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Twin turbo kits


Gazboy
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http://www.japengineshop.com/images/column_1218561117/DSCF5706.jpg

 

http://www.japengineshop.com/images/column_1218561117/DSCF5702.jpg

 

£312 + delivery

You can ask for any flange setup i.e. t3, t4, td06 etc etc and they can also do a dual/signle vband setup with vband or older flange

 

I have seen one of there single manifolds recently and the quality and workmanship was spot on TBH

 

They did build me a one off Veilside type intake manifold for a 7MGTE supra as there is nothing off the shelf to speak, and i could'nt fault that either.

 

[email protected]

His name is Note

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no the pipe you see in the pic still needs a flange welded on to mount the wastegate (but with so many different flange sizes and types... its not on)

You would have to do custom wastegate dump (screamer) pipe routing, but if your going to undertake a Twin coinversion then its not a big deal.

 

Nice pair of gt28rs turbos would make an interesting setup

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well the gt2835 is based on the gt30 housings to allow better flow. i think its actually one of the GT3071R families

 

There was a great write up on another site..

 

The "GT3071R" is really a sub family of Garretts BB GT30 turbine based turbos . There are some not so obvious but significant variations in both the turbine and compressor sides of this 3071 series .

 

As a side note the HKS maketed and Garrett manufactured GT2835 series are also of the GT3071R family .

 

 

1) The Turbine side : The BB GT30 family is of the UHP or Ultra High Pressure Ratio turbine design . It is completly different to the high performance GT28 or NS111 turbine type - not merely scaled up .

 

There is one full sized and two cropped or ground down versions of the BB GT30 turbine . The full sized one measures 59.9mm inducer by 54.9mm exducer (60x55 essentially) and its trim size is 84 .

 

Some time back HKS was looking for something in between the GT28 and GT30 turbine sizes to gain a little more exhaust flow than the GT28 and a little more response than the full sized GT30 . The propper solution would have been a new turbine and matching series of turbine housings but that costs money , Garrett wound up taking the original GT30 turbine and resizing it smaller (56.6mm) and in two trim sizes (84 , 90) . Off the top of my head these cropped turbines measured 56.6x51.8 (84T) and 56.6x53.6 (90T) .

HKS and Garrett have both sold cartridges (turbo minus both housings) with turbine housings from the GT28 and GT30 series and THE significant point is that they don't work very well in the GT28 turbine (exhaust) housing . The problem is that GT28 turbine housings are designed to work with their native GT28 turbine of 53.8mm diametre and the nozzle or collector section inside the housings volute (internal passage) is sized to match the GT28 turbines exducer tip height . To fit the cropped GT30 turbine a fair chunk of the nozzle section has to be machined away and so does not work as it was originally designed to . You will find that HKS marketed their GT2835 turbos with bored out GT28 integral (internal) waste gate turbine housings to suit CA/SR applications . Garrett are also selling some of the same cartridges and bored out GT28 turbine housings but calling them GT3071R "WG" or waste gated .

HKS did do the right thing with 2835's using non waste gated turbine housings BUT these are GT30 based turbine housings with the T2/25/28 (same) mounting flage size . They also do a T3 flanged integral gate GT30 based turbine housing which is fitted to their GT2835 Pro S turbos .

The bottom line is that to get ANY variation of GT30 turbine to work properly it NEEDS a GT30 based turbine housing regardless of what flange is cast into it . Garrett has screwed up badly here with the GT3071R "WG" because they keep fitting the band aided bored out (butchered) GT28 turbine housing .

The only saving grace is that they do make a PROPPER or what I call "real" GT3071R and this has the full sized (60x55mm) GT30 turbine in a real T3 flanged GT30 turbine housing . You can save a GT3071R WG by fitting a T3 flanged 2835 Pro S turbine housing but be quick as HKS are taking them off the market meaning you won't be able to buy them separately for long .

 

2) Compressor Side : Garrett have made cartridges with three trim sizes of the 71.1mm or GT35 BCI-18 series wheels . They are 48/52/56 trims and as per normal Garretts versions only have the largest or 56T .

HKS used all three sizes in the "straight" GT2835 , but only 56T in the GT2835 Pro and R versions . The 2835R version incidentally is the only one to get the 90T cropped turbine .

 

Personally I think the 56T compressor is a bit over the top for either of the cropped GT30 turbines though quite reasonable in the real GT3071R - not "WG" . The 48 and 52T compressor options are a better load balance of compressor to turbine and show up how the limiting factor with all the cropped turbine versions is exhaust restriction . Getting a bit OT but IMO a small or 48T GT2871R is propably about the efficient limit in a T28 flanged GT BB from Garrett . The GT-RS (HKS version GT2871R 52T) would be reasonable but their port shrouded compressor housing gets around compressor surge issues .

 

 

I will see if i can dig out some flow data between the 2. As most gt28rs' are internally gated then there would be no reason for the external wastegate pipie work on the mani

 

 

IIRC Dimitri's brother runs twin gt28's though i dont know if theres any info on here about his setup

Edited by bondango (see edit history)
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Just looked on Driftworks at a GT28RS:

 

The internal wastegate, would I be right that this would be quieter and easier to pass noise limits on track days?

