NEW EFR?
 

My son tells me there is a new (perfect for the Miata) EFR Turbo coming out that is between the 61 and 67 in size?
Is this true?

I have googled the crap out of this but all I get is "New EFR turbos"...As in the ones already in use?

Thanks in advance!

see Trackspeed thread. it will be a while before it's out

The 5951 I think? I know it was at SEMA but I'm not sure if there's been any more info about it.

Release date mid-2018.

Holy crap, just looked up a snippet for the EFR5951

"For SEMA 2016, BorgWarner showcased a couple of refinements and one new turbocharger coming to the EFR catalog. The EFR 5951 (pictured center) is a concept turbo destined to become the new ‘baby’ of the EFR range. Compared to the EFR 6258 (currently the smallest EFR offering) the 5951 has a smaller physical size, but is able to flow up to 95 per cent of its bigger brother with 35 per cent less inertia."


What about those EFR's with quick spool valves?

Thanks for the quick responses!

Seems like it will be an autocrosser's dream come true.
95% of the 6258? We shall see I guess, but judging by the way the 6258 chokes at high rpm...I think the smaller turbo is going to take a big HP bath....Who knows?
Miata is a strange world where physics may not directly apply! :)

QUOTE=psyber_0ptix;1392854]
What about those EFR's with quick spool valves?[/QUOTE]

We used to run those on high performance diesel trucks where we had massive turbos (I ran Precision 3 X 3.35s at 180ish Psi) ...You need a twin scroll turbo....I think you can get an EFR with twin scroll, but you get the wrong A/R with that turbo as far as I heard?
The idea of waking up an EFR 6758 several hundred rpm lower is not lost on me!

Thanks for the replies!
Jamie

The 5951 will be the holy grail of miata turbos. It will package even better, yet still make over 300 whp, while spooling insanely quickly. Maybe TSE will have a complete kit by then...

I'm trying to figure out how you came to this conclusion.
Are we talking about 8K+ rpm or 400HP+?

If you think the 6258 chokes at high RPM, the 5951 should not even be on your radar.

Not making a judgement on either turbo here...Just some observations I made from the dyno graphs here that may well prove wrong comparing the torque curves of the 6258 and the 6758.
Horsepower/torque comparisons are irrelevant here. The shape of the torque curve and boost pressure that tell us where the turbo is at in its performance envelope.

If you look at Soviets 6758 at 400hp graph the torque curve it is pretty flat with a gentle roll off at 6500rpm. Given more boost the curve would be dead flat. Obviously fuel was the limitation here...not the turbo.
That is what a perfectly functioning turbo should look like in my world. Nothing is working too hard and the IATs are nice and low.
If you look at his E85 450hp graph the turbo is starting to choke. I don't remember the exact numbers, but it took another 15ish pounds of boost, and more timing to gain 50 horsepower.
The turbo (as far as we know) was the restriction there.

The 6258 at 300hp makes 280ish ftlbs then from 5500 to 7500 it loses 80ish ftlbs...The torque curves dives like a fat kid on a smarty!
Raise the power to 325hp and the torque drop starts at 5000 rpm!
Why?
The turbo is at the top end of its performance envelope.

Maybe I am on crack here, but what happens to that mid range torque and horsepower when you switch in a new turbo 3mm smaller on the intake side, 7mm on the exhaust?
Given the same horsepower (Not going to happen), how much less torque are you going to have?
More importantly how much less power under the curve?

Bottom line is you are going to give up the monster mid range torque and horsepower of the 6258 in return for a little better spool and performance below 3500rpm?
Perfect for autocross? Could be, but that is not my thing so I have no idea.

I do think the 6258 is the perfect track turbo.

Haha !
Yeah no, not for us.

My son wanted the 7163 and I was just able to talk him down to the 6758.
We borrowed a friends 325hp (3071R) Miata and took out for a run a while back.
Junior near swallowed his tongue!
I hope to get him down to the 6258, but he is a 20 year old kid and I don't know much.... :)

They announced alot of new tech but the new 2017 turbo's still dont have all the tech. Sema few years ago they had some quick spool valve on the twinscroll manifold but still nothing in production

The EFR 7163 is the first one with mixed flow turbine and the subie guys love that turbo. Some say it has a better spool than a 6758, but unfortunately the 7163 is the only one yet and no sign yet for a MFT on the 6258 or 6758

It is probably worth mentioning that a lot of the subaru folks may be running a 0.85 A/R between the 6758 and the 7163 for a 2.0 or 2.5L platform. So a comparison on a 1.8L miata motor may not be as easily compared say between a 0.64/0.85 6758 and 0.85 7163.

I'm not sure, but has anyone really put an EFR7163 through a Miata yet? Lot of build threads that aren't complete. It'd be good to see some numbers. Or even 0.85 A/R 6758's for that matter....

I see what you mean about torque drop off, but I'm not sure I'd agree that a "well working turbo" is one without any torque drop off up top. The way I look at it, if power isn't nosing over, there is still room to push it and the limit is not reached.

I did this on a very conservative CA91 pump gas tune on a 6258
https://www.miataturbo.net/attachmen...ine=1443078169

Boost is not really dropping that much (it's shaky due to weak actuator) and power aint dropping, I say it will do 350 on good gas without too much effort

Soviets 400-450hp runs were only 3psi different. Lots of timing, e85. And 29psi vs 26psi.

Want to tune my pitiful stock engine with a 6258?

hit me up when you're ready and we'll go from there :)

Is there a reason that graph looks familiar? :D

I dunno what you're talking about :giggle:

AIUI, the standard 4500-ish torque peak is a result of the stock Miata cams.

--Ian