i have loved, and used, alcohol for our magnificent turbo rotaries since 2003. from 2003 til 2013 i used methanol (no water) as AI. worked well for me. there really wasn't an E85 option for most of that time. i changed my base fuel to E85 primarily to run the Texas Mile in 2013. we did a dyno run to 205 mph a few days before making the trip. i felt that after the first quarter mile you shifted into 5th and were pedal to the metal for another 17 seconds.

alcohol please.

after losing a fuel pump fuse on the second run i had collapsed corner seal springs and upon taking my motor apart wasn't happy w the wear and the tar. so i switched back to pump and meth/AI and haven't yet gotten back to the Texas Mile.

i also have taken 5 of the motors i have built for customers apart that were run on E85. none were broken, we were just installing stud kits...
I didn't like the wear or the tar... diff tuners, dif premixes, diff apex seals.

so why did i order a flex fuel sensor today?

i recently acquired a Link G4X Extreme and it has greatly extended my capabilities. probably to get into trouble. i recently moved from Wisconsin (altitude 600 ft) to the mountains of NE Georgia (altitude 2200 ft). i am getting just a small amount of detonation. since it is a new ECU it is hard to say if it is meaningful . i do run, and have since 2013, two RX8 knock sensors. my new ECU allows me to input exactly what the knock cps is for my motor... 3500hz. previously i was stuck with 4000 to 6000hz. it worked fine and i got used to the variations but currently, who knows... also i am now generating knock data at 16 readings per second versus 6.

during the intervening years lots has been written and experienced w ethanol... most know that you get diminished additional benefit past 40% (by volume). this is an interesting consideration to me as less % ethanol, less internal issues.

Strokercharged has done very well around 30/40%. (as i am sure have others).

now that i have really amazing instrumentation i am going a slightly different route. i am going to start at 20% E and see what happens to my detonation. i will raise E content until i am back to 5 to 10 readings instead of the current spike high of 45. all this shouldn't take very long as my sensor will show this week. i am going to splice it into the return line back by the gas tank.

it is pretty neat not to have the car put away 6 months a year. now if i could only find a straight road... there are none around here.

 

Have you read this?: https://www.researchgate.net/publica...asoline_Blends

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i am aware, and have read numerous studies, re varied amounts of alcohol/gas. bottom line is that alcohol benefits do reach a point where the benefit does not line up w the additional amount. that point is going to vary w each of us. i just want to find where that point is for my needs. i do have really good instrumentation and want to run as little alcohol in my base fuel as possible.

 

There's almost zero that I can contribute to this topic but I certainly do enjoy reading your exploits, so thanks for sharing!

 

Howard, Thanks for continuing to document, helps everyone.

Please clarify for me. Are you going to start with E20% as your base fuel source and ditch your A/I for now? Or are you still planning to run pump gas and E20 as your AI?

 

Making power is the easy part.

Getting the car to start and idle smoothly and consistently when it's below freezing and with varying ethanol blends (like you find at a normal E85 pump), that's the hard part.

 

"Are you going to start with E20% as your base fuel source and ditch your A/I for now?"

i am going to leave everything as is with the AI on to get apples to apples. i am starting at a total of 20% E and will raise it depending on the data. i may at some point turn off the AI out of curiosity. i am not in love w alcohol as a (partial) base fuel but want to get my knock down to close to zero.

 

idling smoothly is not hard, cold starting on ethanol is a bit difficult. I have mine to the point where it will no throttle start cold but will usually die a couple of times before it will stay running. hot starting is no problem

 

I know about those studies, but have always questioned that when it comes to very high performance/racing. Regardless of MON/RON it’s hard for me to accept that there aren’t additional benefits coming from the additional alcohol such as charge cooling etc. When was the last time you ever heard of a professional motorsport organization lowering E85 to something else? Like never ... and don’t forget that Mazda ran E85 in the 3-rotor Furai as well. The only thing I’m saying is to possibly not be so quick to think there aren’t other factors in play. Those studies don’t necessarily account for all situations, but are often taken as black&white by the average layperson rather than the gray that they usually are.

I’m a bit surprised to hear you’re using the Renesis knock sensors. Everything I’ve ever seen or heard about them is that the only thing they’re “good” for is detecting noise and reducing performance unnecessarily.
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"Renesis knock sensors"

as far as i am concerned they are the only thing good on the Renesis engine. good because they are the new style Bosch knock sensor and good because they are tuned to the 2 rotor block resonance.

they have worked superbly for me since 2013.

 

looking forward to your results Howard.

 

Howard- Any updates?

