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boost is good
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Discussion Starter #1
ive got the greddy t78 kit, and thought that i was getting compressor surge after i installed it. so i took it too a place and they said that with such a big turbo that it is normal for a little air to get by the bov and go back against the turbo. they even showed me how their t66 race supra did the same thing. just a little fluttering when i let off. is this normal? ive got a brand new hks racing bov, and it is venting a ton of air still even in nuetral when i rev it. thanx
 
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Sound like you need a larger BOV. I'm currently using the HKS Racing BOV. I run a Turbo Dynamics T-63 Ball Barring with a Delta wastgate and have none what so ever problems. I have not dynod my car yet but frends with the same setup are running over 700 RWHP and have no at all. :)
 
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What boost controller are you using? I'm trying to get a picture of your setup.
 
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If you have the surge only when you reach the max boost that is dailed in to you wastgate, The wastgate can not react fast enouth and your surge is normal. The turbo keeps on making more boost, even thou you have reached the disired boost level. And you overload the BOV capacity. That is where you get your surge from. The only way to controll this by using a electronic boost controller.
 
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Is your turbo a Non-Ball Barring Turbo or is it is so large that even under constant rpm is has not found its pressure ballance? In that case I don't think a boost controller will help you but a smaller turbo with BB will solve your problem. I can ask some of my friends to see if they have any experiance with the same setup as you have.
 

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boost is good
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Discussion Starter #9
nope the greddy isnt ball bearing. ide really appreciate if you would ask around for me, theres no one around me with a similar setup, so im kinda stumpt. it seems to drive really good though, even when i shift if boost builds boost right back up fast, it doesnt seem like theres enough air coming about into the turbo to actually do any damage, just enough to make it flutter a little bit.
 

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Supra OG
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What BOV do you have? If it's the Greddy Type R BOV, that's why you have a flutter... they do that.

I'd replace it with either an HKS Racing BOV ($500) or two HKS SSBOVs ($250x2).

Andi
 
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One Element217(Stephen)'s car we were having a bit of the same problem. He tooled around with the screw on it and it has seemed to help. It might take a few high boost and low boost trips around the neighborhood but I'd try playing with that too. Also check the vacuum hose hooked to it. Good luck.
 

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How much boost are you running? It's hard to control compressor surge with a BOV such as yours at low boost. The spring in the BOV is too stiff and the BOV doesn't open all the way at low boost. BOVs like the Greddy Type R and HKS Racing are meant for race cars, not street cars. They are not designed to open at low boost or low rpm. They do work extremely well at high rpm and high boost, however.

For the street with such a large turbo you would be better off with two smaller BOV's than one with such a stiff spring. Maybe two TypeS's or SS's
 

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boost is good
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Discussion Starter #13
Andi-

im using the hks racing.

slow eclipse-
i used to have an hks ssbov and it still did the same thing even at really low boost, around 2-3psi. the hks racing should be fine even at low boost i think, i asked dusty before i bought it and he said it should be fine.

like i said the place i took it too had a T66 supra there, and it did the exact same thing. another guy that worked there has a GN with a huge turbo on it and said it does it too, and that his fathers GN also does it.
 

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Maybe you're stuck with it... My T3/T4 does it also at very low boost. I'm using a Greddy Type S. I have been told that you just have to learn to live with it... I have since changed my driving habbits... I usually let off the throttle very gradually if I'm at very low boost, since whenever I am at low boost I am driving very slowly anyway. If I am in the transitional area between high and low boost, say 7 to 10 psi, I usually just gun it a little before I let off. This sizzles up the turbo so the boost is a little higher before I let off, then I get a clean "blowoff"...
 

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Before somone goes off and tells me how wrong I am, I'm just gonna give my personal opinion in relation to my experience. I'm not saying that I have the right answer especially because there are so many possibilities and unanswered questions.Like everyone else we're just trying to help and equally have given good possibilities. Though many set-ups seem similar they're not the same and just because someone elses race car is that way dosen't mean it's correct. Obviously there is a problem, your gut instict is correct and it doesn't take a mechanic to figure out that, a leak is a leak.
As others mentioned the HKS racing bov, I think they are refering to the older standard style racing bov.... not the new HKS racing bov. Big difference, these have a larger valve... is this better? Again, what is your gut instinct? I'm also curious as to where your bov is mounted....before the intercooler or after the intercooler? Does it make a difference? I'm sure it could....which is better? I don't know, but I prefer to mount the bov before the intercooler and close to the turbo as possible. You claim it leaks when you rev it.... well at that point you are under vacumn, which is what induces a bov to open, but I haven't come across this problem nor have I a T-78. A change or a quick drop in boost can also induce a bov to open, which can be caused by your big turbo to initially and prematurely burst the wastegate open for a split second, when you stab the throttle. I have cured flutter using higher rate wastegate springs in the past. What is your wastegate spring-rate? They are available in different rates for a reason, I would easily assume you need a higher rate spring for a T-78. Anyone? Are you using both signal ports on the wastegate? (pressure&vacumn) Is your boost controller hooked up to both ports? Anyone? Some get away with using one port because of a higher rate spring. Which boost controller are you using? Many boost controllers reqiure opposite vacumn routing with external type wastegates vs. stock. Some boost controllers are just better. Where are you getting your vacumn signal from? Is the vacumn hose a small or large diameter? Is your power steering sharing the same signal hose? Anyone? Well I hope you solve it and maybe you can go back and show those race car guys that instead of 10's maybe they can hit 9's. Saiyonara ;)
 

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No Mercy
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BOV sound

I was at UPRD tonight with some folks and we were checking out the various turbo cars.

There was a T3/T4 3.0VTEC Honda Accord there, with the Tial wastegate and Tial blow-off-valve.

We were all expecting some crazy swooshing sound from the Tial BOV, but all we got was low-pitched fluttering that sounded like compressor surge. The car was running low boost on stock internals and stock fuel. Owner said 60hp above stock, so I figure 4-6psi.

When we were watching the Accord blow-off through the Tial, someone (I think Mani) mentioned that the HKS Racing BOV sounds a lot like the Tial.

Personally I like my Apex'i, with its nice clean PSCHHHHT sound... none of this silly fluttering. :D ;)
 
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Andy, I have what's called the "HKS Race BOV". It's that funny looking piece of crap that comes with the partial RPS kit. Anyway, I get this fluttering sound too when I let off the throttle at low boost or just going slow. I was able to look in the BOV and rev the engine...when ever I revved the engine the BOV would close, when I released the throttle, the BOV would open. Good enough for me until I can get that piece of acient crap off my car :), but it does appear to be working.

Don't worry so much, be happy :D.

Melvin
 

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Roelof said:
Sound like you need a larger BOV. I'm currently using the HKS Racing BOV. I run a Turbo Dynamics T-63 Ball Barring with a Delta wastgate and have none what so ever problems. I have not dynod my car yet but frends with the same setup are running over 700 RWHP and have no at all. :)

Roelof, you have a SP63, and a Racegate. FYI...... Not a Turbo dynamics....


Lar
SP
 

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We were all expecting some crazy swooshing sound from the Tial BOV, but all we got was low-pitched fluttering that sounded like compressor surge. The car was running low boost on stock internals and stock fuel. Owner said 60hp above stock, so I figure 4-6psi.
That was compressor surge. That particular BOV is WAY too stiff for a low boost turbo kit such as the one on the accord...
 
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Larry,

good to see you here. Is it not time for you to set some new records... Also, what do you think of his surge problem? Have encountered that problem with any of your other turbo installs like the Large Twin setup or the stock Greedy setup?

Roelof.
 
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