How come on every web site i look on they say a dump valve is useless! yet you say you HAVE to have one!!

why?

that and they sound pants! and imho i find my car runs alot slower with a dv fitted (yes i used to have one)

 

on T4's it fucks them up if you dont have one. I did just write a technical explination but knowing me it will be wrong so I will leave it to the experts.

your right though. they do sound shite

although I think my car runs slower without one because I love the chatter so much I listen to it between ger changes and take longer to change up

 

I understand your point, and have discussed it with others of the same opinion as yourself. Let me formulate myself in another way to fully express mine. Ever thought of the difference between having a compressor at full spinn filling a pipe, and one barely spinning at all? The rate of filling is quite a diffent matter in those cases, believe me. Actually having no dump valve-fitted will cause stall in the turbo for quite a while after the moment that you increased throttle, so thats no alternativ at all, you cant feed your engine with more air than it wants, thats REAL bad for efficiency and wear of the turbo, and for the performance of the engine over all.

Let me elaborate further, whether you have a good evacuation of air or a bad one, the pressure will drop to a certain level when switching gear. Whats the best situation, to have the impeller spin wild or barely at all? Whats the best case, immediately having an increase of pressure, as soon as you increase throttle or having to wait for it due to stalling or momentum reversals?

 

Agree with you 100%

If using my car on the strip / track I normally take the valve off or adjust the spring so that it is really strong so it hardly dumps. Makes a big difference to throttle response

 

The reason for bad performance when having dump valves on high loads is a simple case of lack of response and evacuation rate in the valve. Think about it, you are evacuating 2 bars of pressure in a pipe 2.5-3 times the dump valve in diameter... Is that in any way logical? How on earth can one presume that standard sized, and spec:d, parts could perform under conditions that are totally beyond their original ones.

 

Its a case of what makes sense in theory doesn't always work in practice, from my experiences anyway


Use a Blitz on mine and it is very well made. Sounds good too

Used HKS in the past and it was cr#p broke after a few hours use and Torque Developments would not replace it either

 

Your theoretical and practical knowledge is apparently lacking in that case... Sorry

 

I thought I was doing something wrong

All those years of testing have apparently gone to waste

Not to worry I may as well put a couple more dump valves on the thing to release as much gas as possible then to reduce lag if you say so. Got to keep that turbine wheel spining

Seeing you use a massive dump valve on your car for track racing I will listen to your wealth of expertise.

Thanks

 

Your sense of irony is ... Massive.

Please, stick to your vacuum-controlled dump valves... You wont be able to get anything else i presume? You may want to add as many crappy valves as you want, the lack of response in them will be there anyway, i sense its to your liking, stick with it. Lack of response seems to be the way to go... My oh my, wont i be the unpopular one!? LOL

You are most welcome.

 

Lets agree to disagree.

Out of interest what set up do you use on your car??????????????

 

Hexxon,
So what would you use to evacuate the pressure? .

I have to agree with Austen and Nick on this, as in my experience vacuum activated dump valves do NOT aid the prevention of lag for the very reason that Nick describes.

Also when pushing turbos to near their limits, I have known of failures caused by the over-speeding of the turbo, due to the venting of pressure meaning the turbo has no air pressure to "lean" on. Over a period of time, this kills the bearings.

A T4 and the like have to have one, as the air flow that these generate can literally snap the shafts if is is reversed through the turbo (as it stalls it with such a force).

 

My dump valves are depending on fast sensors. Being able to exactly tune the moment of opening and closing the valve exactly, having eliminated most of the response issues. If i find during rolling road that fully evacuating pressure when switching gear is best for performance, considering my style of driving, i set the valves to perform in that way. If its a different case, as an example opening quickly and then not totally evacuating pressure, i set them to this. The rest of the information i leave to your experience

 

This is purely a case of bad bearings and dimensioning of turbo capacity. Has nothing to do with the eventual case of sound performing dump valves.

 

Please explain then how after removal of the dump valve, the turbo life span has then not been an issue - we're talking TO3/4s here , so nothing special ?

 

Hoho What manner of testing has been performed on the shafts of two cars with exact spec, just differing in the case of dump valve or not from your side? Please, if you provide me with a test result that says that no axial affections are related to not using a dump valve on a high boost engine, i will proudly present myself as the largest jack ass around.

Im just aware of the problems thats been evident on, as an example, turbo charged race cars in the early 80:s, not using ALS or dump valves, as well as the testings performed on these and many other such cars.

 

Mike...are you saying you kill a turbo because of a dumpvalve......is this because a dv can leak air....

 

Sorry meant to put Gumball Skyline, when I was in it with Porkie going up to USC it made the same noise at the Skyline on 2f2f, is that just something skybusses do or is it a HKS??

 

But i was on about a blow off valve you numtpy not Anti-lag

 

Patrik,
Well just like Austen, I will have to agree to differ . My tests consist of running TO3/4s to their limit with dumpvalves fitted and the turbo failing regularly and then removing it - problem solved. The explanation as to why this was happening was given to me by a mapping guru some years ago .

Wimerf,
No I am saying that they fail due to over-spinning. The best analogy I can give is imagine pushing against a door, while you have this pressure pusing back against you everything is hunky-dorey. Now imagine someone suddenly opens the door while you are pushing hard against it. Yep, you fall flat on your face. This is what happens to a turbo with a dump valve, while it has pressure to push against it is fine, but when it gets a vacuum due to the dumpvalve releasing the pressure, it briefly over-speeds. Over a period of time this kills the turbo bearings (in my experience). The reason it doesn't with the larger turbos is that the airflow is sufficiently high that despite the release, you still get a bit of turbo stall (hence why on a T4 you get a whoosh and a flutter when you close the throttle). The dump-valve is enough to prevent the complete sudden stall and the pressure still in the system is still enough to stop the turbo from overspeeding.

