Boost Issue

[rmagictastic]

HEELLPPPP!!

it worked, now its gone again!!!

symptom:

boosts full to 4500rpm.
after this point the boost drops progressively 0.8...0.7/0.6/0.5/0.4/0.3/0.2/0.1/  as i get toward redline.

i do not know if transition is happening?

are these the symptoms of the 2nd turbo not coming on line eg. the first turbo can only out put so much boost, as the engine takes up more load the 1st tub cannot handle the load on its own and therefore boost decreases.

Basically is this the 2nd tub not coming on line?? or would i expect to just see no boost straight away at 4500rpm??

BTW ive just done the rats nest!! but i need to know the above to diagnose the problem.

cheers

Nick

[Warthog]

After I blew my twins up on the strip and another set of stock twins were fitted a boost problem started now and then. It got more frequent as time went on.
I would go for boost and get the full 1.4 bar, come off boost driving along then go for it again and only get 0.5 bar. I noted that I could predict when I was going to get boost as I could hear the exhaust tone change prior to 0.5 bar. It seems I may have caused some damage or some oil may have got into the bottom actuator that opens the flow of gasses in the link between the twins ( I know what I mean even if your scratching your head ) anyway I rang Geff at RE:WORX explained all the symptons and he said it would most prob be that actuator and the next time down we would change it.
Sure enough went down for my new 1.5 locking diff to be fitted and he had the car on the ramp and the bottom actuator changed in next to no time.
Result back to full boost, what a star, don\'t know if this sheds any light on your prob mate but defo give Geff a ring and run your prob past him. HTH.

[rmagictastic]

Im thinking that the second tub might not be coming on at all!!

 

The way im thinking is that if you just leave the 1st tub on line throughout the whole rev range when it passes its max power @around 5000rpm, the it will not meet the requirements of the loaded engine eg. Engine Load increases displayed boost would decrease?

Do the tubs come on together when people say the 2nd tub comes online? Know what I mean, at 4500 revs do you actually have both tubs on line, I was always under the impression that the tubs actually switched but I now think im wrong.

 
Did you understand any of that??

 See attached graphs just to confuse matters

[nikp]

When the second turbo comes online, it comes online with the first. So both are in operation at the same time.

[rmagictastic]

When the second turbo comes online, it comes online with the first. So both are in operation at the same time.

THANK YOU!!!!

[Warthog]

Thats what I was saying about that bottom actuator, It\'s the one that opens up the valve or whatever it is that lets the boost flow to bring the second
turbo on line. The problem I was having was that it was letting it happen now and then instead of when I wanted it too. It may be that it\'s not opening the valve on your FD, but as I say best to make that call and talk to a tuner who knows what they are doing. Whoever you have faith in.
I have total faith in Geff as he has always been spot on. Thats why my FD is making the power it is, I followed his advice on how to get to where I am now and did it in the correct sequence. He has saved me a lot of waised time and money. HTH.