ive got my turbo charger setup starting to go on this weekend ....ive rebuilt the engine with the most expensive rings bearings and gaskets u can find......but now after all that ive been told even to run 5psi i will need to lower the comp ratios or my engine wont even last a couple of minutes....this guy i was talkin to reckons i need to get a shim (decomp plate)or take a bit off top off my pistons to lower the comp....he said without this ill be lucky to get 5 kms outa the engine????

whats the deal with this u guys do i need to lower just for like 5,6,7 psi

also what are u guys using for detonation control

ps i trust ur opinions more than this dude even though he seemed to know his ####.

what engine? what's the CR?

I've used an ACL 'head saver' shim on a turbo A14 before with no problems, but
you will also need to modify the dissy for less mechanical advance. Running a bit rich can help reduce the chance of detonation too. Be very careful when you first set it up and start tuning it - you're likely to have detonation issues to sort out, and you don't want to destroy the engine you've just built.

I very much doubt anyone with a turbo has enough self control to limit it to 5 or 6psi for very long!

sorry its an a14...... id say it has stock comp whateva that is which aparently is the problem......ive also been told that my head gasket is extreemly good but obviously not a shim......"modify dissy" so it does see as much advance u say...is there an easy way todo this.....yes i understand the first few minutes off runin need to be very careful because of the detonation issues..i geuss i just gotta make sure i run it rich and keep the boost down.....Quote:
i dunno ive heard they go welland i think ill be happy wif dat fornow maybe do it up to run more boost laters..im pretty sensible wif that sorta stuff though...

The advice you are getting is correct. Look at it this way...... If you rebuild your engine to have a 10:1 compression (on atmospheric pressure at your intake), then increasing the pressure of the intake by as much as 10 - 12psi will raise your compression to the extent where your engine starts working like a diesel, otherwise known as Pinging!
You can maybe look at an alternative piston choice - maybe something with a hole machined in the crown. Or like you said, a thicker head gasket. Placing an extra washer behing your spark-plugs can slightly recuce compression too.

not just for the first few minutes - until you have all the tuning sorted and no detonation problems. The first few minutes you just want to be sure you are getting oil pressure to the turbo and engine. Sitting there idling isn't going to be a concern if you have oil supply sorted. You might have trouble finding a mechanic willing to touch the thing, so you'll probably have to do it yourself. While tuning and road testing, if you hear any hint of detonation, back off immediately and go do some more head scratching. That can't be stressed enough! it doesn't take much detonation to kill an engine running forced induction, or at least do enough damage to cause piston/ring failure in the not too distant future. Less timing or more fuel will be the main things you'll be adjusting obviously. If you can get access to a portable sniffer unit they are invaluable, so you can keep an eye on your mixtures while road testing. Boost gauge is pretty much mandatory too so you have some idea what's going on when tuning.

If you really are going to only run 5 or 6lb boost you might get away without a head shim.

Our rough'n'ready A14 turbo engine was a standard A14 with .030" ACL head shim, locked dissy (ie no mech advance) set at 10degrees advance, which was not the greatest for off-boost driveability, but that wasn't a real objective of ours. That's the easiest way, but certainly not the best. Bit hard to describe how to limit the dissy's advance mechanism, but its not particularly hard to do. We also ran water injection and up to 12lb boost. It seemed that 4lb was the point where it started doing anything useful - under that and it may as well have been naturally aspirated. 5 or 6psi won't be a rocketship or anything, but you should get a useful power gain.

1200rc's twin (tiny) turbos ran ten pounds through an intercooler in a blow through carby setup standard a15. genuine graphite nissan gaskets are very very hard to go past. have you got any form of inlet charge cooling? intercooler or water injection or anything?

it sounds like most are u are saying.....u can do it....but......u probablyshouldnt cause it wont last......i meen if i need a shim ill have to get one....it cant be that hard to just rip the head off chuck it in and start it up....and a shim cant cost more then 100 or sumfin.....its just a shame since i just paid #### loads for a mad gasket that i was told is invinceable.......seriously ill be runnin 7 psi MAX like that is the highest...and apparently there is a dude in my area that knows his carby tunin that will do it for me....


put it this way lets say i whack it on....get it tuned perfect.....what is the owrst that will happen....blow head gasket??? then i just rip it apart and chuck a shim in....i could be way off with this but i dunno.....
also to lock the dizzy cant i just plug the vac hose up....

ps thankx heaps for ur help with everything u guys really have some knowledge

sorry ...to answer the other question yes i will run small cooler

ive been lookin for ages.....what the hell is the stock comp ratio in a a14???