Rb20det With Garett Gt2871r To Laggy?

[Interloper]

We have a winner. Thw GT-RS . Based on the fact that ppl typically say his dyno reads low, and a quick comparison is...

At 90km/h i have 72rwkws you have 65rwkws.

At 110km/h I have 150rwkws, you have 150rwkws

At 130km/h i have 210rwkws, you have 190rwkws.

At 150km/h i have 234rwkws you have 217rwkws.

At 170km/h i have 235rwkws you have 200rwkws.

So allowing for the fact that his dyno reads low, its looks like the GT-RS tracks about the same as 20G but with more down low....and about the same top end (we are running the same boost)

To me its making the same numbers as my setup without all the agro of manifold and gate...so its a bolt on winner

The only thing that seems to fly in the face of my results is the way the power falls away. Do you run cam gears? I will look at what mine are set to in the morning...lol oh, thats about now. Time to put down the scotch glass and go to bed

nope no cam gears, but i agree its interesting how much it all falls away after 160km/h...do you think cam gears would make up the difference by that much? i would love to have the power stable towards the redline like you do

But in order to put all speculation to rest....you have to run your setup on DrDrifts dyno....so we can then overlay the power curves on one page ...i'm sure Sam would be keen to see the results too, as so far my GTRS produced the biggest numbers on his dyno for an RB20....so its up to you to break the record

[kwazza11]

I think you have got the difference in characteristics nailed:

top end flow, at the expense of low end/mid range. Depending on what you actually want the car to do, that ski jump mid range can make it tiresome, if exciting to drive.

I agree, it will be interesting to see the extent of the differences. Bear in mind the first upgrade Interloper was running shared the same spec VG30/R34 housing you want to use.

FWIW, I suspect the 56T cartridge is just a little too large for a responsive match to RB25, let alone an RB20. While the RB20/25 spec turbine housing would keep the results biased towards mid range, the larger A/R R34 unit wouldn't allow the assembly to respond quickly. Keen to see your results though.

cheers

I drove it alittle with the rb25 housing on and it definately felt very responsive, i've got both modified housings available so if i find the vg30 housing laggy i can swap them over and get back to back tests.

the 52t assembly like the gt-rs would be better again and i actually ordered the 52t one but the workshop i got to build it didnt do what i asked and i ended up with the 56t one. if i hadnt measured it myself i would of never known either.

i cant wait to see what the potential of this turbo is, as surely they could make more than a 2535 with a bit of engine breathing assistance.

[Roy]

nope no cam gears, but i agree its interesting how much it all falls away after 160km/h...do you think cam gears would make up the difference by that much? i would love to have the power stable towards the redline like you do

But in order to put all speculation to rest....you have to run your setup on DrDrifts dyno....so we can then overlay the power curves on one page ...i'm sure Sam would be keen to see the results too, as so far my GTRS produced the biggest numbers on his dyno for an RB20....so its up to you to break the record

LOL...happy to give it a run. If the GT-RS does everything the 20G does with the realiability of the ball bearing core and the simplicity of the std manifold and heat shields etc, it would make for a far friendleier track turbo

[Interloper]

cool, you have pm.

[salad]

yeah, top end power does drop off a bit too fast.

with my rb25 turbo i have the same amount of power at 8000rpm as i do at 5350 rpm.

most probly due to your runnin a lot more power than me...

i only pulled 156rwkw on the dyno in adelaide that sam used that reads low.

very interested in this turbo though, was lookin at it a while back cos i saw a dyno sheet with a very linear response but still had lots of top end poke.

hks kit is a bit expensive though, might go the highflow (gt2871r) in the rb25 housing, .63 a/r, should be pretty darn similar

[Roy]

Well my engine is std and it holds the power reasonably well, and doesnt really fall over. I always thought it was part cams gears but mostly tune

[Interloper]

I'll have to ask DrDrift what he thinks about the power dropping off...

[Dr_Drift]

Couple of quick answers for power dropping off... Very conservative tune at request of Interloper, 0.64 exhaust housing, quiet street exhaust, and RB20's loose volumetric efficiency on the standard cams over 210 rwkw (my dyno). This RB20 is the orginal motor and has been making 200+ rwkw for a few years now without missing a beat... With the load from the GTS4 increasing the thermal stress a conservative tune is the best approach. I'm confident there's still more in it!

[Interloper]

come on, the exhaust isn't that quiet

...straight pipe with only 1 rear can

[limpus]

Interesting results...sam...i've finally gotten a job so i'll be getting a new snail soon...will be in touch for a retune...cheers...

[Interloper]

if anyones interested i have now looked closely while driving as to when full boost hits, even though its hard to be exact cos it hits pretty hard....i'm pretty sure i get 18psi in 5th gear at 3800rpm and still below 4000rpm in lower gears

i love this turbo

[RNS11Z]

Attatched is my dyno graph

the car isnt full tuned yet, as you see i have shit mid range. I have been running it off the waste gate with b/c turned off. The 2 graphs are w/g rod connected and dis connected (green). Im having boost issues once sorted will get it re tuned.

This is on a sr20

once fully tuned it should make abit over 300, on 18psi.

