Discussion
Mainly for the education of N17 TVR but if anyone else is interested, they are needed for performance turbo cars.
First of all, there are two types. One recirculates the air and puts it back into the turbo, the other vents into the atmosphere which causes the ptttshhh sound (woosh is more of a turbo sound).
The recirculating dump valves are better than none but since they force hot air back into the turbo, not ideal for boost pressure. An atmospheric dump valve gets rid of the pressure before it has a chance to be forced back through the turbinbe blades, slowing them, stalling them, or smashing them. The blades will then keep spinning and providing you can change gear properly they will keep their speed and be spinning at full whack as soon as you are back on the throttle. This greatly reduces turbo lag and obviously makes the car faster and more predictable. It is a very simple but greatly efficient piece of kit.
As for the sound, my car has a sequential atmospheric dump valve, it makes small chattering noises when you are on and off the throttle and saves the big one for gear changes. With a 300bhp turbo car you don't really want to be trying to stop the turbo spinning so it is therefore very useful.
And whoever asked about rally cars, yes they do have them, anti lag turns the turbo into a bit of a jet to keep the turbine spinning and many of the crackles when a rally car is slowing down are the excess fuel being burnt when the anti lag kicks in. The chattering sound from rally cars is the sequential dump valve and waste gate. As for my car, it sounds like a group A rally car without the 3000rpm crackly idle and not quite as much popping and banging. I, personally, love the way it sounds, as do most people who have heard it, but anyway each to their own. I suppose if a dump valve puts me in the same league as Maxy P boys then having a convertible puts you in the Barry and Tracy sunstrip brigade. I obviously don't believe that because it is ridiculous and I love decent cars, but there you go.
I think your beef is not with dump valves but with the maxy P boys who have them. What's it all about anyway, did a Nova show you a clean pair of bean can exhausts from the lights or something?
First of all, there are two types. One recirculates the air and puts it back into the turbo, the other vents into the atmosphere which causes the ptttshhh sound (woosh is more of a turbo sound).
The recirculating dump valves are better than none but since they force hot air back into the turbo, not ideal for boost pressure. An atmospheric dump valve gets rid of the pressure before it has a chance to be forced back through the turbinbe blades, slowing them, stalling them, or smashing them. The blades will then keep spinning and providing you can change gear properly they will keep their speed and be spinning at full whack as soon as you are back on the throttle. This greatly reduces turbo lag and obviously makes the car faster and more predictable. It is a very simple but greatly efficient piece of kit.
As for the sound, my car has a sequential atmospheric dump valve, it makes small chattering noises when you are on and off the throttle and saves the big one for gear changes. With a 300bhp turbo car you don't really want to be trying to stop the turbo spinning so it is therefore very useful.
And whoever asked about rally cars, yes they do have them, anti lag turns the turbo into a bit of a jet to keep the turbine spinning and many of the crackles when a rally car is slowing down are the excess fuel being burnt when the anti lag kicks in. The chattering sound from rally cars is the sequential dump valve and waste gate. As for my car, it sounds like a group A rally car without the 3000rpm crackly idle and not quite as much popping and banging. I, personally, love the way it sounds, as do most people who have heard it, but anyway each to their own. I suppose if a dump valve puts me in the same league as Maxy P boys then having a convertible puts you in the Barry and Tracy sunstrip brigade. I obviously don't believe that because it is ridiculous and I love decent cars, but there you go.
I think your beef is not with dump valves but with the maxy P boys who have them. What's it all about anyway, did a Nova show you a clean pair of bean can exhausts from the lights or something?
This post leads on nicely to the difference between a dump valve and a wastegate. As I understand it the dump valve works on the induction side and releases excess pressure build up between the throttle bodies and the compressor whereas a wastegate acts on the hot side of the turbo and releases excess exhaust pressure between manifold and turbine.
Now, I think this is right but any clarification would be welcome as I'd like to get my facts right on this one...!
Roop
Now, I think this is right but any clarification would be welcome as I'd like to get my facts right on this one...!
Roop
quote:
Mainly for the education of N17 TVR
Ooooooooohhhhhhh, get her !
Before I am chased out of town like a common pygmy, I want to clarify that my beef is NOT with dump valves that serve a porpoise on Turbo'd cars, it is when they are added to un-turbo'd Nova's, Corsa's & Escorts along with under car strobe lighting and 600 watt JBL subs.
I have decided to join them rather than beat them and have today called a number of TVR dealerships to ask if I can have one fitted.
Can't wait to get the V8 warmed up, gurgling crackling and popping and then let out a
wwwwwwhhhhooooooossssshhhhhhhhhhhhhhhh
Before I am chased out of town like a common pygmy, I want to clarify that my beef is NOT with dump valves that serve a porpoise on Turbo'd cars, it is when they are added to un-turbo'd Nova's, Corsa's & Escorts
EH? People fit these things to cars without turbochargers? WHY? How on earth do they work without being plumbed in to the charger system?
oh no,..............I'm digging myself an even bigger hole.
