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My 2006 Civic Si has a turbo kit installed and I am tossing around the idea of reliably running more boost while keeping the car as a daily driver. My thoughts are to run 12psi daily and bump it up to 15psi for track days. With that being said, what would be recommended for the engine buildup on the bottom end? I was thinking about using Carillo connecting rods and Weisco pistons running a 9.5:1 compression ratio. I am not sure if the sleeves or anything else would be good to upgrade at the same time.

As for the head, I was thinking about just upgrading the springs and retainers and keeping everything else the same. I'd welcome any suggested upgrades in this area as well.

Thanks!
 

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Building a bottom end makes it strong, but can also drastically decreases the longevity of it.
One aspect of it is piston slap... forged pistons expand a significant amount from being cold to getting warmed up. So when it's cold you have a piston basically flopping against your cylinder walls wearing at them. also, i'm sure the rigidity of the forged pistons will also cause more wear.

Just somthing to think about...:D
 

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WTF....never heard about that! All the stuff thats floating around stating that building the bottom end is the best thing you can do for to insure your engine lives a long life and its all wrong!!!!! Don't tell me that Santa deosn't exist either.... :(
 

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well here it goes......

stick with either cp or arias piston a bit more pricey than the wiseco but have a higher silicon content to minimize thermal expansion as greg spoke about. carrillo is a top quality rod so is pauter and manley whenever you can actually get a hold of them. for the setup you speak of i would stay around 10:1 CR and run either pauter or carrilo rods. with oem honda bearings. swap out your oil pump as well. the 10:1 CR will minimize turbo lag while still giving more than enough margin for error while tuning and will not require the use of race gas for psi either. making for a pretty mean street car. stock sleeves are fine. i would recommend +.020 oversize to get the rings a fresh area to work against after installation. piston slap is only an issue with excessive wall clearance. in most case a mild street motor will not need the extensive amount of clearance that most high hp motors demand for reliability.
 

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It all depends on what kind of piston and who does the motor... a piston like a JE is not as strong as say a CP or a Ross but is more suited for a street motor.... but I like a forced induction motor to have tall ringland and be a bit on the loose side due to the extra heat.... this kinda motor will have piston slap and burn some oil when cold... but it all depends on things like piston desgin and siclone content of the piston.. and also who sets it up.. you dont want a race motor on the street... it will wear out quick... but a nice set of rods and a stock style forged JE replacment piston will help you in the safty dpt.. plus 9.5 cr with 12psi of ic boost is going to be great on pump gas....
 

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why would you want to run 12 psi for daily drive? stay under 5-6 psi for DD.
a built motor with forged internals is pointless if all youll do is run 5-6 psi daily. any motor with forged pistons and rods can easily sustain 14-15 psi daily. you dont see any factory turbocharged cars other than the mazda running such mediocre boost levels.
 

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I have though of doing the exact thing in the future. The sleeves on the honda are cast iron and should handle around 600whp and depending on shop; making a block for the sleeve depending on how much whp.

Pauter, malley, crowler, carillo and eagle make good rods (Eagles are the cheapest) and CP, weisco and ross are pistons that have good rep. Discussion with the shop I work with most pistons will take 6-8 weeks. I've had conversations with CP over the last few weeks and would require your head to verify the compression of the piston and verify piston would clear the head.

A built motor can run 15-18psi as a DD no issues but that depends on the tuning method. Building a motor apparently the easy part.. the million dollar question is tuning solutions for the K20Z3 motor. I'm hoping in the coming months to help find a tuning solution that works.
 

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These are some of the best answers to that question that I've ever seen. :) My take on this is that you will be fine with a proper build...it doesn't drastically decrease longevity unless you build it wrong or you are trying to make retarded amounts of power and you have assumed you'll be rebuilding every couple months.

For a street turbo application, I highly recommend the 4032 alloy, the lower thermal expansion one. I'm partial to CP because they have some good people there and they do good work.

If you are working with a shop that knows how to build a good engine, then they will pay special attention to what you plan to do with the car because that will affect the piston-to-cylinder wall clearance you should have. I'd go with 2.5 thou on 4032 piston up to 400 hp. If you are going to run over 400 hp, I'd probably opt for more like 2.8 or 3.0. You don't really need to run a 2816 piston until you want to start making as much power as you can.... for example, we just finished a 2.2L GSR Dart block Turbo build using 5.5 thou because the customer wanted to be able to run 30+ psi and make 700 hp.

