LS3 E85 & Boost advance

[Chad1234hol]

Just out of curiosity as I am finishing up some pieces for a whipple ls3 camaro. What advance are you guys seeing for e85? Have been told 21-23 is safe. Just on my FF adder from my 93 timing of 15.5 degrees. Currently on 9.5 boost. .78 on WOT

[cc-rider]

I?ve got a 2010 Kenne Bell Camaro. So very similar. I?m pulling around 23 degrees advance on E85. Only thing I?ll add is that I lowered my compression to 9:1 on my rebuild as opposed to stock compression.

[Chad1234hol]

That sounds good. Yeah I?m still on stock CR . Have ARP head studs but not to high on boost was just curious as what others were seeing. I?m showing 21.5 degrees on wot on 9-9.5 lbs. no KR

[cc-rider]

E85 is good stuff. Amazing how much more power the extra timing can produce. I run 10 psi as well. Never see any KR. Best I?ve seen is 62% ethanol too. Would be nice to find some true 85% ethanol. But can?t seem to get it around me.

[Chad1234hol]

NKY cincy I?m seeing 74-78% at the moment. Agree it?s a night a day difference. Glad I made the switch

[07GTS]

just be careful as u prob wont ever see knock on ethanol until ur way way too far, u really need a dyno so u can see actual gains/losses to know where timing is at, with my stock LS2 compression and 14psi on ethanol mine was 16 deg timing max

[edcmat-l1]

just be careful as u prob wont ever see knock on ethanol until ur way way too far, u really need a dyno so u can see actual gains/losses to know where timing is at, with my stock LS2 compression and 14psi on ethanol mine was 16 deg timing max

This right here. People throw some crazy numbers out there for E85.

[Alvin]

A lot E85 cars will start making less power before they show knock. Or they make the exact same power +/- 3 degrees from max. A dyno is important for doing them.

[JayRolla]

Im running 12psi (3psi low because of altitude) on an LSA supercharger that's 9.1:1 compression. 24* on e50+ is where I found no gains on my draggy trying to do controlled runs of 30-100mph. Like the others said you will surpass MBT and never see any knock. I ran 29* on a 4 cylinder with 30+psi and 7.8:1 compression for many years and never had an issue or saw any detonation.

[JayRolla]

E85 is good stuff. Amazing how much more power the extra timing can produce. I run 10 psi as well. Never see any KR. Best I?ve seen is 62% ethanol too. Would be nice to find some true 85% ethanol. But can?t seem to get it around me.

You don't really need it if your able to hit MBT and not seeing detonation. Once you hit e40 the octane is pretty much maxed at 105-106RON. Anything more is giving you cooler cylinder temps since you're injecting more fuel and a loss of MPG.

[GHuggins]

60% is usually peak for any timing gains too You'll still gain a little more power on 80, but it's not much...

[cc-rider]

Interesting. That?s good info. I did not know that E50/60 is basically good to go. I guess I?ll stop my quest for finding anything higher and just be happy with the E60 I get at my local station.

[Chad1234hol]

Yeah that is what I heard also aside from here. I dropped a couple degrees from my PE advance alcohol table for a safety net until I end up getting on dyno to figure out where the power gains are minimal.

[ctsv2011]

im at 24 degrees .79 lambda on my lsa at 51% ethanol

[edcmat-l1]

im at 24 degrees .79 lambda on my lsa at 51% ethanol

Statements like that are worthless without knowing compression ratio and boost.

[kingtal0n]

Statements like that are worthless without knowing compression ratio and boost.

Boost is not a major determining factor. For example 9:1 compression and 32psi of boost with zero degrees of timing is fine on 93 octane fuel at 112*F in an 86x86 engine like a 4g63, 2jz or sr20. 500-600rwhp that dynojet.
14psi of boost in the same engine at 150*F IAT is a disaster in progress, total destruction on 93 octane even with zero degrees of timing.

While boost can give us some idea of cylinder fill that has some influence on rate, IAT is far more influential as the fuel quality goes down.

And then as fuel quality goes up, e.g. alcohol we can get away with roughly similar timing at 15 as 30psi on some engines. Again showing that boost is not a limiting.
For example a RB25 could be fine 16* at 20psi on E80, hundreds of those out there running air to air intercoolers and 108-112*F IAT
Say we install air/water and get down to 65-77*F IAT, boost drops but the wastegate detects it and the turbine demand increased wheel speed to maintain the same boost pressure.
Now massflow has increased at the same boost pressure, wheel speed is higher, power increases at the new lower IAT, and we are removing couple degrees of timing instead of adding it despite same boost and reduced IAT.

Thus, boost can go down and we remove timing. Boost can go up and we remove timing. Boost isn't the deciding factor and cylinder VE only plays part of the role in timing decision.

[ctsv2011]

Statements like that are worthless without knowing compression ratio and boost.

stock lsa so 9:0 to 1 compression boost is at 11psi
i just got done with a rebuild i opened up my ring gap to .026/.028 to not break another ringland. i believe my actual compression is lower as i only have 150 cranking compression on a fresh rebuild. trapping 123 in 1/4 so not horribly down on power but i know there is some blow by.

