Got A 3076r - Just A Conclusion

[unique1]

Hey Slaps what cams are you running now? i have same issue with power dropping off at 6000rpm with stock rb26 cams

[discopotato03]

Well I can't speak for Nissan's manifold but I can for the GT30 turbine housings . Like I did I suggest those interested go to the turbobygarrett site and look at the turbine maps for the GT3076R and GT3582R . Note the lines representing the 1.06 A/R housing on the GT30 turbine and the 0.82 A/R housing on the GT35 turbine .

I think a lot of the reason why people can't run the GT3076R to its airflow potential limit is because they don't use the largest available housing for it .

Its easy to understand that people are reluctant to do so because the boost threshold gets a bit higher - personally on a twin cam RB 30 I don't think this would be an issue .

I don't find it surprising that any engine , sorry Wolf , with a GT3082R feels a bit strange . I don't know why Garrett ever made them , possibly it was marketing exercise that went wrong . Actually thinking about it I'd say it was a poor second cousin to the HKS spec GT3040 which is same deal wheel wise but they used the 50 rather than the 56 trim compressor of the same BCCW-18C family . There is a map of that 50T wheel at the Garret site but in a different GT40 comp housing , search GT4082 .

Getting off the topic but HKS's closest thing to a GT3582R is the "GT3240" , similar beginnings to the 3582R but with a cropped turbine and a 54 trim version of the same family compressor instead of 56T .

Before I bow out I'll say this , a turbine housing actually is a controlled fixed restriction . Its purpose is to collect the gasses from all intended cylinders and accelerate them into the turbine housings nossel which feeds the turbine blades .

The A/R size of the housing is about what rate the gasses are accelerated into the nozzle section , the smaller the greater and the larger the lesser . The largest housing is less of a restriction than the smaller ones so the larger it is the lower the exhaust manifold pressure will be for a given exhaust gas output .

As engine power outputs get higher and higher so does the requirement to expel greater volumes of exhaust gas , if you don't increase the size of a turbine housing the exhaust manifold pressure gets higher and higher .

Again as I mentioned earlier I'm told that the turbine housings on GT3582Rs are bored out GT30 housings - they actually look like the same castings . If this is the case then the GT35 turbine being 8mm larger in diameter and very probably having a greater inducer tip height needs a larger wider passage machined into it to take the larger turbine wheel . So you get a larger and wider effective nossel and a larger diameter outlet hole (exducer) so you'd expect the housing with the larger turbine to pass the exhaust gasses with less restriction for a given A/R size compared to the GT30 turbine .

If , using the force again , all the above is true then getting pretty much the same gas flow with a turbine that's designed to work with its native housing and nossel is a no brainer - provided the GT37 compressor can pump all the air you need .

Just on those HKS cast RB20 manifolds , I know the pad is large enough to drill and tap for T4 pattern fasteners but is there enough meat in the casting to take the outlet ports up to T4 TS size ?

The RB26 one was always intended to take a T4 TS turbine housing (TA45S) and from memory they are larger in the passages than their RB20 manifold .

I know someone that has a 26 one and I must compare my RB20 one with theirs .

Always open to others ideas , cheers A .

[megrac]

As engine power outputs get higher and higher so does the requirement to expel greater volumes of exhaust gas , if you don't increase the size of a turbine housing the exhaust manifold pressure gets higher and higher .

Again as I mentioned earlier I'm told that the turbine housings on GT3582Rs are bored out GT30 housings - they actually look like the same castings . If this is the case then the GT35 turbine being 8mm larger in diameter and very probably having a greater inducer tip height needs a larger wider passage machined into it to take the larger turbine wheel . So you get a larger and wider effective nossel and a larger diameter outlet hole (exducer) so you'd expect the housing with the larger turbine to pass the exhaust gasses with less restriction for a given A/R size compared to the GT30 turbine .

If , using the force again , all the above is true then getting pretty much the same gas flow with a turbine that's designed to work with its native housing and nossel is a no brainer - provided the GT37 compressor can pump all the air you need .

