Rb20det With Garett Gt2871r To Laggy?

[ZILR-34]

hi guys

im in the porcess of buying one of this turbos and i just want to know is it will be to lagy for a RB20det. ive got a choses from the .64 and the .86 rear houing

http://www.horsepowerinabox.com/hpiab2/prod414.htm

if i go with the .86 exhaust housing it comes with the larger 71mm comp wheel (56 trim) im goin to using it for street and drag. but the only thing thats stoping me is that the .64 housing is only rated at 390hp and the .86 housing is rated at 440hp both the same price.

the mods ive got already is

FMIC 600x300x100

3"inh turbo back wit hi-flow cat

040 fuel pump

555cc injetors

z32 afm

pod

wat u guys think?

cheers

bill

[Cubes]

The garrett GT2871r 56trim is available in both the .82 and .63 gated. The .63 is optional.

http://www.turbobygarrett.com/turbobygarre...1R_743347_2.htm

Here's the 52trim... Not much in it compared to the 56trim.

http://www.turbobygarrett.com/turbobygarre...R_472560_15.htm

[ZILR-34]

yea theres not much of a difference's 'cubes' but wat u think will be a better setup on a rb20det?

cheers

bill

[Cubes]

Yer I was pointing out both the .63 and .82 come with the 71mm 56trim.

I don't like lag so for the street I would go the .63. If you find its too restrictive work out something with your local turbo bloke, the local turbo bloke down here suggested I can try either housing. Then keep what ever works best.

What have others used in the rb20det 260rwkw turbo thread?

[Cubes]

http://www.nissansilvia.com/forums/index.p...&hl=GT2871r

[discopotato03]

Sorry to be a bitch Cubes but the GT28 exhaust housings are .64 and .86AR ratio , T3/GT30/GT35 are available in .63 and .82AR ratio .

Seems to come up often the question of which GT28BB based Garrett for the RB20 . Results from 2L 4's don't reflect what a 2L six needs .

My opinion only (not based on experience) is that the turbo needs to compliment the standard state of tune of the engine so its not out of step with gearing and so on .

There are a couple of options for RB20's and as usual the issues are cost and fitting convenience . The two bolt up options are HKS's RB20/25 specific GT2530 and the GCG Hi Flow . I think HKS also do an RB specific GT-RS which is a Garrett GT2871R 52 comp trim but with HKS's T3 flanged integral gate .64AR exhaust housing and their own custom port shrouded comp cover . I've got a few pics from this site of an RB specific GT2535 as well .

Garrett has been a bit lazy and don't make a T3 flanged GT28 exhaust housing so if you buy one of theirs it usually means a T28 flange which won't bolt to your manifold . Hi Flows aside you really need that HKS T3 flanged housing to marry the GT28BB series to a T3 flanged manifold . If you beg/borrow/buy this housing cheaper Garrett GT28 BB's will bolt up as will the std or aftermarket dump pipe . The results from the Garrett GT28RS (GT2860RS) are very similar to a GT2530 as they can both be optioned with the same TO4B .60AR comp cover .

When you go above the 60mm compressors you start to compromise response for extra airflow capacity so its a judgment call where you want the useful usable power spread to be in the engines rev range . I don't have a high opinion of the 2871 series because I think its a bit more load than the turbine likes and if I couldn't get enough air from a 60mm compressor it would be the smallest or 48 trim GT2871R . Turbobygarrett's maps are convienent but notice how they pretty much use the same turbine map for the three different comp trim versions , fibs because turbine efficiency varies with comp trim which is directly related to drive loads . If you look at the comp maps for all 3 note where the surge and choke (minimum/maximum flow) areas are along the 2 pressure ratio or 1 bar boost line . Off the top of my head the 48 comp trim version starts at ~ 11 lbs of air and chokes at ~ 39 lbs air At 2PR or 1 bar . The 56 trim version I think spans 16 to 44 lbs so the range has moved up . What I'm try to point out is that the smaller comp trim version will pull from lower revs and be less likely to surge if you need the smaller .64AR exhaust housing to excite it with . With 39lbs of air you have the potential to make ~ 390 Hp which may be enough . People say RB20's need all the help they can get low down so erring on the conservative side compressor wise I feel is a better compromise than risking losing a bit too much bottom end and getting caught in the dead zone at upchange time .

