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

Now there is a tune!

That is a lot better looking than the other plots I looked at....Not in the same ballpark!
The torque is low in the range, but it only drops 50flbs over 3000 rpm...Which is downright amazing compared to the others I have seen.

Why would anybody want a torque curve at lower rpm than this? You are already making almost 10psi and 200Ftlbs @ 3000 rpm? First and second gear tires on fire? :)
A smaller turbo will move the torque band lower making traction more problematic while punishing you on the shortest of straights.

Does this motor have the VVT head?
I understand it makes boost come on sooner, but offers no horsepower gains at higher rpms?
Does the torque curve broaden at all?

Thanks for commenting!

There are factors far beyond the turbo when it comes to motor setup. A squaretop IM will carry torque past 5000rpm better than a VICS manifold, as long as the turbo can carry it. VVT cams will see a slight falloff past 6500rpm in exchange for better torque between 3500 and 5000rpm. You can't just look at a single plot and use it to assume the behavior of the turbocharger. You have to look at lots of data to get a better idea of what the turbos are capable of.

The 5951 will respond better and should still make 250-275whp on top, which is why people here are interested in it.

The 5951 will respond better and should still make 250-275whp on top, which is why people here are interested in it.[/QUOTE]


This. If it existed I would have gone this route for the street all day long. I don't plan on switching from my 6258 though.

Thanks, it's an absolute blast to drive, as I'm sure EO2K can attest.
As everyone said it's all about insane fast response (though the 6258 is not lacking in that department either), and I think during normal street driving, you're not necessarily wringing out every gear, so that when you're in 4th/5th/6th at say 2500rpm (think of your typical 45mph city street), more torque down there is always welcomed. Especially when you're running proper 3.6 final drive

*edit: its basically the same reason people throw twin screw's on v8's: no one needs 500wtq at 2500, it mostly results in tire spin in the lower gears, but chugging along effortlessly at 2500 without even revving the engine to propel the car like a locomotive definitely feels amazing.

This will be the best stock-block miata turbo. If I get my car fully tuned NA this year, then perhaps I can turbo it with a full TSE kit next year.

Keep in mind that stock rods won't appreciate boost even earlier in the rev range.

Yeah, what I had in mind was a rods-only rebuild, but then why not get the 6258... I will be in the market when the whole TSE kit is ready. I have been through 5 other cars since it was initially announced, but I still have my ratty 01 SE that would be perfect for a track-ish build.

TSE kit IS ready? What'reyou waiting on?

Is this about a transmission solution?

he's talking about a complete turbo kit

On the money!
If you are making +- 6 pounds at 2000 rpm a smaller EFR will probably make 10-15 there.....I can only imagine how much boost it would make with a bit of anti lag!

With 10+PSI on tap the temptation will be to roll on at at low rpms...Which will induce LLSPI ( Low Speed Pre Ignition) with stock pistons.
Those stock rods will fold in days.
Timing wont fix it as LSPI happens before the ignition event. The only fix it is to go pig rich at WOT under 2500ish rpm....Not a long term solution

Hard to say 100% before it gets here, but rods and pistons are pretty much going to be essential.

Even with the 6758 having a few psi at 2k rpm in 5th gear made it temping to roll on at like 45mph because noises.

Ah, no. Not only do 6258s not make 6psi at 2k, a 5951 isn't going to tack on 4psi to that. Maybe 1psi at best over what a 6258 can do down low.

LSPI is virtually unheard of in port-injection engines. It's only become an issue in GDI engines with tons of static compression and tiny, tiny turbochargers. Way smaller than the 5951 being discussed here. On a 9:1 port injection motor, it's a non-issue.

I think that's a hugely premature statement to be making, based on dubious assumptions at best. We're talking about a 59mm/51mm wheel combo. 2554Rs use a much smaller compressor wheel than that (54.3mm) with a turbine that's not much bigger (53mm), and nobody complains about rod-bending torque or LSPI in those. You can even get a version of the T25 thats smaller than that, and I've used that turbo successfully on a stock engine. Everyone here swore up and down that EFR6258s would blow up every stock motor too, and that never came to fruition either. Should you be tuning a small turbo to the ragged edge on pump gas? Probably not. Is it a foregone conclusion that a small turbo will bend the rods on a stock motor? Hardly.

