really worth your time reading this info for your turbo setup choice when you have picked out the motor you like.

http://www.turbobygarrett.com/turboby ... center/turbo_tech103.html

The guy at the turbo shop would have the compressor maps handy if he is saying those turbos are ok?. Looking back at your posts on this setup it looks very much like those turbos are not a good match at all in their present config.Have a look at the garrett site and you might be able to work out where to aim some numbers at. Aim at nothing and you hit it every time as they say.

I think the twin setup will be easier to sort with a few more cubes as well..GO the mighty A15!

crome rings are generly no good for a series as the bore is to soft i found out the hard way

sorry to but in. i usd a 1400 open chamber head to lower comprshion on my 1200 years ago but these are rare you can have a decomprshion plate made

Quote:
Its not a stock motor either.
My guess is you have never given it a boot full and then pulled the plugs.
If it runs fat down low, there isnt really any point driving it home and letting it idle and then pulling the plugs. You already know it runs fat down low.
You need to look at the problem in the conditions its happening.

Its hard to find a hole in a tyre when there is no air in it.

sifting through some of these replies has given me a lot of good information, thanks guys (even the negative stuff is appreciated)

by building a boost friendly a-series, i intended to fix the tune, injectors and other obvious problems also, not just try to build a titanic block

speaking to the turbo guy he was quite confident turbo size is not an issue, he did port out the wastegate as i told him i had too much boost, but i will be waiting for the second turbo he fixes to be ported aswell to match

yesterday i picked up a pulsar a-14 head, this looks to have a very open chamber and should be good for lowering compression (will get picture, not sure on effects to squish )

the talk of injectors maxing out leading to detonation which is damaging rings has been really helpfull

anyway this has been a good thread, im sticking with twin turbo, but it could be some time before this setup makes a comeback, especially if the ute sells i wont really have a hole for it


to answer some smaller questions:

-i've never pulled out white plugs from the turbo setup

-all motors have used stock CR, and essentially been stock internal, the two a15s were practically fresh rebuilds, the other two were basically dead when i started with em

-"how many more engines will it take before you realise that twin turbo setup is fundamentally flawed?" AT LEAST FIVE TO TEN i'd love to hear your explanation of that theory (i have dragged off modified wrx's, skylines and 250kW plus commodores) its got potential as long as i get it half reliable.

from this thread i have learnt, as some people have said recently, getting it tuned right is more important than anything else

im still keen to make a decent block for it, and hence why i asked the questions

unfamilia,

the idea that two 1,000cc engine turbo's are good for an A12 or A14 or A15 is the wrong way to go thinking things through.

There are a bunch of things involved in turbo selection not least of which is understanding the airflow capabillities and characteristics of an engine and matching it against some compressor maps for a start.

I would begin by pointing out that you usually pick a turbo size by first describing the engine it's intended for. This importantly includes size. A 20% increase in capacity(going from A12 to A15) is a different pair of turbos / turbo spec.

None of that is needed. You can spend all the money you want on an engine. Build one out of gold if you want. Run it lean and get the internals white hot and it will go bang.
Just because an engine is running strong, does not mean it is running good. A thing as simple as looking at your spark plugs will tell you the truth about your tune.
Learn what spark plug burn colours mean.
Then when you see your plugs are white, ask yourself what it actually takes to burn metal to go white.

having know 1200rc for years through this site, the set up was originally off an a12 with blowthrough if my old brain can remember, but not much exisits off that original set up anymore.

The problem is the injectors running out of flow and leaning out from history, and if your still using the welded cor for the cooler, that always had some flow issues.

A decompressed a series will hold but not reliably with upwards of 10psi for a daily driver.
I like the twin set up, it has its merrits and potential. The boost needs contoling but with that said theoretically tow turbos from a 1 litre are well matched to the engine in a parralel set up, at least its not sequential (staged set yps like rx7) set upwhich have more problems.

My only advise is like ANGE, keep with it 1200rc, but build one motor this time and do it right! maybe an a12 with a15 head etc... long stroke large bore engines like a15 historically dont like high compressions, but small stroke large bore ones do..

maybe a a12 with 76mm bore for the a15 head and thick head gasket might be a goer...

These threads are like broken records. Im 100% certain that both L18_B110 and I said with the first motor that blew up, that the tune is the most important thing. Run it lean and it with melt the rings.
If you havent learnt that yet, it doesnt look like you will.
Your boost problems are turbo size issues.
Your blown engines are tuning issues not engine strength issues.

"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"

aftermarket kits for standard engine do exist and don't seem to blow motors. So standard CR should be possible IF the boost could be kept low. But 14PSI is a bit much.

FUNDAMENTALLY the problem is the TUNE!!!!!!!!!!!!
No matter what turbos Mike uses, no matter what squish, or what PSI he is using, what rings he has, what pistons he has ....if the engine is running lean then changing all of the obove won't help him much.

imagine If you have air in your braking system, fitting : larger rotors, different pads, different tires, adjusting brake balance..........won't help!!! Bleeding the brakes will!!