Is the EFR6258 too much for stock engine? - Page 2 - Miata Turbo Forum - Boost cars, acquire cats.

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Old 08-27-2014, 08:51 AM   #21
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or just control your boost.
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Old 08-27-2014, 09:08 AM   #22
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Quote:
Originally Posted by Braineack View Post
or just control your boost.
Well, its hard to keep it to 10psi when you use the stock 14psi actuator.
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Old 08-27-2014, 09:12 AM   #23
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I will have both the light and medium actuator and it has the EBC as well.
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Old 08-27-2014, 12:57 PM   #24
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Originally Posted by Mech5700 View Post
From what I can tell, this thing starts building boost just over 2k rpm, is that not quick enough?!
That's not a good measure of spoolup.
Better measures are:
what RPM does it make 5 psi? 10 psi? 15 psi?
How quickly does it go from vacuum to full boost at 3500 RPM? 4000 RPM?
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Old 08-27-2014, 01:00 PM   #25
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Originally Posted by JasonC SBB View Post
How quickly does it go from vacuum to full boost at 3500 RPM? 4000 RPM?
It will be difficult/impossible to match the EFR here. The trick turbine wheel reduces rotating inertia and lets the wheel spin up fast. There's no way a 2560R car matches the response. A 2554R car might come close, but give up 100whp on the top end.
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Old 08-27-2014, 01:01 PM   #26
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rpm is a terrible unit for spool, miliseconds is much better. Over 4k aint nothing going to spool faster than an EFR I dont care how small it is.

Boost threshold wise, thats the rear question. yeah at 2krpms in 5th my 6758 can make a copule psi, got to give it a second though. But its still able to make stock block breaking cylinder pressure by 3.5krpms.
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Old 08-27-2014, 01:27 PM   #27
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Here is some spool data I found on the collective spool data thread:

https://www.miataturbo.net/showthread.php?p=1109010&styleid=22

Post 203 and 218
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Old 08-27-2014, 02:02 PM   #28
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It may be more work than you're looking for, especially as new it isn't much cheaper than a 6258, but it might be worth looking into the Focus ST stock turbo: https://www.miataturbo.net/diy-turbo...ler-efr-79947/
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Old 08-27-2014, 02:10 PM   #29
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That is pretty interesting, but definitely a bit out of my realm at this point.
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Old 08-27-2014, 02:11 PM   #30
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I like how people relate the spooling of the EFR to magic lol
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Old 08-27-2014, 02:17 PM   #31
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Arthur C Clarke's third law: Any sufficiently advanced technology is indistinguishable from magic.
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Old 08-27-2014, 09:03 PM   #32
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You will need this past 10 PSI
Attached Thumbnails
Is the EFR6258 too much for stock engine?-7f9353fc-9c69-4c7c-b516-8cce6303f704.jpg   Is the EFR6258 too much for stock engine?-4ae69440-cfad-44a8-b137-34030aa79d2a-1217-0000021108cebcc4.jpg  
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Old 08-28-2014, 11:53 AM   #33
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Quote:
Originally Posted by Savington View Post
It will be difficult/impossible to match the EFR here. The trick turbine wheel reduces rotating inertia and lets the wheel spin up fast. There's no way a 2560R car matches the response. A 2554R car might come close, but give up 100whp on the top end.

Quote:
Originally Posted by Mech5700 View Post
Here is some spool data I found on the collective spool data thread:

I want your spool data! - Page 11 - Miata Turbo Forum - Turbo Kitten is watching you test compression.

Post 203 and 218
2500 and 3000 RPM data:

EFR in #203: 6.5 and 12.5 psi <-- this is a 2.0L!
EFR in #208: 4.5 and 10 psi
My 2560 data: 7 and 14 psi.

My 2554 data:
9 psi at 2500 (and 5 psi at 2000)

So GT2560 has better low end than EFR6258 even on a 2.0.
Still a pretty big difference.

Because the 2554 can make more than enough torque to break stock rods, it's a great street turbo for a stock motor. For a built street/track car, I personally like the GTX2863 on paper.
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Old 08-28-2014, 12:00 PM   #34
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So in your tests the 2560 spools faster than the 2554?

And I think they will next mention transients, "which you can't see on a dyno"
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Old 08-28-2014, 12:08 PM   #35
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Look as his dad again, 2554 was at 2k and 2.5k the rest were at 2.5k and 3k. Who cares about making boost down there anyways? You've never using that boost.
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Old 08-28-2014, 12:12 PM   #36
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Quote:
Originally Posted by Leafy View Post
Look as his dad again, 2554 was at 2k and 2.5k the rest were at 2.5k and 3k. Who cares about making boost down there anyways? You've never using that boost.
That's what I have been preaching for years, and now that I'm DD'ing my car and its all city streets I notice that I'm in 2-3k range pretty much exclusively.
I don't think I or anyone else really needs any more than a couple psi down there and about 150-160tq, but that much alone would make the car amazing at effortless, quiet (more or less) acceleration.

I dunno
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Old 08-28-2014, 12:22 PM   #37
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The car just isnt geared for that. And if it was it would just result in hitting boost on the highway on a slight grade like the td04 2.5L wrx. I feel like the only one around here that thinks stock power is perfectly adequate for driving on the street. And fun, you get to feel like boy racer reving to 4k just to accelerate with the rest of traffic and no one knows. But yeah the racecar has noticeably more pickup even at 2k rpms once the tarbo went on compared to N/A.
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Old 08-28-2014, 12:29 PM   #38
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The car is absolutely geared for that. I have literally been driving this way since I got it years ago. 6sp+3.9+45mph streets most the way there, means i'm in the 2500 range almost always if I don't rev it out like a boy racer. And even when I get on the freeway I can shift at 3k and still merge on and if I keep it at 65 (I only take the freeway for 1 exit, or 1 mile) its still close to 3k.

The older I get the more appealing a corvette powerband becomes to me. I loved driving the vette to work - get pushed back in your seat and still only turning 2k rpm, and making no noise.
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Old 08-28-2014, 12:32 PM   #39
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Quote:
Originally Posted by 18psi View Post
The car is absolutely geared for that. I have literally been driving this way since I got it years ago. 6sp+3.9+45mph streets most the way there, means i'm in the 2500 range almost always if I don't rev it out like a boy racer. And even when I get on the freeway I can shift at 3k and still merge on and if I keep it at 65 (I only take the freeway for 1 exit, or 1 mile) its still close to 3k.

The older I get the more appealing a corvette powerband becomes to me. I loved driving the vette to work - get pushed back in your seat and still only turning 2k rpm, and making no noise.
I am glad you are seeing the light, I hope you love the 2554 when you get it on.
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Old 08-28-2014, 01:06 PM   #40
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EFR6258 and GTX2863 compressor maps awfully similar:

Red is the EFR:

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Is the EFR6258 too much for stock engine?-efr6258-gtx2863-overlayed.png  
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