Is it a non issue because of the lower compression and port injection? Or because neither turbo will make more than low single digit boost down that low? How about if there was a supercharger or something capable of making 8-10psi at those TPMs? 15? 20? Or is that just a matter of tuning like higher RPM where you just need to get timing and mixture right?

Sorry for all the questions, I have never heard of this before at all. Itcs these tidbits of info that I don't know that I don't know that keep me reading these threads. Will have to do some googling later on it.

All of the above. You need a very small engine, a very small turbo, a cam profile designed to make lots of boost and torque right off idle, direct injection so your fuel spray disturbs the oil layer on the cylinder walls and creates a homogenized fuel-oil mixture, and an oil with high calcium levels (apparently). The short answer is that it's never going to be a problem for us.

This, 100 percent. Only people who tune these cars desire this, and fail to acknowledge a characteristic called diminishing return. "My goal is to have all my torque before 2500 RPM and accept a massive amount of torque loss over the last 2500 RPM of my power-band, because torque wins races and I am way too literal!"... Give me a fucking break ha. But seriously, a 6258 (on any 1.8 Miata engine, I.M. aside, cam aside) spools plenty fast enough, and damn close to optimum. Torque 1000 RPMs sooner than a 6258 will not gain you anything.

It may not gain you anything. But a lot of people want torque right off the bat.

Look at any new turbo car. Torque asap, and choke up top. Just cuz you have some idea of what "everyone wants" doesn't mean you are right.

Must be painful to be ignorant

I have always considered this an American automotive culture thing. How do you want your shirt, plaid or striped? One not necessarily better, just personal preference.

Of course its preference. I'm just saying there are obviously people that want it. Where NBoost seems to believe everybody is exactly like him and only wants max power.

All torque all the time. Modulate it with your foot. Problem solved.

He's too painfully ignorant to realize that 99% of the cars on the road are driven below 4k 99% of the time and not everyone drives 10/10ths on their way to the grocery store.
Or that part throttle boost in the upper gears at low rpm/high load is delicious in a street car, its what just about everyone wants, as evidenced by every automaker under the sun building more and more tiny turbo cars.
Why not run a 7163? Or a 9180? I mean we all want 800whp from 6-7k right? :)

I love a 6258, but let's not be silly and say that a smaller snail isn't even desirable for some people.

Agreed with this. There is a huge different in the way the power band feels between OEM systems and systems that are sized for #allofit. Spooling at 3000 rpm is fine for performance because you're always above that if you're in the correct gear, but getting the torque curve to be low, instant, and smooth is a totally different feeling. Some desire that feeling, and don't want the rush of torque increase between 2500 and 3500 rpm.

So wrong it hurts, dude. Nobody here is suggesting full torque at 2500rpm is a good thing (mostly because we disposed of techsalvager a long time ago). What you fail to realize is that most people on this forum don't have 300+whp turbo cars. Most people have a stock engine and want to make 220 or 230whp.

If you take a big turbo that isn't being used to its potential and go smaller, there are a huge number of benefits. You get a little more torque down low, you lose nothing up top, and your throttle response/linearity improves dramatically.

We want 1000rpm full torque all the way to the redline

EDIT: and about 600whp

I would even settle for this :likecat:
https://cimg2.ibsrv.net/gimg/www.mia...509bb65583.jpg

But without the supercharger whine

There's no supercharger on the car with that plot ;)

Its just got 4 extra cylinders.

6. But who's counting

Looking at the torque and HP i would say a Viper with a little tune

Correct you are.

I'd also settle for this


https://cimg9.ibsrv.net/gimg/www.mia...8f47dcdeff.jpg

In a miata

only 819whp?

https://cimg5.ibsrv.net/gimg/www.mia...9303c18dd8.jpg

I keep telling my son about the awesome sauce of just being able to grunt away in 5th or 6th gear or drop a gear or two and be able to have big power everywhere at every rpm...

Unfortunately the allure of the big HP is strong! He comes by that honestly! :)

I had him look at your torque/hp and comparing it to the few dyno graphs I could find on the 6758....It doesn't look like the 6758 has more horsepower until 6000rpm or so.
From there the torque is in the expensive part snapping range....
I may have seen a light go on.

So how do you perfect your build?
If someone gave you $5000.00 and said go spend this on your current motor (can't spend it elsewhere)...What would you change?

Jamie

Savington,
Not sure where your post went, but I appreciate you taking the time to explain how turbos work....I am already there....How everything else works with the Miata engine...I am just starting to learn
I have looked at every dyno curve I could find on both turbos....Not just one.
I haven't bothered reading the compressor maps, because of the built in air flow issues of the Miata power plant...I figured I was better off reading dyno graphs and replicate a proven build then venture off into the unknown.

