Im gathering parts for my next motor build and i have decided to use Wiseco Pistons for many reasons. The problem is that when i look at their catalog the shelf pistons they list for my application are either below 8.9:1 or above 10.0:1. I was really hoping to be around the 9.2:1 - 9.4:1 range. So i guess im wondering how big of a deal it would be to run around 8.8:1 compression. Or how much more it would cost to order custom pistons. I could also consider going with another company but i would like to buy the wiseco's. Im looking for the ~500whp range.

 

the piston isnt the only thing that determines compression. how much the block has been decked or the head milled, flat face valves or dish, heagasket thickness, etc. all play a role.

 

Correct. The compression numbers i stated were for my exact setup.

 

I'd say go with the lower compression. For 500 WHP it will make it easier to tune and give you more margin for error. Both my turbo motors were 8.4-8.5:1.

 

get the 10:1, youll be happy with that. if you want lower, then bore the combustion chambers and/or use a b16 head, and/or use a thicker head gasket.


Modified by zeimbo at 5:15 PM 2/17/2007

 

The 8.8 cr would be fine. And like stated earlier give you more room when tuning. I have a set of brand new wiseco 8.8:1 cr pistons sittin here on my shelf that I will use in my next build.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by zeimbo &raquo;</TD></TR><TR><TD CLASS="quote">get the 10:1, youll be happy with that. if you want lower, then bore the combustion chambers and/or use a b16 head, and/or use a thicker head gasket.


Modified by zeimbo at 5:15 PM 2/17/2007</TD></TR></TABLE>

Huh?? You are advocating higher comp in a turbo motor, which is your opinion. I however do not understand the using the thicker hg. A thicker hg will lower comp not raise it. If I were going to lower the comp and had my choice I would do it with pistons not a hg.

If I remember correctly a b16 head has slightly higher comp than a gsr head.

 

8:8 is fine. I run wiseco 8:8 wiseco forged pistons on my ls vtec and it runs stock made 250 whp on 7psi

 

If your looking for around 9.5:1 pistons contact http://www.importbuilders.com he can get them for you

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by KeyserSoze &raquo;</TD></TR><TR><TD CLASS="quote">The 8.8 cr would be fine. And like stated earlier give you more room when tuning. I have a set of brand new wiseco 8.8:1 cr pistons sittin here on my shelf that I will use in my next build.

Huh?? You are advocating higher comp in a turbo motor, which is your opinion. I however do not understand the using the thicker hg. A thicker hg will lower comp not raise it. If I were going to lower the comp and had my choice I would do it with pistons not a hg.

If I remember correctly a b16 head has slightly higher comp than a gsr head.</TD></TR></TABLE>

He means go with the higher CR pistons, but do what you can to drop it down. In other words, go for the pistons that would yeild 9.3-9.8 with modifications. And FYI the GSR head yeilds higher compression due to 1.1cc less combustion chamber volume.

I'd go with 8.8 for 500whp tho. Its not like dohc 1.8's are that bad out of boost because of 1 point of compression, you'll hardly see a difference.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by zeimbo &raquo;</TD></TR><TR><TD CLASS="quote">get the 10:1, youll be happy with that. if you want lower, then bore the combustion chambers and/or use a b16 head, and/or use a thicker head gasket.


Modified by zeimbo at 5:15 PM 2/17/2007</TD></TR></TABLE>

what im using.

 

9.5:1 - 10:1 is fine

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by HiProfile &raquo;</TD></TR><TR><TD CLASS="quote">And FYI the GSR head yeilds higher compression due to 1.1cc less combustion chamber volume.</TD></TR></TABLE>

Good to know.

