Gt3076r Not Holding Boost

[limpus]

I'd expect it to make as much as a rb30det which is around the 300ish rwkw mark...the only difference is that a 2JZ is meant to have much stronger internals over a dirty 30...

[zebra]

One thing I have noticed between RB's and JZ's is that the JZs always seem to require a few more (2-3) psi to make the same power (with stock intake manifolds) and identical turbos. Now whether that is to do with the standard intake plenums or the intake ports or the factory cams, I am not sure, but I notice it all the time, mainly when comparing 1JZ's to RB25s, I know that JZ's really wake up with aftermarket cams, so that would be my guess.

[Lithium]

Glad someone else thought that, I've been burnt by suggesting that around JZ folks before so decided to assume that'd be the case here. JZs do seem to have more midrange though. A dyno plot would be very interesting to see.

A lad on Skylinesdownunder (NZ Skyline website) is getting his RB30DET GTSt tuned with a 1.06a/r GT3076R shortly on a hub dyno, that should be interesting.

http://www.skylinesdownunder.com/forums/sh...ead.php?t=59213

[GTScotT]

I honestly thing the issue here is the turbine AR.

I dare say going up in AR would make for a faster accelerating car, despite the fact the boost would come on slower. You would see the power roll on better.

Go for the 1.06 and a gate off the housing and I think you will be find yourself a massive upgrade.

[SimonR32]

JZ have tiny inlet ports so need a few extra psi to squeeze the same amount of air through them

[discopotato03]

Thanks for the heads up Lithium , I've always wanted to see the results of the larger 1.06 A/R turbine housing on a real GT3076R and trials on a 3 litre engine should make it pretty obvious .

Watching this one , cheers A .

[Ruffels]

just because a turbo can be 'Forced' by ways of crude modifications to hold boost, isnt nessasarily a good thing!

both I and a mate have trialed a couple of hypergear turbos on our car, both sets of turbos on both sets of cars had lots of trouble holding boost, by ways of blocking off/restricting the wastegate hole via a retro fitted modification the turbos were made to hold boost 'fairly well' and yet no more power was achieved as the modification mearly forced the turbo to do something it didnt want to do, creating excessive heat, high exhaust manifold pressure, and in turn hot valves, and detonation

just because you can modify a turbo to un naturally hold boost, doesnt mean it is a good thing for either the engine or the turbo?

and unfortunatly alot of people don't understand this, are only interested in the basic figures, like "how much boost" and "how much power"

[zebra]

just because a turbo can be 'Forced' by ways of crude modifications to hold boost, isnt nessasarily a good thing!

both I and a mate have trialed a couple of hypergear turbos on our car, both sets of turbos on both sets of cars had lots of trouble holding boost, by ways of blocking off/restricting the wastegate hole via a retro fitted modification the turbos were made to hold boost 'fairly well' and yet no more power was achieved as the modification mearly forced the turbo to do something it didnt want to do, creating excessive heat, high exhaust manifold pressure, and in turn hot valves, and detonation

just because you can modify a turbo to un naturally hold boost, doesnt mean it is a good thing for either the engine or the turbo?

and unfortunatly alot of people don't understand this, are only interested in the basic figures, like "how much boost" and "how much power"

Finally someone who thinks the same.

Its dropping boost for a reason, jamming it shut has got to be the most backyard thing I have ever seen.

[sriver killer]

Ok hypergear...point taken...i'm tired of arguing with you...lets agree to disagree... and leave it at that...

Scotty nm35...yup...you're right...no dodgy dip at the changeover point too....

ive upgraded fmo my garret 3071R to a hypergear atr43 g3

Finally someone who thinks the same.

Its dropping boost for a reason, jamming it shut has got to be the most backyard thing I have ever seen.

Its good theory and it works

[SimonR32]

Finally someone who thinks the same.

Its dropping boost for a reason, jamming it shut has got to be the most backyard thing I have ever seen.

Technically a spring in either a internal gate actuator or a external gate is always jamming it shut when the set boost level isn't achieved...

Are they backyard?

[zebra]

Nope, because that is what is suppose to hold the gate shut.

Resricting its movement so that incase of cold whether or a bit of extra load etc it overboosts and pings it nut off and kills a motor, is what I call back yard. Just another potential engine killer from the way I see it.

