Gt3076r

[huddy]

i was wondering if it a common problem for the gt3076r IW to overboost.

i have just bought one, and so has a mate - he has his fitted on his rb20 and found overboosting a major problem.

is it a common problem?

is it as simple as making the size of the wastegate hole larger? (machining it out? and if so - how/where)

it is a .63 IW rear housing (5 bolt style) . 0.6 front cover, 56 trim... etc...

just like to get some info before i fit mine on - as i dont want the same problems.

cheers

-Matt

[R31Nismoid]

Sorta on the same topic

http://www.skylinesaustralia.com/forums/St...mp;hl=overboost

Are you running a genuine Garrett .63 housing?

What exhaust setup is being used?

What boost control methods?

What boost is being used? Does it constantly climb or only after a certain RPM?

[SKYHY]

i was wondering if it a common problem for the gt3076r IW to overboost.

i have just bought one, and so has a mate - he has his fitted on his rb20 and found overboosting a major problem.

is it a common problem?

is it as simple as making the size of the wastegate hole larger? (machining it out? and if so - how/where)

it is a .63 IW rear housing (5 bolt style) . 0.6 front cover, 56 trim... etc...

just like to get some info before i fit mine on - as i dont want the same problems.

cheers

-Matt

hey dude i have the same problem and my one is a .82 rear, i haev been told if you get the hole ported it helps with the overboosting, if not get a extranl waste gate setup something like a 50mm.

[The Mafia]

my 0.63 overboosts on the RB25

but I'm pushing 19psi and 300rwkw

[skylinecouple]

Thats why I ordered the 3071 with .82 housing. I have heard too many times of overboosting with large compressors and small turbine housings. More air in means more air out so if it can't get out...........? From everything I've learned on this forum the matching of comp. to turbine is not something to be taken lightly. I would rather have a slightly small comp. to exhaust ratio than the other way round. Have you ever noticed how the standard hi flow will make much more power with the vg30 turbine housing ? It usually isn't the compressor that limits power in most cases. Exhaust flow is more important than compressor flow. And the concept of having an exhaust that flows too much is ludicrous bordering on just plain ignorant. The turbine is the smallest part of the flow path. It is the turbine that dictates exhaust flow.

[The Mafia]

I'm not too worried, the most it gets to is 19psi before I hit 7,000rpm so I've just set my boost at that

314rwkw as a result..

With the 3.0l I'll definately be putting on the 0.82 housing though.

[discopotato03]

Hi Skylinecouple , just another 2c to spend - just my opinions .

I would hesitate to say that exhaust flow is more important than compressor flow , IMO it is at least as important and the reason I'm guilty of thrashing the exhaust side theme is because its the part thats most often short changed .

I think its entirely possible to over do things on the exhaust side and while the engine won't suffer it very likely won't get torque from boost in the rev ranges that most people use day to day .

The GT3071R (-23 version) was always going to be a bit fussy in single scroll form because the turbine and compressor major diametres are reasonably close (60/71mm) and the trim sizes both sides are reasonably big . All you can really hope to do with turbine housing A/R is "tune" the exhaust gas velocity to make it spool up approximately where you need the torque from boost to start .

Where this changes is when you alter an engines VE by say porting the head/larger valves/better cam profiles/manifold etc . If you can get the engine to make more low to mid range torque through breathing enhancements (breathing out in this case) you can go up a little on turbine housing A/R size so that the turbo increases performance from higher in the engines rev range .

Its a pity HKS and Garrett didn't make GT30 IW turbine housings in 0.73 A/R like HKS did for some of their T28 flanged GT30 housings . You may find that 0.63 could bit a smidge small and the 0.82 a smidge big and the only real option is the 3037 Pro S IW 0.68 - hint .

The burning question for you is will the 0.82 housing spin a real GT3071R fast enough early enough to make an acceptable boost threshold . If not I doubt there'd be any shortage of people wanting to buy a fresh 2nd hand IW housing from you which suits real GT3071R's/GT3076R's . Possibly with a bit of swapping going on people can experiment and end up getting what they want without buying several new housings .

Cheers , A .

