really mess things up otherwise. Forced induction is the way to go if you want power, there is nothing that says you can't turbo an engine with a 10:1 CR, whoever tunes it just needs to be good and know what they are doing. You just acknowledged the the 2.0L and 2.3L are the same block but somehow you think the 2.0L is a "Japanese motor" Wrong. They are ALL technally Ford motors, the logo is cast right into the block. The Focus even had the 2.0L and 2.3L as its engine options for years. Who told you our cars run lean from the factory. They actually run rich, my AFR is 10.9 at WOT. Also, that 3" exhaust you have is likely hurting your performance, not helping it. There is no reason to go larger than 2 1/4" on an N/A 2.0L, the factory 2" I believe is actually ideal if you replace the muffler on it.

:Edit: Sorry shipo, I didn't see your post before making mine. You pretty much said the same thing and I wasn't trying to copy you.

If you want to stay N/A then your best bet is to get a 2.5L. They are dirt cheap, actually have a lager bore, and the cylinders sleeves are stronger than the 2.0/2.3. Build that motor, drop it in, and have it dynotuned. Or, buy a wrecked MazdaSpeed 3 and swap everything into your car.



To give you an idea of what it takes to build a high power N/A 4 cylinder... And this is an engine with a lot of aftermarket support, ours have far less which means custom parts.
 
#5 ·
  • The bore in the 2.0 and 2.3 liter engines is identical; 87.5mm if I recall correctly.
  • What you don't appear to understand is the air to fuel ratio is what it is unless and until you allow more air to enter the engine than the injectors are rated for.
  • Running richer will not provide any benefit; period, full stop, the end.
  • Raising your compression ratio, and doing nothing else to the rest of the engine, will provide a modest gain across the powerband, assuming you have a tune capable of dealing with what will be a detonation prone engine.
  • Plenty of engines with 10:1 compression ratios are turbocharged; need proof, look no further than the 2.0T in the GTI.
  • Sorry, the 2.0 engine in your 2008 is a Ford motor and has FoMoCo stamped all over it.
  • I have no idea what you've heard about how lean these engines run, but the fact is, when under power, they run rich; all gasoline engines do. Yes, they may go lean when off-power, but if you're leaning on it, either accelerating or climbing a hill, the engine is running rich.
  • Anybody who tells you they can get 10-15 hp from your engine by changing the stock tune is full of crap.

Sorry to say it, but you're pretty much wrong in all of your assessments.
 
#7 ·
Okay so it seems I'm a little confused. I thought the 2.0 was designed by Ford and Mazda but actually manufactured in Japan. Either way no big deal. On the topic of forced induction I was reading when you add boost to a n/a motor the comp ratio increase, which makes sense because your cramming more air into the same amount of space at tdc, can tuners compensate this? If so, how, just curious, I'm obviously gonna get it done professionally.
Mazdaedit, what is it? Do I just go to a tuner that has the software, is it something I have to buy and take to the tuners? If so where can I get it
On the N/A side, if the 2.3 gets larger displacement through stroke would swapping the crank effectively get me the same displacement?
 
#9 ·
On the topic of forced induction I was reading when you add boost to a n/a motor the comp ratio increase, which makes sense because your cramming more air into the same amount of space at tdc, can tuners compensate this? If so, how, just curious, I'm obviously gonna get it done professionally.
Well, yes and no. While there is in fact more air is going into the engine, the issue is the temperature of the intake charge. Given most turbocharging applications these days are done with intercoolers, the intake charge is barely warmer than if the engine was normally aspirated. Regarding the compression ratio is purely a mechanical calculation, regardless of whether the engine is normally aspirated or uses forced induction.

And also believe it or not when I had just a 3" straight pipe after the stock manifold plus cat there was a definite noticeable increase in acceleration, however it was just way too loud so I added the muffler which took away about half of the gains that gave me
The noise I buy, and I might even buy a tad more power at WOT at redline, but your low and mid range torque definitely took a hit.
 
