New to this forum but not to Miatas or turbos - Page 2 - Miata Turbo Forum - Boost cars, acquire cats.

Welcome to Miataturbo.net   Members
 


Meet and Greet Say Hi. De-noob yourself.

Reply
 
 
 
LinkBack Thread Tools
Old 01-29-2009, 12:35 PM   #21
y8s
2 Props,3 Dildos,& 1 Cat
iTrader: (8)
 
y8s's Avatar
 
Join Date: Jun 2005
Location: Fake Virginia
Posts: 19,037
Total Cats: 406
Default

Dear Doctor Turbo,

I bought a GT25 back in the day when there were only 3 or so GT series turbos in existence--before Garrett renamed everything with a ball bearing a GT turbo. It's a GT2876R (.64 A/R turbine housing) per the naming convention change.

Why does the turbo by garrett site list it as "not recommended for general performance applications" on the info page?

I will admit it's a little large for a streetable 1.8L, but it's been great for power at low boost and isn't a bad compromise in terms of spool. Here's my dyno graph at about 9.5 psi (the RED line). (the green line is a twin turbo 1.8L miata--2x GT1548)

y8s is offline   Reply With Quote
Old 01-29-2009, 04:11 PM   #22
Elite Member
iTrader: (22)
 
Join Date: Dec 2006
Location: Sunny Spanish speaking Non US Caribbean
Posts: 3,257
Total Cats: 3
Default

Quote:
Originally Posted by pbmiata View Post
Dr. Turbo! With a name like that you can expect to get a few tech questions! I'm really looking forward to you future posts.

Welcome!

I wonder- has anyone with the Doctor's background ever evaluated one of those China chargers I keep hearing about? I mean, really took one part and evaluated the tollerances, metalurgy, design of the vanes etc. and compared it to the Garrett?

It would be pretty neat to have a (turbocharger) engineer's perspective.

Dr. Would you be willing?
+1. Great question!
Rafa is offline   Reply With Quote
Old 01-29-2009, 06:36 PM   #23
Newb
 
Join Date: Jan 2009
Posts: 41
Total Cats: 0
Default

Quote:
Originally Posted by m2cupcar View Post
Yes, welcome. To validate your identity please answer the following.

Q: According to Garrett, under what circumstance should a restrictor be used with a journal bearing turbocharger?
LOL, funny trick question! However, you shoulda picked a harder one. Even a turboknewb dumbass like me knew how to answer that question.

If I knew it, then WHO KNOWS what kind of riffraff DrTurbo could be, posing as a Garrett engineer!

I demand more proof...something REALLY wonky and supersekrit that only a Garrett engineer would know...something NONE of us could possibly know and verify!

mrwoolery is offline   Reply With Quote
Old 01-30-2009, 02:56 PM   #24
Elite Member
iTrader: (2)
 
Join Date: Jun 2006
Location: ABQ, NM
Posts: 1,850
Total Cats: -8
Default

What is your favorite color!

BenR is offline   Reply With Quote
Old 01-31-2009, 02:51 AM   #25
Elite Member
 
Join Date: Jul 2005
Posts: 6,454
Total Cats: 80
Default

Heheh, how about more complete turbine maps for the GT25, 28, 30, and 32 ...
JasonC SBB is offline   Reply With Quote
Old 02-03-2009, 10:27 PM   #26
Newb
Thread Starter
 
Join Date: Jul 2008
Location: Long Beach, CA
Posts: 42
Total Cats: 0
Default

Quote:
Originally Posted by patsmx5 View Post
Thanks for the explanation. As for oil restrictors... I'm running a .070" restrictor on my GT3271. I don't have a "real" oil pressure gauge, but I'd imagine it's around 60 or so at cruise and 90ish by redline. If these numbers were correct, would a restrictor be warranted? Or even better: Would a restritor hurt anything? I've seen a lot of people run a restrictor on journal bearing turbo that had premature oil seal problems in the past that they contributed it to not using a restrictor.
Pat,

I see no reason to use a restrictor with a journal bearing turbo. Unless you are seeing oil leakage into the compressor or turbine, you don't have a problem. If you are leaking as evidenced by oil in the compressor or turbine, make sure you check all the other potential sources of CHRA seal leakage before resorting to a restrictor. There are many potential causes of leakage including oil backup due to a improperly designed oil drain. Here are links to a couple tips on this from Garrett:

TurboByGarrett.com - FAQ's

TurboByGarrett.com - Turbo System Optimization

The last thing you want is to starve your turbo bearings of oil.

Dan
DrTurbo is offline   Reply With Quote
Old 02-03-2009, 10:41 PM   #27
Newb
Thread Starter
 
Join Date: Jul 2008
Location: Long Beach, CA
Posts: 42
Total Cats: 0
Default

Quote:
Originally Posted by pbmiata View Post
Dr. Turbo! With a name like that you can expect to get a few tech questions! I'm really looking forward to you future posts.

Welcome!

