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Hey guys,

well the old K27 has given up the ghost so its time for an upgrade, i'm chasing the same sort of power but am thinking of getting rid of the high mount and ext gate setup and running a hks cast low mount with an internal gated turbo.

i've been hunting around for a suitable turbo but everyone on the forum using a Garrett on an rb20det seems to be either in the 220kw range (GT28RS, HKS2530) or 270-280kw (GT30). i'm only chasing around 240-250 and that would be at max boost so what is there available in between these? the td06 such as roy is using sounds ideal but dont feel like chasing down another manifold and my current one is split pulse so wouldnt really adapt to the trust flange very well. and i assume you cant get t3 flanged housings for the TD06?

any advice would be muchly appreciated :(

Cheers

Karl

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have a look at garrett gt2871R, you might have to do a bit of research in terms of fitment for rb20det, but i don't imagine you'll run into too many problems, most of the people i know running garrett turbos' have them on sr20's and i haven't done the research into what will fit on rb's yet, maybe someone here knows.... But anyway gt2871r is something to consider (400hp compared with gt28rs 350hp). Still nice and responsive but with a bit more power, and not as laggy as gt30r (500hp)

GT30 is too big for my liking, want full boost around the 4k mark.

the HKS 2835R actually sounds quite promising with the .73 ar rear would be perfect. probably really hard to find though, wonder if the garrett gt30 rear housings would fit? .63 external gated would be the next best thing.

as for the gt2871r had a look at the garrett site and looks like theres a couple to choose from, the GT2871R - 472560 - 15 sounds like the best but i cant find if there is any t3 flanged rears for them? the low mount i'm looking at only comes in t3 or t4 flange.

For my money since you have the extra capacity it would be the real GT3071R with one of Garretts soon to be released T3 flanged integral wastegate turbine housings . Someone here recently put one of these on an RB20 with good results so with 2.4 even better .

If you want to get fancy you could get someone to stick a gt30 turbine up the guts of a 2871R 52T (Garrett now sells what HKS calls the GT-RS ie 2871R 52T) to make a GT3071R 52T . Very responsive , integral gate T3 flange , and Nissan Garrett style compressor cover with bolt up air inlet and outlet flanges .

Cheers A .

hey disco,

thanks for the reply. i'm not looking for the sort of power the gt30 guys are making though, and was thinking with the extra capacity i wont need to run a huge turbo to make the power i'm after.

i've seen the rb25 guys making good results with the gt-rs so perhaps the 2871R 52T is the way to go. what AR rear would you recommend, garrett's site says theres only a .64 or .86 available for the 2871r?

The whole idea of the GT30 turbine based GT3071R is that it uses T3 flanged turbine housings . The fact that it uses a 71mm compressor , like 2871R's/GT-RS's and 2835's do means its more responsive than the 76mm compressors that GT30R's normally use . It is an inbetween Garrett hybrid , sort of a productionised version of their TR30R competition turbocharger .

I would not purposely put a T28 flanged turbo on a six cylinder because its difficult to get a propper compact manifold collector to work well .

If you want to get fancy you could get someone to stick a gt30 turbine up the guts of a 2871R 52T (Garrett now sells what HKS calls the GT-RS ie 2871R 52T) to make a GT3071R 52T . Very responsive , integral gate T3 flange , and Nissan Garrett style compressor cover with bolt up air inlet and outlet flanges .

Cheers A .

so is a hks gt-rs is a garrett gt3071r 52t or a garrett gt2871r 52t :(

Its the same cartridge with similar housings used by the GT2871R 52 trim SR20 application . HKS does a Skyline GT-RS variation but it uses a T3 flanged turbine housing and a port shrouded compressor cover because they knew it would surge on the six cylinder . There is a very good chance that HKS uses minor variations in the diffuser and nossle sections of their housings .

Cheers A .

looking at the specs on the hks 2835R's they look pretty much identical to the GT3071R anyway. does this mean i can use a gt30 .64 T3 housing on a hks 2835r? basically running on a budget here so if i can get a cheap 2835r with the right housing it would get me out of trouble.

also you suggested using the 2871r with a gt30 56.5mm turbine, wouldnt that mean i'm still stuck with the t28 flanged housings or can a gt30 turbine housing then be adapted?

Edited by kwazza11
looking at the specs on the hks 2835R's they look pretty much identical to the GT3071R anyway. does this mean i can use a gt30 .64 T3 housing on a hks 2835r? basically running on a budget here so if i can get a cheap 2835r with the right housing it would get me out of trouble.

also you suggested using the 2871r with a gt30 56.5mm turbine, wouldnt that mean i'm still stuck with the t28 flanged housings or can a gt30 turbine housing then be adapted?