Always open to others ideas , cheers A .

Wouldn't the main restriction in a housing be the start of the scroll just befor it opens up to the turbine not the area that enters the inducer of the turbine? This is where other manufacturers like mhi and holset get the cm^2 from, this would mean going to a larger turbine for the same housing would not get you all the gains the new larger wheel has to offer.

I've been making a few holsets over the past months these include using the 14cm and 18cm housings from an hx35, things i've found is an hx40 67mm exducer turbine has the same egbp in a 14cm housing as a hx35 60mm wheel in an 18cm housing, i would of thought a larger egbp drop would of been recorded but if you think about it we still have a 14cm restriction.

Thoughts?

[discopotato03]

What Mitsubishi and Holset , amongst others , have is an area measurement . Its a means of identifying housing size as in an 18cm housing is larger than a 14cm one .

What Garrett use is an area to radius ratio , basically the area decreases as the radius from the center of the volutes passage to the center of the shafts axis decreases . It is a constant meaning constant reduction in area and radius .

I've never cut one in half but I can't see the logic in a turbine housing necking down to a point and then increasing in area before its nossel section . The whole point of the thing is to collect and accelerate the exhaust gasses into the turbine blades .

Whenever you have gasses travelling through a reducing passage the velocity rises and with this comes a pressure rise .

Its the amount that the pressure rises that can be a stumbling block because engines don't like major pressure rises in their exhaust systems .

It's just a fact of life that to drive a radial in flow turbine the gasses need to be moving reasonably quickly and you generally get a greater pressure rise in single scroll systems because you can't benefit from the pressure rise and fall of the exhaust pulses like you can in a twin scroll system .

Also hot gasses want to expand and take off down the path of least resistance , there is a thing know as expansion ratio and I think its why an adequately sized turbine in a large ratio housing tends to work better than a large turbine in a small AR ratio housing . I'm told its the better expansion ratio and getting more effective use of the heat energy in the exhaust gas .

As for turbine housing use honest engineers will tell you that boring out a housing to take a larger major diameter turbine is not good because you are removing part of the depth of the nossel section and therefore changing its shape . Usually it shows up as lower turbine efficiency so not the best use of your hot exhaust gas .

The more I look at these GT3582R's the less I like them because they have so many compromises , IMO the center section and shaft diameter is a bit small and the housings don't appear to be the best match for the compressor and turbine wheels . Probably the best you can do for the frame size is use that TS T4 flanged 1.06 housing and try to get the proper Garrett port shrouded compressor housing particularly if you don't want to use big enough turbine housings - for a GT35 turbine . Same deal as the 3037/3076R , small turbine housings work better with ported comp covers because driving the compressor into boost at lower engine speeds often makes them surge and the ported comp cover helps reduce the compressor surge .

Ultimately smaller turbine housings become the eventual choke point and limit both the engine and compressor section in what they can put out .

This is why I reckon building an engine that makes good usable power off boost helps because you don't need more restrictive read smaller turbine housings to get boost for torque down low . You can afford to go up a bit in housing size make more power because the pressure balance across the engine is closer to being the same than it would have been with the smaller turbine housing .

Note that both the GT30 and GT35 UHP turbines are fairly large in trim size at 84T and this is why I think they work better in large AR housings than smaller ones . I think Garrett wants us to use turbines of smaller major diameter but larger trim to get good gas flow and low inertia in a reasonably compact turbocharger for the power output .

Many of the older T series turbines were in 76 trim ie T04 P , TA45's , T51's etc etc . They can at times be a little more responsive that the GT UHP turbines but they are heavier and bulkier as well .

Anyway , your respective calls . If you can live with 500 Hp potential but want GT35 turbine/0.82 AR like exhaust gas throughput potential you can have that with the 1.06 A/R GT30 housing on a GT3076R turbo .

