zakscooby1

iTrader: (8)

Car is a version 3 sti with simtek 20g turbo,parallel fuel rail mod with 740cc injectors and walbro fuel pump,also has fmic full exhaust from turbo back and headers,few other mods but cnt remember from top of my head,it's at garage at the min getting silicone intake hose fitted alongside the 20g,now the query I have is,can I completely block of the dump valve from intake hose side and fmic piping side so I get wastegate chatter?isit safe to do this and if not how do I get a recirculating one connected to fmic piping and intake?
Car is being mapped next month so want to finish off everything before and get it done right
Thanks in advance
Zak

zakscooby1

iTrader: (8)

The reason I'm thinking I cnt put recirculating valve back on is I have blocked most intake hose fittings due to fitting oil catch tank and deleting anything extra under the inlet (make it a bit tidy)

coleman

iTrader: (3)

I'm sure the sound your describing isn't wastegate chatter. the wastegate it self will never ake make any noise.

Think your on about compressor surge, i'm sure the sound is made when you close the throttle and the air is forced back towards the compressor blades on the turbo and the sound is the air hitting the blades.

zakscooby1

iTrader: (8)

Think that's what I'm on about,was thinkining if I block the dump valve completely it would obviously dump through turbo somewhere which o assumed wategate?dnt like sound of dump valve at all hence the reason I wanted to block altogether,would this mod damage the turbo at all?

coleman

iTrader: (3)

I can't see it doing any really harm. Alot of cars like the rs turbo, renault turbo and the like ran with no dump valve what so ever.

Although it can't be good for the turbo with the air rushing back into the compressor housing and stopping the blades dead.

My plan when i fit my front mount is to lose the dump valve, i quite like the pigeon noise compressor surge gives....

Loco

iTrader: (1)

err, i think it would be terrible for the turbo, wouldnt it?! your basically saying your forcing the turbo to stall by forcing air in the opposite direction it is supposed to be flowing - which is disastrous.

Also, although not every turbo car has an atmospheric dump valve, every turbo car will have some kind of recirculating wastegate, as the built up pressure must go somewhere when you let off...

please correct me if i am wrong, but pretty sure i am right

coleman

iTrader: (3)

I think you wrong about EVERY car having one.

I also doubt it does a hell of a lot of damage, Turbos are very hard-wearing

Loco

iTrader: (1)

I think we need other opinions, as I am quite sure that forcing a turbo to stall can be pretty catastrophic. even if it isnt catastrophic, it will most likely cause longer turbo lag between gears, and reduce performance

New_scooby_04

iTrader: (4)

The sound is compressor stall not wastegate chatter.

Whether it's advisable depends on the turbo in question. TD range are as tough as old boots, Early VFs fragile, but should be ok with the VF30 onwards. I ran a VF35 for two years with no DV with no problems.

If running a MAF equipped car running without a dump valve can result in maf reversion artifacts (a judder when coming off the throttle).

birchy2010

iTrader: (12)

It's turbo stall. That's what the noise is. It's not horrendous for a turbo asking as it's a strong one but will shorten the life of your turbo.

zakscooby1

iTrader: (8)

I was going to do it on my vf35 but was told the ihi are delicate lol,was also told that the Td series were strong and this wouldn't effect it,would I reduce lag or make it more laggier by doing this?

B0DSKI

iTrader: (17)

Run no dump valave on mine with a 321T. Mark at Lateral said there would be no problem with the turbo coping with it. Unsure how a 20G would cope. Where did the 20G come from ??

zakscooby1

iTrader: (8)

i bought it second hand and it has a receipt from zen performance,it is a proper 20g with the mitsubishi housing...

scooblee

I ran cossies for years like this, one or two of them on their original turbos, it will cause premature wear though.

Dedrater

Is the sound you lot are on about, the same sound WRC cars make?

tempop1

Im sure running no dump dalve lessens lag between gear changes, because the boost/charge system doesnt have to reboost/recharge again. Im going to be doing this on my sc46 blillet.

Loco

iTrader: (1)

I think the point of a dump valve is to release the excess pressure, so the turbine inside the turbo continues to spin, so when you put your foot down again, it is already spinning, and takes a lot less time to spin up to maximum speed and maximum boost.

