Is the EFR6258 too much for stock engine?
 

The background: 10AE, 153k miles, was supercharged at one point in its life, was used primarily for autox before I bought it, I track it a few times year + it's my DD, and has ~210 psi in each cylinder. I've had it for almost 10k miles. It runs strong, sounds great, and the engine has never given me any mechanical problems, so now I'm looking to boost it.

I have a MS3x coming this thursday. Will obviously lrn2tune before I attempt to run a turbo. duh.

I am looking at a EFR6258 setup with ARTech all the way back, ID1000's, yada yada yada, you know which setup I'm talking about...

Am I thinking crazy? I know this little engine can handle a decent amount of power, but is this too much? I'm not looking for 300+, I'm talking 2-250 max whp here. I read threads of people putting holes in their block with this thing, but what was the real cause? Bad tune? Detonation? Too much boost?

Will this turbo be ok at the lower HP levels I'm looking to go for? Or should I be looking at a different turbo?

For specs: BorgWarner EFR 6258 Turbo - Full-Race.com

Just some clarification is what I'm looking for, any input will help.

Thanks dudes.

https://www.miataturbo.net/attachmen...ine=1409095357

For more specs on the car: https://www.miataturbo.net/meet-gree...sh-meat-77383/

The turbo is irrelevant. The stock engine can safely handle 225wtq. A low-boost EFR with a soft timing map will make less power than that, so you can safely run a 6258 on a stock engine.

Ok that makes sense. From what I gather, the EFR6258 wouldn't be overkill for my goals then?

there are no guarantees
and it will likely pop your engine because you'll likely get addicted and keep raising the torque

but yeah, what sav said

Didnt someone pop a stock engine with a 6258 on waste gate pressure? I know I was making enough on the 6758 to be pushing it into the danger zone on just a 7psi iwga and the base map timing map from TSE.

99mx5 did. at 9-10psi or so

https://www.miataturbo.net/attachmen...ine=1332733104

https://www.miataturbo.net/attachmen...d-dcp_5048-jpg

I know 99mx5 did, but what was his root cause of failure? I have been going thru his thread and it seems like he blew it up and just dove into a full out rebuild. Didn't dwell much on what happened lol.

I did see Brain comment on his timing and AFR's from his log files tho...

lol oh hey there!

I guess now that you are here, did you find out why this actually happened?

You should get the fastest spooling turbo for your power goals. If you won't be building your motor down the road, that might be a GT2554 or GT2560.

From that page...
What the hell does this mean?:

**will not shuffle in twin turbo configuration like twin garretts** C

Too much power + stock engine + heavy foot = boom!
I was around 300WHP and pushing it on the track. Rod #3 was also giving out when #2 let go.

that looks like a snapped rod.

not much guesswork there.

*edit: he beat me to it.

That's a nod to the RB26 community. The stock charge pipes suck and with larger turbos could cause a condition where turbulence from one turbo undergoes reversion and stalls the other. Since it's essentially surge, it's the same as if you had turbos that were too large and actually surged at idle.

I have no idea why these goofy brits and aussies call it shuffle but just think surge with 2 turbos.

Lol I see that, but 99 gave me what I was looking for... 300 whp on a stock motor on the track, of course it was gonna let go sooner or later!

From what I can tell, this thing starts building boost just over 2k rpm, is that not quick enough?!

And a motor build is definitely not out of the question, just not happening any time soon. *Unless I have to do a forced upgrade like 99mx5 did...

Put your turbo in, get it tuned to 6-7 PSI and start building a short block right away; It only gets more expensive if you just let it blow up when you start crancking up the boost and it granades... You may need a head as well if you wait that long...

conservative tune. keep torque under 250.

And get the light weight actuator. Which will be blow open at higher rpms by the exhaust, but that'll help you keep the power low.

or just control your boost.

Well, its hard to keep it to 10psi when you use the stock 14psi actuator.

I will have both the light and medium actuator and it has the EBC as well.

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?

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.

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.

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

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/

That is pretty interesting, but definitely a bit out of my realm at this point.

I like how people relate the spooling of the EFR to magic lol

Arthur C Clarke's third law: Any sufficiently advanced technology is indistinguishable from magic.

https://www.miataturbo.net/attachmen...ine=1409184207
You will need this past 10 PSI
https://www.miataturbo.net/attachmen...ine=1409184207

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.

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"

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

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.

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.

EFR6258 and GTX2863 compressor maps awfully similar:

Red is the EFR:

https://www.miataturbo.net/attachmen...1&d=1409241969

What are you basing that statement on? Have you driven a 2554?

