weisco piston question
12-01-2008, 11:30 AM
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weisco piston question
was on ttr and saw them with the diffrent compression ratio and diffrent bore whats the diffrence between the two compression rations, which one would be better for a n/a build running nitrous and with the overbore of 20, do you have to do anyhting to your stock sleeves? thanx
12-01-2008, 11:42 AM
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was on ttr and saw them with the diffrent compression ratio and diffrent bore whats the diffrence between the two compression rations, which one would be better for a n/a build running nitrous and with the overbore of 20, do you have to do anyhting to your stock sleeves? thanx
12-01-2008, 01:26 PM
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Our stock compression is 10:1. If you are going for an NA nitrous build then you may want to stick with stock compression(or higher) but you want to call wiseco and make sure they can handle the amount of power you want to make under nitrous.
Overbore requires you to modify your sleeves and it just gives you a bit more displacement.
Overbore requires you to modify your sleeves and it just gives you a bit more displacement.
12-01-2008, 03:17 PM
#4
was on ttr and saw them with the diffrent compression ratio and diffrent bore whats the diffrence between the two compression rations, which one would be better for a n/a build running nitrous and with the overbore of 20, do you have to do anyhting to your stock sleeves? thanx
12-01-2008, 03:45 PM
#5
Our stock compression is 10:1. If you are going for an NA nitrous build then you may want to stick with stock compression(or higher) but you want to call wiseco and make sure they can handle the amount of power you want to make under nitrous.
Overbore requires you to modify your sleeves and it just gives you a bit more displacement.
Overbore requires you to modify your sleeves and it just gives you a bit more displacement.
Last edited by HunterKiller89; 12-02-2008 at 06:12 PM.
12-01-2008, 03:56 PM
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If you get the .20 overbore, you will have to get your sleeves bored out .20
Even with stock bore, it's still a good idea to get a slight honing done on them because like they said above, the forged aluminum expands more than cast.
Even with stock bore, it's still a good idea to get a slight honing done on them because like they said above, the forged aluminum expands more than cast.
12-02-2008, 05:41 PM
#10
I'm old school
Here the skinny...
Wiseco makes 2 compression ratios. A stock compression, and a reduced. The 10:1 stock ratio is designed to be used in cars that will remain NA, but make more power. So, as you can probably figure, that would be nitrous. The lower compression ratio (8.9-1) is for forced induction applications, like a turbo. Those are the pistons I have.
The .020 overbore (not 0.20, that would be huge) is for REPAIRING a damaged engine. It is really not designed to be used as a means for increasing displacement. When you go overbore, you have to recut the particular sleeve that was damaged .020 oversize to match the piston. This process is used to cut away any kind of deep scratches in your cylinder that might have happened as a result of a rod breaking. It is designed so you can replace one piston, and still leave the rest alone at stock size. It is not meant to replace all 4 at once.
Do the math. The L61 Ecotec has a bore and stroke of 86mm * 94.6mm.
86 diameter, 43 radius.
3.14 x 43 x 43 = 5808.8 x 94.6 = 549512.94 cubic mm of displacement per cylinder.
Times 4 cylinders is 2198051.74, or 2198 CC's for the whole engine (the actual published spec is 2189).
Now change the bore from 86 to 86.5 (the .020 overbore), and the new number is 2223684.78, for a difference of 25633.04. That's 25 CC's if you overbore all 4 cylinders.
You would gain one percent of displacement. And the cost to get it would be rediculous.
Wiseco makes 2 compression ratios. A stock compression, and a reduced. The 10:1 stock ratio is designed to be used in cars that will remain NA, but make more power. So, as you can probably figure, that would be nitrous. The lower compression ratio (8.9-1) is for forced induction applications, like a turbo. Those are the pistons I have.
The .020 overbore (not 0.20, that would be huge) is for REPAIRING a damaged engine. It is really not designed to be used as a means for increasing displacement. When you go overbore, you have to recut the particular sleeve that was damaged .020 oversize to match the piston. This process is used to cut away any kind of deep scratches in your cylinder that might have happened as a result of a rod breaking. It is designed so you can replace one piston, and still leave the rest alone at stock size. It is not meant to replace all 4 at once.
Do the math. The L61 Ecotec has a bore and stroke of 86mm * 94.6mm.
86 diameter, 43 radius.
3.14 x 43 x 43 = 5808.8 x 94.6 = 549512.94 cubic mm of displacement per cylinder.
Times 4 cylinders is 2198051.74, or 2198 CC's for the whole engine (the actual published spec is 2189).
Now change the bore from 86 to 86.5 (the .020 overbore), and the new number is 2223684.78, for a difference of 25633.04. That's 25 CC's if you overbore all 4 cylinders.
You would gain one percent of displacement. And the cost to get it would be rediculous.
12-02-2008, 06:46 PM
#13
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now, in the case of my M10 that i'm building, i AM overboreing for more displacement, but, i'm all stroking it out, so i'm going from 1.8l to 2.2l.
that's a big difference.
i don't know if it's possible to do, but it may be worth looking at fitting a 2.4 litre crank to your car, give you a little more stroke.
Last edited by joeworkstoohard; 12-02-2008 at 06:46 PM. Reason: Automerged Doublepost
12-02-2008, 06:55 PM
#15
Senior Member
again, in the M10 (which i realize is a 30 year old engine from another country) the different blocks were just machined differently and any block can be bored to the max size.
12-02-2008, 08:22 PM
#18
someone else brought it up too...i think it was a big hassle due to something about the crank reluctor wheel, so in addition to boring out the block (or getting a 2.4 block), you would need to swap electronics as well. in the end, it was decided that the HP gain is definitely not worth the cost
anyway, thanks for the info on the overboring. i learned something new today
anyway, thanks for the info on the overboring. i learned something new today
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