 

Agree with differing with both of you, not interested in tweaking your views of it at all, just presenting my ideas, wanting others to do this as well.

This is a clear case of pushing the turbo harder than it can take according to me... Over-spin in this case is simply because at some point the exhaust flow is greater than recommended. A margin of failure should always be present.

 

i get flutter and woosh on my car with t34 fitted

does this mean my turbo will last longer

 

So what one u going for the Dom? Twin one?

 

As my turbos capable of twice the power a RS500 T4 is good for, i got no AFMs, and i can get them cheap as fuck, ive got 2x "GrpA" Forge Motorsport non-piston ones to go on my mota.

Id rather not run any, but i spose i need to (esp as 2bar+), wont fuck up performance in any way, surely? (just people saying DVs are shit is trashing me out now, lol)


Mac- As ive no idea what sound you mean, i dont know. But if it IS the DV it proves my point that the HKS valve makes no different noise to most others as the Gumball one has a Blitz one on it.

 

but what should i do then......with dv is over spinning.....and without the turbo stalls........

 

Lets see a picture of one of your super dooper special electronic dump valves if they exist?????

Or is it a case of an over active imagination??? Or do you not have a digital camera to hand

How the hell can you test throttle response of a dump valve on a rolling road???

In my experience the only way to test it would be on the drag strip before and after a dump valve fitted.

Hang on a second!!!!!!!!!!!!!!!!!!!!!!!!!






I've already done this at Pod about 5 years ago and the results speak for themselves.

 

Please, do not be so simple minded and naive. You are the expert clearly, not me, have never claimed being it. Why the fuzz? Please elaborate on my ideas for yourself and present them for me, you seem to know a LOT about my setup

No, i will not present any pictures of my valves until they are done and tested. You clearly dont seem to be interested, so dont mind. Please piss on me in case of future failure instead of basing it around obvious lack of information and thought. You are the one with imagination, you know exactly the way my engine will perform based on square-nothing, by the sound of it. This interests me, since ive never been able to so correctly predict such things using ignorance, WOW

I am not in ANY way interested in racing which involves the locking of my steering wheel. But ok, what you are saying is that throttle response is most efficiently reviewed on a drag strip? Interesting... Me, I have always had these problems as being on track, gear shifting in different situations, situations which can be simulated on a rolling road. And on a rolling road, the figures wont be presented by imagination.

Cheers!

 

[quote="hexxon"]My dump valves are depending on fast sensors. Being able to exactly tune the moment of opening and closing the valve exactly, having eliminated most of the response issues.
quote]

Talk is cheap on this forum

Pics please

 

Are you experiencing text comprehension difficulties?

My talk is for free. I, differently from yourself clearly, feel no need in asserting myself. Call me whatever you want. Pictures of my sketches and schematics is not available for the public, why would i share something not wanting to do this?

If you have experienced any personal violation, threatening your enlightened ego, due to anything concerning my dump valves. Please forgive me. I simply stated that there are alternativs to technology developed 30 years ago. Dont take it personally, in case you werent the original developer?

[quote="AustenW"]

 

As for been simple minded I have two degree's and a masters. I must be very simple

BSc Information Technology & Telecoms
BA Business Studies

and an MBA

Haven't a clue about your setup mate, If you even have one at all, you being a 20 year old student and all? How can you afford all this development?

Pics would be nice of your engine build or even your car for that matter?

As for been an expert I will be the first to admit I know very little about engine tuning as I am only 30, when I get in my 50's then I will know a bit.

I know as much as I need to for the moment for my needs.

I learn from my mistakes as do most people on this board.

Having played with turbo'd cars for over 12 years also helps.

This is the second time I have asked for pictures from your posts on PF

The first was for this super dooper inlet you are making.

When ever you are confronted to back up you statements / posts with hard proof you seem to clam up and avoid the question?? It must be so we don't pinch your ideas

When asked a while ago to provide me with flow figures from a flow bench you "used for doing your head development" you said that you didn't have the data to hand and did not have it stored.

How convenient

 

Im 22. Being simple minded is possible even being the bright mind you clearly are. No one is perfect i assume...

I have not claimed to have created anything super dooper? Why are you constantly buggering me, have i offended you in any way!? If i dont want to share something, i dont share it. Dont know you in any way, and you are clearly not putting yourself forward positively. Why would i reveal things for you that i dont reveal for close friends? Forget it. If I seem to be a total nobody in your eyes, let me not change your mind, I have no interest in that.

The development is not something which i "afford", its free for me. I am surrounded by friends and relatives being engineers of different practices. So dont you go about worrying about my economy.

I prefer not to discuss my engine at all with people i dont know really, though thinking that it might be nice of me contributing with some ideas and theories on this forum. But theres no need for that apparently...

 

i can easily imagine a dump valve that is electrically operated by a solenoid in much the same way that you might also do it to an external wastegate (ignoring the temperature issues for a moment).

but what i can't really see is any major advantages. ok you can control how far the valves opens, and the rate at which it does so depending on boost level, engine speed etc, but much of this can be done using conventional vaccum operated (or pressure differential operated) d/v's with a bit of tuning of the spring rates, and maybe other pnuematic control devices. obviously the electronic version is simpler to do it with, but i'm not convinced that it will make a massive difference to the driveability of the car.

unless you're not dumping back to atmosphere, but instead to a reservoir to be re-introduced when the throttle opens again. but this is a completely different topic.