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Discussion Starter · #1 ·
I am having some problems with my 20g.

The kit supplied by Trust/Greddy comes with a wastegate spring rated to only 1.3 bar. Infact you cannot get above 1.5 bar without turning the wastegate screw in repeatedly. This moves the boost range from 0.7-1.5 bar to 1.2-2.0 bar. On full boost, up to 2 bar - no problem. Lift or ease off, or drive it on part throttle and it bucks link a bronco - the boost guage fluttering by up to 0.5 bar. What is strange is just that I see it happen in 5th, for example, between 4000 and 5000 revs just holding the accelerator pedal at constant speed. It seems that the only way round it is to floor it.

Mark Shead took a look at Combe and said it looked like compressor surge, which I accept if there is high boost too low down the rev range - but other times this effect happens it doesn't seem to tie in with compressor surge to my mind. I suspect some of the other components at work:

1) Wastegate spring - Greddy do them rated up to 2 bar, perhaps I should try one of those?
2) Boost solenoid - I am using the one from the Blitz dual sbc - which we had trouble getting the GEMS to control - is there some other unit on the market I can use instead?
3) Wastegate plumbing - the wastegate features 2 connections, one on the side and one on the top. The top is not used, the side connects to the boost controller. I have had various suggestions about connecting this. RC and Norris suggested looping back from the top connector to the manifold (or even taking the feed from the compressor cover). Doing this, the wastegate just holds open! Mark suggested a restrictor in the pipe from the solenoid to the wastegate as the solenoid may be contributing to flutter.

I know I can probably map round it, but before I try that I want to make sure I have all of the right mechanical componentry.
Can anyone help?
 
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Discussion Starter · #2 ·
Sounds a lot like a surging compressor to me too.

With the wastegate - is the side connection below the diaphragm and the top connection above?
 
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Discussion Starter · #3 ·
Not sure... how can I tell?

The wastegate is inverted, so the top connection is at the bottom of the car....
 
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Discussion Starter · #5 ·
hi blade

i think it is your boost control method. have you tried to use the standard two port solenoid with the gems instead or the blitz one?

the fluttering in boost that you are getting will be due to teh wastegate opening and closing. if your car can hold what ever boost you ask it to then the wastegate is fine, the wastegate is controlled by the pressure coming from your solenoid, so if this is not working fast enough then it could be that. it could be that you are just running too high of s solenoid duty cycle or senstivity ?

what don't you try something like a dawes boost controller to start with, it is very easy to fit and works very will and you should be able to tell then if it is to do with the boost control or the wastegate spring.
i could be wrong off course :D
 
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Discussion Starter · #6 ·
Try taking the solenoid control from the Gems and using the Blitz unit to control it and see if the boost is held properly. It seems to me that the Gems is not controlling the solenoid properly.
 
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Discussion Starter · #7 ·
I had the same problem with the Blitz too - running that at a constant 1.5 bar, it would shudder and flutter in the same way - when i turned the gain down to 0 it helped, but didn't go away. I think the blitz solenoid is at fault - it worked fine with the standard turbo though.
 
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Discussion Starter · #8 ·
the first thing to do tony is try to pin point the problem . ah you say as some one else has said
disconect the boost controler run standard boost and check with a know boost gauge and record .
then if you can get your hand on a bleed valve conect into the system . set to say 1.2 bar on bleed ,then set your boost unit to the same check with a good boost gauge . run car on both set ups and see if there is a differance???????? . hopefully there is but if not then i think like you have said you need to change the spring in the wastegate . best regards EVO400 DAVE
 
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Discussion Starter · #10 ·
i've been thinking about this problem and it's a bit tough without experiencing exactly what's happening.

I would try the evo400 method of ditching the electronic control temporarily and fitting a manual bleed valve. Try at various fixed boost levels (start low and work high) and see if you can replicate the problem.

If it reappears then it is a surge problem and you need to run either a 3d boost map (rpm, throttle, boost) or lower boost. If not then it's a problem with the electronic boost control. Either the Blitz valve, the tubing diameter (restrictor?), the Gems/Blitz combination.

