Forums/Z31P/z31-performance-upgrade-forums engine-mechanical-aa/z32 NA wiseco pistons in a z31 turbo application?
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300zxtproject: (2008-04-03 04:25:01)
hello there i was in the process of rebuilding my z31 turbo with NA (9:1 CR) but i just found out i need new rods (bent) and i was looking at the z32 wiseco pistons with the eagle rods but i want to retain the higher compression to have some more lower end torque, so my question would the NA pistons (10.5:1 CR in the z32 so that equals 9.5:1 CR in the z31) hold up to about 14-16 psi and about 7,000 rpm redline? many people have said that the NA (z31) pistons would hold up well over 350 whp so would .5 more CR make a BIG difference? thanks
brewster240: (2008-04-03 06:43:43)
should be fine.
unless there is some design flaw im unaware of?
good tune is crucial.
1SickZ: (2008-04-03 14:09:12)
Yes it makes a BIG difference because it is a domed piston.
9:5
[archived image: l85_piston.jpg]
Versus
10:5
[archived image: h86_piston.jpg]
Your valves won't be happy.
300zxtproject: (2008-04-03 17:13:55)
[quote]1SickZ wrote:
so my question would the NA pistons (10.5:1 CR in the z32 so that equals 9.5:1 CR in the z31) hold up to about 14-16 psi and about 7,000 rpm redline? many people have said that the NA (z31) pistons would hold up well over 350 whp so would .5 more CR make a BIG difference? thanks
Yes it makes a BIG difference because it is a domed piston.
9:5
[archived image: l85_piston.jpg]
Versus
10:5
[archived image: h86_piston.jpg]
Your valves won't be happy.
oh wow… i didn't know that the NA pistons have the dome design. thanks
so does anyone know of some good aftermarket pistons with custom CR for the z31?
1SickZ: (2008-04-03 17:53:44)
BRC
300zxtproject: (2008-04-03 20:35:19)
thanks 1SickZ. i called BRC and the have both 8.5/1 (dish) or 9.2/1 CR (flat) pistons and they also have some connecting rods to go with them for only 360 for the set of rods.... not bad at all. so i guess i'll go with them. 1SickZ, you don't happen to have any pictures of you pistons and/or rods, do you? thanks
300zxtproject: (2008-04-04 05:02:34)
Does anyone know if the BRC rods would fit STOCK w-series z31 pistons? i need some new rods and i want to keep the 9:1 NA CR. thanks
Kennedy: (2008-04-04 07:36:04)
BRC makes custom parts.. so they will fit if you ask them to make one that fit.
300zxtproject: (2008-04-06 17:37:02)
ok now i know that the NA wiseco pistons won't fit due to the dome design that they have. so does any other company make flat or dished pistons (besides BRC) for the NA z32 that will fit a Z31? i would really like to have 9.5:1 CR or at least 9:1 with some forged aftermarket pistons. thanks
SATAN: (2008-04-06 17:43:50)
Well, the problem you are facing is that in order to up the compression you have to have dome on the piston. Since there is going to have a dome and be made for the z32, It is not going to match the combustion chamber of the z31.
300zxtproject: (2008-04-06 21:14:27)
yea i understand, thanks for the response. so it seems like the BRC 8.5:1 CR piston are the closest i'll get to the stock NA CR. thanks
Andrevas: (2008-04-06 22:03:42)
stop thinking off the shelf and look into what companies want for custom compression ratios that will work with SOHC heads. there's a reason so much shit is custom fabbed in this community, because there's little to no aftermarket =(
VG36ET: (2008-04-20 21:46:47)
What he said.............. Guy think they can slap any pistson in their block…lol. Different valve cuts/reliefs and different pistons designs(dome, dish etc.) might not play nice.
I don't like the bottom end of a 8.5:1 turbo car on the street to say the least. I'll take a 9:1 turbo street car any day over the later.
BRC makes top shelf shit.........period. I wouldn't hesitate to use them again for ANY custom piston application from a N/A VG to the custom BMW V8 a friend is building. You don't need Ceramic coated tops but moly coated skirts is worth every red cent IMVHO and IME.
Peace
DMANN: (2008-04-21 10:54:08)
BRC made 9:1's for my Z even made them to fit my stock rods--88na-t