To blow-off or not to blow-off ?????????

[Carl]

on out and out drag cars you don\'t need one cos the gearboxes change with the throttle staying wide open and not having to shut so obviously there is no need.
On road cars though the throttle is shutting all the time so it is better,although as Mark say\'s not essential to have one.
If I have invested in a fancy turbo on a road car,I would have one.On my drag car I would not with the right drag gearbox where the throttle stay\'s wide open between changes, whereasif it was a clutched manual that I have to shut the throttle on shifts then I would still have one.
Regards
Carl

[BlitzBoy]

But are they missing because they "hurt performance"? or because they use extremely short inlet tracts. 468bhp and only 11.39 - i guess you know it all :rolleyes:

who said I know it all?, I am just presenting evidence for and against the use of dumpvalves, I believe they hurt performance thats my opnion as I believe time is lost in repressurizing the pipes and its an opnion shared by some pro drag racers but I didnt say all tsccch.

BTW Im sorry my daily street driven FD is slow in your eyes, please share with us your car spec and results attained as it seems by the way you speak you seem to be an expert in the field of Rotaries

[Initial-D]

But... surely even a manual road can safley run without a dump valve. It would have to take a ton of punishment before the turbo finally gives up. I\'d be intrested to see a comparison of figures with/without.

[BlitzBoy]

.
 
Dump valve only releases the excess pressure between throttle and turbo compressor wheel, which prevents slowing down or stalling of the turbine.  Without one the compressor wheel loses a lot of speed, so is no longer \'on boost\'.
 
.

hmmm sounds like a description of a pop off valve, I thought a dump valve releases what ever pressure there was in the pipes on every gear change when on boost

[BlitzBoy]

But... surely even a manual road can safley run without a dump valve. It would have to take a ton of punishment before the turbo finally gives up. I\'d be intrested to see a comparison of figures with/without.

well the only time I was able to test this when I run with the old Street Port setup and To4R (0.85 BAR) it had a blitz blow off valve installed, went to POD running consitant 12.8s when I disconnected the valve I was running 12.6s and picked up a couple more mph over the line

[rico2k_uk]

i just realised, the title of this thread would make a good porn vid name

[Bramble]

I remember about 6-7 years ago it was actually COOL to have a dump valve. I had one and I loved it. Now it seems every chav has got one and its a sign that a toss pot is driving down the street. I must admit I have 2 on my FD, any noticeable difference? Not really enough to be sure, I just have it to help prolong turbo life by reducing the chance of compressor stall.

[rx7veilside]

fwiw my opinion..
dump valves whether recirc or vta are designed for 2 reasons
one is to prolong life of turbo(how many people keep a perf car longer than a couple of years and manufactures give 3 year warranty on new cars so do not want claims)
all production cars come with some kind of relief valve mostly recirc
they do prolong life of turbo and only racers will notice any kind of perf gain
second is sound some prefer ppttssshhh some prefer flutter
but just understand that ppttsshh is air leaving the system safely and flutter is approx 15psi upwards of air flowing back over a turbine that is spinning at a trillion times a second too many years of that will create problems
Understand that drag/rally cars etc all have regular strip downs and maintenance unlike your average non sponsored road car
you pays ur money and makes ur choice but i would hesitate buying a non dump valved turbo car for this reason

[Bramble]

Ptsssuuuuuuuuuuuuuuuuu Innnnnnnnnnnniiiiiitttttttttttttt M8

[BlitzBoy]

By the way I have never discounted the reliabilty aims of recirc and dump valves.
I wouldnt run one purely on performance terms plus as I run a big shaft turbo so its not prone to shaft damage as a small turbo would be.

Anyway the Rotary engine is most likely to pop first then the turbo :rollin

[John_Hudson]

i just realised, the title of this thread would make a good porn vid name

:spank :spank :spank

[benRX7]

hmmm sounds like a description of a pop off valve, I thought a dump valve releases what ever pressure there was in the pipes on every gear change when on boost

I`m pretty sure a pop off valve prevents overboosting ie, It senses too much boost so opens releaving the pressure.
 
The dump valve is as the guy says, stops the pressurised air from bouncing back off a closed throttle butterfly and stalling the turbo by opening and venting the air in the pipes.
 
On a side note I have 2 brand new SSQV for sale, http://www.mazdarotaryclub.com/forums/showthread.php?t=42450

[BlitzBoy]

I know Ben, Prof described it as venting excess pressure which sounds the same as relieving excess boost pressure as a pop off would do

[Bramble]

My Janspeed turbo has an old skool style \'pop off valve\' I dont think you get them on modern cars though, there are far better ways to control boost.

[mx1311]

I`m pretty sure a pop off valve prevents overboosting ie, It senses too much boost so opens releaving the pressure.
 
The dump valve is as the guy says, stops the pressurised air from bouncing back off a closed throttle butterfly and stalling the turbo by opening and venting the air in the pipes.
 
On a side note I have 2 brand new SSQV for sale, http://www.mazdarotaryclub.com/forums/showthread.php?t=42450

great plug my man

colum