General Attention High Compression E85 Users-Ignition timing questions

[diambo4life]

I may have missed it but was the knock sensor replaced?

 

[Kapok6]

I may have missed it but was the knock sensor replaced?

Yes. Brand new oem. Same results so I know the old one is fine too! Ha ha.

 

[Kapok6]

Update. Dumped a bunch of fuel in it on the way to get some dog food, put afr's at like 9.5-10.0. Did a pull, got one quick blip of 2cts of knock that disappeared after 200rpm and nothing after that all the way up to 8600. Fine bi***, take more timing. Bumped up the timing to 5* around 5000 ramping up to 12* at 8600. 1 instant blip of 1ct around 5600 and NOTHING all the way up to 8600. This was with boost initially hitting 28psi coming down to about 24psi by 8600.

(I think the hotside of this turbo is a restriction with this setup).

I need to keep playing with it, but so far seems like some progress, minus possibly needing a whole new turbo setup.

 

[bastarddsm]

Wow. I'm very surprised that it responded to all that fuel. That's good to hear though.

 

[Kapok6]

Wow. I'm very surprised that it responded to all that fuel. That's good to hear though.

I PMed you the fine details but yeah, the post above is everything in a nutshell. The key is replicating theses results consistently as I only did 2 pulls.

 

[biglady112]

Wideband not reading correctly? Too far away or too close to the turbo? We had a car that would not run right. Wideband was lying to us. We were street tuning it and could not figure it out. All it took was some one to drive behind is and tell us it was dieseling out the back. Started leaning the car out and what do you know. Ran great. We have also had instances where we thought we were rich and the motor wasn't happy. Kept adding fuel and it came to life.

Getting the car to run correctly is not important. That is where having a feel for things and things like plug reading come into play.

 

[Kapok6]

I have no current reason to believe it's not reading correctly. The sensor is in the stock location, where I have put them for the last 6yrs. What I do know is I added fuel, knock all but disappeared. In regards to the other end of the spectrum, as I have seen with e85 in the past, it wants to break up if I cruise at leaner than 15, which seems to be on point per my previous experience. That being said, you may be right. I'll look into replacing the sensor soon.

 

[bastarddsm]

I kinda thought about the suggestion of the WB being off, but thought, that's way off.

Anyway you can play the numbers game and ballpark it to see if it seems right.

idc * injflow * sqrt(bfp/43.5) * .0044 * AFRgas scale = airflow (lb/min)

injflow is in cc/min, and bfp is in psi.

Run that and see if it seems about right.

 

[Kapok6]

Injector flow meaning what the injectors are rated at? 1550cc?

 

[bastarddsm]

Yep. Whatever they flow at 43.5psi.

 

[GST with PSI]

9.5-10.0 is crazy rich on E85. If you can replicate your results you should post up a log.

Throughout this whole fiasco, have you been having any ignition issues? I know you said lean cruise AFRs caused breakup, what about WOT? Any breakup recently after going super rich?

 

[Kapok6]

I was just saying in regards to the 02 readings, over the past few years with e85 I have noticed if I try to go leaner than 15 at cruise, the car(s) would want to break up a little bit, which is the same here, once I get to a little leaner than 15, same behavior, so nothing to this point has made me think anything is off with the o2 sensor, (though obviously I could be wrong).

As for breaking up going super rich, I think I heard one quick pop pop pop in the middle of the last pull I did but it was there and gone. Ima try to lean the areas where it's richer than 10 out to try to get it a little closer to 10-10.3ish. I didn't have a lot of time to tune. I was running an errand, it was getting dark and kids were going to bed soon (no they weren't in the car with me), so I just dumped a bunch of fuel in before I left, did a pull, pulled over, added timing, did another pull, got dog food, and went home. Ha ha.

Weather and time permitting i'll try to play with it some more this weekend and get some logs.

 

[Kapok6]

Yep. Whatever they flow at 43.5psi.

I don't have the flow sheet from FIC but I want to say it was pretty darn close to 1550 and within 1.5% of each other, so you equation above would look like:

78% * 1550 * sqrt(43/43.5) * 4.4 * 9.6 = airflow (lb/min)

No I am not a mathematician, so this equation makes no sense to me:

.78*1550='s 1209

1209*(43/43.5)='s 1197

1197*4.4=s' 5266

5266*9.6='s 50,557

So where am I doing this wrong?