You will if it was there. I had a 2554 then switched to a built motor with a 2560. I find myself shifting at higher RPM when puttering around town in the 2560 than the 2554. I liked the 2554 better for daily driving. The 2560 is a compromise to get more peak power. There is a definite softness to the boost response in the 2560 in the 3500-4000 RPM range which isn't there in the 2554.

There's a pleasantness to having a very wide torque band which is there in my 540i, and which the 2554 was better at than the 2560.

Yes you can see it on the dyno by plotting torque vs. time and you hold an RPM at light throttle then floor it.

And unless the same person drives the 2 turbos then the only way to compare 2 different setups is through datalogs.

I've driven both turbos. My subjective opinion is that the EFR responds better than every Garrett setup I've driven, including my old BP4W/2554R setup. I agree that the 2560R is a softer turbo, and the 2860RS is softer again (IMO that turbo is too big for a 1.6 and as large as I would ever go for a 1.8 street car, having owned a 2871R). The 6258's spool was as good or better than my 2554R setup was, and the transient response was better.

However your 2554 was on an NA 1.8, and the EFR6258, on a VVT, correct?

VVT spools > 99/00 > NA 1.8

The EFR I drove was on a BP05 and it was essentially untuned. It was still as good as my polished BP4W/2554R setup.

Do not run an EFR6258 on a stock block! Even with the "low boost" actuator set with minimal preload i was not able to keep it below 8psi. It broke a rod at the first autocross this year.

8psi = 200ft.lbs at most. If you broke a rod at 200ft.lbs, it was the tune, not the turbo.

Did you have EBC working and tuned ? I can keep 10psi on the medium boost canister w EBC (for the reccord i did not try cold weather or lower boost settings)

So far no one has been able to run EFR6258 on stock block without blowing it up :fael:

The guy who built your setup had no problem doing it :party:

Agreed, i said i was not able to keep it to 8psi...

That autox was below 45*F air temp in Maryland. First run was able to keep to 8psi, but 2nd and 3rd run were not able to keep it below 10psi. A stock engine could have probably held that power if it was in a little bit better condition. This engine already had 120k on it with 60k above 200hp from my old BEGI turbo.

The point is that EFR turbo does not belong on a stock engine...

Then your EMS4 basemap timing is more aggressive than I thought. This was on a minimally pre-loaded 7psi actuator it creeped to 10psi at peak torque and more or less on your timing and vvt maps (putting a car with electrical problems the dyno is some expensive troubleshooting), lol. I think 8psi on the 6258 or 6758 EFR is going to be worth more than 200ftlbs with a more aggressive timing map.

https://www.miataturbo.net/attachmen...ine=1371503403

We all know that EFR on stock block is on thin ice at best, why even waste time arguing about it?

Anything at all outside ideal circumstances happens, and boom.

Exactly!!!

Now who wants to build me a new block...?:facepalm::facepalm::facepalm:

200ft.lbs is based on BMEP calculations, not on a wild-ass guess. Miatas generally don't make more than ~72lbs of torque per liter per atmosphere of pressure. 8 PSIg = ~1.54bar * 1.84L * 72lb/L-ATM = 204ft.lbs. You can see where the torque levels out at ~5k before beginning to creep again, and it levels out at 195ft.lbs. That's exactly what I would expect an EFR6258 to make at ~7psi.

And thats 200ftlbs on a low reading dynapac, which would be closer to 220 on a dynojet.

Thank you for this! I've been between these exact two choices for a while.

For me personally its either, EFR$$Custom$$, or Begi S6 iron mani down the street with tial vband gtx2863, support is close by if anything goes wrong.

But dat low end EFR spooool :drool:

This thread actually had the best actual comparison data I've seen. Are there any others?

https://www.miataturbo.net/diy-turbo...cussion-79576/

And I ran a defective EFR for a month... its just a matter of time. Evan ran his setup for just 2 months on stock motor.

I'm currently sitting on a 6258 so I've had a good time following this thread.

This sums up my thinking exactly. I'm going to try my best not to do my install until there is a built motor between the frame rails. I have no doubt that someone with careful planning, experience and knowledge of how these systems work would be able to keep things "stock block" compliant, but I'm not that person. I see no reason to run a baller manifold & $$$ turbo that'll do 44lbs/min at something silly like 5~6psi to preserve the stock block.

If all you want is 200/200 and epic spool, go buy a FMII & 2554.

And that's the way it looks like it's gonna go... the kit was sold to another member who pm'd the seller before I did... but for $2500, that woulda been one hell of a setup.

But you are right, no sense in attempting to tame that beast for the sake of a stock block...(and probably failing at that, too.)

It is kinda lame that the FMII kit is gonna cost me more tho, that's the part I don't like.