I'd rather have the grey area the top 10% of the engines power output rather than the bottom 10% because I know where the greater part of my time will be spent - particularly in a road car .

I really have to dig out that diesel spec GT3576 I have in the cave to give you all an idea what housings Garrett use on serious GT35 turbochargers - note it uses the 76.2mm GT37 compressor but some did have the 82mm GT40 comp .

Something to look at from a GT3571 - yes Garrett did actually use a 71.1mm 52T GT35 compressor on some diesel spec GT35 turbos . Note the 0.94 A/R TS turbine housing .

A .

[wolverine]

I don't find it surprising that any engine , sorry Wolf , with a GT3082R feels a bit strange .

I am really offended

I would be the first to say go for a different turbo (GT3076 or thereabouts for a similar application) but with all the right gear and set up a GT3040 works fine.

The HKS GT-RS (T3 flanged version) has a similar mismatch of turbine to compressor and no one really gripes about how they drive. It may not be the best way to go but it works fairly effectively in the real world.

I bought mine for the right price with all the accompanying goodies (HKS manifold, extrude honing already done on the lot etc) that it was hard to pass over.

If I was replacing the turbo (and using the HKS manifold) I would use a twin scroll housing on a GT3076 or lean on a GT3071.

[Lithium]

It's just a fact of life that to drive a radial in flow turbine the gasses need to be moving reasonably quickly and you generally get a greater pressure rise in single scroll systems because you can't benefit from the pressure rise and fall of the exhaust pulses like you can in a twin scroll system .

Also hot gasses want to expand and take off down the path of least resistance , there is a thing know as expansion ratio and I think its why an adequately sized turbine in a large ratio housing tends to work better than a large turbine in a small AR ratio housing . I'm told its the better expansion ratio and getting more effective use of the heat energy in the exhaust gas .

I am going to have to reflect and maybe study a little more on this rant, it is definitely an interesting one though more theory based than anything? When it comes to the real world, what negative effect do you feel the GT3582R would have versus using a GT3076R for a similar power level?

The reason I ask, is from my own experience with .82a/r GT3076R going to a .82a/r GT3582R on an RB25 I feel that the compromise in low down spool is no more relative than the extra flow level you gain. GT3582Rs behave very very well for the amount they flow - in fact from my experiences with them I'd call them damn near the most reasonable stepping stone from being a proper street turbo into the "Big laggy turbo pond". They are still well useable, but they really can make some big numbers... theoretical breakdown of what may or may not aid their cause aside.

Similar rated Holsets argueably spool similar to similar rated Garretts, and they are famous for their wheel and housing designs - the way many would match a Holset turbo would be the equivalent of a tight a/r on a big wheel and they seem to behave very very well despite being a plain bearing job. Any thoughts on how/why - is this apples for oranges?

[D_Stirls]

On a side note as anyone got any pictures of the new T3 twin gate Split Pulse housings that Garrett has just released for the EVO's? i know there were some online a couple months ago but now i can't find them.

Also how much of a market do you guys think would be for a EVO flanged RB exhaust manifold so the new housings can be used on RB's?

[megrac]

Similar rated Holsets argueably spool similar to similar rated Garretts, and they are famous for their wheel and housing designs - the way many would match a Holset turbo would be the equivalent of a tight a/r on a big wheel and they seem to behave very very well despite being a plain bearing job. Any thoughts on how/why - is this apples for oranges?

On my engine and the holset's i've made they have always liked the larger turbine housings, egbp goes through the roof with the smaller housings, fine if your engine setup doesn't mind it so much but mine hates it.

Spool is ok but i have a flap in one scroll that opens when full boost is reached(TS housing on SC manifold), this works so well more people should do it, there's a good 4-500rpm in it. This means you can move to a very large housing. With a 2.5L my holset hx40/50 67mm exducer turbine/63mm inducer compressor, 14cm housing gets 1bar at 4250rpm in 3rd.

I've made a few garretts of similar size but never really liked them compraed to how the same sized holsets have performed, the hx3540 with the billet 60mm compressor is a great turbo.