 

What are the pros and cons of internal and external wastegates?

 

There is a choice of A/R - 0.64 or 0.86, for stock cams & internals would the top end of the .86 be superfluous and the 0.64 be better suited, especialy for mid range?

 

http://www.driftworks.com/catalog/products/garrett-200sx-turbo-gt28rs-disco-potato.html

 

Hope there is room to plumb in an ARC airbox.

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What are the pros and cons of internal and external wastegates?

 

 

main advantages of an internal wastegate are that it can vent the exhaust gases arriving from all cylinders in an efficient manor it also offers the advantage of compactness being located in turbine housing so no additional tubes or pipes are required to vent the gases. A properly sized internal wastegate will be good for 15-20psi I would say. The dissadvantage is that at higher boost levels the exhaust stream passing through an internal wastegate dumps directly into the exhaust downpipe right next to the exhaust that passes through the turbine, this waste gas stream can interfere with the exhaust stream exiting the turbine causing increased back pressure

 

For all out performance external gates win everytime

 

1) gases dont interfere with back pressure directly downstream of the turbine like the internal gate can

 

2) they are lass prone to boost creep like internal wastegates can be at times. Mainly becuase they are much larger in size and have a much higher flow threshold before they choke

 

3)exteranal units are fitted with there own built in actuators which can be fine tuned with different springs or pre loaded washers to change the release rate of the unit. They sometimes have a adjustable pre load spring as well which can be tinkered with as well to set the opening point of the wastegate

 

Hope this helps

 

Ps if I were in a position to go for a twin setup I would be looking at the new kit "speedforsale" have on offer. Its a twin kit based on stockers but with gt28 internals so all sits in a stock location and operates as the sequential system does :cool: good for at least 500 and with sequential operation would make an interesting road car imo

Edited by mikeyb10supra (see edit history)
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I'm wondering if twin 28's will be a bit big.

 

What's Dimitri's brothers user name?

 

Another interesting point would be EGT probes one on each downpipe before the collector or just one after?

 

Defi do a 3 guage single din pod, so which two temp gauges would the panel advise?

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Having done the big twin thing, I can quite honestly say that I wouldn't do it again.

Don't get me wrong it's bloody satsifying to get them working, and they look great, but performance wise per £, definitely not worth while.

 

I can only comment on the Blitz kit, which I would suggest that unless you have access to your own machine shop and a sound engineering background, I would avoid it. That said, the actual quality of the parts that you do get in the kit are really very good. One caveat though is watchout for people selling the kits second hand. You need to make sure you get the correct turbine housings (I can't remember which ones were which now - but I was sold ones that were far too large) and you really want to make sure you get all the gaskets as they're a right royal pain to source seperately.

 

Good luck to you with whichever kit you choose though!

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Having done the big twin thing, I can quite honestly say that I wouldn't do it again.

Don't get me wrong it's bloody satsifying to get them working, and they look great, but performance wise per £, definitely not worth while.

 

I can only comment on the Blitz kit, which I would suggest that unless you have access to your own machine shop and a sound engineering background, I would avoid it. That said, the actual quality of the parts that you do get in the kit are really very good. One caveat though is watchout for people selling the kits second hand. You need to make sure you get the correct turbine housings (I can't remember which ones were which now - but I was sold ones that were far too large) and you really want to make sure you get all the gaskets as they're a right royal pain to source seperately.

 

Good luck to you with whichever kit you choose though!

 

Cheers Tony.

 

I did read your thread, mostly with horror but also with intrigue and a bit of awe. I guess this is the problem with the 2JZ is that the aftermarket has been utterly dominated by the USA and their dragstrip culture so single turbo kits are both plentiful and trusted. Twin kits on either side of the Atlantic are almost extinct, Whifbitz sell the GT2835 only and Envy's website is very hit or miss in regards to information and do not have prices but do seem to sell and supply just about anything and if they don't then they could probably source it.

 

It is mighty hard to look past the BL61 kit or the PHR Street kit, both tried and trusted with excellent after-care should you need it and both offer cheap speed for a bolt on and play experiance with no mucking about.

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Out of interest i take it a GT2830rs sequential twin setup would be a feasible turbo solution for the 2jz-gte?

I'm looking atm at the ability to remanufacture the oem turbo using the GT2830 spools. It would require machining the diameters etc to fit the comp and turbine wheels the only thing i am not sure of is the depth of the compressor as to whether it will actually fit into the compressor housing.

Don't mean to hijack the thread just want to pick some brains

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That is pretty much what speedforsale have done, use the internals of a GT28 inside a CT12 housing, then charged the earth for it.

 

Bondango, does this chap who fabs bespoke parts have specific knowledge of the 2jz or is he a general fabricator? Does he do other bits like two into one downpipes and two into one intercooler entry pipes?

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