I looked at a variety of sites and only one mentioned timing without giving details of the engine.
What factors affect total timing you can gain using E85?
I looked at a variety of sites and only one mentioned timing without giving details of the engine.
What factors affect total timing you can gain using E85?
GRM to the rescue again!
in that article is this chart (this is a miata engine):
Admittedly, this doesn't go into much detail about where in the RPM range the timing was changed, but the point is that the timing didn't change much with e85.
I'd think if you're setting timing by twisting a dizzy, starting with a gasoline optimal setting would be good enough to start and drive, and then tune it for max power just like you would for gas.
Everything about the engine? Head design, flow, cams, etc.
On the BRZ, when I ran E85 and watched the logs on the OFT, BTDC would spike to around 50° on throttle tip in.
They should really redo that test with a modern engine. For example, the Twins have enough fuel capacity stock to even run methanol. And E85 only uses about 30% more fuel in that engine vs 63%
I like everything about methanol except that it wants to poison you in several different ways. Won't go there.
In general spark timing is affected by fuel burn rate and knock resistance.
While most modern engines have some kind of sensor to detect knock and just ignition timing to compensate they're designed to produce peak cylinder pressure slightly after TDC without knock. As a result when you change fuels ignition timing changes are only required to adjust for the burn rate and in terms of ignition timing they're not big changes.
When we increase compression, add boost or change cam timing to increase cylinder pressure then we can create engines where we need to retard timing moving peaks cylinder pressure later into the power stroke to avoid knock. In those cases you can see big changes in ignition timing with a switch to a more knock resistant fuel.
In other words if the engine isn't knock limited on gasoline you're not going to see a big change in ignition timing or power by switching to E85. You'll just get worse fuel mileage and a better smelling exhaust.
kb58 said:I like everything about methanol except that it wants to poison you in several different ways. Won't go there.
What about Hydrazine? takes a stock 90hp flathead ford to 300 hp with no other changes...
https://www.dragzine.com/news/flashback-friday-the-story-of-the-leathal-fuel-called-hydrazine/
The timing is remarkably similar to gasoline. It takes longer to get the fire going, but it burns more quickly, so the two mostly balance out.
The next question is, if your engine is knock limited for timing on pump gasoline. If you have to retard from best torque to stay out of detonation, then you should be able to advance up to the point of best torque. If you are not knock limited, then you won't really see any gains from advancing timing.
This is one of those "how long is a piece of string" situations. I will allow that on a turbo engine, an E85 timing map and a C16 timing map look a lot alike.
You all realize I'm talking about a V12. But the timing of them varies dramatically.
The first version ( carbs or EFI )
Compression ratio 7.8-1 timing 38
81-92 was 11.5-1 Timing 17
93-97 was 10.5 Timing 18
the bore on all of them was 3&1/2"
the stroke on all of the 5.3 liter was 2.75
The stroke on all of the 6.0 liter was 3.00
Since the octane of E85 is around 105 octane.
my thinking is + 5 degrees ? The V12 never had a knock sensor
With 71-92 I'm twisting the distributor around so it's easy peasy. But with the 6.0 ( 1993-1997 ) I'll have to move the crank sensor. ( even though the 96&97 had OBD2 it's not reprogramable.
Robbie (Forum Supporter) said:kb58 said:I like everything about methanol except that it wants to poison you in several different ways. Won't go there.
What about Hydrazine? takes a stock 90hp flathead ford to 300 hp with no other changes...
https://www.dragzine.com/news/flashback-friday-the-story-of-the-leathal-fuel-called-hydrazine/
Isn't hydrazine used in something like Meth production so it's wickedly controlled?
frenchyd said:Isn't hydrazine used in something like Meth production so it's wickedly controlled?
Not AFAIK. It's just wickedly toxic and half of a common hypergolic rocket fuel mix (along with dinitrogen tetroxide, which is even more toxic).
In reply to codrus (Forum Supporter) :
That sounds interesting. Would an engine be able to live with a tank full of that or is it one shot on the dyno and then start sweeping up parts?
frenchyd said:In reply to codrus (Forum Supporter) :
That sounds interesting. Would an engine be able to live with a tank full of that or is it one shot on the dyno and then start sweeping up parts?
Engine is fine. But the condensation that collects in the carb is highly unstable. Tap the carb body with a wrench and the condensation inside causes it to explode. Also apparently after a run there is enough left over in the oil that when you start the motor next time the crank slaps the surface of the oil and puts your crank on the ground.
I think for drag racing they put "mechanics" at the end of the braking zone to drain the unspent fuel right out onto the ground ASAP without even shutting off the motor. Then change oil and clean everything really well before you start it again.
Dont get it on your hootus.
In reply to Robbie (Forum Supporter) :
Well since I'm a road racer. Not a drag racer it doesn't sound even the least bit reasonable.
Considering all the guys I knew who died early messing with methanol and this stuff is worse, I'll forget about it.
In reply to Robbie (Forum Supporter) :
Nitromethane is the same way, it can get explodey if you don't perform the correct rituals.
Like changing the oil before you try to start the engine.
I remember watching a neighbor try to get his old Offy in the field. He pulled the bypass jet from the Hilborn and put a smaller one in. Then dumped about a quart of nitro in the tank and lined up the car for the push off.
Definitely had a meaner bark to it and it got him second in the consolation race. Which got him in the field.
I suspect he had a few gallons of nitro in the 55 gallon tank it had for the main because he wound up almost taking 1 st but ran out of fuel just in front of the. Checked flag. Wasn't any fuel to check. Tsssk tssk.
Nitro is easier to deal with on efi. Idling at stoich and everything. Still exciting on the pedal.
That being said, wot timing for na is very similar to 93/94 octane unless the engine is knock limited. If it is, more timing until you find timing for peak tq.
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