What solenoid valve do Gems reccommend?

Does the Gems do full 3d boost map with throttle angle as Motec?

Is the Blitz valve connected as per the original instructions for an external wastegate?
 
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Discussion Starter · #11 ·
Sounds like wastegate flutter 2 me. I notice that u have the wastegate pressure port connected via the boost controller , the typical configuration is pressure port 2 compressor outlet with the boost controller connected 2 the feedback port (top connection) then 2 manifold.
The wastegate pressure port connection will require a restrictor , best 2 use a variable needle type valve so the system can b adjusted. This config will operate like a pressure balance system.
 
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Discussion Starter · #12 ·
Evotrak - what is a 3port setup? Is this like using an air injector instead of a spring?

Lightspeed - The GEMS is controlling it and has 3d throttle/rpm/boost table control.
The tubing is suspect. Don't have any instructions for wastegate plumbing or the blitz controller (does anyone, would be useful....)
I think restricting the tubing is a good way, the needle valve (EVOBOY) is an interesting idea...

Am going to try that, and the standard solenoid too...

I still think it is wastegate flutter, not sure I understood your instructions for connection evoboy...

The boost controller goes to the side port, and the boost controller is fed from the inlet manifold...
the top connector goes nowhere...

So are you saying connect the side to the inlet manifold (or compressor cover), the top back to the manifold with a restrictor in the feed from the boost controller? That may explain some things...
 
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Discussion Starter · #13 ·
Blade,

There is a 3 port solenoid that is very popular with the MOTEC users. It is the DELCO 3 port solenoid, one port connects the solenoid with the turbo outlet, the other port goes to the wastegate and the last port either vents externally or back to the inlet system. You can get this solenoid from MOTEC EUROPE, BRD, etc.

Carlos H.
 
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Discussion Starter · #14 ·
how confusing as far as i can tell its setup wrong ideally for electronic control u want a 3 port solinoid with the input port connected to a line coming from the compressor outlet and 1 ouput port going to the wastegate and the other output just venting to atmosphere
the ecu then cycles the solinoid output between the two ports in response to the boost the MAP sensor is seeing vs the boost the boost according to the map. you then set the sensitivity (or gain) to give the fastest possible response without it going into oscillation ie over correcting
this way the spring tension of the wastegate doesnt control anything other than it needs to be reasonable
no restrictors/bleeds/valves or other plumbing required and just two lines, compressor to solinoid and solinoid to wastegate
this solinoid is just then wired to the original solinoid power connector which presumably is controlled by the gems
the only other thing to get right is which output port is which

the other thing it still could be the bov if this doesnt release properly then it is going to get wastegate flutter and bucking bronco syndrom

also on the 3d boost map you want to set it so that there is no boost if less than about 40% throttle if not done already
 
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Discussion Starter · #18 ·
Blade,

I'm surprised you are having probs, I never had any with the turbo and wastegate on my set-up. I would get slight compressor surge on a very light throttle but otherwise it was ok. Running 1.3/1.35 bar was the max capability of the wastegate spring. After speaking with Tim from SVS..the UK GReddy dealer he said to run more boost I would need the upgraded spring from GReddy at about £30. Maybe thats what you need???

Si
 
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Discussion Starter · #19 ·
Simon - looks like the BC plumbing is all wrong! I will contact splodge to see how yours was connected... but from the diagrams from Blitz it is totally wrong (nice one PE... :()

We are sorting it out :D

Thinking of going for a 25g - about to take the engine out to give it a full on mapping on the dyno, so may as well go all the way and shove an even bigger turbo on! If I can only find someone to buy the old kit... (5 months old!!! Yikes!)
 
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Discussion Starter · #20 ·
can you accept weekleypayments say £20 lol lol on a serious note BLADE make sure you go in a car with a 25g kit on before selling the 20g kit . i think your doing the wrong thing my self but if you feel the need for a huge turbo then go for it . i just think that you are getting a way from what you set out to do

ASK YOUR SELF THIS QUESTION

WHAT DO YOU WANT??????????

A FAST CAR

OR

A QUICK CAR



REGARDS EVO400
 
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