[Lithium]

On my engine and the holset's i've made they have always liked the larger turbine housings, egbp goes through the roof with the smaller housings, fine if your engine setup doesn't mind it so much but mine hates it.

Spool is ok but i have a flap in one scroll that opens when full boost is reached(TS housing on SC manifold), this works so well more people should do it, there's a good 4-500rpm in it. This means you can move to a very large housing. With a 2.5L my holset hx40/50 67mm exducer turbine/63mm inducer compressor, 14cm housing gets 1bar at 4250rpm in 3rd.

I've made a few garretts of similar size but never really liked them compraed to how the same sized holsets have performed, the hx3540 with the billet 60mm compressor is a great turbo.

I don't think of a 14cm twin scroll housing as THAT big so I guess it depends on what you mean haha. Works out as roughly the equivalent to .96a/r if I have it right?

Are you running an RB25? I don't really like the idea of a single entry manifold with a twin scroll turbo, wouldn't the "spool valve" method you are using only be effectively a bandaid to mismatching the exhaust pulse collection. It would be interesting to see what the difference would be if you had a nicely designed twin scroll manifold - though me and mates have blue skied about building a twin scroll manifold with an actuator designed to close off flow to one scroll and bypass the flow so that its a single scroll 1/2 a/r turbo until acceptable boost is reached then revert to twin scroll.

[megrac]

No its a 2.5 subaru engine. I don't think running the same housing on a twinscroll manifold will get the same results as running it with the flap on a sc manifold but i have never tried it though, i just can't be bothered making the manifold twinscroll. My manifold is a nice equal lenght 4-2-1.

From looking at what other people have found there seems to be no change in power running a tw or sc housing on a sc manifold. You can gain from running a tw housing on a ts manifold but if it beats the flap or not would need to be tested on the same engine.

I have many datatlogs of egbp/boost with the flaped housings but i wouldn't want to litter this thread with it.

What a started out saying in my first post was bigger turbines need bigger housings to see the best gains from them. If you clamp a good sized turbine with a small housing you end up with a pig of a turbo that cant make good power. You may as well step down in turbine size and use the right sized housing for it.

[unique1]

so on a gt3076r with a 0.82 rear, getting changed to a 1.06, will these effect the position of the turbo at all or will everything be a direct bolt on compared to the 0.82 housing? is the housing an unbolt, bolt on proposition or does it need to be done by a turbo shop? any idea what a rear housing is worth? and a v band one as well?

Edited August 31, 2009 by unique1

[discopotato03]

Well Lithium I don't think you have lots to lose by trying a a 0.82 A/R GT3582R , you would prove one way or the other that its got what it takes to make power without super high boost pressure . For me the trade off would be more lag than I'd like to live with in a 2.5 litre road engine , I wouldn't like to contemplate a 0.63 A/R housing on one of these because the boost threshold got a bit high .

If I really had to use a GT3582R I'd be nagging someone to dredge up a HKS spec GT3040 or GT3240 . Their GT3040 had the 50 rather than 56T compressor so with a GT35 turbine swapped in should be less laggy than a 56T GT3582R .

The 3240 has a bit more turbine than a GT30 but a bit less than a full GT35 turbine - factory Garrett cropped GT35 UHP turbine . The comp wheel is as I said 54T rather than 56T and still a bit big IMO for 2.5 L streeter .

Search for the GT4082's comp map because it uses the 82mm GT40 compressor in 50 trim as well .

A .

[Tangles]

my ID tag is 700177-5015

front v45 ported comp.housing 60trim

rear avo .73 skyline exh.housing

http://www.turbobygarrett.com/turbobygarre...am_May_2007.pdf

[discopotato03]

The cartridges with the 76.2mm GT37 series compressor wheels are 700177-5006 and 700177-5007 . These in complete turbo form are the GT3037's or what people generally call GT3076R in the Garrett range .

A .