pistion type dump valve

[danbmx_69]

fitted one of these to my car the otherday am very happy with it as it dosent go off all the time so you can drive normaly with out it sounding, it dose sound but very quiet but i do think i may have a problem as the first day i fitted it when comeing of full boost it was quite loud when dumping the air, but now after a few days it seams to have gone very quiet evan letting of form accelerating quite hard ie on to a motoway, evan before you could be doing say 30 in 4th gear put your food down just to build full boost and then let off and it would sound quite loud but now doing the same a few days later it seams very quiet, so i am wondering is it possible that i have a boost leak and the air is now getting out some where else when the throttle is closed, or is it at all possible the vavle itself could be stuck open sligtly?
http://i24.photobucket.com/albums/c18/danbmx_69/IMG-20130209-WA0000_zps11916cde.jpg

[VVC-Geeza]

I would say give it a few more days,very easy to start imagining different sounds when something new has been fitted.You could always source a Forge one if your not happy with it.Love mine Tishhh :D

[E_T_V]

Check the pipes haven't come off!

[danbmx_69]

After my drive to work today I do think I have a boost leak as now my boost gauge goes up to 12psi and then tails back to around 10psi and before it use to stay at a solid 12psi and not move at all

[E_T_V]

Is 12psi standard boost?

[danbmx_69]

No 12 psi isn't standard boost I dont think, mine is running 12 due to the map

[VVC-Geeza]

Standard boost is 9 psi

[E_T_V]

Is it a clean 9psi or is it artificially modulated to lower levels at low revs (like the T16 turbos that I'm used to).

I think I already know the answer to that as if it was a natural 9psi then there would be no need for the boost control valve.

T16 turbos were 7psi up to 4500prm and then modulated gradually up to 11.5psi at the top end. This was done to protect the gearbox and give a nice linear power progression. Is the K turbo similar?

And what is the dinky little original turbo capable up to?

[VVC-Geeza]

Is it a clean 9psi or is it artificially modulated to lower levels

Standard factory map,boost is bottom line

http://i155.photobucket.com/albums/s303/mick_064/powergraph039.jpg

[E_T_V]

EEeek those curves look pretty horrid. Turbo is obviously too small as boost tails off above 5k. Not sure I like the torque/boost spike either.

Did they do AFR's on the run too?

[danbmx_69]

http://i24.photobucket.com/albums/c18/danbmx_69/20121103_205359.jpg
mine with the z and f map
need to wait till the week end so i can take a look at this dump valve to see if i am leaking boost

[E_T_V]

That looks much better. I'd like to see boost and AFR's though to check they are safe. :)

[VVC-Geeza]

EEeek those curves look pretty horrid. Turbo is obviously too small as boost tails off above 5k. Not sure I like the torque/boost spike either.

Did they do AFR's on the run too?

It was a basic powergraph so unfortunately no AFR reading.

As Dan illustrates,Z&F can make the graph look very different :)

[E_T_V]

I can make the graph look very different. But perhaps not in a good way!

What turbo is fitted to these and what does it flow? I'd have throught it would be really on its last legs hitting 200bhp.

[danbmx_69]

I can make the graph look very different. But perhaps not in a good way!

What turbo is fitted to these and what does it flow? I'd have throught it would be really on its last legs hitting 200bhp.
its a gt2052ls turbo with these engines you start to push your luck around 220bhp i have been told by mark at Z and F,who did a lot of development back at MG rover with these, and i dont think much more boost then 12PSI is recomended, but i do think it is possible to run these around 220BHP with a good enough intercooler/ charge cooler as i think its boost that kills them hence not pushing it much more over 12psi

[E_T_V]

I'll try and find a compressor map for it if one is available. The boost tailing off at high rpm would indicate it is a little on the small side. (I'm used to running a T28 and a T3 on non K series).

[danbmx_69]

I'll try and find a compressor map for it if one is available. The boost tailing off at high rpm would indicate it is a little on the small side. (I'm used to running a T28 and a T3 on non K series).
i think this is the whole idear on the turbo of these cars is just to generate some low and mid range torque just to get the thing going