I think you will find that disco will be refering to the 60mm exhaust wheel

Spoke to Bill Keen at ATS here in adelaide today and he suggested getting the 2871r for response and 3071r for more top end but make sure you go with a .86 rear as he thought the .64 would be way too small! however everyone seems to swear by them with the gt30's..

he also didnt seem too worried about using an adapter plate for the 2871r either...

so many different oppinions, its making my head spin!

Yo, ive got a Garret GT25R (0.70 front & 0.64 rear) on my RB20 using a stainless high mount T3 manifold with a T3-T28 adaptor, making 258rwkw@18psi full boost at 4500rpm. I imagine it would be alot better on an RB24. or seeing as the GT25R doesnt get a great review buy some maybe the 2871R 52T would be capeable of similar power but with a lot better response. those are probably ur best options??

Its the same cartridge with similar housings used by the GT2871R 52 trim SR20 application . HKS does a Skyline GT-RS variation but it uses a T3 flanged turbine housing and a port shrouded compressor cover because they knew it would surge on the six cylinder . There is a very good chance that HKS uses minor variations in the diffuser and nossle sections of their housings .

Cheers A .

i assume port shrouding is the holes in the side of the inlet of the turbo.

how does port shrouding work? how does it help a turbo to not surge?

  • 4 weeks later...

wakey wakey thread.

am i right in assuming the port shrouding allows air to bypass the inducer and go straight to the meat of the compressor wheel? or am i totally wrong, heres a pic of the front cover of the gt-rs made for the rb20/25 (taken from http://www.hks-power.co.jp/products/turbo/...s/ac_gtrs.html)

image_01s.jpg

Well i've decided on going with a gt2871r 52t with a machined out rb25 exhaust housing, retain t3 flange and end up with ar of somewhere between the .64 and .73. probably be another week or two before i can fit and tune it though. should be nicely responsive with a hks low mount manifold and the extra 400cc on a rb20det.

A bit of confusion about GT28 and GT30 turbines .

Its easy to think that GT2835's are GT28 turbine based but the only thing that is optionally GT28 is the turbine housing and flange .

Turbine dimensions :

GT28 76 Trim = 53.8mm major diametre by 47mm minor or outlet diametre .

GT30 56.6mm = 56.6mm by 51.6mm 84 trim or 56.6mm by 53.8mm 90 trim .

GT30 60mm = 60mm by 55mm 84 trim .

GT28 turbines should use GT28 exhaust housings and GT30 turbines should use GT30 turbine housings .

When HKS had the GT2835 series made they wanted a bolt on option for SR20's which have T25/28 flanged exhaust manifolds . Cheap easy solution was to bore Garretts GT28 housings out to suit the ground down or cropped 56.6mm GT30 turbine so the turbo would bolt up and retain the integral waste gate . It was a flop because turbine housings are designed around a specific outer or major turbine diametre and boring them larger than intended screws up the nozzle angle and shape .

HKS had their own non gated housings made up for this turbine in T25/28 and T3 flange but they are GT30 turbine based housings so they don't have the GT28 overbored housing issues . They also have their own GT Pro T3 flanged integral gate housings for this turbine .

Garretts GT3071R (the real one cartridge no 700177-0023) uses the standard sized 60mm GT30 turbine which luckily was not offered in bored out GT28 housings . Don't be scared by the "GT30" part of GT3071R because its compressor is the same family as the GT2835 series . Garrett calls the GT35 compressor 71 as in 71mm OD so in HKS speak a "GT3071R" would be a GT3035 ie GT30 turbine with GT35 compressor .

People automatically think all "GT30R" turbos are laggy but this is mainly because most GT30 turbine based turbos use compressors of larger diametre ie 76mm OD (GT37 series or dinosaur TO4S series) or even 82mm which is the GT40 series . As the compressor OD drops so does the load on the turbine so the 71mm or GT35 compressors are easy for them to drive . A large trim compressor demands more turbine power than a smaller trim so if you can use them you get even better transient response and lower boost threshold .

As I've said in the past I'd get the mid or 52 compressor trim GT2871R refitted with a GT30 turbine/housing because it gets you the Nissan/Garrett style compressor cover . ATP turbo in the US are now selling a split pulse T3 flanged turbine housing for the GT30 based turbos plus Garrett make an open type .63AR one as well .

Cheers A .

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