I wonder- has anyone with the Doctor's background ever evaluated one of those China chargers I keep hearing about? I mean, really took one part and evaluated the tollerances, metalurgy, design of the vanes etc. and compared it to the Garrett?

It would be pretty neat to have a (turbocharger) engineer's perspective.

Dr. Would you be willing?
That type of competitor benchmarking is routinely performed by companies like Garrett although probably not for smaller companies turbos. Now days, a lot of these small companies are buying Garrett/Mitsu/IHI/etc turbos, disassembling them, and reverse engineering to steal their aero designs. Then, performance just comes down to how well they can measure and reproduce the originals. This usually doesn't turn out well. If they are doing their own aero designs, they surely don't have the design and testing resources to compete with the Garrett designs. Then there is the question of reliability. The materials and manufacturing processes are likely not as well controlled as for an OE type manufacturer. The ultimate test is performance and reliability in the field. If you are considering going with an off-brand turbo, I would definitely recommend doing some research first. As far as me doing any benchmarking - I must decline. While it would be interesting, it would take an enormous time commitment not to mention the money to buy the candidate turbo. I already have a day job and don't have any spare cash. Keep the questions coming though and I will answer what I can.

Dan
DrTurbo is offline   Reply With Quote
Old 02-03-2009, 10:52 PM   #28
Elite Member
iTrader: (2)
 
Join Date: Jan 2007
Location: Lexington, SC
Posts: 2,084
Total Cats: 0
Default

I think markp was having decent luck with the chinachargers last I heard. Welcome Dr.
mazda/nissan is offline   Reply With Quote
Old 02-03-2009, 11:06 PM   #29
Newb
Thread Starter
 
Join Date: Jul 2008
Location: Long Beach, CA
Posts: 42
Total Cats: 0
Default

Quote:
Originally Posted by y8s View Post
Dear Doctor Turbo,

I bought a GT25 back in the day when there were only 3 or so GT series turbos in existence--before Garrett renamed everything with a ball bearing a GT turbo. It's a GT2876R (.64 A/R turbine housing) per the naming convention change.

Why does the turbo by garrett site list it as "not recommended for general performance applications" on the info page?

I will admit it's a little large for a streetable 1.8L, but it's been great for power at low boost and isn't a bad compromise in terms of spool. Here's my dyno graph at about 9.5 psi (the RED line). (the green line is a twin turbo 1.8L miata--2x GT1548)
y8s,

Not sure why the Garrett site lists that. My best guess is that it is because the sizes of compressor and turbine are not well matched. (I won't get into the details of that here.) While your power and torque numbers look good, it looks like you are not on full boost until about 4000 rpm. For a low boost setup that is not targeting big power, there are other turbos that would provide the same performance at 9.5psi with better boost response. For street use, fast, linear boost response is usually what you want. The bottom line is that the compressor wheel on that turbo is just too big. Hope that helps.

Dan
DrTurbo is offline   Reply With Quote
Old 02-03-2009, 11:07 PM   #30
Newb
Thread Starter
 
Join Date: Jul 2008
Location: Long Beach, CA
Posts: 42
Total Cats: 0
Default

Quote:
Originally Posted by BenR View Post
What is your favorite color!

Blue, no yellow. Ahhhhhhhhh!
DrTurbo is offline   Reply With Quote
Old 02-03-2009, 11:10 PM   #31
Newb
Thread Starter
 
Join Date: Jul 2008
Location: Long Beach, CA
Posts: 42
Total Cats: 0
Default

Quote:
Originally Posted by JasonC SBB View Post
Heheh, how about more complete turbine maps for the GT25, 28, 30, and 32 ...
I said FORMER Garrett turbo engineer. Sorry, I don't have access to that stuff anymore. I'll pass along your request to my friends at Garrett though.
DrTurbo is offline   Reply With Quote
Old 02-03-2009, 11:52 PM   #32
y8s
2 Props,3 Dildos,& 1 Cat
iTrader: (8)
 
y8s's Avatar
 
Join Date: Jun 2005
Location: Fake Virginia
Posts: 19,037
Total Cats: 406
Default

Quote:
Originally Posted by DrTurbo View Post
y8s,

Not sure why the Garrett site lists that. My best guess is that it is because the sizes of compressor and turbine are not well matched. (I won't get into the details of that here.) While your power and torque numbers look good, it looks like you are not on full boost until about 4000 rpm. For a low boost setup that is not targeting big power, there are other turbos that would provide the same performance at 9.5psi with better boost response. For street use, fast, linear boost response is usually what you want. The bottom line is that the compressor wheel on that turbo is just too big. Hope that helps.

Dan
darn. either I run more boost or find a smaller wheel. is there such a thing as a bolt-on wheel and housing for that turbo?
y8s is offline   Reply With Quote
Old 02-04-2009, 12:21 AM   #33
Elite Member
 
Join Date: Jul 2005
Posts: 6,454
Total Cats: 80
Default

Such as a GT2860 LOL...
JasonC SBB is offline   Reply With Quote
Old 02-04-2009, 02:21 PM   #34
Junior Member
iTrader: (1)
 
Join Date: Aug 2008
Posts: 373
Total Cats: 36
Default

y8s, the smaller bb turbos like yours have a backplate that is integral to the center housing. This means the counterbore for the comp wheel is specific to that wheel's OD.

