3sgte Turbo Upgrade - Help Interpret Efficiency Chart

[medwin46]

Hey guys

Well, pending the sale of my current setup (GT2876RS Custom Built Turbo, 0.63 Exhaust and 0.70 Compressor) i'll be upgrading the turbo setup on my RWD 3sgte conversion.

The car has been built to participate in hill climbes, track days and have the ability to take out on a peaceful sunday drive when i feel like it (Peaceful WTF?! ) Hence why i opted for the 28 when i purchased it. Spools up almost with no lag at all, but i fear its flattening off higher in the RPM range as its just too small to continue delivering the volume of air needed.

Upon speaking to a few guys, they've recommended something from the GT35 range, in particular the GT3582R. My concern in that it's going too big on my 2L, too lag-gy. (engine will be receiving aftermarket cams, already has all other supporting mods, Microtech, 800cc injectors etc) This particular turbo maintains the 0.70 Compressor A/R, and is available with the optional 0.63 Exhaust A/R, to make a responsive high output turbo.

GT3582R Turbine Map: http://www.turbobygarrett.com/turbob..._2_turbo_e.gif

GT3582R Compressor Map:
http://www.turbobygarrett.com/turbob...8_2_comp_e.gif

I've never been able to get my head around these maps, (i need someone to explain them to me) so it is difficult for me to interpret what they are telling me, other than they are efficiency graphs.

Basically, i want a minimal lag turbo, that is capable of putting out high HP and doesnt 'flatten off' in the higher RPM range.

One guy i've spoken to has put this turbo (GT3582R) with the 0.63 Turbine on a stock SR20 motor (apexi FC and bigger injectors) and is laying down 260rwkw @15psi, and says the response is insane, virtually lag free.

So, anyone who is in the know regarding these Charts ^^^, would you mind giving a quick run down on what you forsee the issues to be with this turbo on the 2L, and do you think it will satisfy my criteria?

Next question: Say i am to go to this GT35, i will be fitting it to a fully built motor and in the process be upgrading the cams to HKS items, with matching adjustable gears.

The cams are available in 264 or 272 Duration for both the exhaust and inlet side. What would be recommended as the most suitable for this application, please list the pros and cons you see either way.

Thankyou for reading, and thanks in advance for any help.

[Talasas]

You can't directly read what the compressor map says without doing some calculations. Basically you need to work out the values on the x and y axes (air flow and pressure ratio) and then look the point where the values intersect on the graph. The location of that point indicates how effective the turbo will be for your setup (I'll let someone more experienced elaborate on that).

The basics of it are, you want to aim to be within the smallest island or as close as possible to it as this is where the turbo is more efficient/effective. The further away you are the less effective the setup will be. The direction you are away from the smallest island indicates what would be the cause of it not running at its peak.

- Too far to the left and you'll get compressor surge, due to stalling compressor blades, generally means turbo is too large
- Too far to the right and you get choking, the turbo is too small and may be prone to overspeed depending on how far away you are from peak efficiency.
- The horizontal lines, which are speed lines, indicating in this case the rpm of the turbine assembly. Overspeed must be avoided to prevented the turbo failing.

That's the real basics of it, there's a lot more the graph can tell you but I'll leave that to someone more experienced than myself to cover.

[wilbo666]

In regards to turbo maps, google should be able to help ya out with reading them

Joshstix has a GT35 from memory on his 3s...might be worth seeing what he has said about it / more info

Cheers
Wilbo

[Joshstix]

Yeah I have the GT3582R with a .82 trubine on it. I make peak boost at ~5200rpm. That's with big cams big valves etc, may be possible to improve spool by changing the cam timing but I haven't played with it.

My recomendation to you would be to get a GT3076R. Unless you're making massive amounts of power I really doubt the compressor wheel is running out of flow. The turbine side will be what is causing it to choke at the top end. A GT30 turbine housing and external gate should fix that problem and give you better flow up top without too much loss of bottom end.

I love my GT3582R and think it's a brilliant match for a built 3S for some purposes but I think it's too big for your stated prefferences.

There is a bunch of flow chart analysis in relation to turbo matching for a 3S-GTE over at www.mr2oc.com if you're more interested in the theoretical side of it.