[Haines]

I get overboosting with an AVO .74 housing on a 3076r

Its not a great deal and I am going to tune my car to suit (it just hits 1 bar at 6500rpm)

[Bliksem]

I'm not too worried, the most it gets to is 19psi before I hit 7,000rpm so I've just set my boost at that

314rwkw as a result..

With the 3.0l I'll definately be putting on the 0.82 housing though.

I remember reading a while back you recommended running a GT35r on an RB30, are you only keeping the 3076 to retain IW & manifold due to expense? only asking as i'll be upgrading my turbo to suit the 3.0L block and dont want to run into the overboost issues seen with the 3076 IW...

[Dale FZ1]

i was wondering if it a common problem for the gt3076r IW to overboost.

i have just bought one, and so has a mate - he has his fitted on his rb20 and found overboosting a major problem.

is it a common problem?

Does your mate use a boost controller? The reason for this question is to determine whether the wastegate is being held shut for longer than if only a pneumatic actuator was employed. He might be getting a sharp "knee" in the boost curve (ie quick rise), but if the mass flow increase is rapid then there might be difficulty venting and keeping things under control.

Also what power level was targeted, and what boost level is being used to achieve it?

From everything I've learned on this forum the matching of comp. to turbine is not something to be taken lightly. I would rather have a slightly small comp. to exhaust ratio than the other way round. Have you ever noticed how the standard hi flow will make much more power with the vg30 turbine housing ? It usually isn't the compressor that limits power in most cases. Exhaust flow is more important than compressor flow. And the concept of having an exhaust that flows too much is ludicrous bordering on just plain ignorant. The turbine is the smallest part of the flow path. It is the turbine that dictates exhaust flow.

The bolded sentence I agree with, however what is important to keep sight of is that the compressor and turbine operate in a mutually interdependent master/slave relationship. Each one feeds the other. You need a compressor big enough to do the job, and a turbine that is not so underdone from a mass-flow perspective that it chokes the thing.

I would hesitate to say that exhaust flow is more important than compressor flow , IMO it is at least as important and the reason I'm guilty of thrashing the exhaust side theme is because its the part thats most often short changed .

I think its entirely possible to over do things on the exhaust side and while the engine won't suffer it very likely won't get torque from boost in the rev ranges that most people use day to day .

All you can really hope to do with turbine housing A/R is "tune" the exhaust gas velocity to make it spool up approximately where you need the torque from boost to start .

Where this changes is when you alter an engines VE by say porting the head/larger valves/better cam profiles/manifold etc . If you can get the engine to make more low to mid range torque through breathing enhancements (breathing out in this case) you can go up a little on turbine housing A/R size so that the turbo increases performance from higher in the engines rev range .

The burning question for you is will the 0.82 housing spin a real GT3071R fast enough early enough to make an acceptable boost threshold .

Possibly with a bit of swapping going on people can experiment and end up getting what they want without buying several new housings .

Pretty well put Adrian. The bolded sentence is the key for me.

The change in VE that Nissan achieved with the RB25 Neo, purely from the double VVT (and perhaps changed cam profiles??) is how I see they got away with using the OP6 housing but not suffering any noticeable losses anywhere through the range. And obviously that's where things head when blokes install Poncams etc. The larger turbos start to give a better overall showing of their capabilities.

I hope that Gary's 0.82 selection will give the right sort of response for street use, though I recall with his earlier criticism of the high flow, he was running into heat build up and knock on the track. The larger housing should (I think) give a slightly doughier bottom end and part throttle response, requiring a bigger throttle % to get it happening. But boost creep shouldn't come into the equation especially if it is spec'd with the larger wastegate version.

I believe Cubes has better knowledge/experience in this area.

[discopotato03]

Does your mate use a boost controller? The reason for this question is to determine whether the wastegate is being held shut for longer than if only a pneumatic actuator was employed. He might be getting a sharp "knee" in the boost curve (ie quick rise), but if the mass flow increase is rapid then there might be difficulty venting and keeping things under control.

Also what power level was targeted, and what boost level is being used to achieve it?