Sure it may work ok now, but havent really been tested for a long period, even still you will never see one on my car.

[Lithium]

ive upgraded fmo my garret 3071R to a hypergear atr43 g3

Weren't you saying you got a GT3076R a few weeks ago?

[Ruffels]

Technically a spring in either a internal gate actuator or a external gate is always jamming it shut when the set boost level isn't achieved...

Are they backyard?

well no its not, because

a. they are usually rated to the turbo's capability that they come fitted on

b. the gate is not restricted in motion (eg if the desired pressure is reached, the gate is completly free to funtion as normal (as aposed to having a screw behind it physically blocking it from opening)

c. the wastegate port hole is also free to flow air once preset pressure is achieved, so that all exces air can vent, unlike another "modification method of screwing down bolts to block flow out from the wastegate hole

therefor the wastegate actuator spring idea is not backyard, however i believe the other methods states in the later parts of b. and c. are 'backyard'

this is why i always say i would like to see tests on the turbo's using these other forms of "boost control" performed such as exhaust gas temp tests, and exhaust manifold pressure tests also! as it's not just about boost and power... its about the otehr detremental things happening to your engine through poor modifications made to turbo's in order to force them to hold boost

[Ruffels]

ive upgraded fmo my garret 3071R to a hypergear atr43 g3

If it was a genuine 5 bolt un cropped garrett gt3071r, you sir are a fool!

[sriver killer]

Weren't you saying you got a GT3076R a few weeks ago?

plan scrapped. I ended up picking the right turbo for the job

If it was a genuine 5 bolt un cropped garrett gt3071r, you sir are a fool!

ease up. it had a nissan 6 bolt rear on it =[

[Trozzle]

I thought the screw in "wastegate controller" merely restricted the exhaust gasses before the gate, so that exhaust pressure had less to play in boost drop as it wasn't forcing the gate open as much...would have the same effect on backpressure through the exhaust housing and manifold as it would without the screws but with the wastegate holding itself where it needs to be.

[Ruffels]

I thought the screw in "wastegate controller" merely restricted the exhaust gasses before the gate, so that exhaust pressure had less to play in boost drop as it wasn't forcing the gate open as much...would have the same effect on backpressure through the exhaust housing and manifold as it would without the screws but with the wastegate holding itself where it needs to be.

if the exhaust manifold pressures are so high that the wastegate is being forced open.. you've got a massive restriction that you'd wanna do something about

as you know a turbo makes boost 'virtually' exponentially, so the wastegate is a vent before the turbine wheel to relieve pressure to 'regulate' boost being made by the turbo, if you physically block (even partially) that 'vent hole' then it forces more air through the turbine wheel, if your already at the turbo's upper flow rate limits, then you can only imagine what stress this is putting on the turbo, not to mention unstable conditions like boost spiking, its not just the turbo that you have to worry about, excess boost, and air that cannot be exhausted will generate high exhaust manifold pressures, which generates high temps, which 'COULD' cause knock conditions and damage to rings, valves, manifolds etc

[JonnoHR31]

tried full solenoid duty where its dropping boost? the highest you mentioned was 80%

[hypergear]

if the exhaust manifold pressures are so high that the wastegate is being forced open.. you've got a massive restriction that you'd wanna do something about

as you know a turbo makes boost 'virtually' exponentially, so the wastegate is a vent before the turbine wheel to relieve pressure to 'regulate' boost being made by the turbo, if you physically block (even partially) that 'vent hole' then it forces more air through the turbine wheel, if your already at the turbo's upper flow rate limits, then you can only imagine what stress this is putting on the turbo, not to mention unstable conditions like boost spiking, its not just the turbo that you have to worry about, excess boost, and air that cannot be exhausted will generate high exhaust manifold pressures, which generates high temps, which 'COULD' cause knock conditions and damage to rings, valves, manifolds etc

In Theory it is correct BUT depending on the extend of boost you are trying to hold. Boost dropped caused by lose of turbine pressure. Assume you can holding 20psi with a super strong actuator vs holding same psi with a gate controller the amount of pressure bleed out is identical, means turbine wheel flows the same amount air. Intake / exhaust restrictions can also simulate similar effects.

If it was a genuine 5 bolt un cropped garrett gt3071r, you sir are a fool!