I don't know how (or why) the wwwwhhhhhhhoooooosssshhhhh things work, I just know the cars I have seen/heard them on were v.unlikely to have a turbo, perhaps I'm wrong.
May god strike me down, because I have opened a whole nest of vipers with my opposition to these things.
I would imagine I will be public enemy No1 in Max Power next month at this rate.
I don't know how (or why) the wwwwhhhhhhhoooooosssshhhhh things work, I just know the cars I have seen/heard them on were v.unlikely to have a turbo, perhaps I'm wrong.
May god strike me down, because I have opened a whole nest of vipers with my opposition to these things.
I would imagine I will be public enemy No1 in Max Power next month at this rate.
moleamol you have missed one point though. Atmospheric Dump valves can also be silienced with no effect on their performance. The beef I believe TVR is on is the fact the max-power boys have ones that actually exagerate the sound similar to baked bean can exhaust ie makes lots of noise but is pointless. Mind you I just find them funny, sounds like Ivor the Engine chuffing up behind you.
quote:
Before I am chased out of town like a common pygmy, I want to clarify that my beef is NOT with dump valves that serve a porpoise on Turbo'd cars, it is when they are added to un-turbo'd Nova's, Corsa's & Escorts
EH? People fit these things to cars without turbochargers? WHY? How on earth do they work without being plumbed in to the charger system?
I have heard that, in the states at least, you can get a piece of kit which makes the same noise on an NA car so you can pretend you have a turbo on your rice burner.
quote:
moleamol you have missed one point though. Atmospheric Dump valves can also be silienced with no effect on their performance. The beef I believe TVR is on is the fact the max-power boys have ones that actually exagerate the sound similar to baked bean can exhaust ie makes lots of noise but is pointless. Mind you I just find them funny, sounds like Ivor the Engine chuffing up behind you.
How, exactly? Never heard about that. But I know what you mean TVR, these are the same chaps who will all out accelerate in the middle of a town centre to get them to work. Near me there is a 'cruise' every single night these days, I'm sick of the little scroats, you should see the shit they leave on the car park too
I have never heard of one on an NA car though, but give the 'turbo whistler' I'd believe it So am I allowed to have one on my car then chaps? It sounds right, she burbles and crackles and pops too
Edited because a smiley didn't work
>> Edited by moleamol on Wednesday 25th September 21:07
quote:
The recirculating dump valves are better than none but since they force hot air back into the turbo, not ideal for boost pressure.
The recirculating dump valves are generally percieved to be better as they channel the unwanted intake pressure back into the turbo inlet to keep it spinning
faster than it would if the pressure was vented to air. The air wouldn't be significantly hot as it has to pass through the intercooler/chargecooler and it would only be a short blast anyway. Recirculating dump valves are fitted as standard to subaru imprezas, sierra cosworths, audi TT's and more.
quote:
An atmospheric dump valve gets rid of the pressure before it has a chance to be forced back through the turbinbe blades, slowing them, stalling them, or smashing them. The blades will then keep spinning and providing you can change gear properly they will keep their speed and be spinning at full whack as soon as you are back on the throttle. This greatly reduces turbo lag and obviously makes the car faster and more predictable. It is a very simple but greatly efficient piece of kit.
Yes, but this is exactly what the recirc ones do too but with added benefits and no noise. The only 'benefit' that an atmospheric DV has over a recirc one is that it makes a noise.....oh and spits oil out over your engine bay....and makes your car a target for thieves. Fair enough if you want the noise, but you can't try to make out that they are
any better than a recirc DV.
quote:
The recirculating dump valves are generally percieved to be better as they channel the unwanted intake pressure back into the turbo inlet to keep it spinning
faster than it would if the pressure was vented to air. The air wouldn't be significantly hot as it has to pass through the intercooler/chargecooler and it would only be a short blast anyway. Recirculating dump valves are fitted as standard to subaru imprezas, sierra cosworths, audi TT's and more.
My car was fitted with a recirc as standard but seeing as how you can't even get a sequential recirc I fail to see how it will work better. The reason they are fitted as OEM is that they can quite easily handle low boost pressures, cost a lot less (as they are usually plastic) and aren't offensive. Fair enough, but my car is not standard, and the same guys who ported/polished/flowed the head, fitted the bigger turbo, fitted angrier cams, all thought a sequential one would be the best idea.
As for it helping the turbo keep spinning, it actually slows it as the pressure is released as (hot) air is vented and by the time it is back into the inlet it has slowed sufficiently to slow the turbine blades. As for the air being cool, the air goes straight from the turbo (where it reaches quite a temperature you will find) back into the turbo, the intercooler is long done with. Engine bay, clean as a whistle, I think they are meant to vent air, not oil
I don't know, maybe you know something I don't, I think you better get on the phone to Prodrive and Ford Motorsport, tell them they've been getting it wrong on their group A rally cars for all these years
quote:
What a strange web site.... My the turbo waste dumps on my Noble sound nothing like that
Friend of mine had a Fiat Turbo with a dump valve fitted... couldn't hear it at all... just depends on what you want I think...
... lets be honest, in a car like a Noble, they don't need to know you've got a turbo... it speaks for itself!
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