Timing vs knock for E85/boost

[FastCarFanBoy]

what is ballpark timing on a E85/10psi setup at 0 knock? I'm seeing 18@0 and up to 21.5@-3 ... does that seem right or a little conservative?

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[SolarFlare]

I figured commanded would be 20-21

 

[MyLilPony]

at 13# and 7700rpm i am at 21* and -3 knock...

 

[beefcake]

that will depend on your tuner as far as what they have it set at usually 20-21ish

 

[BadGTR]

Factor in actual ethanol content too. Everyone calls for e85, but allot of pumps never hit e85. E70ish is the norm and will have less timing threshold vs knock then actual e85.

 

[MyLilPony]

Factor in actual ethanol content too. Everyone calls for e85, but allot of pumps never hit e85. E70ish is the norm and will have less timing threshold vs knock then actual e85.

This ^

I always test before I fill. I have one station that always tests 85% but it takes 2 gallons of gas to get there and back. The one next to my house tests at 80%.

 

[FastCarFanBoy]

so 21 all in is about right, thx for the replies.

 

[Burkey]

Can someone please explain to me why so little extra advance from the ethanol?
As in, if I’m seeing 19 degrees @ 12psi on ~92 octane, 21 @ 10psi appears to make e85 almost pointless other than the safety margin it provides.
What am I missing here?

 

[BadGTR]

Can someone please explain to me why so little extra advance from the ethanol?
As in, if I’m seeing 19 degrees @ 12psi on ~92 octane, 21 @ 10psi appears to make e85 almost pointless other than the safety margin it provides.
What am I missing here?

19 degrees on Super at 12psi is rather aggressive. And with true e85, I would think 24 degrees on 12#s would be within safe margins. On my other twin turbo car, I run 32#s of boost with 24 degrees timing on e85. Although it is only 9.5 compression.

 

[kcc0521]

The negative number is usually it adding timing. Your base table must be like 15 and it is adding 3 degrees. I am on a Paxton with 3.48 pulley and I see 21-23. You should be 21 bare minimum.

 

[JennyStang]

I got 17.5 on 93 until I hit about 5.5k rpm then it jumps to 19 at 6k then 20 at 6.5k and maxes at 21 at 7k till 8k redline with zero knock

I’d be pissed to only see 21 on e85. You sure it don’t go higher than 21 closer to redline?

 

[FastCarFanBoy]

I would upload a log if I could figure out how, but I don't see over 20deg until 6700 in 3rd gear.

I know it hits the limiter on the 1-2 and closes throttle...that has been addressed in the last revision so disregard that.

 

[JennyStang]

I would upload a log if I could figure out how, but I don't see over 20deg until 6700 in 3rd gear.

I know it hits the limiter on the 1-2 and closes throttle...that has been addressed in the last revision so disregard that.

That looks like a log with max timing for 93 and not e85

 

[markmurfie]

You are running like 7-8% rich, I'd test your E85 make sure you are not getting much less than what it was set for. If your tuner is thinking its E85 and you are actually getting e70 or less, this can raise your load, artificially, putting you at a lower borderline base value. Knock sensors will look happy and add in all the timing, but you will still be short cause it starts at a lower value. at 10 psi You should see like 1.6-1.7 load and possibly get to 22-24*, but with the timing in there from the start, starting at 19*, not be capped at 21 and have it adding in really slow like you are running 15-16PSI aka 1.9-2.0 load.

 

[Tommy V]

I am.at 14 to 15 psi,and see 22 degrees of timing.Boost may be down.a little more now that i switched from cat deletes to long tubes.

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