Like my boost curve? lol its the worst, peak power @ 6600rpm with .64 rear

[Cubes]

once fully tuned it should make abit over 300, on 18psi.

Like my boost curve? lol its the worst, peak power @ 6600rpm with .64 rear

lol.. yes.. Easy to confuse it with the power curve.

[ZILR-34]

so overall which would be the best turbo to get? which will blot rite up. i was thinking of the

*HKS GTRS kit which is $2600 or

*Garett GT2871R @ $1700 or

*might go the highflow (gt2871r) in the rb25 housing, .63 a/r,

which will be the same price as the Garett GT2871R but i wont have to buy the Adaptor to make it fit with is $40-50

[Dale FZ1]

Depends on how you want to approach the job. Check the link to the GT2871 based highflow into my RB25. There are a couple of fiddly bits to deal with when going that way (ie stock comp and turbine housings onto Garrett core). At least all the air in/out ducting bolted back up.

There may be some power/efficiency benefit in using the RB20/25 turbine housing and Garrett comp cover; but this means more fabrication work for ducting.

There is even more fabrication / purchases needed if you run the stock Garrett turbine housing and use adaptors. Remember there is a 5 bolt dump you need to marry up to that housing - different from the Skyline 6 bolt.

Overall the HKS is the best option if you just want to have something that fits up without any issues. It MAY work better. It DOES cost more. Consider what funds you have available, and whether you are interested/able to deal with the fiddly bits that go with fitting a custom turbo.

A primary issue to consider though, is which comp trim you reckon is best suited to your engine and driving habits/needs. A 2mm difference in the inducer size does make a difference. Obviously the HKS is only available in 52T.

cheers

Edited August 4, 2006 by Dale FZ1

[kwazza11]

Attatched is my dyno graph

the car isnt full tuned yet, as you see i have shit mid range. I have been running it off the waste gate with b/c turned off. The 2 graphs are w/g rod connected and dis connected (green). Im having boost issues once sorted will get it re tuned.

This is on a sr20

once fully tuned it should make abit over 300, on 18psi.

Like my boost curve? lol its the worst, peak power @ 6600rpm with .64 rear

Same issue i had when i fitted the gt2871r using an rb25 housing and stock wastegate size. what rear housing are you using? basically set the wastegate at 10psi and it'd climb to 18 before redline. i solved this by going to a vg30 rear and boring out the wastegate using a custom wastegate flap so i could really open it up (something like 26mm stock to 34mm now).

the fact that the comp wheel flows so much really means it either needs an external gate or a biggish turbine housing to function properly without massive manifold backpressure..

Dale have you had any troubles with boost? odd that the sr and my 2.4 RB suffers from it but doesnt seem like the stocker rb20 is having any dramas.

[Dale FZ1]

Same issue i had when i fitted the gt2871r using an rb25 housing and stock wastegate size. what rear housing are you using? basically set the wastegate at 10psi and it'd climb to 18 before redline. i solved this by going to a vg30 rear and boring out the wastegate using a custom wastegate flap so i could really open it up (something like 26mm stock to 34mm now).

the fact that the comp wheel flows so much really means it either needs an external gate or a biggish turbine housing to function properly without massive manifold backpressure..

Dale have you had any troubles with boost? odd that the sr and my 2.4 RB suffers from it but doesnt seem like the stocker rb20 is having any dramas.

No problems controlling boost as yet. At this stage I am limited to 10psi; waiting on a chance to run it up on the dyno and get the chance to lean on it a bit. My calculations suggest the 48T will start to run out of puff at 16psi tops on the RB25, and I should hit the power target @ 14psi or so. With luck the turbine housing and wastegate won't be a limiting factor.

What is interesting in my case is that boost is fairly controllable by throttle position.

I did have some concerns about the ability to bypass sufficient gas through the stock wastegate valve, but had to trial it and see. Anybody looking at this sort of high flow job should really insist on having the valve and port upsized. I 'm not a big supporter of using the VG30/R34 turbine housing on a stock-ish R33 spec engine or the RB20. Too much lost mid range response in the pursuit of high end power for my liking.

cheers

[RNS11Z]

well, finally got my car tuned.

didnt make as much power as thought, 280rwhp @ 18psi and more.

Took it to the track last night, couldnt pb my et but mph is up from 108 to 113 wich it did easyly on a 13.2 sec pass. I reckon it has 115mph in it.

will post my dyno graph

[RS500]

hey guys,

interesting discussion here.

so what's the final consensus on the suitable combination for a streeetable RB20DET?

i think the 48T GT2871R with an A/R .86 exhaust housing would be a good comprimise b/w spool and outright power given the smaller trim compressor wheel and larger exhauast housing, or for even better response the GT28RS (hks 2530 equivalent) with the A/R .86 housing.

the only downside to this is the GT25 inlet flange on the exhaust housing.

[kwazza11]

Well i've got the 56t 2871 with a vg30 rear on my rb24det atm. it makes 12psi at ~3400rpm and 224rwkws, i've yet to run more boost through it as i've had some dramas with a certain retarded tuner, but i think with the rb25 rear and a 52t comp wheel it'd be a very tidy and easy package for an rb20det.

i will hopefully have some better results with lots more boost when i get it retuned by Mildren next week.