Garret GT Series !HELP!

[mikesim]

ok. i've read daemos' thread and quite a few others already, but i would like to know some specific things:

let's compare similar turbine housings on very different units:

GT25/40R (450HP)

Turbine-Wheel: 53mm w/ 62 trim-Housing: .64 ar, .86 ar

Compressor-Wheel: 60mm w/ 60 trim-Housing: .70 ar

GT28RS (350HP)

Turbine-Wheel: 53.85mm w/ 76 trim-Housing: .64 or .86 ar-Maps

Compressor-Wheel: 60mm w/ 62 trim-Housing: .60 ar

now i'm confused at to why these turbos are rated so differently. it cannot be the compressor housing alone that creates '100' more HP.

i read that TRIM is an area ratio used to describe both turbine and compressor wheels. Trim is calculated using the inducer and exducer diameters. As trim is increased, the wheel can support more air/gas flow.

BUT i don't understand how it is calculated. the GT2540R is a 60 trim and the GT28RS is a 76 trim compressor wheel. and by the statement above, wouldn't the GT28RS flow more than the GT2540R?

this is where i get super confused. for the compressor and the turbine you have 3 specs; wheel size, trim, and housing A/R. it doesn't make any sense to me what spools better, makes more HP, saves low-end torque, etc.

then there's compressor maps, which i learned to read and analyse from

http://www.turbomustangs.com/turbotech/main.htm#ar

and from doing their basic calculations and using the compressor maps on that site, based on a 1.8L 8000RPM redline i'd have a PR of 1.37 (approximation) @10psi, i'd choose a T04E 54 trim because it hits 74-76% efficiency at 4000RPM, at 6000RPM it's at 76-78%, and at 8000RPM it only falls off to 72-74%. unless, that is, i'm wrong about the PR.

but that info still leaves me hanging about why trims, housing A/Rs and compressor/turbine matchings are the way that they are.

I could just ask which is better? GT28RS or GT2540R or whatever, but i'd like to know HOW AND WHY!

thanks for any input guys.

[r34 gtr]

the gt25 has a t04e compressor. its a monster, thats why it makes so much more power. the gt28rs will most likely spool faster, but my gt28r doesnt look like it will hit full boost under 4k so i think the lag time is gonna be a ballsack either way. one problem (if you would even call it that) with the gt25r is that it needs a simply monsterous 4in intake pipe.

either go with a gt25r or buy a t3 manifold from ss autochrome on ebay and get a t3/t04e 48 trim for some faster spooling, cheaply-replaced turbo insanity. damn you ss autochrome for producing those manifolds right after i got my gt28r!!!!!

- tim

[fanta]

http://www.turbobygarrett.com/....html

Here's their catalog, PDF file:http://www.turbobygarrett.com/...3.pdf

[r34 gtr]

well, yeah, if you want to be all fancy. stupid technology..

- tim

[float_6969]

You are on a "look at me, I'm retarded" kick today, aren't you Tim?

[mikesim]

mmm.... haxors suxors

wtf do they even exist to delete posts?

SO, bottom line. i want a turbo that will hold its efficiency, that means maintain high boost until redline. 4500-8000RPM full boost. you guys don't think the GT25/40R is too big, do you?

[iliketocrash]

that hurts. my post was deleted. i thought i made a somewhat relevant statement. i know i didn't quite explain myself though. i was suggesting just sticking with a t3/t04e because mikesim doesn't seem too concerned about spool time. Also, it would be cheaper in the long run. I say this because its like what, 500-600 for a t3/t04e? They flow a lot, have high efficiency with large efficiency islands and they're cheaper to rebuild. So if you pick up a t3/t04e for about $600 and a t3/t4 tubular, SS exhaust mani from SS autochrome for $350 then you're up to about $950 which is cheaper than the gt25/40r which is $1,075.00. So in the end you end up with a nice stainless manifold which flows a lot better than the stock one and a nice, high flowing, efficient, reliable and cheaply rebuildable turbo. This is just how i feel because i don't have a ton of money to throw around and this setup just seems a lot more cost effective, especially in the long run. And by the way, the SS Autochrome manifolds aren't as bad as most people make them out to be.

[r34 gtr]

ryan, yes i was on a "look at me, im retarded" kick because i had this nasty 6 hour gap between classes. anyway, i do believe the t3/t04e would be your best bet/bang for the buck, but of the GT series, i would go with the gt24/40r.

- tim

[mikesim]

thanks for the info guys. i was originally thinking a 50 or 54 trim T04E like in my first post, but i wasn't sure about the whole fabrication of a turbo manifold.

what is SS autochrome's website? i googled it and all i have is alot of freshalloy links and other forums.

can you buy an internally wastegated T3/T04 combo? or should i look at buying a tial wastegate too? changing the oil and water lines over is what really worries me. i was thinking GT series turbo because of their BB design and they're 'bolt-on'.

