Full Turbo Kit Rb25

[discopotato03]

From a cartridge point of view yes the Garrett GT30R/GT3076R is the same as HKS's GT3037 in 56 compressor trim just make sure it has the part numbers mentioned above .

There is a bit of a grey area with HKS's GT3037 because it can be had with 48 52 or 56 trim compressors of the 76mm diametre GT family . I've never seen the 48 trim version but the 52 trim one is around though not as common as the 56 trim version . In the US the SR20 is quite popular and they seem to work well with the 52 trim GT3037 and HKS's .73 AR ratio exhaust housing . They claim that the 56 comp trim version's boost threshold is about 5-600 RPM higher than the 52 trim one which is worth noting . It's a shame that HKS don't offer the 3037 in 52 comp trim with the Pro S versions integral wastegate exhaust housing .

The slightly smaller wheel trim makes all the difference from a turbo response perspective . Many have found that the Garrett version (GT30R which is essentially a 3037 56T) to be a bit laggy which is not surprising when you look at its compressor and turbine diametres and flow maps . I would be holding out for the 52T version if it had to be a 3037 , you can achieve the same thing airflow wise with the right Garrett GT3071R - it uses a smaller 71mm (vs 76mm) GT compressor but in 56 trim (same comp wheel as HKS GT2835 56T) in the same style of comp cover as the 3037 52T .

To my way of thinking that GT3071R is good because it uses the same turbine as the 3037 range with the compressor wheel from the larger trim 2835 . The really critical thing is getting the turbine housing AR ratio right with the GT3071R and I'd say HKS picked the right numbers ie .68 and .87 for their Pro S integral gate T3 flanged GT30 exhaust housings . The 68 would be nice on the street and should give a good spread of power provided you don't ask it for 40 lbs boost . The .87 would better suit the 3037 in 56 trim if you don't mind it motorvating a bit higher up the rev range .

Its not a good idea to put smaller AR turbine housings on turbos with large big trim compressors because they tend to make the turbo surge in the spool up phase and choke the exhaust side up high - dumb really .

GT30Rs/3037's can be good things but the right versions may not be a cheap easy solution - depends on how much you can do yourself and how much munjaras you have to spend . More than one punter has pulled them off because the lag factor was unacceptable so choose conservatively which compressor version to use . Its very much a case of least is best in a daily driver .

Edited June 9, 2006 by discopotato03

[BezerkR32]

No its cheaper. There is a number of choices of exhaust housings you can use on the 30/37. I run them on CA18 and SR20 and RB20 with ar.48 turbine housing. Cold step it up for a RB25 no problems.

Yea, I do see what you're saying - but the pure wank factor of the high mount would be good.

I've been looking around for a 3037 internal wastegate kit, but haven't found on as yet - can someone link me.

Also, the 3037R from Garret isn't the same a 3037 from HKS, is it?

Cheers

[BezerkR32]

No its cheaper. There is a number of choices of exhaust housings you can use on the 30/37. I run them on CA18 and SR20 and RB20 with ar.48 turbine housing. Cold step it up for a RB25 no problems.

[R334DR]

No worries mate

I prefer to use the GT3037R, as it has the 57mm inducer wheel and is slightly bigger than the GT30R, but smaller than the GT3040R

identical to the HKS unit

If the above is true, it would be nice.

Can pick up that turbo, with high mount, and a tial 38 mm gate for $2,800 and a 44mm Tial gate for $3,100. Add for $400 for braided lines. Does that sound alright?

Or again, will it just be way too much for street - I'm thinking yes, it probably will be, but it would be nice to have that bit extra for track use, IF I decide to do it.

[discopotato03]

As far as I know the lowest propper GT30 turbine housing AR ratio is .61 made for HKS , Garretts lowest is .63AR ratio . Are you sure the .48 is not a bored out T3/TA or TB housing ? All of Garretts and HKS's housings have the conical stand off style outlet 4 bolt set up - Pro S housings aside . I have seen some being sold in the US with the housings outlet virtually flush but these are not GT30 housings .

[BezerkR32]

Sounds good. allow a bit for dump pipe & intercooler/intake pipe and your there. Make sure manifold is good quality, not one of those $300 jobs off ebay as they crack over and over.

If the above is true, it would be nice.

Can pick up that turbo, with high mount, and a tial 38 mm gate for $2,800 and a 44mm Tial gate for $3,100. Add for $400 for braided lines. Does that sound alright?

Or again, will it just be way too much for street - I'm thinking yes, it probably will be, but it would be nice to have that bit extra for track use, IF I decide to do it.

[BezerkR32]

The .48 housings are profiled out to suit, but they have the 4 bolt dump pipe flange, both GCG and turbologic do these, but i think he should be looking at the .63 anyway.

As far as I know the lowest propper GT30 turbine housing AR ratio is .61 made for HKS , Garretts lowest is .63AR ratio . Are you sure the .48 is not a bored out T3/TA or TB housing ? All of Garretts and HKS's housings have the conical stand off style outlet 4 bolt set up - Pro S housings aside . I have seen some being sold in the US with the housings outlet virtually flush but these are not GT30 housings .

Edited June 10, 2006 by BezerkR32

[R334DR]

Yea, the manifold is the bit I'm worried about. It's Tuneagent, which I've never heard of - could be okay, they said they've never had any complaints, or any bought back.

[BezerkR32]

No its cheaper. There is a number of choices of exhaust housings you can use on the 30/37. I run them on CA18 and SR20 and RB20 with ar.48 turbine housing. Cold step it up for a RB25 no problems.

[discopotato03]

Will have to ask Fred and Brett next time I see them .

Both the GT30R/GT3076R and the 56T GT3037 use the same identical compressor and turbine . Turbobygarrett list its unit and CHRA numbers and these are pics of the HKS GT3037 version .

Compressor is the 76.2mm 56 trim BCI-18C family also known as GT37 series hence GT30 37 .

56 comp trim CHRA is 700177-7 . 52 comp trim CHRA is 700177-6 . Pretty sure 48T version is -5 .

Its interesting to note that HKS rate the power potential of the three trim sizes at 470 , 440 and 420 PS , they also rate their largest comp trim version of the GT2835 ® version as 420 as well . Compared to Garretts their numbers are conservative as has been said before . The jump from 440 to 470 is big but not unusual for a 2mm rise in inducer size . Its asking a lot for the GT30 turbine to power these compressors much past this sort of level let alone pass the exhaust gas to allow it . To me it says go the 52 trim or use a larger family turbo for greater power output . For better response the right 3071R uses the right turbine with the right compressor and dosen't have the all expensive High Kost Spec tag . I agree with the propper Garrett .63 GT30 exhaust housing it should work quite well , if an RB20 can get it on at 3000 a 25 should be better again .

Nite all ..

Edited June 10, 2006 by discopotato03