Gt3076r Iw Need Help To Achieve 21 Psi Flat Line

[conan7772]

Just fitted the GT3076R to an RB25/30.

Engine management is Haltech S2000, closed loop boost control.

Turbo kit came with standard Garrett 5psi actuator.

Can only peak briefly at 18psi then drops to 15. 310 rwkw max.

Really would like 330 - 340

Another example here is Als. Pretty much a similar engine to mine, injector sizes, cams, only he opted for the 15psi actuator.

However Al only gained an extra 2 psi across the graph, and our curves are identical, same peak and drop, but he's got 20 kw more.

Is this the typical symptom of the IW 3076 ? or is it still crap actuators ?

If I was to fit a large can 18 psi actuator, could I achieve 21 psi flat line.

Also wouldn't mind boost to come on a little earlier

Please don't tell me to go External wastegate.

Cheers.

[DaveO74]

What size is the rear housing?

[conan7772]

What size is the rear housing?

We both have 0.82 rear 56 trim

[TiTAN]

you are running near the limits of the turbo as it is.

the dyno you are using may just read lower than the one AL is using.

[JonnoHR31]

i think hes refering more to the boost plot than the power. try a heavier actuator, i've got a 12psi with a profec b and can hold 22psi fairly well. make sure you wind in as much preload without restricting the full opening of the gate too

[Ceffy]

I switched to a 0.9bar actuator on my GT30 IW and it held 20psi well on the dyno, but has been set to 16psi by my tuner (thru the EBC). Ideally you want to run an actuator pressure as close to what you want to run. Find yourself a 1.4bar actuator....

[conan7772]

What's the difference between small and big head actuators ?

[Brandon]

Well I've got the sorta the same problem from my tune. The boost would only hold up to 1.1bar and wouldnt hold at 1.2 or 1.3... I'm thinking its the boost controller thats the problem but the tuner reckon its wastegate.

[conan7772]

Well I've got the sorta the same problem from my tune. The boost would only hold up to 1.1bar and wouldnt hold at 1.2 or 1.3... I'm thinking its the boost controller thats the problem but the tuner reckon its wastegate.

What RPM is your peak boost?

[R31Nismoid]

However Al only gained an extra 2 psi across the graph, and our curves are identical, same peak and drop, but he's got 20 kw more.

Dyno differences more than anything else if its only 15-20rwkw.

[Brandon]

No idea. Only got 340awhp (255awkw) outta it at 1.15bar but when I'm driving, I hardly hit that. Its normally sitting at 1.1bar. Heres the graph from the dyno.

[jdmtom]

Do what i did. Twin 44mm tails and boost will we right on the money all day long

[bradsm87]

Move the boost pickup to the cold pipe instead of the hot pipe if it isn't already. This helps reduce boost tapering down. Also GT3076R's are designed for low boost with their T04E 0.6 compressor housing so i wouldn't go higher than 19psi or so on one anyway. Try to get it to hold 19psi with the pickup on the cold pipe.

[discopotato03]

If you want the most out of that turbo you HAVE to run the the largest 1.06 A/R ratio turbine housing . Others with these turbos on twin cam RB30's for some reason fear turbine lag with this housing and I can't understand why . Some have said that these engines are a bit laggy with a 1.06 turbine housing on a GT3582R but thats largly because the GT35 turbine is 8mm larger on the OD and a fair bit larger on exducer size than the GT30 turbine .

I know 8mm doesn't sound like much but do the area of a circle calcs and you soon work out the difference is significant .

I can't tell you what the boost threshold difference is between a 1.06 A/R GT3076R and a 1.06 A/R GT3582R but the wheels are larger and heaver in the latters case . The other thing is that the GT30 turbine has been designed to work with a GT30 turbine housing as a matching pair , everything I see points to the GT3582R's using a bored out GT30 turbine housing so not exactly an ideal situation . Real GT35 turbine housings from the diesel world start at about .96 I think A/R with the twin entry T3 like Euro T4 flange and grow to about 1.17 + A/R with the large T4 international TS flange on turbos like the GT3576 .

If I wanted a reasonably free reving RB30 twin cam and 320 + Kw I would have no hesitation at all in running the big housing on a GT3076R , big engine with big exhaust flow requirement needs a bigish turbine housing to cope with it .

I'm not so sure the GT3076R is a "low boost turbo" because it wears a T04E compressor housing . I don't think the beginnings of gas flow restriction start with the compressor housing , I reckon its all in the turbine housing . The fact that they come std with a port shrouded compressor housing shows that Garrett knows the compressor will potentially surge with small and possibly medium sized turbine housings .

Both wheels in the over the counter GT3076R are big on trim size - 84 for the turbine and 56 for the compressor and this is not something added to give stellar turbine response . It's done to maximise gas throughput for the basic size of each wheel .

If really serious with three litres forget all about these small frame GT BB turbos , step up to a split pulsed T4 flange manifold with two external gates and bolt on a GT4088R . Arguably one of the best dedicated petrol engine performance turbos Garrett ever made .

Your calls , cheers A .

[lachlanw]

get a higher pressure actuator . its never gonna work properly when your target boost is over 4X your waste gate pressure

duty cycle would have to be massive if not 100% depending on your plumbing . and changing 1% will have a massive effect due to massive difference between actuator pressure and target pressure

[bradsm87]

If you want the most out of that turbo you HAVE to run the the largest 1.06 A/R ratio turbine housing . Others with these turbos on twin cam RB30's for some reason fear turbine lag with this housing and I can't understand why . Some have said that these engines are a bit laggy with a 1.06 turbine housing on a GT3582R but thats largly because the GT35 turbine is 8mm larger on the OD and a fair bit larger on exducer size than the GT30 turbine .