#8 ·
And also believe it or not when I had just a 3" straight pipe after the stock manifold plus cat there was a definite noticeable increase in acceleration, however it was just way too loud so I added the muffler which took away about half of the gains that gave me
 
#11 ·
I've read about building engines on forums for years. From what I have gleaned, every extra piece of chrome adds approximately 12hp, while performance stickers add anywhere from 5hp-30hp. The hp rating for stickers is based on a combination of font, color combination, and effects. Cold air intakes make even more betterer performance gainz, YO!

Oh, and magnets on the fuel line increase fuel mileage up to 18%!
 
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#30 ·
Preignition- ignition due to over compression before plugs even fire, similar to a diesel
Detonation- when sparks fire uncontrolled burn, multiple ignition points, "engine knock", due to temps

Correct me if I'm wrong. I'm going to use low temp plugs, intercooler, and 93 gas to take care of detonation. I'm just trying trying to make sure a static ~15.5:1 cpr won't ignitie the mixture before spark.
 
#37 ·
This is why direct injection engines can run higher compression and more boost than a port injection engine. The air entering the cylinder isn't a air/fuel mixture that is susceptible to igniting before the plug actually fires due to the heat build up of the charged air as it is compressed more by the piston. The timing of the fuel injected into the cylinder can be delayed until late into the compression stroke. Of course, that is where larger intercoolers and meth injection and higher octane/racing fuel come into play to help both types of injection systems to be able to increase boost/power.

Basically you would have to run a tolerable boost that can be controlled by tuning/fuel octane increase. When that is maxed, you would have to increase fuel octane and tune and larger intercooler, meth and other means to continue to increase boost. Of course, at that point you would have to upgrade engine internals including possibly changing static compression as needed to match the boost system for the power numbers intending to be run.

Curious what you have found as a baseline boost for a stockish 3. I've seen 7 to 8 psi as a common number although one site mentioned up to 10 psi of boost as being OK.
 
#40 ·
I'm glad someone on here can understand what I'm trying to say. As far as my knowledge goes ur right, we can safely run 7-8 psi on stock internals with high octane. With methanol inj alone we can get close to 10-11psi but that's when piston rings and rod bearing begin to go bad quickly. Anything above 10psi should be coupled with low comp pistons, short stroke, or a decomp plate. However running 93 & low temp plugs @8psi can give the tuner enough room to advance timing to produce more hp than 10psi of boost with further retarded timing.

This all of course doesn't take your drivetrain into consideration and assuming you have a good tune
 
#38 ·
I just find it funny that you're fretting about running 8psi on a 10:1 CR motor yet one of the Youtube channels I'm watching is building a K24 that they intend to put probably upwards of 30PSI of boost into with, guess what, a 10:1 CR. This is under the supervision of one of the top Honda tuners in the country too. I think you're overthinking everything while at the same time lacking a basic understanding of the subject at hand.
 
#39 ·
U know what, you're exactly right. I am overthinking everything because like I've said I want all my numbers to add up before I jump in half assed; "Measure twice, cut once", Maybe it's a mechanic thing. Which goes back to my initial question before shipo jumps in talking about how I'm wrong about something completely different than the question. I do not know at what effective cpr pump gas ignites, either 87/89/91/93. I would like to know this before I continue. I understand he is saying IAT determines this. But of course I am speaking in terms of an appropriate sized turbo and intercooler at 8psi. ~115-135f depending on ambient air.

Also honda's are built differently than our ford motors which is why I said previously I prefer Japanese motors. I have a mechanic buddy, with his own impressive shop, he's a Honda fanatic. He has a civic with a stock bottom end that runs 18psi with 345 to the wheels, and a stock tranny. I've seen him dyno it. Trying to compare a jap 4cyl to an American 4cyl is like trying to compare ramen noodles to traditional jap noodles. We've mastered the v engines they have the inlines.
 
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