You know how they say no woman in history has ever calmed down after being told to calm down? "Perhaps I misunderstood when you said if I found something I liked I should get it" has pretty much the same effect...Originally Posted by TGS
It is all funny, now
This is highly dependent on the turbo car in question. Many modern cars have excellent knock detection and can accurately and effectively reduce ignition timing advance and add fuel to reduce knock from lower quality gas. Many others don't do this as well as they're purported to.
There's also a very real difference between getting a tank of 89 and babying it to get back to 91 or 93, and getting a tank of 89 and driving it like a teenager trying to impress his buddies. I've seen a lot of nuked 2.3L Ecoboost 4 cyls in S550 Mustangs and Focus ST's from the latter, even in stock form.
For any turbocharged car these days, if the owners manual says 'best with 91 or better' then feed it that. Some turbocharged engines really are tuned to just be happy with 87 or 89, typically in things like trucks or SUV's. But let the owners manual tell you as such, don't make assumptions.
On anything older than about 2008 or so, if it's got a turbocharger it should get 91 octane at the bare minimum. No exceptions. If there's an emergency then fill with the best available but drive it like you're a grandmother in a school zone.
I looked into the Ecoboost Mustang awhile back. Would not modify one even with just a tuner without building an all new motor. There are classic mechanical engineering detail design issues associated with the points where the blocks fail and the headifold creates its own issues when you add a lot of heat.
I'd like to see something like a 2.5L block, Ecoboost 2.3L crank, and maybe the Focus 2.0 GDI (non-turbo) head for its individual exhaust ports. Basically, a whole different engine.
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Not another dime.
Just curious, but if one were to get multiple tunes to a car to have on hand to reflash an ECU depending on fuel shortages/availability.....
....roughly how much horsepower and torque would I look at losing on an 87 tune if the factory 93 mapping gives me 300hp on a 2.0 4-cyl?
"Are you ready? Okay. Let's roll."- Last words of Todd Beamer
Yep, though you can stave off the headifold issues by going a bit larger on the turbine housing along with a bigger downpipe and high flow cat mounted further away from the turbo. Plus avoiding excessively low ignition timing advance, nice fat rich A:F's under load, all the usual stuff involved in reducing EGT's really.
For the 2.3L in general, they did make some good improvements with the Focus RS and later S550s but ARP head studs are still basically an essential modification for any tuning work, and there's some very real and relatively low thresholds where expensive stuff starts breaking at ~380-425whp.
I'd agree 100% your suggested engine combo being much better overall. As it is, I'd only deal with the 2.3L for the sake of a Focus RS. The S550 'Stang is just so so so good with the Coyote V8 that it's insane to get any other engine IMHO.
That'll depend on the car and how much work the tuner wants to do to preserve what HP they can.
The easiest way to do a lower octane tune is to simply reduce the boost pressure a bit and reduce peak torque in the midrange by playing with the variable cam timing to soften things up there. I dislike overly reducing ignition timing advance because that tends to ruin fuel mileage and increase EGT's so I'd rather just reduce boost pressure.
Generally speaking, an OEM tune for 93 making 300hp with a modern turbo 2.0L I'd ballpark a safe 86-87 octane tune to make ~250-260hp or so. Really the big hit on power will be in midrange torque at part throttle, just as the turbo's spooling and making things happen between 2500-4000rpm. Some engines can preserve most if not damn near all of that torque and only lose the peak HP at high RPM (e.g. turbocharged Hondas) others start detonating at peak torque very easily and you have to nerf the whole map to keep the engine alive with lower octane fuel (e.g. Subarus)
Most German makes fall somewhere in the middle as the engine control tech is usually pretty good, but tuners don't always have 'access' to play with every tuning parameter, so being limited exclusively to ignition timing and fuel mapping means you'll take a bigger hit on HP and MPG if they can't reduce the boost pressure or change VVT settings, and then you're stuck with retarding ignition timing and dumping fuel to reduce knock.
My favorite method is simply reducing boost pressure and monitoring knock count if you can datalog what the knock sensors are doing.
Based on some of the things you have imparted here, I got in the habit of running 93 in my 2016 Focus ST. I used to run 87/89 if I was looking at a highway trip, though I do think (and you mentioned before) that might go through the plugs a little quicker (first set only lasted ~39k).
In my truck, 2014 3.5-EB I have been running midgrade, would that be best? Maybe only when towing?
These days the car doesn't run enough to matter, so not so worried there. I guess in the truck it is probably more psychological, probably only costing an extra $15.
I don't understand what head studs are supposed to accomplish if the casting anneals and yields under them.
LS all the things.
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Not another dime.
For the 3.5L's of that vintage, midgrade is fine for day to day stuff.
If you're towing, especially in hot weather or with heavy loads (or both) I would step up to premium. In my experience, an aggressive schedule on spark plug replacement is always good with a turbocharged engine no matter the vintage.
I'd stick with 93 only for the ST, simply not worth the risk for the relatively small cost savings.
With those 2.3L's, particularly the early ones, the factory headbolts would stretch (or pull threads) and allow head lift long before the cylinder head itself yielded. All the tuning tricks to reduce EGT's also helps keep the head from taking too much of a heat cycle beating and annealing early.
Can confirm!
I'm sure you have more direct experience than I do. There was a lot of talk of ARP studs and stuff. But I remember watching a teardown video of an engine that had run hard and failed the head gasket. They were talking about the studs stretching, but then they showed where the washers had sunk into the aluminum. I know aluminum anneals around 500F, and the headifold can easily concentrate a lot more than that where the runners come together. I just kind of bundled it by deciding it wouldn't be worth messing with the headifold.
The other thing that was interesting was the cracks on a horizontal plane from the water jacket out through the two stud pockets. It aligns perfectly with the last thread on the stud, which is a classic stress riser failure point. Until I figured out what's up with the 2.5L block, I was thinking it might be interesting to mill the bottom of the stud pockets open and complete the threading all the way through, then use studs that would engage all the available aluminum, thus eliminating the "last thread" stress riser.
BTW, do you know if the Mustang Ecoboost intake manifold can bolt to the ports of the Focus 2.0 manifold and have everything line up? It looked like it might work, but I couldn't find anyone who had actually done it.
For the project I was contemplating, I ended up forgetting about the Ecoboost system and just organizing my thinking around a Fazda 2.5 block and head.
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Not another dime.
From 2008-2017 or so, some of ARP's head stud kits were shipping with undersized washers, which exacerbated the AL cylinder head annealing/collapse problems on many engines, not just the 2.3L.
The Toyota 7M-GTE's ARP SKU was affected by that as well. Another common problem has been engine assemblystaffmonkeys who overtorque the bejesus out of ARP head studs when assembling an engine.
As I know you know already - If 75ft-lbs is fine, 95ft-lbs isn't always mo bettah.
Correctly installed head studs when using correctly sized washers to properly distribute the clamping force make a big difference even on the headifold heads. Our biggest power 2.3L Focus ST build was ~560whp on E85. While it had clutch and powertrain problems the engine survived a ton of abuse at that HP level without incident.
So I can't speak to the Mustang intake manifold being compatible or not, it honestly never crossed our minds.
If I were getting weird with an aluminum 4 cyl it'll be a Honda K-motor. There's lots of other cool engines but none have the innate advantages or aftermarket support of the K.
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