If the excess pressure is not released, either by atmospheric dump or recirculation, it goes backwards towards the turbo, causing to stall, as discussed above. If the turbine in the turbo is forced to stall, it means when you put your foot down again, the turbine has to completely spool up from a standstill to produce boost, which will take a lot longer than if the turbine is already still spinning.

Therefore, I would have thought that no dump valve or wastegate on your car will most certainly cause longer lag times.

rosschalmers

stalling a turbo which is spinning somewhere in the region of 250,000rpm is never a good idea. it puts massive stresses on the shaft and bearings and can lead to failures. unfortunately im speaking from experience here. my previous car was an 03 astra GSi turbo and after approx 50miles of driving with the dump valve blocked it wreaked the oil seals and fooked the bearings on a 5 month old turbo was a very expensive price to pay for a cool noise. granted the K04 on the astra is not as strong as a TD04(not sure about 20G) but still could be an expensive mistake and as Loco says it will increase lag as the turbo will have to spool everytime you shut the throttle. not a mistake ill be making again though

B0DSKI

iTrader: (17)

What people seem to be forgetting with running a dump valve is it releases pressure therefore needing more boost to get it spinning again.
I find running no dump valve actually improves pick up and punch out of corners when back onto the throttle

P600wrx

iTrader: (1)

i know a few lads who have done thi yes it sounds cool, but there blowers didn't last very long, the only suabru that i know does this all the time is the world rally car cus it has a new blower every time, i would run a re-circ mate get a really good quality one as that sound ain't worth blowing the seals and shafts on ya turbo

RS TURBO

i have a rs turbo and it has the wastegate chatter and has had it for 5 years plus without a problem just now i changed turbo but changing back to my old 1. sounds better than any dumpvalve in my opinion

Dr Who

What you appear not to know is that a turbo doesn't rely on "Boost" as you claim to keep it spinning, but does in fact rely on exhaust gas flow! Closing the throttle stops exhaust gas flow so the turbo compressor will slow anyway, the exception is as mentioned above on the type of turbo being used or more precise the bearings that are fitted to the impellor shaft itself.
Running with no dump valve whilst using an AF Meter can also create reversion pulses to flow back through the AF Meter so what your "Finding" by running no dump valve is questionable depending on what set up your car is running!

New_scooby_04

iTrader: (4)

As I said above:

Whether it is a good idea, depends on what turbo you're running and whether you're using a maf based ECU or a speed/density based ECU

Early VFs i.e. before the VF30 are quite fragile. After that you should be ok

Running no DV on a maf based ECU can result in reversion artifacts; a judder when coming off the boost

My experience was that having no DV slightly improved lag between gear changes. The compressor does not simply stop as soon as air flowing the other way hits it!! IIRC the term "stall" refers to the air over the blades stalling not the compressor itself.

In summary: if you have a TD series turbo or late VF series turbo and a Map based ECU such as Simtek, go for it.

If you have a early VF series turbo, keep the DV.

If you have a maf based ecu but a TD or late VF turbo, you may get some reversion artifacts if you go DV-less.

If in doubt, ask your friendly mapper what they think!

Stoff1

iTrader: (3)

so how do you block a std dumpvalve?

Abbylad

iTrader: (4)

you dont, you take it off and put bungs in the pipework

zakscooby1

iTrader: (8)

think im going to block dump valve as the intake hose side is now blocked and fitted
i have a simtek which means no MAF,also on next remap im hoping to get 400 with the TD series turbo,spoke to my mechanic about this issue and he said it will be fine especially with the spec on my car and said it will have premature wear but wont f**k the seals on turbo or be very laggy depending on my mapper

Loco

iTrader: (1)

I just don't know why people would want to shorten the lifespan of their turbo's for the sake of a sound. Personally, for the sake of the sound of what the boost blow off sounds like, I would be aiming to make my car as reliable as possible,

zakscooby1

iTrader: (8)

alot of mixed thoughts out here lol,think the best person to tell would be my mapper (simon) will email him later,if he says run a dump valve then im going to put on something REALLY quite

zakscooby1

iTrader: (8)

wel i just received an email from simon (jgm) regarding running no dump valve and how safe it is

''20g strong enough
Quicker response on gear change''

B0DSKI

iTrader: (17)

And ???