RB20DET, which turbo to upgrade?

Post by **dohctor_yaj** » Thu Mar 27, 2003 4:45 am

I figure since we have a post for the rb25det then why not have one for the rb20det...i'm pretty sure if people are gonna swap their motors for a rb, their either gonna swap for a rb20 for the price or the rb25 for their future mad power...i'm pretty sure its 50% each way so why not have a thread for the rb20det...

anyways, i took my turbo out yesterday and looked at how freakin puney it is...i want a turbo that will get me 350whp effectively...i'm pretty sure 90% of people who decided to go with the rb20 instead of 25 isn't looking for 700 figures and so on but 350 is about where alot of people want to be...

at the moment i'm looking at a t3/to4e to bolt directly up to my stock turbo manifold...is there someone who know's these t3/t4's hell of alot better then me who can lead me into which one i should get?

is it possible to get a internal wastegate and still boost a high boost to get into the 350 range? I heard one should go external instead...(yes i know, very rookie question but one donesn't find these direct answers around too much)...

Post by **rbsileighty** » Thu Mar 27, 2003 4:45 am

I'm getting the HKS GT2835ProS turbo (internal wastegate for better spool up.. so hks says). He said it will boost to 17psi no prob but probably can go higher (might mean that 17psi is at the top of the highest efficiancy range).

This turbo is a T3 flange so it will bolt up, and spools early (starts around 3-3500 on a wrx they tested... said it should be sooner on the 20 since it has more cylinders). It is also said to produce 420ps which should translate to around 350-380 at the wheels, assuming around 15% drivetrain loss.

Post by **dohctor_yaj** » Thu Mar 27, 2003 4:45 am

GOT DAYM dude...thats a sweet turbo but i dont think most of us have $2800 for a turbo...

I was thinking more of $600 or so...thanks for your reply though...anyone else with a good option with a T3 turbo flange?

Post by **dohctor_yaj** » Thu Mar 27, 2003 4:45 am

can someone explain the difference to me briefly about these trim turbos:

.48 a/r T3 and .50 T04E .48 a/r T3 and .60 T04E .63 a/r T3 and .50 T04E .63 a/r T3 and .60 T04E .63 a/r T3 and .70 T04E

how much approx. can each of these turbo's make?

is there a difference between a internal wastegate and a adjustable wastegate? aren't they the same thing?

and all these t3/to4e turbo's are both water and oil cooled like the rb's right?

is there such thing as clipping the turbine blades 11 degrees for faster spool?

sorry but i'm just full of questions, thanks in advance though...

Post by **WDRacing** » Thu Mar 27, 2003 4:45 am

The major differences in each turbine trim you listed is lag and efficiency. The larger the trim the longer it will take to spool up. But I can safely say that the large T3/T4 hybrid would be the best bet. I had an over sized TO4E on my RB20DET. The lag was bad until 4500. But it was an 96 A/R P-trim . So a 63 should be fine.

It depends on how much boost you want to run though. You could go with a smaller one. But it will become a heat pump at higher boost levels.

WD

Post by **ZERO** » Thu Mar 27, 2003 4:45 am

Try http://www.cheapturbo.com, they might have something for you...

Post by **themadscientist** » Thu Mar 27, 2003 4:45 am

I have a T300S with a T3 flange, AR 63 exhuast and AR 70 compressor. It's an external wastegate style so you will have to get a wastegate. It will bolt to the stock RB manifold and you can have a foot welded on for whatever wastegate you get.

Post by **dohctor_yaj** » Thu Mar 27, 2003 4:45 am

well after doing some studying, at the moment i'm looking at the .63 a/r turbine and .50 compressor and the .63 a/r turbine and .60 T04E compressor.

people have been telling me that don't take the .63 a/r and the .60 compressor because that would be more for drag only and high end only...would this be true?

if this is the case, then i would get the .50 compressor trim...because i dont want too much lag and loosing too much mid power...so do you guys think the .63 turbine and .60 compressor would still be fine for a rb20det with say 550's, walbro fuel pump, big intercooler 26x8x3, and looking to do 350hp?

Post by **themadscientist** » Thu Mar 27, 2003 4:45 am

there are guys at the turbo retailer that get paid to crunch these numbers, use them. The AR .63 is great for a 2.0 liter.

Post by **d240t2** » Thu Mar 27, 2003 4:45 am

NightXCZ77 wrote:.50 would also be good for the 2L and allow very fast spool up.

Night

You mean .48? Because there isn't a .50 T3 turbine housing...and .50 is a compressor housing, which doesn't contribute to spool up.

Post by **d240t2** » Thu Mar 27, 2003 4:45 am

NightXCZ77 wrote:A turbo I have in my garage has a compressor housing of .50 and a turbo housing of .48

Umm yeah...that is what I said:

Quote »You mean .48? Because there isn't a .50 T3 turbine housing...and .50 is a compressor housing, which doesn't contribute to spool up.[/quote]

Post by **dohctor_yaj** » Thu Mar 27, 2003 4:45 am

well, after surfing thought several forums on the net, i think i'm gonna settle for the .63 t/h and the .50 c/h...I think the .63 t/h is pretty much in the hole but still very confused on which c/h to pick...

ASAD from FA said bigger a/r for compressor is good for low boost and smaller is good for high boost but ultimately it's not gonna matter...so i'm still contemplating on which one to pick...less anyone else can sway me with more info that they have...

Post by **themadscientist** » Thu Mar 27, 2003 4:45 am

.48 is too small for a T4 exhuast housing on a 2 liter. That is the a/r HKS puts on it's CA18 kit. a/r .63 is as low as I would go.

