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Location:
sunny coast, qld
Registered:
October 2002
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inspecting a GT30 turbo?
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Fri, 05 December 2003 00:37
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hi,
I am going to go and look at a turbo tonight. The fella i spoke to said it is a Garrett GT30 500hp turbo. (new) I have never inspected one before so what should i be looking for to make sure that it is what he says? I can tell if it is new though.
also, what AR's do these come in? and does it say it on the compressor like i have seen on others?
also, does a GT30 have the same flange as a GT35?
thanks
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Location:
Perth
Registered:
September 2003
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Re: inspecting a GT30 turbo?
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Fri, 05 December 2003 01:21
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try and 'wiggle' the shaft. there will be a small amount of movement even in a new one, but if you can make the wheel touch the compressor or exhaust housing then it's stuffed. if any oil comes out of the core's banjo fitting, check it to see if it has been running on clean oil. if the oil's dirty in the core, let it go.
check for cracks around the clamp fittings, wastegate flap in the exhaust housing and flange bolt holes (where it bolts to the manifold). also check for leaks.
check the blades as well, both compressor and exhaust. look for hairline cracks around the base of the 'fins', this is a sign of overspeeding from excessive boost. it 'shouldn't' happen on a steel turbine, but it has happenend. also look for pitting in the fins as well, a sign that the engine and turbo have sucked grit/sand/small rocks/fingers in it's lifetime thru being driven without a filter.
whether it labels the A/R on the compressor or not is up to either the brand, if it's been machined off (for polishing) or just plain removed for aesthetics.
most GT30s should be in the 0.66 - 0.70 range though, otherwise it'd be a pretty poorly matched GT30! and yes it should be the same bolt pattern as a GT35.
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Location:
sunny coast, qld
Registered:
October 2002
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Re: inspecting a GT30 turbo?
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Fri, 05 December 2003 02:26
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thanks mate.
so would a 500hp GT30 with the AR you mentioned be alright on my 1jz-gte?
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Location:
Perth
Registered:
June 2002
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Re: inspecting a GT30 turbo?
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Fri, 05 December 2003 04:36
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GT-30's come only have one variation in compressor housing, and thats 0.70.
There are three variations in turbine housing though, 0.63, 0.82 and 1.06
The ratios are sometimes on the inside of the housing but still visable without pulling the turbo apart.
A "GT30 500HP TURBO" will most probably have the mid range 0.82 compressor housing
Gabe
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Location:
Perth
Registered:
October 2003
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Re: inspecting a GT30 turbo?
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Fri, 05 December 2003 04:40
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Does the 30 part of GT30 refer to just the size of the exhaust housing? I thought they were designated like GT 3037 or GT 3040, the GT 3040 having a bigger compressor housing than the GT 3037 and therefore capable of making more power?
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Location:
Canberra
Registered:
May 2002
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Re: inspecting a GT30 turbo?
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Fri, 05 December 2003 06:40
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This is a tough topic. The current range of ball bearing "new generation" turbos from Garrett & HKS are always getting mixed up with their designations.
The common trend is for the "30" in GT30 to designate the core size (in most instances).
Garrett manufacture a GT30, which comes in 3 different designations & corresponding hp levels (from memory). They all use a 0.7A/R compressor housing, with a 4" inlet, and a T3 exhaust mounting flange, but have 3 different exhaust housing A/R's as Gabe mentioned. Each will have a different boost response on a given engine, and a different maximum flow, hence the hp ratings.
The same applies for the garrett GT25 series, which are all internally wastegated.
HKS on the other hand use designations like GT2510 2530, 2535, 2540 for their varying combinations of the GT25 turbo, but the confusing thing is that you can order them with either a T25 or T3 flange... 
Then you move onto the GT3037, 3040 etc etc for the larger "T3" based turbos.
This is a very general overview, but I think you can see how confusing it can get. Especially when HKS then start to throw in variants like the "SS" & "RS" models as well, which are direct bolt in replacements for silvias and the like.
I think garrets sizing structure is a bit easier to understand.
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Location:
sunny coast, qld
Registered:
October 2002
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Re: inspecting a GT30 turbo?
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Tue, 09 December 2003 01:12
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had a look at the turbo. Dude was dodgy as! The turbo looked like a t25 it even had an internal wastegate. He was still trying to tell me that it could be external or internal? wanted $800!  he said it is ball bearing, and turn the turbine! wow, it spins!
then he showed me his 't04e'. He said it cost $2000 new and it is second hand. I have seen them for $1200 new with a wastegate. wanted $1000 for it! pfft
dodgy!
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Registered:
June 2002
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Re: inspecting a GT30 turbo?
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Tue, 09 December 2003 02:30
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You just have to remember when looking at these modern Ballbearing turbos is that they are not rebuildable.
Sure the shaft might not have any/much play doesn't mean it is going to last.
Safer to buy a new one or get a conventional turbo that can be rebuilt hi-flowed etc....
From my limited knowledge of the BB turbos is they seem to fail catastrophically rather than wear out.
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Location:
sunny coast, qld
Registered:
October 2002
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Re: inspecting a GT30 turbo?
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Tue, 09 December 2003 05:17
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he claimed that the 'BB' turbo was new!!!!
dreaming
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