But on a 15-20 psi street motor K20 build, I'd recommend 2.8-3.0 thou on a 4032 alloy piston and you'll be golden without having much piston noise to be angry about on cold mornings. :) Oh, and the piston noise goes away when the car is warm.... so it's just a start up.

Cheers,
Chris at RedShift
 

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oh, and I'd recommend that you don't overbore at all unless you have to because you weaken the sleeve. And I know that .020 is almost nothing, but it's something; so don't do it unless you have to. Although, I guess if you don't want to pull the motor and then wait for parts once you verify what you need, then you should do the overbore just to be sure. But go with the smallest overbore you can... usually a .010" over (.25 mm).

Chris
 

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Discussion Starter #13
well here it goes......

stick with either cp or arias piston a bit more pricey than the wiseco but have a higher silicon content to minimize thermal expansion as greg spoke about. carrillo is a top quality rod so is pauter and manley whenever you can actually get a hold of them. for the setup you speak of i would stay around 10:1 CR and run either pauter or carrilo rods. with oem honda bearings. swap out your oil pump as well. the 10:1 CR will minimize turbo lag while still giving more than enough margin for error while tuning and will not require the use of race gas for psi either. making for a pretty mean street car. stock sleeves are fine. i would recommend +.020 oversize to get the rings a fresh area to work against after installation. piston slap is only an issue with excessive wall clearance. in most case a mild street motor will not need the extensive amount of clearance that most high hp motors demand for reliability.
Wow...Thanks for all of the great responses. Regarding the above, can the stock one be easily modified, or would it be better to replace it with an RSX oil pump assembly?
 

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Discussion Starter #14
chugiboi said:
why would you want to run 12 psi for daily drive? stay under 5-6 psi for DD.
Because I want to make sure that the engine can take the daily abuse at 12psi and 15psi at the track yet remain reliable. I have a boost controller that takes care of boost by gear, so I'd have the lower gears run a lower boost setting. I'd also like to see how well 12psi on the Civic compares to the 12psi on my RX-7. :biggrin:
 

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Because I want to make sure that the engine can take the daily abuse at 12psi and 15psi at the track yet remain reliable. I have a boost controller that takes care of boost by gear, so I'd have the lower gears run a lower boost setting. I'd also like to see how well 12psi on the Civic compares to the 12psi on my RX-7. :biggrin:
on a built motor is okay, but on a stock motor? wow, i was like what the heck are you thinking for running 12psi all day with a stock motor. :SHOCKED:
 

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good thread. i would run around 15 dd if i were to drop it as low as 9.5 though.
 

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Wow...Thanks for all of the great responses. Regarding the above, can the stock one be easily modified, or would it be better to replace it with an RSX oil pump assembly?
The 2 reasons to change the pump are to get rid of the balance shafts that are part of the stock assembly and to improve flow. Best option is to use an S2000 pump and port it for better flow so you don't have flow and foaming issues at high rpm. That's why you want to change the pump.

Also, because the Si has balance shafts and essentially no oil pan baffles (the balance shafts are in the space where a baffle would normally sit), you will want to add a baffle in the oil pan. Hytech has been supplying these on K20 road race cars for awhile; so you might want to see if you can get in touch with the Hytech owner John Grudinski about that.

:eek2: Chris
 

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on a built motor is okay, but on a stock motor? wow, i was like what the heck are you thinking for running 12psi all day with a stock motor. :SHOCKED:
Nothing wrong with 12 psi DD at 11:1 if you are running good pump fuel and have tuned it right. It's all in the tune, especially when it's cold outside and you have crazy dense air. You probably want to recognize that you'll be close to the ragged edge on pump fuel and you don't want to run at 12 psi for too long without knowing what fuel you need for the conditions. 93 Octane should be good for 12 psi if tuned carefully (and maybe a bit conservatively).

Just like "it's not speed that kills...it's the sudden stop", you can apply a similar notion here. Something like "it's not the boost that blows your engine, it's the sudden knock". And good fuel and tuning will keep that at bay.

Chris at RedShift
 
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