Things I discovered about ethanol and NA engines.
07-10-2015, 01:53 AM
#1
Things I discovered about ethanol and NA engines.
I'm not saying this is how it should work, I'm just saying this is what HAS worked for me. Think about that before condemning me as a fool. I'm mainly putting this info here for when I go into a coma for six months after having an aneurysm over something an idiot on Facebook says, and my amnesia causes me to forget everything I knew about tuning. But the second reason is for anyone out there who is curious about figuring out how far you can push your L61. I really wish more people would build NA motors, but that's just my underdog syndrome talking.
Thing #1: Stock injectors probably can't handle E47 at sea level. I'm at ~4000ft elevation now and my injector duty cycle is 80%. With gasoline, my fully bolted L61 ran 66% IDC at ~4000ft and roughly 6700rpm, but when I moved to North Dakota for a winter I logged 80% IDC at only 6000rpm. Even E47 would be an unbearable load on stock injectors. I get away with it now because I never travel far from my ethanol station. LSJ injectors are a minimum for anyone at a lower elevation.
Thing #2: Fuel transients get very weird with ethanol. Fuel transients are basically a set of complex BS factors in my tune that determine how much fuel is hitting/evaporating from/etc... the walls of the cylinder head. Basically, AFR(Air to Fuel Ratio) shoots waaaay rich when you press the pedal down at all and AFR shoots waaaaay lean when you let off the throttle. My stupid ****ing computer is not trustworthy so I can't tune these away until I get a new one.
Thing #3: Just because you can add timing doesn't mean you should. I could have up to 32* of timing at full throttle with zero KR. Thing is, the car was noticeably slower, especially in the mid-range rpm. There is a table in your tune which gives you the calculated maximum brake torque timing. Using these values has resulted in the best seat-of-the-pants feel to me, especially when compared to using as much spark as you could get away with. This is something you could probably never discover on a boosted Cobalt anyway. Most tunes I've seen don't go anywhere near that timing.
Thing #4: Idle quality sucks until you discover the Base Dwell table. I fought for months with a shitty idle when I swapped to E47. The AFR would surge all over the damn place, and so would the RPMs. I used to have a video, but again my computer is an *******. That is, until I decided one day to try increasing the base dwell table in the 11V-15V range. I increased it by 25-30%, being careful not to exceed 6ms, which is what I read somewhere on HPT was the maximum you could run these coils on and still have them last 200k miles. The biggest values were in the idle areas, which is also where I came comfortably close to 6ms. No, this will not give you a power boost, but oh hell yes the car idles so smoothly now!
Thing #5: Ethanol isn't a huge boost in peak HP while NA, but the lower RPMs feel soooo much better. This is really dependent on your tune, but the dip in power at low RPMs is really noticeable with gasoline. E47 is way less noticeable. It doesn't disappear entirely, but there is a night and day difference between gas and ethanol when it comes to lower RPMs. A lot of this is timing. I can't touch the timing values I use with Ethanol when I am forced to run gasoline, unless I want bad KR. Gasoline just doesn't like the lower RPM I suppose. Or maybe my car sucks lol.
That's all for now! I'm getting some ZZP cams from 07blackg5 very soon and I have every intention of running them NA at different timing to see if the car gains or loses power. Having two cams makes this feasible. I'd never get away with that **** in a single-cam car like my SBCs I'm used to.
Thing #1: Stock injectors probably can't handle E47 at sea level. I'm at ~4000ft elevation now and my injector duty cycle is 80%. With gasoline, my fully bolted L61 ran 66% IDC at ~4000ft and roughly 6700rpm, but when I moved to North Dakota for a winter I logged 80% IDC at only 6000rpm. Even E47 would be an unbearable load on stock injectors. I get away with it now because I never travel far from my ethanol station. LSJ injectors are a minimum for anyone at a lower elevation.
Thing #2: Fuel transients get very weird with ethanol. Fuel transients are basically a set of complex BS factors in my tune that determine how much fuel is hitting/evaporating from/etc... the walls of the cylinder head. Basically, AFR(Air to Fuel Ratio) shoots waaaay rich when you press the pedal down at all and AFR shoots waaaaay lean when you let off the throttle. My stupid ****ing computer is not trustworthy so I can't tune these away until I get a new one.
Thing #3: Just because you can add timing doesn't mean you should. I could have up to 32* of timing at full throttle with zero KR. Thing is, the car was noticeably slower, especially in the mid-range rpm. There is a table in your tune which gives you the calculated maximum brake torque timing. Using these values has resulted in the best seat-of-the-pants feel to me, especially when compared to using as much spark as you could get away with. This is something you could probably never discover on a boosted Cobalt anyway. Most tunes I've seen don't go anywhere near that timing.