 

I have wisco 8.8's in my 1.8l now. I make around 600whp on C-16. It made 485whp @ 19psi on pump gas.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by nonvtecallmotor &raquo;</TD></TR><TR><TD CLASS="quote">I have wisco 8.8's in my 1.8l now. I make around 600whp on C-16. It made 485whp @ 19psi on pump gas.</TD></TR></TABLE>

8.8 just seems a little low to me but its all personal preference.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by HiProfile &raquo;</TD></TR><TR><TD CLASS="quote">He means go with the higher CR pistons, but do what you can to drop it down. In other words, go for the pistons that would yeild 9.3-9.8 with modifications. </TD></TR></TABLE>


i think the lower compression stuff is better for track cars but its good to have to have like 9:1-9.6:1 so you have a little bit more low end for the street. either way, its possible to get the compression that he wants, he just has to work the numbers. you can either do the 8.8 and mill the head to get into 9:1 and higher or get the 10:1 and bore the combustion chambers and/or run a thicker headgasket.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by cuin9sec &raquo;</TD></TR><TR><TD CLASS="quote">

8.8 just seems a little low to me but its all personal preference. </TD></TR></TABLE> its not too low when you run pump gas all the time.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by cuin9sec &raquo;</TD></TR><TR><TD CLASS="quote">

8.8 just seems a little low to me but its all personal preference. </TD></TR></TABLE>

Says the person who's building a sleeved 81.5mm motor instead of a larger bore. An 83/84mm 8.5:1 motor is going to make a whole trainload more torque and have much better throttle response than an 81.5mm 10.5:1 motor, so what's your reasoning again for liking higher compression?

You could go drive three IDENTICAL cars, one at 8.5:1 one at 9.5:1 and one at 10.5:1 all other variables being the same and you would not be able to give a 100% positive answer on which one is which without dynoing it. It's not something you'd bet your house on, and the difference is too minute to say "I prefer this" without giving any PROOF other than saying because you like it.

 

Im pretty sure boosted hybrid or whatever did do a test on a turbo car and it was like a 20 whp difference on the dyno.

 

i can speak form experience i have used 10-10.5 for the past 6years on my motor its nice the way the car feel but if you run the car on pump gas its suck caus if you change anything and i mean anything with out retuning the car it will blow up.

 

8.8 isn't exactly low in the realm of boosted car. most stock cars run 8.5 or lower. you wont notice a difference from 8.8 to 9.2. i say run the off the shelf 8.8 piston.

 

Don't use a thicker headgasket. You'll lose your quench area and that could lead to detonation and/or preignition. And as Mike said, run the 8.8 off the shelf pistons. Or have the higher compression pistons milled down and then CC your setup.

 

well contact endyn then. they have custom pistons that will give you the compression your want (9-9.5:1)

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by patriot &raquo;</TD></TR><TR><TD CLASS="quote">Don't use a thicker headgasket. You'll lose your quench area and that could lead to detonation and/or preignition. And as Mike said, run the 8.8 off the shelf pistons. Or have the higher compression pistons milled down and then CC your setup.</TD></TR></TABLE>

ding ding! Quench area is very important, thick headgaskets are bandaids, it's retarded to use a high comp piston and thick headgasket if you don't have to. 8.5-8.8 is great for a street car. Trust me, at 350+hp on pump gas, your engine will be MUCH happier with the lower compression. Take a tip from the oems that use turbos, you think they build them at 8.5:1 and below for no reason?

I use the Wiseco 8.8:1's on most of my street builds. Don't be fooled into thinking you're going to loose a bunch of power with the lower compression...

 

is a 83mm wiseco with 8.8 to 9.2 cr a custom piston?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote &raquo;</TD></TR><TR><TD CLASS="quote">ding ding! Quench area is very important, thick headgaskets are bandaids, it's retarded to use a high comp piston and thick headgasket if you don't have to. 8.5-8.8 is great for a street car. Trust me, at 350+hp on pump gas, your engine will be MUCH happier with the lower compression. Take a tip from the oems that use turbos, you think they build them at 8.5:1 and below for no reason?

I use the Wiseco 8.8:1's on most of my street builds. Don't be fooled into thinking you're going to loose a bunch of power with the lower compression... </TD></TR></TABLE>

But But But ... What about off boost (vacuum) driving. You will loose that 50HP you have J/K. I agree. 8.8:1 is fine