[kingtal0n]

stock lsa so 9:0 to 1 compression boost is at 11psi
i just got done with a rebuild i opened up my ring gap to .026/.028 to not break another ringland. i believe my actual compression is lower as i only have 150 cranking compression on a fresh rebuild. trapping 123 in 1/4 so not horribly down on power but i know there is some blow by.

Blow by increases if the PCV is not setup properly, leads to ring flutter and may stress the ring land
The most common cause of piston brittle fracture failure in OEM pistons is high IAT and EGT, uncontrollable rise in piston temperature differential. In small displacement JDM engines 2L 3L they have oil piston squirts to combat this issue for high mileage 200k reliability 15-22psi of boost pressure is common on 93 octane fuels for 20 years.
The second most common cause is wrong timing adjustments due to ignorant dyno or street tuning strategy



The setup solutions are
1. Ensure reasonable IAT I like to see no more than 112*F IAT on gasoline 2.2x output apps (2.2 or twice factory output as is without the forced induction)
2. Control Oil Temperature to +/- 10*F near the boiling point of water and maintain it less than 10-12*F from the coolant temp e.g. 212*F coolant and 220*F Oil is good.
3. Correctly setup OEM pcv system to produce pressure below atmospheric in the crankcase at all times WOT which will control piston ring behavior
4. Use minimum timing to relay minimum pressure peak values when the engine piston temperature is borderline overheating

Its not hard to do but its hard to get people to acknowledge the truth as ignorance is rampant

[GHuggins]

I don't know where you find all of this info, but this is good info.

Don't forget what metal the rings are made out of can cause as much of a problem too. A few AM piston companies sell what I'm going to call inferior metal quality piston rings and if you don't run enough gap they'll kiss due to heat expansion and either seize in the land or pop it along with reshaping and killing compression Don't know what's different about the OE rings, but they seem to hold up better to heat.

[kingtal0n]

Yes this is the major problem of lack of experience among novices and ignorance among would be tuners. Metal expands when hot, kind of obvious but difficult to picture in the engine and what it entails when comparing ductile to brittle materials.
Factory pistons are brittle, they do not like to expand. They do not like high temperature differential (difference from top to bottom) and they do not like being heated much because it forces the materials to try and expand which breaks covalent bonds between the atoms. A forged piston will tolerate the differential and heating because the ductile materials can expand easily in the bore which requires larger piston-wall clearance and makes them somewhat unsuitable for daily drivers because of the this warming up period requirement (Must warm up and expand in the bore before the engine can be loaded without damage to the bore due to slop or slap dragging the edge of the piston up or down the bore when cold).

Factory brittle pistons for the similar reason do not like high pressure or to be 'smacked' with pressure. Knocking and high pressure (stress over area) both attempt to deform the piston which breaks covalent bonds causing the material to deteriorate, it turns to dust, forming microscopic cracks in those spots, eventually a chunk breaks off. A failed piston can still appear whole and intact, but it has cracks inside. They are tight in the bore so heating expansion can expand them enough to create stress similar to high pressure. With enough heat input the covalent bonds break due to expansion and also while contracting cooling, and bonds break due to stress exceeding failure criterion, basically this means we need to treat them carefully: low pressure, low heating, gentle pressure application. If we can do this they basically last forever 1,000,000 miles is not impossible even at high output. Because they are nice and tight when cold they can be loaded on a cold engine without damaging the bore making them ideal for daily driver applications. To keep the pressure low we use minimum timing, not Mean Best Torque or whatever the kids think MBT is these days, a performance application isn't a factory application the two should NOT be tuned the same way. To keep pressure low we use high quality fuels even racing fuels as needed. To keep pressure low we use low temperature intake air. To keep the piston cool we use low EGT and low oil temperature to promote low piston temperature. To keep piston cool it we also must balance heat throughput (power:displacement ratio) and energy removal due to heat transfer (The type of engine's coolant passage design and whether it have piston oil squirts) and heat removal due to fuel type (alcohol fuels remove more heat from the piston if the alcohol is evaporating near the piston instead of near the valve). To keep the piston cool we can use 100% distilled water injection to bring down the EGT and cylinder temperatures if needed when using gasoline style fuels such as C16 which are 'hot' fuels they don't take much temperature out of the engine materials. The key to using water injection to safety in the brittle piston is spraying liquid water into the cylinder and allowing it to evaporate inside the cylinder, not in the airflow pathways outside.

If the piston is subjected to high temps the materials expand covalent bonds break and it falls apart. If pressure is high then stress is high and same thing happens it will fracture failure criterion. Any mechanical engineer must know the criterion for failure due to pressure/area but few seem to understand the heat-chemistry related failure aspect of a brittle material because engineering curriculum rarely covers in depth analysis of chemistry concepts related to the covalent bonding structure or physical chemistry of the metal materials. I was lucky to have a background in both and put them together along with the experience of tuning hundreds of JDM engines which factory utilize boost pressure turbocharged and arrived to america with these brittle pistons intact at 250,000 miles looking brand new with great compression- showing me what is possible and giving me a chance to understand how it happens.