E85 vs. CA18DET

[BeerBringer]

Bumping this thread!

I have done alot of reading and what I have gathered is that E85 is tricky to map. Knock is suppose to be very hard to hear and when E85 does knock it knocks very badly. Some Swedish tuners destroyed engines with knock before they realised this (using dyno looking for MBT). They used there usual method of hose and head gear to listen for knock but that was no good on E85.

This does not mean the CA18DET is knock limited on E85.
What are you guys opinion on the mather. Is it "safe" to just look for MBT on the CA18 with E85?
It's been a while, any new info on logging knock with Phormula KS-4 or KnockBlock?

I'm debating what setup I'm going to run but probably a small turbo like the GT2560R + the usual stuff.

/Marcus

[PL]

Yes, that's what I've found too. If you have good quality E85 then you will not hear knock. It's spooky! I recently did an engine on our Australian Caltex "pump E85" and it did audibly knock. First time I've seen (heard) E85 do that. I'd heard that the quality of the Caltex pump E85 is questionable, so there's your proof.

I'll send you a link to something that Trent sent me some time ago regarding knock vs pre-ignition. You'll find that knock is generally not an issue with E85 but pre-ignition could still ruin your day. Here's the relevant part of the rather large read:

"Remember, the spark plug ignites the mixture and a sharp pressure spike occurs after that, when the detonation occurs. That's what you hear. With pre-ignition, the ignition of the charge happens far ahead of the spark plug firing, in my example, very, very far ahead of it when the compression stroke just starts. There is no very rapid pressure spike like with detonation. Instead, it is a tremendous amount of pressure which is present for a very long dwell time, i.e., the entire compression stroke. That's what puts such large loads on the parts. There is no sharp pressure spike to resonate the block and the head to cause any noise. So you never hear it, the engine just blows up! That's why pre-ignition is so insidious. It is hardly detectable before it occurs. When it occurs you only know about it after the fact. It causes a catastrophic failure very quickly because the heat and pressures are so intense."

Here's the link to the whole thing :

http://www.skylinesaustralia.com/forums ... -in-knock/

I've always tuned E85 using the MBT method and this has served me well. The problem is fuel consistency. If you tune on a "good" tank of E85 and then the customer later fills with E85 of lesser quality then you're in trouble. I always recommend that anyone running big power engines uses E85 in drums from the race fuel suppliers to provide better consistency.


PL

[Vetal]

Guys what timing are you running at 6000-7000rpm on CA with E85? After reading the thread my 21deg started to look low Also it's not far from what I ran on 98 gas.
Also what is your timing curve at WOT 1000-2000 rpm, when there is no boost (or very little of it)?

[RomChip200]

Here are my timings maps for E85:

200SX S13 CA18DET 440cc 1bar RB20DET MAF:

CA18DET_E85_440cc_timing.jpg

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300ZX Z32 VG30DETT 740cc 15.5psi OEM MAF:

Z32_E85_740cc_timing.jpg

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[Vetal]

I'm interested in WOT timing curve in lower half of the rev range... Maybe you can post some logs?

[RomChip200]

I've just never been able to detect knock with my little microphone setup. And I've tried.

I was experimenting with an SR20 one night - I had a very experienced tuner with me and we were adding timing purely to see where knock would occur. We got to 35 degrees on full boost and just looked at each other in amazement. There was no knock. I'd be impressed if any electronic form of knock monitoring would pick it up.

So we went back to only adding timing until torque stops increasing. Which I must admit does seem to vary a lot. Average seems to be 5 to 10 degrees on top of what you'd run with 98.

PL

That's strange, on my 300zx, the piezo OEM det sensor still detects some knock in some area in the case of E85 (blue area in the map above), typically when the load is high at very low RPM (throttle floored, 2000-3000rpm, boost is building) and I rely on it to work at the limit of knock ....
All 90' Nissan use the same piezo det sensor, so ....

[Vetal]

does Nistune + CA18 show knock now?

[Matt]

If the board has Rev15 then it supports knock count reporting (CA18DET is supported btw)

[RomChip200]

I'm interested in WOT timing curve in lower half of the rev range... Maybe you can post some logs?

Timing logged sticks to the values of the table displayed above, what's your backward-thinking ?

[RomChip200]

300ZX Z32 VG30DETT 740cc 15.6psi max. OEM MAF OEM turbos (rebuilt):
more agressive timing in the mid-range but E85 likes it and driveaiblity too (for E85 only !)
Knock detection area is reduced b/c OEM sensor detects false knock when rpm is about 3000 and TP 43-54 range
You get TP=78 for 15.5psi (K base=200, my auto-K is floating b/w 200 and 216)
For TP=68, AFR=12.2 (stabilized) 3200rpm
For TP>70, AFR=11.8-12 3200rpm

Z32_E85_740cc_timing2.jpg

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[Vetal]

I'm interested in WOT timing curve in lower half of the rev range... Maybe you can post some logs?

Timing logged sticks to the values of the table displayed above, what's your backward-thinking ?

Have you noticed there is more than 1 value for each value of RPM? So you cannot know what was the actual timing without knowing which load cells were used

[RomChip200]

I'm interested in WOT timing curve in lower half of the rev range... Maybe you can post some logs?

Timing logged sticks to the values of the table displayed above, what's your backward-thinking ?

Have you noticed there is more than 1 value for each value of RPM? So you cannot know what was the actual timing without knowing which load cells were used

Be smart, the timing applied is interpolated on 4 cells around TP, and rpm,
you can increment more than 1 b/w 2 rpms, everything is interpolated, it's not a problem at all.
So, take the map as it is, logs confirmed me the values applied.

[Vetal]

So, how can I know what TP did your ECU calculate for your setup for each rpm range?