Wastegate & dump valve questions for an HKS T51-R KAI turbo

[lockwood77]

Having bought a shiny new FD with an HKS T51R-KAI turbo attached, I\'ve discovered that it\'s rather raucous. The setup is currently as follows:

HKS mushroom intake
No dump valve
Wastegate vents to atmosphere
Exhaust is an HKS Silent Hi-Power (ironically named...)

As you might expect, when it hits full boost (421bhp at 0.85 bar as you ask) it gets pretty noisy. There is a blanked-off section of the exhaust roughly where I think the cat would originally have been placed (never actually seen an FD with a cat), so presumably I can plumb the wastegate into this to relieve some of the noise - entertaining as it is, I don\'t think too many tracks will appreciate it... :2Mad

My questions related to this are:

1. Is there likely to be an exhaust part available from HKS for the plumbing, or am I looking at a custom fabrication?

2. Once done, would I need to have it remapped? I\'m guessing yes, but you never know...


There is then the question of a dump valve. At the moment, lifting off the throttle produces the "tsch tsch tsch" of turbo stall pushing air back through the intake. I\'ve been advised that a dump valve reduces this and that stalling isn\'t the best thing for the turbo. Two questions:

1. Is a dump valve better for the turbo than my current setup?

2. Do I need a particular model of dump valve/custom fabrication to fit it to my particular turbo?


Having only had stock twins before, all this non-standard turbo setup is new to me and I\'m a bit confused! I will be using the car on track, so minimum noise/maximum reliability is what I\'m after.

Thanks in advance for the help of those more knowledgable than me!

[Jit]

Can\'t advise on the wastegate and plumbing back in. I wouldn\'t worry about a dump valve. Both my T51 FD and my other single turbo FD hve no dump valves and I\'ve not noticed any I\'ll effects. There are many others who also don\'t run with one.

[batman]

tracks only measure sound at about 3000 rpm so no worrys about noise on the waste gate and whats wrong with the scream "man up mills"  lol

[turbotoaster]

what you talking about, they have drive by testers down some of the straights at circuits, running a noisy screamer pipe could easily set them off.

you will have to do some custom fabrication to take the wastegate pipe back into the exhaust, the further away you can get it to join into the main exhaust pipe the better though.

running it into the exhaust means that the setup isnt as free flowing as such so will make the car run slightly richer, depending on where in the exhaust it joins depends on how rich, but being realistic, not enough that id bother getting it remapped.

stalling isnt a good thing for a turbo but alot of them do cope with this fine(my twins do at 20psi) but then if your on track you want ultimate response so i would suggest fitting one.

the reason being by forcing air back through the turboblades you infact slow the rotation down, when you apply the throttle again you then have to respool the turbine wheel back to where it was causing a delay.

Im not saying fitting a dump valve will suddenly give you full boost all the time like antilag, but the effects of changing gear will be lessened

[jackaleks]

there\'s a lot of pro-BOV and anti-BOV rhetoric on the internets...

personally, i think they\'re unnecessary and chavvy (can\'t wait to get rid of mine). compressor stall won\'t damage your turbo, compressor surge will, but that\'s a whole different thing.

[PGiljevic]

Having bought a shiny new FD with an HKS T51R-KAI turbo attached, I\'ve discovered that it\'s rather raucous. The setup is currently as follows:

HKS mushroom intake
No dump valve
Wastegate vents to atmosphere
Exhaust is an HKS Silent Hi-Power (ironically named...)

As you might expect, when it hits full boost (421bhp at 0.85 bar as you ask) it gets pretty noisy. There is a blanked-off section of the exhaust roughly where I think the cat would originally have been placed (never actually seen an FD with a cat), so presumably I can plumb the wastegate into this to relieve some of the noise - entertaining as it is, I don\'t think too many tracks will appreciate it... :2Mad

My questions related to this are:

1. Is there likely to be an exhaust part available from HKS for the plumbing, or am I looking at a custom fabrication?

2. Once done, would I need to have it remapped? I\'m guessing yes, but you never know...


There is then the question of a dump valve. At the moment, lifting off the throttle produces the "tsch tsch tsch" of turbo stall pushing air back through the intake. I\'ve been advised that a dump valve reduces this and that stalling isn\'t the best thing for the turbo. Two questions:

1. Is a dump valve better for the turbo than my current setup?

2. Do I need a particular model of dump valve/custom fabrication to fit it to my particular turbo?


Having only had stock twins before, all this non-standard turbo setup is new to me and I\'m a bit confused! I will be using the car on track, so minimum noise/maximum reliability is what I\'m after.

Thanks in advance for the help of those more knowledgable than me!

You need to read up this thread in detail (linked below), it\'s the standard setter for high power and efficiency without the noise and it 100% legal with better emissions than stock.

