Why don't flex fuel vehicles adjust timing?

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Why don't FF vehicles adjust timing automatically to provide more power on E85? It's basic enough knowledge that E85 is higher octane (100+) and therefore it seems like it's just some simple software engineering to be able to advertise a 20% increase in horsepower when you use E85. I couldn't ever see using E85 unless it became ridiculously cheap, OR the vehicle took advantage of the power potential.
 
There's still less thermal energy per unit compared with gasoline. In my understanding, you can really benefit from it in turbocharged applications, where ignition timing is kept under strict control to prevent detonation. In this forced-induction environment, the engine can take advantage of the additional timing the E85 allows.

But with natural aspiration, I don't think there's "enough there" to work with. It could be that timing is indeed advanced...and it's just not noticed by the user because of the lower thermal energy of the fuel. Someone with a scan gauge who can switch back and forth between the two fuels could confirm that.
 
Most vehicles already do play with ignition timing quite a bit. They advance it as far as possible, then retard when there is a knock.

Like Hokiefyd said - there's not enough energy there to make the car feel that much different.
 
My understanding would be because of emissions. I took advantage of E-85 on my Tahoe and had Justin of Blackbear Performance come up with a E-85 tune. After the tune the truck got the same MPG as with Regular Unleaded. At the time E-85 was at Min $1.00 less a gallon. Truck ran awesome. Just couldn't run E-85 in the middle of winter. I would have him Tweak my new Tahoe the same way but do not have E-85 within 200 miles.
 
Probably the flex fuel vehicles do bump timing abit when they can, but that doesn't help HP all that much in a NA engine, also they are trying to preserve some mpg's so I doubt the manufacturers want to go to an all out HP tune that runs very rich for not much more HP.
Now the turbo cars could run much more boost when on E85, but most turbos are sized to avoid lag and increase low end torque, so even with ethanol, there may not be a lot of room left to increase HP much above factory.
 
We have 2 FFV's. My Impala takes a 3-4 MPG loss with E85 with no difference in performance perceived. My wife's Chrysler 200 with the 3.6L FFV engine also takes about the same loss in mpg's but there's a noticeable difference in throttle response and the car is definitely snappier to drive. E85 is close to a dollar difference here in price. The 3.6L in the 200 really struggles to start on E85 in the cold months here, and won't start cold with the factory remote at all on E85 in close to zero weather. No difference in starting with either the remote start or key on my Impala.
 
My FX4 adjusts the timing--it has to do something along these lines because the HP rating with E85 is higher according to Ford. I notice quite a bit of difference in power when towing with E85 versus E10 though, obviously, the mileage suffers.
 
Originally Posted By: horse123
Why don't FF vehicles adjust timing automatically to provide more power on E85? It's basic enough knowledge that E85 is higher octane (100+) and therefore it seems like it's just some simple software engineering to be able to advertise a 20% increase in horsepower when you use E85. I couldn't ever see using E85 unless it became ridiculously cheap, OR the vehicle took advantage of the power potential.


My 2008 Ram 1500 (4.7FF) does adjust timing on E85, there's quite a bit more overall power and (especially, since its lacking on that engine)noticeably more low-end torque.

But there are limits to how much extra power you can extract by advancing the timing- even if you had infinite octane, there comes a point where advancing the timing starts to DECREASE output very quickly. Especially with an engine that already has dual plugs and rapid combustion anyway- its not long before you get more of the combustion happening before TDC than after it, and that's not beneficial. If the engine was boosted, then the computer could increase the boost and get quite a bit more power out on E85, but its not. Are there any turbo or supercharged flex-fuel engines out there? Ecoboost Fords maybe?

FWIW, the difference in cost between E85 and E10 has to be 30 cents/gallon just to break even due to the difference in mileage on my Ram. Often that's the case and so I do occasionally use E85. But when the cost is 25 cents/gal less for E85, its a money-losing choice and I don't do it.
 
What an engine really needs to develop more power with E85 is another couple of points more compression. Straight alcohol motors run in the 14-15/1 range.
 
Originally Posted By: 4wheeldog
What an engine really needs to develop more power with E85 is another couple of points more compression. Straight alcohol motors run in the 14-15/1 range.



Which is, effectively, what PCM-regulated boost can do. When the PCM detects E85 it can start dialing up the boost appropriately.
 
My 2013 Siverado 1500 5.3L adjusted for E85. The dyno chart from GM themselves shows the 5.3L getting 10 more HP and 6 more lb torque from E85 than regular. I have not found a dyno chart on the 6.0L in my 2015 2500 that shows similar as the 5.3L.

I would agree, that NA motors are not going to appreciably show improvements in power, nor get good mpg from E85. But some of the motors I have seen that Ricardo and Cummins have developed that primarily are designed around E85 and turbocharged, are putting out some very impressive power and fuel economy numbers. Almost on par with diesel motors. Richard's EBDI 3.2L motor is kicking out the same power and equivalent fuel economy as the 6.6L Duramax diesel. Cummins' 2.8L inline 4 E85 motor is putting out similar power as the 5.7L Hemi. That motor is targeted already for putting into some commercial vans from Dodge in a couple of years.
 
Note that combustion is initiated well before TDC in almost any modern engine.

Alky is wonderful for HP but the flow must be tremendously larger than gasoline due to BTU content. Ever see the fuel pumps and lines on an Alky dragster?

Our flex fuel vehicles run well on the stuff, I like the peppy feel and better shifting due to the timing advancement. But they drink it down like CRAZY....
 
My 14 Sierra 5.3 has an inline alcohol sensor that detects alcohol content so the computer can adjust timing (and power). I loose about 2-3 MPG running E85 but when E85 was $1.00 less a gallon then E10 it was actually less per mile to run E85. The 5.3 has 11:1 compression (6.2 is 11.5:1 but is not available in flex fuel). I have a ScanGauge monitoring KR and timing and I can say that these motors are octane sensitive. On 87 the motor won't stay in V4 mode as much and I notice more partial throttle KR. 91 can help reduce this but I no completely. With E85 I have little to no KR.

Horsepower:
355 @ 5600 (gas)
380 @ 5600 (E85)

Torque (lb-ft @ rpm):
383 @ 4100 (gas)
416 @ 4100 (E85)

http://gmauthority.com/blog/gm/gm-engines/l83/#tab-2
 
Short answer: They do. That's why many manufacturers list HP ratings for both gasoline and E85 with the E85 numbers being higher.
 
Originally Posted By: 4wheeldog
What an engine really needs to develop more power with E85 is another couple of points more compression. Straight alcohol motors run in the 14-15/1 range.
They don't get great mpg , though. They use alcohol in part for the cooling effect when it turns to vapor.
 
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Really? The 3.2L EBDI motor developed by Ricardo ( a GM partner ) runs primarily on E85 and puts out similar HP and torque of the 6.6L Dmax diesel and get comparable mpg. Peak torque at 2000 RPM. When the motor is specifically designed with E85 as the focus, it is amazing what can be done.

Cummins did basically the same thing with their 2.8L inline 4 designed with E85 in mind. Similar power and torque of the 5.7L Hemi and better mpg to boot. And gets peak torque at 2100 RPM. That motor is targeted for some commercial vans.
 
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