Help with Corsa A 1.6 8v twin 40's

[Atic]

Hi, sorry im posting in English but there is no other way. Feel free to erase.

I need help with my C16SE. Im using Twin webber DCOE 40mm, a 280º shrick camshaft, -0,75mm head, Ks pistons, 1.6 smoothed head with 1.4 MPI valve cover, 1.2st ignition.

Somehow pistons always break after 1500kms. They break between the rings. The sparks are always dark. They already broke in other 1.6 8v engines with same specs but 1.3 head with 1.8 valves and 1.4 ignition.

This setup was previously running a 14NV engine and no problems came out.

The DCOE specs are:
main jet 120
air corrector 170
idle 55f8
Pumjets 35-40
aux venturi 40

[Atic]

Some pics of my engine:








This piston its not damaged but the arrow indicates where they usualy break.
[/img]

[[T-e-T]I3@8µ|_()N]

So, I think your pressure of the mix of gas is to high. you said your head is -0.75? thats the problem i think.

check www.risse-motorsport.de is german but i hope you can translate it a bit. they are selling "schmiedekolben" (dont know in english). or check out the internet for bether and harder pistons. ask some racing companies like risse mantzel schrick or opc (opel performence centre)!!!!!!

or buy a new head from the C16SE. risse tunes the head for 450€. bigger valves etc.

i hope i could help a little bit.

[Atic]

i hope i could help a little bit.

Every idea is helpfull, Thanks a lot i will check the info you gave me.

[PsychoOne]

[T-e-T]I3@8µ|_()N means with "Schmiedekolben" -> forged pistons.
I also think the pressure is too high. You said that this setup ran on a 14NV without problems, but the C16SE has in contrast to the 14NV an increased compression ratio!
Be aware that the mixture is not too lean!

[Atic]

[T-e-T]I3@8µ|_()N means with "Schmiedekolben" -> forged pistons.
I also think the pressure is too high. You said that this setup ran on a 14NV without problems, but the C16SE has in contrast to the 14NV an increased compression ratio!
Be aware that the mixture is not too lean!

Thanks for the translation, i already checked on a web translater

The mixture seems fine, spark plugs are brown.

Anyone else has experience with this?

[[T-e-T]I3@8µ|_()N]

So I think: check out the kompression. thats my feeling.

[Atic]

So I think: check out the kompression. thats my feeling.

I will next week. Will mesure everything to see if it is too much.

Thanks everyone!