A catalyst will quieten it down a hell of allot and a plumb back waste gate is the only way on a road car :Nono! open sounds rubbish and is super gay to boot.

http://www.rotarycarclub.com/rotary_forum/showthread.php?t=13776

[SiH]

tracks only measure sound at about 3000 rpm so no worrys about noise on the waste gate and whats wrong with the scream "man up mills"  lol

Bobbins.
As mentioned, most measure at something like 4500RPM, or 3/4 of full revs, or a similar metric.
That\'s irrelevant if in neautral anywyas, as you won\'t be creating boost at that.
However, a LOT of tracks measure drive-by\'s, and a screamer will get you almsot instantly black flagged with a lot of these.
Good luck at tracks like Anglesey and Donny with a screamer pipe!

Lockwood - It\'s all going to be custom unfortuantely you can either plumb it back in, or get a small motorbike can and router the screamer into that then back out to atmosphere, so it\'s effectively running it\'s own system There\'s usually enough room for it with most decats

[trotter]

Also check out the argument/discussion that raged here:

http://www.mazdarotaryclub.com/forums/showthread.php?t=4844&highlight=recycle

my contribution FWIW was:

"excuse my ignorance here, but my understanding of it was that compressor stall was when the pressurised charge downstream of the turbo had the effect of \'slowing\' or stalling the turbine off-throttle, thus making it harder to spool again as it\'s working against backpressure rather then a vacuum??

The thermodynamic definition of compressor surge is where (for whatever reason) the compressor can no longer push enough mass flow through to sustain the discharge pressure. This results in the flow reversing direction and forcing its way back through the turbine. What happens next is that the reverse flow then re-pressurises the intake side and normal flow direction is recovered. If the original cause is not corrected, this pattern continues many times per second and puts massive stress on the turbine blades as the flow goes back and forward.

I\'m agreed that compressor surge is indeed worse, i\'m a process engineer and i\'ve been standing next to north sea gas compressors (variants of the RB-211s which used to power commercial jet planes) when they\'ve gone into recycle mode (essentially a recirculating BOV) to protect against surge and it sounds like the end of the world!! I\'ve seen a video of a $6mn compressor actually hitting surge when the recycle valve failed and vibrating itself clean off it\'s mountings!!

The anti-surge (or recycle) control systems that these babies have are usually worth in excess of £1mn, which goes to show that its a problem that\'s taken seriously in industry. For that reason alone I will always go for a BOV."

HTH

graeme

[lockwood77]

Thanks guys, the SMB system looks great, shame it\'s expensive and will take forever to arrive from abroad... So I think it\'s more a case of working with what I\'ve got for the time being.

Sounds like the answer is (a) get the wastegate custom plumbed in, (b) get a dumpvalve fitted according to taste (chavvy yes, but my understanding is it aids gearshift performance) and (c) get it remapped.

One question I\'m still not sure of - will I need custom pipework for the BOV or should it fit straight on?

[PGiljevic]

Thanks guys, the SMB system looks great, shame it\'s expensive and will take forever to arrive from abroad... So I think it\'s more a case of working with what I\'ve got for the time being.

Sounds like the answer is (a) get the wastegate custom plumbed in, (b) get a dumpvalve fitted according to taste (chavvy yes, but my understanding is it aids gearshift performance) and (c) get it remapped.

One question I\'m still not sure of - will I need custom pipework for the BOV or should it fit straight on?

It is a fair price even including air freight, I quoted a bloke a few weeks back and it was not as bad as you think it might be....... there is nothing else out there that is proven if you are after the best for your rotary

If people are interested they can PM me or E-Mail :Thumbsup!

[Grant Monkhouse]

Bovs don\'t sound chavy, go on YouTube and look for Nelson racing engines, he uses dual bovs. Go and watch a few of his buds then tell me that they\'re chavy.

I will be having a huge race port BOV on my up and coming car so it sounds cool!! LMAO!

[PGiljevic]

BOV = absolute waste of space and time on a turbo car BTW :WaveBye save your ca$h and buy other parts and don\'t waste it on sh7t you do not need :Thumbsup!


1.7bar, no BOV cause its not needed, but hey I\'m a Mechanical Engineer so what would I know right? ..... :spank

[BlitzBoy]

I ran NO bov on my T51R for the last 4 years no problemo, BOV on big shaft car turbos waste of time especially if the front housing has a ported shroad

[Grant Monkhouse]

I know the discussion about BOV v\'s NO BOV but come on they sound cool?! And thecloser you put them to the throttle body the louder they are?

Nelson racing must use them for a reason? Constant 1000HP engines built for road cars. Twin turbo V8\'s

[Grant Monkhouse]

How is the 1.7 bar testing going Peter? What\'s the RWKW at now?