[Def]

Hrmm... guess my laziness paid off. I had another browser still open with my original reply in it...

I'm pretty sure both those turbos use the GT Series NS111 turbine wheel(so it's the same for both). The housing options are also the same, 0.64 A/R and 0.86 A/R.

The specs you've got are wrong though, the GT2540R has a 74mm whee(IIRC)l in a T04S compressor housing. The GT28RS specs sound right with a 60mm wheel. So yes, the only real difference between them is on the compressor side.

As for a GT25R(what most people call it) on a CA, I'd say you'd be VERY lucky if you got full boost by 4.5k RPM with the 0.64 A/R housing. On an SR it fully spools a tad after 4k RPM(maybe 4.1-4.2k) and has been pushed to ~360rwhp, but that's is REALLY maxing out the smaller turbine housing.

The GT28RS would probably make full boost by 4k RPM with the 0.64 A/R housing on a CA. Max power would probably be in the 280-300rwhp range.

If you want more top end grunt, look into the GT2871R. Uses the compressor off a GT35R - so 71mm 56 trim in either a T3 or T04B housing(I forget which, but I think it's the T3...). It's a better speed match for the NS111 than the GT25R, and the 0.64 A/R version should spool a few hundred RPM sooner than the same turbine GT25R. Will still be slower than the GT28RS though, and might be a tad too laggy on a CA if you're doing alot of street driving. Some guy pushed this to almost 320rwhp with a 0.86 A/R hotside and an almost completely stock engine(stock O2 housing, cams, intake manifold etc.) - so the potential is there for at least that much power on a tuned up CA.

--- As for a T3/T04E being cheaper than a GT series turbo, I seriously doubt it. You're missing the cost of custom fabricating a downpipe, and having to probably monkey around with your hot pipe moreso than a stock location turbo. I'd be surprised if it was more than $100 cheaper than the GT series turbos, which isn't really a huge difference when you're talking about $1k. So I'd just get the one that you think would fit your needs better.

As for the oil and water lines, you can get some stainless braided lines that are flexible that will make easy work of the job. That's what I plan to do when I upgrade my turbo, as it was enough of a pain getting the stock lines back on with a stock T25 replacement.

[mikesim]

quick question: anyone run the HKS turbos?

i have a solid lead to some HKS GT2510 or GT2530 turbos. from what little information i could find, the 2510 is good to about 290hp and the 2530 good to 310.

and i know where to get the GT2540R new, but no one's compared them to say even the GT28RS or the GT25R.

EDIT: some info on the turbos from prostreetonline.com

HKS GT2530 - 320 PS Output

COMPRESSOR:-Wheel- 63 Trim - 47.7 Inducer / 60.1 Major-Housing- 60 Inlet / 50 Outlet - 0.60 A/RTURBINE:-Wheel- 76 Trim - 53.8 Major / 47.0 Exducer-Housing- GT25/T3 inlets / Internal GT25/Skyline Type oulets - 0.64 A/R

HKS GT2510 - 300 PS Output

COMPRESSOR:-Wheel- 63 Trim - 47.7 Inducer / 60.1 Major-Housing- 60 Inlet / 50 Outlet - 0.60 A/RTURBINE: -Wheel- 62 Trim - 53.0 Major / 41.7 Exducer-Housing- GT25 inlet / Internal GT25 oulet - 0.64 A/R

[float_6969]

Tim, you know I love you man! Can I have your Bud Light? As for the damn Hackers, we figured out what they kept doing to get in and fixed it, so until they find another loophole, we should be good to go.

[RMiller]

Get a GT2530! The GT2540R is the same as a GT25R, HKS may do some tricks to the wheels or something though. I don't know what that means.

[float_6969]

I think HKS has a different blade design than the Garrett units. I think they use Garret cores and housings, but have their own blades.

[r34 gtr]

you sure can ryan! ive got plenty to go around as i am in college. and it was actually me who took care of those hackers, i went to their houses in the middle of the night and permanently blinded them with my hairy, white a$s. they will never be able to use a computer again.

- tim

[float_6969]

You make me feel dirty, ya know that?

[r34 gtr]

yes.

[mikesim]

Get a GT2530! The GT2540R is the same as a GT25R, HKS may do some tricks to the wheels or something though. I don't know what that means.

aaah, i see. now it makes more sense.

thanks for all the input guys.

what is the S15 T28? is it the disco potato? i'm confused, cuz i was writing stuff down from an old thread and things kept bouncing back and forth....

[mikesim]

forget that. i have written GT28R(s15)<GT28RS(disco potato)<GT25R.

oh, i see where i was confused about the GT25R. ATPturbo sells a small GT25R, and a REAL GT25R is really a GT25/40 which is the copy of the HKS GT2540R