Thing #4: Idle quality sucks until you discover the Base Dwell table. I fought for months with a shitty idle when I swapped to E47. The AFR would surge all over the damn place, and so would the RPMs. I used to have a video, but again my computer is an *******. That is, until I decided one day to try increasing the base dwell table in the 11V-15V range. I increased it by 25-30%, being careful not to exceed 6ms, which is what I read somewhere on HPT was the maximum you could run these coils on and still have them last 200k miles. The biggest values were in the idle areas, which is also where I came comfortably close to 6ms. No, this will not give you a power boost, but oh hell yes the car idles so smoothly now!
Thing #5: Ethanol isn't a huge boost in peak HP while NA, but the lower RPMs feel soooo much better. This is really dependent on your tune, but the dip in power at low RPMs is really noticeable with gasoline. E47 is way less noticeable. It doesn't disappear entirely, but there is a night and day difference between gas and ethanol when it comes to lower RPMs. A lot of this is timing. I can't touch the timing values I use with Ethanol when I am forced to run gasoline, unless I want bad KR. Gasoline just doesn't like the lower RPM I suppose. Or maybe my car sucks lol.
That's all for now! I'm getting some ZZP cams from 07blackg5 very soon and I have every intention of running them NA at different timing to see if the car gains or loses power. Having two cams makes this feasible. I'd never get away with that **** in a single-cam car like my SBCs I'm used to.
07-10-2015, 02:21 AM
#3
Tuning E47 for an LNF has been done many times so I'm sure it'd be moderately easy to find what you need. Building L61s is something almost nobody does. I'm told the E69 doesn't have a stoich setting so you have to add airflow to the MAF tables? I don't own one so I don't know. I know those ECMs don't have transient fuel or dwell settings which sucks. Search the HPTuners forums. Especially the LNF bible thread.
Moderator
07-10-2015, 07:18 AM
#6
Senior Member
iTrader: (6)
Things I discovered about ethanol and NA engines.
The E69 has lambda not stoich, so it doesn't care what fuel it will keep adding to get to lambda of 1.0. Not saying you can just go fill up with e85 or blend e47 and be fine. The car will run like crap till your ltft level near 15 or 30% depending on the fuel.
The mbt has been worked on and discovered with the LNF and I'm pretty sure the LSJ also. The best way to determine is with a dyno obviously.
The mbt has been worked on and discovered with the LNF and I'm pretty sure the LSJ also. The best way to determine is with a dyno obviously.
07-10-2015, 04:33 PM
#9
I added 20cc to the intake ports with a simple air rotary grinder, and 15cc to the exhaust ports.
The E69 has lambda not stoich, so it doesn't care what fuel it will keep adding to get to lambda of 1.0. Not saying you can just go fill up with e85 or blend e47 and be fine. The car will run like crap till your ltft level near 15 or 30% depending on the fuel.
The mbt has been worked on and discovered with the LNF and I'm pretty sure the LSJ also. The best way to determine is with a dyno obviously.
The mbt has been worked on and discovered with the LNF and I'm pretty sure the LSJ also. The best way to determine is with a dyno obviously.
The forum is always calm lol. I just worked late last night. I'm going to do a cam comparison as soon as I get home tonight.
07-10-2015, 06:58 PM
#10
Senior Member
iTrader: (6)
At some point I'm going to rent a mustang dyno for a day and run through the mbt on my car, and probably test a few intakes while I'm at it for ***** and giggles
07-10-2015, 10:20 PM
#11
Lol, i work overnights.
" There is a table in your tune which gives you the calculated maximum brake torque timing"
Could you explain this, maybe post a picture?
My buddys eco cav would peak at around 23* on the stock tune and 87 with no kr but it was always below freezing outside.
" There is a table in your tune which gives you the calculated maximum brake torque timing"
Could you explain this, maybe post a picture?
My buddys eco cav would peak at around 23* on the stock tune and 87 with no kr but it was always below freezing outside.
07-10-2015, 10:52 PM
#12
Lol, i work overnights.
" There is a table in your tune which gives you the calculated maximum brake torque timing"
Could you explain this, maybe post a picture?
My buddys eco cav would peak at around 23* on the stock tune and 87 with no kr but it was always below freezing outside.
" There is a table in your tune which gives you the calculated maximum brake torque timing"
Could you explain this, maybe post a picture?
My buddys eco cav would peak at around 23* on the stock tune and 87 with no kr but it was always below freezing outside.
07-11-2015, 12:23 AM
#15
Yeah i went into hptuners and poked around a bit and checked that out.
Im kinda excited i found a selection to disable clutch safety and i think that puts me one step closer to running an 08 file on my 07 car without adding the clutch position sensor.
Im kinda excited i found a selection to disable clutch safety and i think that puts me one step closer to running an 08 file on my 07 car without adding the clutch position sensor.
Thread
Thread Starter
Forum
Replies
Last Post