The bolded sentence I agree with, however what is important to keep sight of is that the compressor and turbine operate in a mutually interdependent master/slave relationship. Each one feeds the other. You need a compressor big enough to do the job, and a turbine that is not so underdone from a mass-flow perspective that it chokes the thing.

Pretty well put Adrian. The bolded sentence is the key for me.

The change in VE that Nissan achieved with the RB25 Neo, purely from the double VVT (and perhaps changed cam profiles??) is how I see they got away with using the OP6 housing but not suffering any noticeable losses anywhere through the range. And obviously that's where things head when blokes install Poncams etc. The larger turbos start to give a better overall showing of their capabilities.

I hope that Gary's 0.82 selection will give the right sort of response for street use, though I recall with his earlier criticism of the high flow, he was running into heat build up and knock on the track. The larger housing should (I think) give a slightly doughier bottom end and part throttle response, requiring a bigger throttle % to get it happening. But boost creep shouldn't come into the equation especially if it is spec'd with the larger wastegate version.

I believe Cubes has better knowledge/experience in this area.

You can make huge differences to an engines characteristics with better profiles and more versatile VCT . Nissan obviously thought that to run the cams they wanted non hydraulic buckets and variable rather than on/off (R33 type) was the go . Because you can then have a say in the cylinders trapping efficiency you can size the turbine housing more around wide range performance than spooling the turbo for low end torque .

Cheers A .

[huddy]

that is AWESOME information - thanks guys!

i'm a bit of a sucker to try my own thing sometimes, so i will persist with setup. BUT i reackon i'll definitely be get the wastegate hole ported out!!!

keep the info coming guys if anyone else has had any results or got any info / feedback

thanks

-Matt

[Bliksem]

FWIW I read on these forums Garret also sell an internally gated 3076 with a larger wastegate port for an additional $100

[huddy]

yeah thats what i specifically asked for... hmmmm i will have to double check on that!

[huddy]

ok... well the setup in question (on the rb20) main problem was that the actuator was not closing the wastegate flap - only half way!!!! SO that would definitely make it laggy as and cause boost issues.

i'm getting mine ported out with a larger flap as it seems Garrett australia and garrett america do things completely different, and talking to guys from MTQ it is just going to be less of a headf*&k to get it ported out.

i've been told that it may still overboost, but will be better than it was.

hopefully shouldnt be too much of a problem as i'm aiming to run around 20psi anyway

i will update as i get more stuff done

[discopotato03]

Those garrett GT30 and GT35 IW turbine housings are made here in Australia so we know where they're getting them from . Many of them are playing with reprofiled Ford Garrett "T3" IW turbine housings because they available and cheaper - result is cheap and nasty .

Up to you but talk to those using the propper housing in original form making high power , the problem you have may not be the IW and if its not then it won't solve much . Also larger flat valves have greater face are for exhaust pressure to work on so don't be surprised if you need a slightly higher rated actuator to maintain your desired boost pressure . Turbine inlet pressure is a PITA but can be beaten if approached properly .

Cheers A .

[huddy]

thanks for the reply - and what you say does make sense,

i recall one of the MTQ guys saying that it was the .63 exhaust housing -m option that was hard to obtain... ? does this make sense???

[dangerman4]

-m option is the larger waste gate hole and flapper i think.

as im running one of the highest kw internal gated cars on here i would not lay all the blame on the waste gate flap.

what actuator are you running?

im guessing but its prob the one that you got with the turbo?

they are often rated at below 1 bar, and if your trying to run 18 -22psi then they will struggle all day long.

a simple way to look at it is pick a desired boost level that your happy with and then buy a new actuator that suits that level. ie if you wish to run 18 - 20 psi on a stock motor thats fine, but get yourself a 18psi actuator.

one of the first things i did when i purchased my gt3582r-iw was toss the 1 bar stock unit and install a 18psi waste gate actuator. the difference was huge.

ive run up to 26psi thru mine and the 18 psi spring was starting to struggle, but was still within 1.5 psi of targeted boost level with only a slight dip to 25 psi then returned to 26psi

my next actuator will be 24psi rated and that will solve my slight wave.

try that first before you start attacking anything with the dremil.

remember, once its gone you cant put it back.