samcowrx

I have been searching for about an hour, i just want to know peoples experiences on running a new 20G with supporting mods, a fmic, and no dump valve at all,
thankyou

Henrik

iTrader: (5)

I used to run autobahn fmic, td05-20g and no dump.

It sounds the nuts, there seemed to be less lag between gear-changes (not as much boost drop-off), but "norma" (off boost) driveability suffered... Coming on/off the throttle would make the car jerk a bit... Not a lot, but I didn't really like it so went back to a top mount with standard dump

I really miss the sound, though

30psi

brrrrrrrr kuf kuf kuf

Henrik

iTrader: (5)

Exactly

Mother Theresa

I have an 18g rather than the 20g. It was horrible until I had a simtek put on due to the sudden jerks coming off boost. It now sounds great and goes great.

samcowrx

thanks guys, any more experiences?

scooby-tc

iTrader: (2)

I had a Hybrid FMIC,20G turbo and removed the DV completely and i had no jerkyness at all,everything was really smooth but the noise of the air rushing back through the turbo started to get on my nerves a bit but other than that good

samcowrx

By the sounds of it if you get the car mapped with no dump valve on it at the time, jerkyness can be minimilised?, that sounds favourite to me.

53

iTrader: (41)

Yes indeedy, and without the Maf its (I am told) smoother still.

My Hybrid FMIC, DV Delete, RCMS mahoosive induction cone and Simtek remap is silky smooth. Really nice to progress through the gears, so much better for the FMIC and induction. But even so the DV delete was never jurky on TMIC having been done at the time of mapping and it has improved lag and power at gear change.

samcowrx

Bob Rawle is mapping my car on the 29th (if its finished!), he did suggest i fit either a recirc forge bov, or run no bov at all, i was just asking what peoples thoughts on this were,( not doubting Bob at all of course!) just wanting to hear experiences, so it looks like i will run no bov at all and enjoy the sound!, i think this will be an interim map while i do the final tweaks for the inevitable remap, losing the maf sounds like it will also be a very good idea to get the best out of the 20G.

Mus

iTrader: (2)

20G blitz filter in the wing autobahn zigen s/s sounds like pornography oh and no dump valve

Henrik

iTrader: (5)

Mine was mapped by Bob also... It's not hugely noticable, but still there and it got annoying after a while.

NXG

Bob's mapping my 2.5 / FMIC conversion over at API a week on Wednesday (running in map ) and the non BOV way is where mine's going. That is with the Simtek though.

G.Mac

iTrader: (2)

Reducing lag and sounding good it music to my ears.

In the new year my plans are FMIC, larger injectors, FPR and SIMTEC over my current mods so see what can be had out the VF35, before moving to a MD321T a few months later

Does anyone have a sound clip of the car running no BOV?

Graeme

green fast machine

iTrader: (2)

i have above set up fmic 20g ect with bov on judders on lift of throttle

with out bov on still does but not as bad any ideas of how to get rid of it altogether ?

o if i accelarate an lift off quickly it dont jerk strange !

Tiss

green fast machine, i've just had mine mapped and it does the same!! am in the process of trying to find how to cure it, supposedly a recirculating bov will solve it, anyone have any experience with this??

AL99

iTrader: (1)

the only real solution is a MAP based ecu ( no airflow meter ) or a blowthrough system whereby the airflow meter is placed near the throttle and measures the air that actually enters the engine. Personally, i would go MAP (simtek as one example) and ditch the afm. If i had the money i would do it tomorrow. You can map out a little of the judder but only really on motorway cruise lift off at a limited range of speeds. at the end of the day you will always get the judder! good luck.

Turbovin

iTrader: (2)

I don't really see how not having a dump valve would give you less turbo lag. Shouldn't the air that has to stop before the closed throttle body just turn and go back through the intercooler pipes to the turbo and slowing down the impeller?

Ok you keep a little more air in the pipes that's ready to be pushed into the inlet manifold but then again you'll make the turbo slower to respond since the returning air has made the impeller slow down.

I can't really see the benefits but I may be wrong. I mean the valves are fitted from the factory for a reason. Early turbo cars didn't have dump valves but now every turbo car that I know of (not talking about diesels) has some sort of DV.

NXG

It gets thrown out the waste gate, hence the 'chatter' on lift (sounds more like laughing to me... )

Legacy_Turbo_EJ22G

What get`s thrown out the wastegate??

Not the intake air anyway. The intake air have nothing to do with the wastegate, and the "chatter" you talk about, is the air in the intercooler and pipes going back through the compressor.

Brett_555_Sti

iTrader: (18)

Waste gate is on the opposite side of the turbo(hot), the chatter is the air pressure going back over the compressor wheel and causing it too slow down, sort of putting it into "reverse" almost.

STI_Baly

iTrader: (23)

It's also referred to as compressor surge and if boost pressure is high enough it will overload your turbine shafts causing bearings and possible complete bearing housing failure on your turbo. (OK if you can afford it i must say).

You can also get wastegate chatter under partial boost conditions such as partial throttle near the boost threshold it sounds a bit like FftFftFft not ShuShuShu and is caused by the rapid opening and closing of the wastegate at boost levels near the spring pressure. This is the less damaging type BTW.

duncatr

iTrader: (18)

I also have a GT Spec FMIC and an Andy F 20G, as well as supporting mods.

Having gone through this thought process myself recently I decided to leave my HKS SSQV fitted to my car. Although Andy F assured me the 20G is more than strong enough. Thats mapped on an Apexi Power FC, just short of 400BHP. I remember reading that the VF series turbos are best left with a dump valve though.