[The Real Roadrunner]

Hey guys

One guy i've spoken to has put this turbo (GT3582R) with the 0.63 Turbine on a stock SR20 motor (apexi FC and bigger injectors) and is laying down 260rwkw @15psi, and says the response is insane, virtually lag free.

lag free above 5500rpm maybe but the boost threshold on a turbo that big would be well above 4500rpm, bar drag racing or dyno queens im yet see a use for a GT3582r on a 2L engine.

GT3076r with a set of HKS 264 cams and you'll be in business.
responsive once above the boost threshold (3800-4200rpm) and will do 300rwkw with the right tuner and about 1.5bar of boost, or about 250rwkw with about 1.1bar of boost.

as i said in your rides thread earlier the GT2876r would have to be one of Garrett's worst mismatched turbo's and only works well if you run a restricted engine (ie IPRA).

the GT2871r is much better at making decent numbers without falling over at the top and will happily make 250rwkw on 1.3bar (done it many times)

cheers
linden

[JustenGT8]

^^^ what he says RE turbo.

RE cams i would stay with the smallest you can that gives you the top end you want ie stay with stock initially. Helps bottom end and spool which is what you want for the events you are aiming at. You can see 270 rwkw on the stock cams. If you can get what you want using lower revs your end will live longer too.

I have run Blitz 264 (pretty near identical to HKS 264s) and combined with a GT2540 made for a pretty doughy engine below 4000rpm, great top end though. 272 wouldn't be much fun on a tight hillclimb course.

[The Real Roadrunner]

If you can get what you want using lower revs your end will live longer too.

what does his end have to do with this thread?

I have run Blitz 264 (pretty near identical to HKS 264s) and combined with a GT2540 made for a pretty doughy engine below 4000rpm, great top end though. 272 wouldn't be much fun on a tight hillclimb course.

did you have the cam gears adjusted accordingly with the 264's?
ive never had a set in a 3S but having fitted many different sets to other vehicles i can vouch for the fact that if they aren't set correctly they will be doughy.

once set correctly though they will wake the engine up well and truely, and should start working above 3500rpm which is where your chasing the power anyway,
cars are full of compromises, if you want more tourque get more cubes or change to a lower gear and put the rpm where it wants to be.

agreed regarding 272's

cheers
linden

[JustenGT8]

damn gheyness of this forum is finally getting to me replace 'end' with nob err i mean arse...nah dammit 'engine'.

RE cams, yup had a sweet set of TTE cam gears and tried a few different cam timing setups.....GT2540 are a bit laggy with the 0.86 turbine housing, so that and the cars weight all added up to a bit doughy. Not woeful but EVOs were a PITA until i was up and hauling

I still say stay stock cams and see what you reckon......it'll be a weapon regardless

[The Real Roadrunner]

i think you will find it was the .86 rear that caused the lack of bottom end.

small cams should be fine but stockers are heaps cheaper so maybe run with them first.

[medwin46]

Thanks Linden and Justin and Joshstix!

I can get a GT3076R with the 0.63 exhaust over night. Will it be too laggy however? How early should we be expecting boost to come on by?

[mr2mark]

I have a gt3076r on my 3sgte mr2. It suits my goals I think. Not many 2L engines can make use of a gt3582r properly.
I have 264 in and out cams. IMO 272 are only needed for 500+ whp

[SillyCarS]

fwiw i am putting the gt3076r with 0.63 housing on my 2L (bastard 1g) with the intention of hillclimbs also

im looking for 250rwkw with 440cc inject, microtech, adjust cams etc im def no expert though i imagine with some lumpy cams you'll be more responvie than the gt35 and have the power in the range you want it for your application

i realise diff ratio's and that play a part also, but im sure youve got that down pact also

[The Real Roadrunner]

Thanks Linden and Justin and Joshstix!

I can get a GT3076R with the 0.63 exhaust over night. Will it be too laggy however? How early should we be expecting boost to come on by?

only as laggy as the way you drive it,
keep it above 4Krpm and i garuantee it will scare the shit out of you in such a light car.
may be average below 4K but above it the response is fine especially on a 2L engine.

put a set of Gen3 cams in and some cam gears if you can get some cheap, that should allow you to adjust when it comes on boost (to a point) and make the engine feel much stronger in the midrange.

cheers
linden

[SillyCarS]

thanks for the info linden sounds promising

[MS-75]

Hey medwin,have a look at this site for a good explanation on turbo selection and other excellent tech info.

http://www.forcedinductions.com/help.htm