Haven't posted here much. been just trying to do a lot of reading. but I'd like some opinions on diff pistons. I plan on picking up either an ek or an eg here pretty soon and doing a boosted gsr motor. got my build for the most part already figured out, just stuck on a few things, piston cr being one of them. im pretty sure I wanna go w/the cp pistons. just not sure if I want to go w/the 9.0:1 or the 9.8:1.

I plan on going w/the bw s372. most likey the race cover. 1.00 or 1.10 a/r.

and not sure if I'm gonna go pauter, manley, or crower rods yet.

preferrably would like to hear from people w/similar builds that have used these pistons and/or rods. but open to all suggestions.

thanks

 

i dont have a huffer that big, but if i were to do my build over again, i would do higher than 9:1 compression. with the b16 head im looking at ~8.8/:1

i did however choose cp pistons with the larger wrist pin, calico coated. and they are holding very well.

 

What are your power goals?

 

power wise, im shooting for mid/high 700's. maybe low 800's.

 

are you running the 372? when are you seeing full spool w/the 9:1's? how many psi you running?

and is the 8.8:1 due to the head gasket?

 

Why would you want to go higher than 9:1?

 

spool. I would imagine there would be a difference in spool going w/a setup like the 9.8's or higher rather than the 9.0's. just dont know if it'd be that noticeable.

 

bump. anyone else have any input?

 

In for info about to buy new pistons

 

I'd recommend JE pistons with an upgraded wrist pin, 9.1 compression and some manley turbo tuff rods.

 

I don't think it would be for spool. That doesn't make much sense to me.
In for reasons on why to go to 9.8:1. Aren't we trying to prevent knock...

 

way to low of a compression at 8.8:1. with that compression your going to struggle to make power without a ton of boost. if your going for decent power you need to match your hp goals, compression ratio and turbo well. without that ur just thrwing things together and hoping it will make power....lame

 

compression doesn't really affect "spool" it will affect overall power out put though and ease of driveability.

 

5th gen accords have 8.8:1 CR's and they are making good power on boosted setups...even on stock internals. Granted my examples aren't honda's, evo's run a compression ratio of 8.8:1 and sti's run at 8.2:1.

I feel like 9.8:1 is too high for a Forced Induction setup to be safe...Of course this depends on a bunch of different variables and what the car is used for.

 

The Acura RDX also uses an 8.8:1 ratio on it's turbo k23

 

im running 10-5-1 comp on my 84mm sleeved block with pro 1 cams and t367 turbo.
making 520 at 15 psi. high comp with the right tunning means higher horse power with less boost which gets the motor to work less for HP #s

 

I guess I would rather just use lower cr pistons to be on the safe side.

 

either compression will work fine for your power goals, cp pistons are a great choice and any of the rods you named will work although crower claims 700hp or something like that for their rods

 

CP 9:1 Pistons, Manley Turbo Tuff Rods. Sleeve your block to 83mm. Perfect set up for 800whp

 

For the price, Supertech pistons are a good value. I use them in my race motor (approx. 600whp) with zero issues. I also like that they have a friction reducing coating on the skirts.

 

You're right, and many of those variables are accounted for with us 9.5:1 and higher compression engines (My other car is 10.5:1 Sleeved 81mm). It's not the power output that's the issue, ( an 8.8:1 engine w/ the same turbo will eventually make the same power as a 10.5:1 engine, but the amount of boost used is VASTLY different, and because each turbo has a different "sweet spot" in terms of its characteristics, it may be better for many to have higher compression than an ultra-low one. That same 8.8:1 engine would take 25psi to make the same power as a 10.5:1 on only 12psi. If the best PR point to use a turbo is at 2.2PR ( about 17psi), the higher compression engine will take less boost (and less heat) to get there, as opposed to the 8.8:1 compression one.

Detonation can be eliminated based upon the fuel and tune used. The old way of thinking was to keep compression ultra low so that inaccurate tuning methods could be used to have the driver get away with somewhat drivable tune and get by; nowadays people want the car to respond as though the factory designed the car for specifically their purpose. So that's why they can do higher CRs.


OEM applications like the ones noted above use low compression like that because they must appeal to the masses of the different grades of fuel used, and account for different fuel availability so they can sell to the masses. They also use a very small turbocharger in which the "sweet spot" is at a very low rpm in order to maximize torque and low-range power, and not to make the car a powerhouse. Those are intended for the Everyday user, not enthusiasts

 

CP

 

Sounds good to me Shodan. The one part of you explanation I hadn't really thought about was that some average drivers may end up using varying grades of fuel. Keeping a lower compression would keep it safe for the driver to use that low of an octane.

I'm also thinking about this in a very DD sense, too so I was thinking 93 octane on a good tune with low compression would be the ideal setup. But I doubt he's building a 700-800hp car for DD lol. Do you guys think with the higher CR he can get away with pump gas for the power he wants? Or is e85 something to look into? I've never driven, let alone tune a high powered car like that before so I have no idea.

 

you also have to look that the motor was designed for longevity.

 

So does that mean people with high power motors don't go for longevity on their motors? Even though it's a race purpose motor, I would still try to get it to last as long as possible.