You may not like this idea but if you started out with a Skyline type GT2530 it gets you the correct exhaust housing , if its not enough then you could fit any of the three compressor trim GT2871R's to it meaning there is an upgrade path . Any decent turbo seller could supply you a 2871R minus the exhaust housing so it makes for a cheap upgrade . All the actuator and plumbing could be reused provided you started with as I said the Skyline specific GT2530 , these should be around 2nd hand cheaper than new .

Nearly forgot to add those T04B comp covers can be port shrouded if they are the large 3" inlet boss type , this means all is not lost if you ran into surge issues . Not at my own computer ATM or I would post a pic I have of a HKS RB20/25 type comp cover that has the original boss machined off and a turned aluminium adapter bolted to it to fit the original inlet plumbing . Not difficult to get around .

Cheers A .

[ZILR-34]

^^^ so would the Gt2871r fit into a rb2b exhaust housing?

[Cubes]

Stick with the std unmolested turbine housing, run an adaptor plate.

[ZILR-34]

thanks cubes.. also wat rpm level will it hit full boost for

.63 and .82 ???

[Cubes]

Thats really difficult to say.. I have NFI..

For any turbo that size you are always looking at 4000rpm+.

[Dale FZ1]

Discopotato is pretty much on the mark. A 56T is going to be more sluggish in terms of response, compared to either of the little brothers 52T or 48T. It's not much good having a bit more power if you're waiting either longer time and/or more rpm for it to become available.

An adaptor plate will work if you follow Cubes advice, but you may well find clearance problems between the fitted turbo and front suspension tower.

A hi-flow using a Garrett core and factory Nissan housings will fit up much more easily but with a couple of its own issues to get all the oil/water lines and heat shields fitted nicely.

[Cubes]

How does molesting the nissan turbine housing really affect spool?

Does it at all?

If so, I would tend to still look in to the adaptor plate, there appears to be plenty of room near the suspension tower to handle a 20-30mm shift.

[kwazza11]

just a quick tip, last few weeks i've been trying to get a 2871r 56t to hold boost with an rb25 rear housing on my rb24. turbo guy i purchased the turbo from told me he'd done it before and wouldnt be any dramas. turned out he was totally wrong! at first the wastegate would blow open causing boost to take ages to build and i couldnt run anything more than 16psi with garrett's 15psi actuator and HKS EVC (WTF?) so off comes the turbo and the wastegate flap rod was extended to try and add more leverage to the actuator can. once the turbo was back on it would ramp up to 8psi, then gradually spike to over 18psi by redline!

off came the turbo again and went with a vg30 housing with a bored out wastegate and larger flap.

problem looks like its solved but cant really do a full run due to a blown HG...

[Cubes]

Yes stick with the std housing... and run an adaptor if it fits..

kwazza11... Any clearance issues you can see by adding 20-30mm?

[kwazza11]

well i used a HKS low mount manifold but should be no change in clearance as i used the VG30 housing... are you thinking of a t28-t3 flange adapter? no need with the VG as its also t3.

you will need one of those if you go with the garrett external gt28, t28 flanged rear housing, i cant really see the problem using one, aslong as its well designed and tapers down. was my other option before i decided (bad decision IMHO) to go to a internal gate nissan housing.

[ZILR-34]

but if i went to go 4 the t28 housing and get an a adaptor plate will the turbo fit on the standard manifold ?

[BHDave]

Yes. I've seen one fitted to an rb25 on the standard manifold

[limpus]

So let me get this straight...is an rb20/25 exhaust housing with a gt28rs or gt2871 compressor and core a bad idea...i was just about to go with this route for me rb20det too but i'm now having second thoughts...

[Dale FZ1]

No, not a bad idea at all. A simple and effective path, but using OE housings has the benefit of fewer changes to associated pipework to get it fitted.

If you're running an RB20 then a VG30 turbine housing is likely to result in a bit of top-end bias.

Re the earlier comment on clearance if using a Garrett turbine housing, be aware that you will have to maintain some sort of air gap around it or risk cooking the loom and air-con fittings nearby. Nissan found it necessary to fit heat shields, so hopefully others would see the benefits of adopting that approach too.

[ZILR-34]

ok let me clear this up for sum people, coz everyone is saying sumthing different about this turbo.

first i want to buy the Garett Gt2871r and blot it up to my standard manifold. which i will be buying an adaptor plate to make it fit.

also ive been reading up on this and it comes out with a 71mm comp wheel a/r .70.. which is abit to big for my setup is there a way to get the comp wheel of .60?

i want to spend about $1700 max on a turbo which atless has about 400hp or around that range. and T3 flange would be good. if anyone can point me in the rite way that will be good

cheers

bill