 

[bastarddsm]

Shit, I'm sorry. Forgot flow rate is in liters. Divide by 1000. so accoridn to that your moving 50.5lbs/min. Does that seem right?

 

[Kapok6]

I was going to say, no way i'm running 50000lbs/min! That would be all the horsepowers + a million! lulz!

Does it seem "right?" Seems low to me, but i'll try to find an old log from my old 8.3 setup where I was trapping 130+ and compare. The car doesn't feel as fast as it did on my old setup...but that's just butt dyno.

I GREATLY appreciate you posting the formula for calculating lbs/min though. I have tried to find that formula for a LONG time.

I wish FP had compressor maps for their turbos available to the general public...

The turbo is rated at 59-61lbs/min, but FP claims some people have seen as high as 65lbs/min. But I also know when turbos are rated, that rating is at the ragged edge all the way to the right usually.

 

[Kapok6]

@bastarddsm

OK, this is retarded, ha ha. So I just found an old log from my 128mph pass at roughly the same boost (28psi; although on that setup, 28psi held through the whole range, whereas now it peaks at 28psi right off the bat falling to 24psi).

On that 128pass, the math works out to 45.76lbs/min.

So how does a full weight car car flowing 45.76lbs/min trap 128?

If all this math is right, I am flowing 4-5lbs/min MORE now than I was then...

 

[bastarddsm]

Just to make your head spin some more ol...

I've seen non projected plugs want 3* or more over a non projected plug on my car. The idea is that it pulls the start of the fire out of the center of the chamber, and increases the duration of heat release.

Also running a tight plug gap has the effect of retarding the timing. It slows down the flame development period, and basically shifts heat release to the right.

now if we consider knock..
knock propensity is a function of several things: induction time, heat transfer to the gases, cylinder pressure, octane ect.

So if we are slowing down the heat release, we increase induction time, and heat transfer to the gases. Meanwhile we are tying to advance timing to make up for the delayed heat release, keeping cylinder pressure high.....You can see how this is bad, and how new modern fast burn chambers can get away with a lot.

On the other side us we "pull timing" to fight knock, basically what we are doing is lowering cylinder pressure to lower the propensity of knock.

 

[bastarddsm]

@bastarddsm

OK, this is retarded, ha ha. So I just found an old log from my 128mph pass at roughly the same boost (28psi; although on that setup, 28psi held through the whole range, whereas now it peaks at 28psi right off the bat falling to 24psi).

On that 128pass, the math works out to 45.76lbs/min.

So how does a full weight car car flowing 45.76lbs/min trap 128?

If all this math is right, I am flowing 4-5lbs/min MORE now than I was then...

that does seem kinda low. I was in that area at ~122-125 mph traps.

 

[Kapok6]

When I do the math at 8200rpm in 2nd gear I wind up with running 3lbs/min more air at 3.3psi LESS.

 

[Kapok6]

Just did the math on the same two logs at 6200rpm and boost was exactly the same at 26.2psi and based on the math at that rpm point, I am flowing 3.5lbs/min MORE now than I did on the old pull at the track.

 

[Kapok6]

For any newcomers, these comparison are on the same converter, same turbo, same injectors, etc.

 

[henrysan]

I am doing the math wrong somewhere. My results using that formula are 64lb/min. Link is saying 51.5lb/min. No way im getting 64lb/min from a s256.

 

[bastarddsm]

The above only applies for E85 fuel, and assumes that you have enough fuel pressure to keep up. It is by no means exact, it's just a ball park guess.

 

[Stew Pidaso]

I am doing the math wrong somewhere. My results using that formula are 64lb/min. Link is saying 51.5lb/min. No way im getting 64lb/min from a s256.

Lets see your equation..

 

[19gsx91]

Forgive me for asking, since most of these equations are a bit over my head, but I recall in the first or second page you said the car felt much slower then it did with your old setup, now that you were able to ramp timing back in does it feel any better then it did before @Kapok6 ?