I know 8mm doesn't sound like much but do the area of a circle calcs and you soon work out the difference is significant .

I can't tell you what the boost threshold difference is between a 1.06 A/R GT3076R and a 1.06 A/R GT3582R but the wheels are larger and heaver in the latters case . The other thing is that the GT30 turbine has been designed to work with a GT30 turbine housing as a matching pair , everything I see points to the GT3582R's using a bored out GT30 turbine housing so not exactly an ideal situation . Real GT35 turbine housings from the diesel world start at about .96 I think A/R with the twin entry T3 like Euro T4 flange and grow to about 1.17 + A/R with the large T4 international TS flange on turbos like the GT3576 .

If I wanted a reasonably free reving RB30 twin cam and 320 + Kw I would have no hesitation at all in running the big housing on a GT3076R , big engine with big exhaust flow requirement needs a bigish turbine housing to cope with it .

I'm not so sure the GT3076R is a "low boost turbo" because it wears a T04E compressor housing . I don't think the beginnings of gas flow restriction start with the compressor housing , I reckon its all in the turbine housing . The fact that they come std with a port shrouded compressor housing shows that Garrett knows the compressor will potentially surge with small and possibly medium sized turbine housings .

Both wheels in the over the counter GT3076R are big on trim size - 84 for the turbine and 56 for the compressor and this is not something added to give stellar turbine response . It's done to maximise gas throughput for the basic size of each wheel .

If really serious with three litres forget all about these small frame GT BB turbos , step up to a split pulsed T4 flange manifold with two external gates and bolt on a GT4088R . Arguably one of the best dedicated petrol engine performance turbos Garrett ever made .

Your calls , cheers A .

Compared to a GT3071R, i think it's a low boost turbo. If u look at the differencer between the compressor maps of both, the 76 has wider lower islands where the 71 has higher narrower islands.

[discopotato03]

I prefer to look at the number of corrected pounds of air that the compressor is pumping , if anything the lower the boost pressure is for a given air flow rate the less the outlet air temp tends to be .

For what ever reasons the real GT3071R didn't end up being the more responsive little brother to the GT3076R that many of thought it would be . I think Garrett attempted to make a production version of their competition spec TR30R turbo and it didn't really work out because unlike the TR30R's 60mm NS111 turbine (in 73 or 76 trim) the 60mm GT30 turbine is 84 trim and 10 bladed instead of 9 .

It makes life hard trying to get more or I should say earlier response with a big trim turbine by using a smaller A/R turbine housing , I reckon what happens is that the smaller volume volute passage gets the gas speed up and the larger aspect ratio exducer side loses much of it .

HKS seemed to get around this best by using the cropped version of the GT30 turbine in a GT30 based turbine housing with the GT2835 series turbos - not the GT28 turbine housing versions of them . Out of this I think they got a bit higher shaft (compressor) speed without necessarily using small ratio turbine housings . Garrett chose to only use these cartridges in GT28 turbine housings for their marketed range and we know they're a POS turbo in that form .

If they'd given us the 60mm NS111 turbine from the TR30R and profiled their GT30 turbine housings to match then the "GT3071R" would have been a more responsive and successful turbo IMO .

The TR30R turbos had either a 76.2 or a 69.something mm compressor wheels in a couple of trim sizes . The largest comp option that I've seen a map for is dimensionally similar to the GT3076R's 76.2mm 56T wheel but it is of a different family and if I remember correctly is 5/5 bladed rather than 6/6 like most GT series wheels .

A .

[conan7772]

Anyone fitted the HKS actuator to one of these ? Any better than the Garrett 18psi large can.

Nengun have a small range of high boost actuators.

All a bit pricey though.

I've decided to go the 18psi unit as I never really ever turn it down.

Also wouldn't mind it to come on a little earlier.

Again Haltech controls it closed loop.

Cheers

[Aberax]

Anyone fitted the HKS actuator to one of these ? Any better than the Garrett 18psi large can.

Nengun have a small range of high boost actuators.

All a bit pricey though.

I've decided to go the 18psi unit as I never really ever turn it down.

Also wouldn't mind it to come on a little earlier.

Again Haltech controls it closed loop.

Cheers

I have a Haltech E11v2 with a boost controller solenoid, my GT3076R (3037S) has a 12psi actuator. How well is that going to control boost? I shall be finding out later this week when i get it installed and tuned, just wanting to know what i should/shouldn't be expecting.

[SLAPS]

One really has to drive the GT3076r with a .82 rear on the RB30 to understand why it is such an awesome combination.

Al's has no issues pulling out to 8k with his .82 rear. Power is limited to around 320-330rwkw on pump with the .82 rear.

The 1.06 gt30 hot side flows approximately the same as a GT35 .82 hotside however the gt30 comp wheel is wasted on it as it runs in to choke well before the hot side is max'd. For a track car sure.. It will help keep EGT's down but for a streeter its best to tighten up the scroll.

Spool is similar between the gt30 .82 and 1.06 GT30 so I really wouldn't bother. A leaf out of the RB30ET's... They simply skip the whole 1.06 rear on the GT30 idea as the gains are minimal for the increased lag.

--

On Topic.. Even the GT35r IW's have issues holding boost regardless of power being made. Back to SK's ideals... Match the wastegate to the boost you wish to run. In my experience its best to try to get the actuator to around -2psi of the total boost you intend to run.

Edited September 26, 2009 by SLAPS