just a quick query i just finished rebuilding my vlt engine and the thing im not sure about is that i heard that the ACL duralite pistons are not that good that was after i had bought them and slotted them in. i know the rings a **** hot along with the big end and main berings but the quiry is with the pistons. i am running a 1.5 mm dcomp plate aswell as a 3 inch exhaust and dump pipe aswell as 3.9 in a nine inch so i want some views on some times i will be expecting i have a big cooler and it will be wound up to around 12 to 15 depending on how much the stock t3 can hold any way any advice or help would be gratfull

The ACL Pistons are pretty good, a lot of people run them on these boards, the biggest killer of pistons is detonation, ACL Pistons are claimed to be able to run up to 18psi but i cant put that in writing. If your going to aim for huge power maybe you should have bought forged pistons or done a bit more homework on what you wanted to achive.

your right about the home work but at the time money was limited and so bought them i was hopeing to get about 15 psi out of it for i have all the fuel system sorted out i have the standard pump in the tank along with a vl turbo pump and a mercadies pump along with a sergtank and 1/2 inch line so i think i should be right with fuel all im not sure about is the pressure i should be running in to the rail i have been told around 35-40 psi of fuel will be quite enough whats your thoughts

Why'd ya put a decomp plate in there ? I had one in mine and ripped it out too laggy, no need for it, unless you're running a non turbo block.

Decomp plates are **** - i talk from experience- keep winding the boost up on them and watch them get spat out the side of the block literally!!!! as for the pistons - mine blew up - i have no trust in cast pistons Some original photos have not been recovered yet.

id your gonna go up to 15 PSI, get your t3 high flowed!

decomp plates are evil things, they should never be used. only ever use the nissan head gasket with these donks. RB30's have no problem with handling only 1bar, and can in fact handle much more. if you really have to lower your CR you should relieve the pistons, but the CR in the turbo RB30 is already low enough. in fact id prolly knock it up to 8:1. the RB30 has good enough head clamping to handle it, and provided your fuel system is up to it, you should never have any serious detonation anyway. i wouldnt bother with the stock VL t3, if you wanna get a turbo that flows decent amount of air and will bolt straight on get a VG30DET roller or an RB25 roller. much better things all round. either will pump about 200kW worth of air, response will be much better with the roller bearings, and they are a bargain at only $700 or so. the t3 on the VL is the same as the limited run of non-roller bearing turbos on early RB20's. crappy things really. :roll:

the only reason y im useing the decomp is because i was told by a number of people that the decomp will give u more room for comustion thus givin the cylender more air/fuel which in turn will give u more power also im useing genuine nissan gaskets im only going to ust the t3 untill the engine has been run in and then when i change it ill most likely throw the decomp plate away what do u guys reckon

nah, get rid of the decomp plate. any gain that you might supposedly get from having more 'room' in the CC will be lost through lower compression, not to mention a much weaker CC due to the decomp plate. also, its best to run the engine in with the compressor that you plan to use all the time. you wont get huge power gains from upping the capacity, as its not a huge engine to start with. in fact you'd prolly make more power if you destroked it.

will i have to get a new head gasket if i get rid of the decomp now for i havent started the engine up yet from rebuild

shouldnt think so, as long as its not damaged at all it should be ok

i think ill change it some other time for its a pain in the ass to change while its in the engine bay but then again i wont have to take off my exhaust mani or inlet mani would i for i only have to lift it up a couple of inches :? all i would have to take off would be the timeing belt?

Just leave the decomp plate dude.. decomps are a good thing, many extremely fast rb30s use decomp plates. Yes, on low boost.. there arent many positives, as there is much more lag than without it.. however if u do plan to run a quik street car, on high boost constantly.. its a huge bonus. It allows u to run Premium unleaded fuel on such high boost (15-18psi) whereas others with standard comp, need to opt for higher octane (avi, c16 etc).. and this becomes quite $$..

i started the car up today and took it for a run i couldnt help myself but to give it a big kick in the ass what a difrence from n/a to forced . in 1st it steped out and im on stock boost (for now) it doesnt have all that much lag but the turbo spulls up at about 2000 rpm so im not worried for i have the stall to compinsate for the lag

no chaser, decomp plates arent good in any setup, they weaken the combustion chamber considerably, besides the fact that the VL turbo has plenty low enough compression anyway. it shouldnt be dropped further. on a highly boosted car, decomp plates are the worst thing you could possibly run. also, whos gonna run c16 in a road car anyway? besides that its expensive, youll be replacing O2 sensors once a month. no point. in the end, its your choice turbes, but there is no point lowering the CR, as long as you have sufficient fuel, and your timing is good, there will be no detonation. youll have less lag at stock CR, on and off boost response will be so much better, and you wont be blowing plates out the side with the slightest detonation.