Do you have compressor maps for the turbos? (maybe the guy who rebuilt your turbos can help there with specifics for the highflow would be of benifit).

I just read your earlier posts describing your rational for turbo choice and the issues you have. I am pretty sure you haven't got the right turbos on there for your application. The actuators etc aren't the problem, the turbo specs are.

lower compression is a must have. Get the right sort of pistons to do it and you don't have big issues.

I'm not really going to bag the twin turbo setup but heres my 2c...

The twin setup can cause issues with boost control and it's very likely to be a problem.

Twin turbo's are tricky to setup. They can have surge and other issues if they aren't selected very accurately. At a guess I would say the ones on this motor are a lucky dip guestimate more than a calculated selection, as such you have a big work around issue. Things like a bit more capacity and a cam can improve things or make them worse depending on the problems. You may require things like a balance pipe also to make it work.A twin setup is really aimed at getting the package to have a big spread of power, not a waste of time in anyones books but, quite a challenge when your the first to give it a shot.

Ultimately you need to be prepared to play with changing around front and rear housing sizes and wheel trims etc. to bring out the true benifits over a well selected single if there is any.

This is all accademic if wearing a 'twin turbo' badge is all your after however.

You still haven't answered my question,
Have any of the engines you've killed been decompressed?
TOPGEAR didn't decomp his A12, but he has a head off a bigger motor. And his conpression is only 5 psi higher than my dished out piston, and decomp shimmed A15.
If you are gonna force a motor with a standard CR, IT'S GOONA BREAK!!!!.
Try decomp shimming a motor, and see if it lasts longer

I think it would be wise to take alot of advice on here, heaps and heaps of experience talking on here, and as Rallycar said before he wanted advice from these experinced motor minded guys...

Good luck Rallycar keep the forced fed Aseries alive

unfortunately i have no good advice to give on the topic..

but i would like to congratulate 1200rc on the success he has achieved so far with the twin turbo a series.

it may have its issues but its original and i have ridden in his old coupe and was very impressed with the power it makes..
and that was before it was efi...

keep up the good work mate


ps. just tryin to help keep you motivated

Dattogal, there clearly is something wrong if he can't CONTROl boost! Whether it's that the turbos are tired, they are outflowing their wastegates or the wastegate actuators are stuffed. The twin turbos have to go. There is absolutely no way that the turbos came with a 14PSI spring and diaphram from the factory so something needs attention. Maybe it is that he has just neglected the plumbing to the wategates and they are leaking?

ANd with the ring theory, you will be looking for ever if you think you are going to find a set of rings that will go straight into his motor and survive with the current set up. The rings are most likely going because of detonation because of too much boost and running turbos out of their efficiency range.

EDIT: beat me to it L18!

how many more engines will it take before you realise that twin turbo setup is fundamentally flawed?

the fact it keeps blowing up indicates there is a problem with the setup/tune. trying to find rings that won't break is treating the symptom not the problem.

personally I wouldn't put a good bottom end under that setup until you have it sorted so that its not blowing engines up all the time. replace the one broken piston (or whatever the problem is this time) and have another go at sorting that setup and tune out properly. then build a good engine.

All of this is well and good but what does it have to do with finding rings to cope with 14 psi???

There's nothing wrong with his turbos, the reason he's rebuilding them is from other issues, like leaking filters etc

So get off his turbos
He can't CONTROL the 14 psi boost
He doesnt actually WANT to run it this hard all the time, its just that he wants a motor to be able to cope with that scenario if he cant get better control of it

Can the squish talk and get back on topic!!!

DGxx

A good aftermarket cam takes some of the restriction issues out and helps the boost arrive earlier with less required to make the same power as a stock cam.

The cam in mine is;

IN opens :30
IN closes :65
EX opens :70
EX closes :30
Lift @ cam .260"

the pulsar turbo pistons;

ACL duralite part no. 4MKRY8055-0.50

This setup is holding onto 14psi pretty easy however I have EFI and an intercooler to keep a lid on things a bit.

I think he is either gonna have the block decked, or his pistons already stick out too far.