On the same time I must point out this issue you currently have is not turbo related. Your engine pinned badly with 12 degrees + timing regardless the size of turbo installed. I don’t think its right to define your “problem” on the turbine housing while it was also an OP6 Genuine Nissan.

Tuners would back timing if cyc temp is high enough to detonate. Also means power lose. Unless that, the heat is not at a level of what you've mentioned. Clearly every one else using the same turbo are making heaps more power with less boost because the average timing run on those was between 15~17 degrees on a safe tune.

Btw your turbo was re-sold and installed on GeorgesR34's R34. he will post a dyno reading once tuned.

[discopotato03]

To the OP a cople of issues that you could look at but first .

From what I can gather there is no such thing as a purpose built T3 flanged single scroll turbine for the GT35 turbine - meaning a GT3582R BB turbocharger . They all appear to be re profiled (bored out) GT30 turbine housings so arguably not ideal for a 35 turbine .

I have seen GT3582R's have issues with these T3 flanged GT30 housings and 3 inch dump pipes , I'm told the tubes ID is actually a little smaller than the conical outlet on the housing .

IMO with a 3 litre engine you want absolute minimum avoidable restriction so the front section of the exhaust off the turbo possibly needs to be 3 1/4 or 3 1/2 inch tube .

With turbine housings and a given turbine wheel you get mass gas flow to a point and then the pressure rises uncontrollably because the volume exceeds the housings and waste gates ability to transfer the gas without restriction .

People tell me that a 1.06 A/R GT3582R on an RB30 twin cam engine wants to "spool up" somewhere in the 3200-3400 engine rev area . I would not expect the same from a GT3076R in the same circumstances ie same A/R turbine housing .

GT35 turbines measure ~ 68 by 61mm where a GT30 one is ~ 60 by 55mm so you'd think the GT30 would have slightly higher trapping efficiency and turn this into rotational energy at slightly lower gas speeds .

If you look at the turbine maps for these two turbos at turbobygarrett site you can see that a 1.06 T housing with a GT30 turbine gives similar flow numbers to the 82 housing and the GT35 turbine . The GT30 map looks more even than the GT35 one which is usually the case when wheels are not used in housings designed for them .

I can think of a few low key examples of what the factories do when a turbo engine is enlarged . In the case of the Z32 four cam single BB turbo VG30 Nissan used the larger than RB25 sized OP6 Hitachi turbine housing . This engine in low boost form cranked out a few more Kw than a 33 25DET and with higher torque .

Really in effect going to a larger volume turbine housing lowers the turbine inlet pressure because for the same volume flow the gas speed is lower . If you didn't want to excite the turbine and drive the compressor up to boosting revs then this is the easiest way to go about it . I'd have though that a 3 liter engine would made more off boost torque than a 2.5 and boost possibly wouldn't be needed at this point .

Ford went through all this with the XR6T engine and wound up with a GT3582R cartridge in the 1.06 T housing and if anything an undersized compressor housing . I haven't see one but I was told that the later Typhoon version actually has a hybrid turbo using the GT35 turbine with the 76.2mm compressor from the GT3076R . Assuming this is the case then this compressor in whatever that turbos comp housing is obviously makes enough power/torque to keep Fords marketing team crowing . Had Ford been turbocharging a 3 rather than a 4 litre six pot then they very likely would have used a GT3076R and experimented with 0.82 and 1.06 A/R turbine housings . I reckon if they wanted a reasonably free revving engine and not tonnes of boost the 1.06 would have been a real good try .

Any turbo engine where manifold pressure is forcing the gate open is trying to tell that the turbine inlet pressure is too high .

Also a waste gate is not intended to be a pressure relief valve even though they can be forced to act a bit like one . Its primary function is to control the gas speed through the turbine housing so the speed of the turbine and therefore the compressor wheel can be set to achieve the desired boost pressure . Obviously the higher the engine revs the more the waste gate has to open to keep the boost pressure constant . When the waste gate is opened fully by its actuator or excessive manifold pressure it can't bypass any more than its maximum and if the engines exhaust gas flow continues to climb so will boost pressure to a point . When no more exhaust gas can be forced through the system generally its pressure and temperature go through the roof and terminal detonation sets in .

Anyway I'd measure the hot side manifold pressure and if its considerably higher than boost air pressure consider going up in turbine housing size .

A .