18psi mentioned there was at least 350hp on tap with his EFR 6258 built (I heard enough air to support 350hp)...Which was why I asked the question...That and if he could, how would he move the power around.
Once a turbo reaches the end of its flow map there is no more power to be made...I understand that.

Not trying to frustrate you, rather trying to sort out which way to point my horsepower hungry son....Who is too inexperienced to realize there is more to a build than a big horsepower number.
FWIW my son has a reading comprehension disability....Which is why I am here figuring out the Miata rats nest on his behalf.
I do appreciate you taking the time to point out the error of my thoughts! I am learning as fast as I can!
Thanks again!

Jamie

OK, I re-re-read and the points I made here were valid. I thought for a moment that you (Jamie) were comparing the 6758 to a Viper engine, which made my argument pointless and silly, but it seems the point is worth making after all. :)

This belies a fundamental misconception of how a turbocharger alters the powerband of an engine. Turbochargers move air based on turbine speed and pressure ratio. Engine RPM has very, very little to do with it (for our purposes, we can say it has nothing to do with it). If you are operating the turbocharger in an area of its compressor map that it's happy with, it will continue to chuck out that mass of air irregardless of engine speed.

Let's take a hypothetical example to show how this works. We have an EFR6258 on a built longblock with a stock '99 head. That turbo will happily produce enough airflow to make a flat 300whp from 6000rpm to 7000rpm, but no more than that. (hypothetically.)

Now let's fully port the cylinder head so that it moves more air given the same cam profile. Torque increases across the board, as does power. The same 300whp that used to be from 6000 to 7000rpm now occurs from 5500 to 6500rpm. Same power = same airflow requirement. Past 6500, the turbo runs out of breath, and suddenly you see a power drop at high RPM, even though nothing else has changed.

Add a set of camshafts which improve breathing again, and the problem gets worse.

You cannot look at a single dyno chart and infer what a turbocharger is capable of doing. You need to have a broader understanding of the engine and its capabilities. In this specific case, your assumption that the 6758 "doesn't make more power until 6000rpm" won't hold up if you look at enough charts comparing the two. All else equal (RPM, boost, etc), the 6758 will make more power at every RPM. The 7163 will make more power at every RPM than the 6758 will.

With turbo selection, there is some give and take, but it's not as extreme as you think it is in this case. In general, when going bigger, you give up a small amount of low-end power and response in exchange for power gains everywhere else. The biggest difference between a 6258 and a 6758 is in the response, IMO (I've driven both extensively in the same setup). There are probably some small torque differences under 3000rpm, but north of that, the 6758 is king.

Replicating a proven build is one of two ways to build a great car. I highly encourage going that route. The other route involves an awful lot of time and money figuring it out yourself :)

90% of the time I'm driving my turbo car is on the street to and from work. I want torque from 2000 to 4500rpms because that is where I spend most of my time on the street. It's hard to hit 7000rpms in stop and go traffic.

On that car, to me the powerband is perfect, and it felt fantastic. I likely wouldn't move anything around at all. It's great for street, track, you name it.

However, if I didn't have a built engine, and wasn't planning to make over 300, I'd probably get me the even smaller EFR and enjoy even more lowend thrust and snappier response (if that's even possible, lol, the 6258 already shines at both those things.....we shall see of course).

AFAIK, 99mx5 is making 375 whp and 319 tq on his 6258. Did he switch to a 6758 when I wasn't looking?

Now that I am off the pain pills and wine (not a great combo) because of a double root canal and a nasty sinus infection....My brain should work a little better!
I see I said some interesting things!
Feeling like an idiot! :facepalm:

I read 99MX5's build front to back. What a great build!
He nuked a stock block with 10PSI boost on a 6258....I didn't know that was a thing until then!!
Did some digging around and it sure is!
He is also at 4000 feet...I wonder about the correction factors?
A quick read of the compressor map says the 6258 is good for 43ish pounds of air which kind of surprised me!

If you look at 18PSI's build and its boost table, you can see that he is all the way down to 16 or 17 psi at the HP peak.
IIRC that is 8 pounds down from 99MX5s. There is a fair bit more left on tap and the bottom end/mid range would be a different level.

More boost 18PSI!!
Let her rip! You know you want to! :)