These turbos seem fairly compatible but I can't seem to find many comparisons of them. From my understanding they both spool pretty quick (3500 or so) and their effeciency is fairly comparible. I've heard 380rwhp is the max out of a GT25R and the Big28 is somwhere around 340rwhp. I believe cost wise they are pretty close, about $1000 for the GT and $800 + core for the Big28. They both for teh most part bolt right up as well. Looking for any hard info on the two setups and personal experiences.
FPBig28 vs. GT25R
Negreac
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20PSI 240SX said:
Yes this is true...but here is where that logic falls short. to compresss 50lb/min (500 whp) to 25psi above atmospheric pressure at 75% efficiency requires somewhere on the order of 30-35 hp to be generated by the turbine. that is going to require alot more mass flow through the turbine section than you would see on a regular T28 or even GT25R. even though you are bypassing a good deal of the exhasut gas flow, you will still have a significant amount of flow trying to get a large amount of work of or a turbine housing that has had the Volutes cut out of it to fit a larger wheel...and therefore has had a good deal of its efficiency removed. so now we say lets take a 60-65% efficient turbine section and try generate 35 hp of shaft output. at 60% efficient for the turbine you are now going to need 1.25 the mass flow through the turbine as compared to a rough estimate of 75% efficiency for a standard GT30 turbine housing and wheel combo.
i dunno...just misc. ramblings on my part about turbine / compressor work relationships.
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Hmmm.... Garrett just released their new catalog and it doen't include the GT25R with the TO4S compressor housing. Check it out on www.turbobygarrett.com
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3,041 Posts
Those turbos in the catalog are turbos that come stock on different vehicles, so the compressor maps are released to the public. The maps for the GT28r and GT25 are property of garrett, so in order to get access to that property, they want you to buy the turbo or consult a shop that has bought them before, therefore letting them make more money. Common business practice, but unusual for the internet!
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791 Posts
Did you DLed the catalog? I'm pretty sure the GT60 isn't on any stock car, no wait I'm absolutley 100% positive it doesn't come on any car stock. The majority of the turbos in the new catalog are not on any stock car. I'd say the reason the new GT25R isn't in there is because it's, well, new.
Negreac said:
actually,
you're right the GT60 isnt on any cars. but there are 4 (yes four) of them on every Caterpillar 797B Earthmover sold.... OEM application doesnt mean AUTOMOTIVE necessarily. the catalog they have on their site is NOT performace application.
Caterpillar 797B
you just got pwn3d
kthxbye
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502 Posts
those also aren't ball bearing turbos in their catalog. journal bearing. i ordered the gt37 using the part number in that catalog. i got in a 1.07 a/r t3 housing i think. i can't remember....waste of $800. if anyone wants it, email me.
shaun
shaun
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791 Posts
There are BB turbos in this catalog. Enthalpy did get me on the GT60 though, sorry my construction equipment engine knowledge isn't up to par... :12dunno However if this isn't their performance catalog than why does it say "Garrett performance products catalog" on the front? Also what OEM vehichle do they use the disco potato on? I've attached teh catalog for those too lazy to go to the Garrett site and DL it.20PSI 240SX said:
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I can't attach it the file is to big and I don't have winzip. Here's a direct link:
New Garrett Catalog
New Garrett Catalog
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You don't think a piece of machinery that comes with 3550 hp from the factory is performance?:1bowdown I'd put some T4s on that thing I bet it could put out another 1000 hp easily with 4 giant ones on it, I'd be like :eek3dance drifting all over the place.Negreac said:
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After all the talk about the GT25R, anyone have any idea what the spool characteristics are on an SR20 with the usual intake, and 3" turboback on stock compression?
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well..that appears to the be the new, long awaited Garrett Catalog. including the performance stuffs!! good find!!
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Sid3ways S13 said:
well after reading the new garrett catalong they have the GT25R listed as a just a ball bearing t25. so i guess we are all really talking about the GT25/40R. but anyway spool times.
.64 exhaust - 3500-3750 for 15 psi
.86 exhaust - 4100-4300 for 15 psi
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791 Posts
Yeah it gets really confusing, some people call it the GT25R and some people call it the GT25/40R. I believe the correct name is GT25/40R. I didn't get that map from the new catalog, it doesn't list the GT25/40R just teh GT25R like you said.
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funny though, the center section is listed from garret as 25r
yeah...it is a bit of a mystery. well welcome to the world of Garrett...where things are changing monthly. pre-production release, production release...i think their roll out of the entire GT series was fubared form the get go. they definitely could have handled the release of these things better.
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the point is... is that i REALLY like that compressor map for the GT25/40r or whatever. If i was on my regular computer I could photoshop some good stuff... but that can wait. Anyways, that map looks basically ideal for the SR or 4g63 at like 15-20 psi of boost... saweeeeet
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