Post by **d240t2** » Thu Mar 27, 2003 4:45 am

Are you talking about changing the compressor wheel as well, or just the housing? If you are deciding between 50 trim/.50 housing and 60 trim/.60 housing, get the 50 trim to avoid surge problems. If you are sticking with the 50 trim and deciding on a housing...there isn't going to be much of a difference...so get what is cheaper/easier, or the .50.

Dennis

Post by **dohctor_yaj** » Thu Mar 27, 2003 4:45 am

can anyone just plz just tell wheather a internal wastegated turbo can go beyond just 18psi? I've been hearing a few people say that it'll be sloppy beyond 18psi...is this true?

Post by **themadscientist** » Thu Mar 27, 2003 4:45 am

maybe a purpose built aftermarket internal wastegate turbo with a huge flapper door but for the average actuated turbo I would say no. It would likely hit a choke point and the boost would spike violently to it's next logical conclusion, kablooey!:(

Post by **dohctor_yaj** » Thu Mar 27, 2003 4:45 am

hmm...i get what you mean now MadSci...the only thing is that if i get a external wastegated one, i would need to get a new exhaust mainfold right?

to the peole who has delt alot with turbos, approx. would 18psi on a t3/t04e .60/.63 be able to hit 350whp on a rb20det? if this question is too vague, then say so...

Post by **apex_7** » Thu Mar 27, 2003 4:45 am

Sorry to bring up an old post, but...What are the ideal specs on a T3/T4 turbo for an RB20 for street and what efficiency range would I have in this 6 cylinder? Thanks,Tony

Post by **wcbjr** » Thu Mar 27, 2003 4:45 am

Anybody have experience with pushing the 400whp barrier on the RB20? I got a clip real cheap and want to test the limits. I'm only to change the headgasket for now because don't care if it grenades, I'll buy another.

Two questions, how big a turbo can fit in the stock location, will I need a top exit manifold? Also, what spec T3/T04 would I need?

Charlie

Post by **jmillheiser** » Thu Mar 27, 2003 4:45 am

that same turbo on an SR will put out around 380-400hp to the wheels at 18psi

Post by **jmillheiser** » Thu Mar 27, 2003 4:45 am

an RB20 should be similar

Post by **themadscientist** » Thu Mar 27, 2003 4:45 am

there are guys that study this stuff for years to get proficent at this, I ain't that guy so apply appropriate weight to my opinion. A/R .63 exhuast T3 turbine side with a .70 60-1 T4 compressor. Measure the space you have before you source your turbo though to make sure the compressor will clear. Also I would section off the pipe out of the back and vent the actuator to the outside to help the flow and combat boost creep.

Post by **wcbjr** » Thu Mar 27, 2003 4:45 am

themadscientist, would you happen to know where I could find a T3/T04 turbo with the .70 T04S compressor? I can't find any that are internally wastegated. These are the best I can find for the prices, http://store.yahoo.com/cheapturbo/gartur.html

Post by **ipt** » Thu Mar 27, 2003 4:45 am

OK here let me clear up a couple of things for you guys.

First: The lower the boost pressure you want to run the better your wastegate has to be. The higher the boost pressure the wastegaste does not have to do as much. Remember that the wasteagate makes the exhaust gases bypass the turbine wheel. If you want to make more boost you want more exhaust to hit the turbine wheel. Thus the Wastegate does not have to bypass as much gas.

Second: The biggest factors that make up turbo lag are the turbine wheel used (Most likely a Stage III) and the Turbine housing A/R (.48 or .63) The compressor side has some to do with the lag, but not as turbine side.A stage III turbine wheel is one of the best all around turbine wheels. It is a middle of the road, great spool but will still allow lots of horsepower. Next is the A/R. There are alot of people out there that say you need a big A/R housing to make big power. That is a load of crap. I have seen 500whp made on a 7cm Mitsubishi turbine housing (roughly .49 A/R) and that was on an AWD dyno in a AWD Talon.

Third: The 50 trim compressor wheel is a great wheel for 2.0L motors. It moves a good amount of air and is very efficent. IT LOVES BOOST!! It is not very happy under 20 psi. Over 20 and look out it is having fun. I have ran 30 psi on my talon with one (on race gas of course) and it never felt SOOO good. That was where it really started to shine. It moves 48lbs/min of air.The 60 trim is the next step up. It moves just a tad more air then the 50 trim, but when it is at its top efficency is not very much of the time. most of the time the 50 trim is more efficent It moves 50lbs/min of air.A 60-1 compressor wheel is big step up. It is not very happy at higher boost pressures and is not as efficent as the 50 or 60 trims, but it moves a TON more air. It moves 55 lbs/min of air.

Well there is some food for thought. LAter

Nic

Post by **ipt** » Thu Mar 27, 2003 4:45 am

Lots of good info on Turbos here Check it out a good overview of how turbos work. LAter

Nic

Post by **apex_7** » Thu Mar 27, 2003 4:45 am

Correct me if I'm wrong, but can you really compare a 4cylinder w/ a six using the same turbo?

Post by **ipt** » Thu Mar 27, 2003 4:45 am

Yes and no. The exhaust pulses will hit the turbine wheel more often and help with spool up, but 2.0L of displacement is 2.0Ls of displacement no matter if it is 4, 6 or 8 cylinders. What matters is if the turbo can push enough air and the best way to look at that is the displacement.

Post by **wcbjr** » Thu Mar 27, 2003 4:45 am

Ok, thanks for the info ipt.

Post by **apex_7** » Thu Mar 27, 2003 4:45 am

Isn't it true that you can't boost a six as high as you can boost a four w/ the same turbo?

RB20DET, which turbo to upgrade?

RB20DET, which turbo to upgrade?

GOOD LORD!

400whp

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