So in order for you to swap out to a smaller comp wheel, you'd have to also swap out the center housing. You're better off just starting over with a different turbo in that case, unless you can somehow find a chra + comp housing (sans turbine housing, since you can re-use the one you have). Maybe call ATP and tell them your situation.
JKav is offline   Reply With Quote
Old 02-04-2009, 02:32 PM   #35
y8s
2 Props,3 Dildos,& 1 Cat
iTrader: (8)
 
y8s's Avatar
 
Join Date: Jun 2005
Location: Fake Virginia
Posts: 19,037
Total Cats: 406
Default

ATP has my original .86 turbine housing. I traded them for the .64 I have now.

I think I'll just stick with this for a while.
y8s is offline   Reply With Quote
Old 02-05-2009, 11:08 PM   #36
Newb
Thread Starter
 
Join Date: Jul 2008
Location: Long Beach, CA
Posts: 42
Total Cats: 0
Default finally some pics

I have gotten some request to post pics of my Miata and from my turbo Rx-7 project. Funny thing is, I looked around and I don't seem to have an pics of my Miata worth posting. I guess I'll do that this weekend. Here are some pics of the 7 to tide you over.

Looks pretty stock from the outside than the CF hood.

Name:  front.jpg
Views: 13
Size:  66.0 KB

All the good stuff is under the hood. Pretty much everything is one-of-a-kind custom fabbed except the HKS exhaust manifold.

Name:  Engine.jpg
Views: 13
Size:  91.3 KB

I designed and built the 1-off turbo while I was still at Garrett. It's basically a GT3276 with a twin scroll turbine housing.

Name:  Turbo1.jpg
Views: 17
Size:  132.5 KB
Name:  turbo_chra1.jpg
Views: 14
Size:  58.8 KB

The intercooler was also a custom job using a 12x18x3 Garrett bar plate core. I use a draw through fan to prevent heat soak at idle and low speeds.

Name:  IC_fan.jpg
Views: 15
Size:  74.8 KB

Finally, a custom parallel flow dual oil cooler setup (one on each side) with custom ducts to the front bumper inlets.

Name:  oil_cooler_duct2.jpg
Views: 55
Size:  206.0 KB
Name:  oil_cooler_lines.jpg
Views: 17
Size:  245.0 KB

Engine management is provided by an Electromotive TEC3.

Now for the interesting stuff. This is the closest I've gotten so far to a turbo Miata setup.



Yep, that's right - I am a member of JKav's Lemons team and had a hand in building that monstrosity. Part of what inspired me to turbo my own Miata. Now the real fun begins.
DrTurbo is offline   Reply With Quote
Old 02-05-2009, 11:13 PM   #37
Murderator
iTrader: (76)
 
18psi's Avatar
 
Join Date: Apr 2008
Posts: 36,165
Total Cats: 2,573
Default

that rx7 is awesome.
18psi is offline   Reply With Quote
Old 02-05-2009, 11:20 PM   #38
meatbag
iTrader: (50)
 
gospeed81's Avatar
 
Join Date: Nov 2008
Location: Houston, TX
Posts: 7,357
Total Cats: 26
Default

are you the homeless person doing all the welding for that build?
gospeed81 is offline   Reply With Quote
Old 02-06-2009, 03:58 PM   #39
Newb
Thread Starter
 
Join Date: Jul 2008
Location: Long Beach, CA
Posts: 42
Total Cats: 0
Default

Quote:
Originally Posted by gospeed81 View Post
are you the homeless person doing all the welding for that build?
I wish. No welding skills yet. We have another guy on the team with those. I do have access to the welder though and have been thinking about taking a class.
DrTurbo is offline   Reply With Quote
Old 02-06-2009, 05:13 PM   #40
Elite Member
iTrader: (22)
 
Join Date: Dec 2006
Location: Sunny Spanish speaking Non US Caribbean
Posts: 3,257
Total Cats: 3
Default

I showed your car's pics to a friend (he also owns an RX-7 like yours) who's rebuilding his engine and he wants to know at what RPMs do you see boost with that T3276.

FWIW, he drags his car regularly but also uses it as a dd.

Thanks
Rafa is offline   Reply With Quote
 
 
Reply

Related Topics
Thread Thread Starter Forum Replies Last Post
MS PNP requires reading and following directions??? satisfied MEGAsquirt 141 10-06-2015 11:44 AM
Noobie first post p51ofaces Meet and Greet 6 09-17-2015 10:08 AM
VE values too low? compuw22c MEGAsquirt 4 09-12-2015 08:42 PM
New here, saying hi, here's what I'm workin with. SuperSneakySecretSquirrel Meet and Greet 5 09-06-2015 09:30 PM


Thread Tools

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off



All times are GMT -4. The time now is 01:59 AM.