Hello all.

I'm having some problems with my zetec turbo.

Trying to set my boost a little higher with a bleedvalve it can't hold a decent amount of boost.

Had a -31 on before and now put an even stiffer one on but it can't hold more then 0.8 bar (12 psi)

i'm getting 1.3 bar (18-19 psi) when the turbo kicks in but rappidly goes to 12

The turbo has some play but can that cause this drop at such low levels?

It's a 2 litre zetec turbo with stage 3 rst t3.

Thanks

 

I might be right in thinking you need to adjust the rod on your actuator rather than trying to raise your boost pressure with a bleed valve. I believe if you try to bleed too must with a bleed valve this produces boost spikes.

 

i bet your on standard valve springs

 

I'll give it a try, weird thing is when i bleed nothing it's at 12 psi but it doesn't mather how much i bleed it goes down all the way to 12 again.
I know it always goes down a bit but when i do around 18-19 it should hold about 15 at least.
Don't even know if i can adjust the rod more, you can hardly pull it out but it has only half the hole stretched.

No, i'm on area-six springs.
Should be ok for 7000 rpm @ 21 psi according to Ian.

 

my be the turbo cant flow enough for the engine ??

 

Hmzz.. Had it on my 2 litre ZVH and it pulled 1.3 bar till 6000 rpm and now it's already on 0.8 bar at 4500-5000 rpm.

turbo is quoted on 28 psi but i think that's for a 1600 engine.
Just wondered if it's becuase the turbo is on it's way ( 2 mm radial play and 0.5 mm axial play ) or it could be something else.

I'll try a 2wd cosworth t3 next weekend if all goed well so then i'll know for sure but if it could be something else i could try it before i swap turbo's.
Have to get something else anyway to run 1.5 bar to about 6800 but till i get that just want to know if it's really the turbo that's causing my problem.

 

sounds like actuator spring can't cope with the exhaust gases, try either another actuator or give it a little more preload.

 

how much preload?

 

Had a -31 on it last week with the same problem...

Half the hole on the end from the rod on the acuator.

 

as said, usualy half hole for pretension on actuator.

have you tried a dawes device for boost control?

I find they are more stable than the regular bleed valve.

 

As i said i have half hole pretension.

Nope haven't tried that yet.

 

what intercooler do u run??

edit : try a smaller intercooler ive seen yours and it looks too big,or check the prerssure before and after the cooler,id expect it to be a significant drop

 

I can expect a drop with the intercooler but as said, on the 2.0 zvh engine it held a 1.3 bar.. and it drops to 0.8 doesnt matter what boost i set it to and what it gets when it first kicks in that's the weird thing.

Or should i get a bigger turbo so the drop will be less? ) planing for a bigger turbo next season anyway.

 

well, put some more preload on the actuator but didn'tmake any difference.

Any more ideas?

 

where are you taking the boost feed to the actuator from?

 

From the turbo compressor housing with the bleedvalve in between.

 

try taking it from the inlet manifold and report back.

 

You thinking there is a pressure drop through the IC?

 

Took it from the inlet manifold to the actuator with the bleedvalve in between.
Plugged off the turbo.

Stil got arround 1 bar , even opened the bleedvalve more but with the same result.

 

Does sound like the turbo doesnt have the minerals mate!

 

Thought so as it has some major play on it lol..

Have to get me something else then....

Maybe t34 or something?

 

whats the spec of the engine ?? and what do you want from it ??

 

Silvertop 2.0 zetec CR 8.5:1
Accralite pistons
Pec steel rods with arp
rover inlet
fmic
tubular manifold
2.5" scorpion system
Standard head appart from the area six valvesprings
want to run about 22-24 psi for now and whatever Bhp that wil give me

 

well i would say that the head will hold you to about 280bhp so aim for that sort of power,on the cheap a t34.48 would be my choice .

 

Thank,

Was thinking about that and also a gt28 orso but they're a bit more expensive lol.

So a t34 .48 can do that pressure all the way up the revs?

 

yes it will flow plenty on a standard silvertop head , a gt28 would be much nicer every where but they are over £1k with all the trimings .
i run a gt2871 on a blacktop and imo its about the best you can get on a road car boosts from nothing and holds it all the way to 7200rpm in any gear 1.3bar low boost and 1.8bar drag map ,bearing in mind i ran a 12.7 1/4mile on just 1.1bar .

 

Ok thanks ..

Had a look on the net and came arround the gt2871 at about $ 1100 abit pricy for me indeed but if i had the cash.
Also saw the cheapo chinese gt's for around 350 but not to sure on those.......

Verry nice figures for that turbo... hope to get one of those sometime later... for now the t34 will be the one for me i think