 

i've always been curious as to whether ceramic seals with e85 would prevent the wear from occurring, and less risk running ceramics

 

i have made lots of runs at an 80/20 ratio... gasoline 80%, ethanol 20%. knock seems to be pretty much similar to just running 93 pump. generalizing a bit on proportions as i am assuming pump is 90/10 (which it isn't but close) and the E85 i mixed in is 85% E (which it isn't but close).. my Flex Fuel sensor reads 20%.

prior to upping the E (which i will at some point) i decided to add water to my 100% meth AI. 60 meth, 40 water by volume.

i am currently running an M15 nozzle which flows 945 cc/min at 100 psi. i log AI system pressure which is 150 psi. minus boost at 16... net 134... so 1.058 X 945 = 1000 CC

600 CC Meth
400 CC Water

while i have done only two runs with the water add, it appears to have lowered knock readings. while i have run 100% meth AI since 2003, as it was recommended to me by Jose Le Duc, i never mixed water as i never had knock. it is generally accepted that water works primarily in the combustion chamber and it certainly appears so.

 

Appreciate the updates.

 

All I can tell you is that they’re known to reduce power on a Renesis that otherwise is not actually detonating and are either turned off, unbolted, or removed by people in the know.

so the question is, what have you done to verify whether they’re actually detecting knock or noise?

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This is true, and only gets tougher as the size of the porting increases. On my semi peripheral port I was able to achieve easy consistent starts with ~E70 using a set of ID2000 primaries. The drive by wire throttle body having a much larger range range of control than the factory ISC helped ALOT with overall idle stability across a wide temperature range and the CDI ignition probably didn't hurt either on the really cold starts. If it was REALLY cold down below freezing, you could always toggle the pumps on for a few minutes before starting and allow the fuel to circulate and build up a little heat before first firing if you really needed to do so.

Skeese

 

i continue to be busy with my car, and while i am not "there" yet i thought it would be good to check in.

given the ability of our motors to flow huge amounts of air and make commensurate power there are a bunch of metrics that need to be measured. while i have been focused on my knock readings both IAT and EGTs also have my attention.

after throwing almost everything at my motor to change my knock readings i am pretty sure that i am just dealing with a different scaling as a result of changing ECUs. and the Link guys support this. in order to change readings i have used different gas vendors... Shell, Exxon and Mobil. i have added Boostane. i have added ethanol... 20%, 37% and now 49%. i have cut the timing in half. i removed my hood and using a 45 degree 4 inch tube had my air filter in genuine 80 degree air. i flipped my AI around from approx 1000 CC of meth to 1000 CC of 60M/40 water. more recently i am 2000 CC of Meth and loving it again.

all that and no change in knock readings.

further, i am at the same vacuum after over 75 pulls. i am currently running just over 20 psi w my EFR 9180 and the car is a rocket ship.

during this same period of time i have evaluated three intercoolers and have a fourth arriving Aug 3. i have meticulous records as to pressure and temp into and out of the IC. i have learned a bunch of things and i am nowhere near the end of my efforts.

on the near horizon is a nitrous spray system on the IC.

i will be adding a new Tremec Magnum F 6 speed as my current T56 has a .50 6th gear and i am planning to shift into 6th in October at the Tex Mile.

once i get tuned out at 49% E i will get back to the thread w some conclusions.

 

An amazing effort. Thank you for continuing to share your results. Curious, what are the knock readings that you're getting on the Link?

 

knock is as much as 65-70 but generally around 40-45. the V88 was 20-30. real knock on the V88 was as much as 350. the max knock reading on my Link G4X Extreme is set at 1000. Link says the knock system is way diff than my V88.

i do believe there is something going on as there are no knock numbers driving around and there is always a rise into boost with rpm. that said, given my fueling, etc it is almost impossible to be having serious knock. perhaps the system is really sensitive picking up... ?
probably past my paygrade ATM. i will be focusing on other things.

 

thank you for always sharing your thoughts and results.

so my apology for being persistently pessimistic, but I still question the ability of the RX8 knock sensors to accurately distinguish between knock and other noise. Because basically what you just posted matches the generally accepted RX8 experience with them.

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"RX8 knock sensors to accurately distinguish between knock and other noise"

i selected them in 2012 because they were the newer style Bosch sensor and Mazda chose them for a block that is very close to the 13brew. they seemed to serve me well between 2013 and 2020. if you have a better Bosch sensor idea i would be happy to give it a shot.

 

it amazes me how in one moment you can be so insightful, yet in another can be so blind to your own assumptions …

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Well I know you sent me a pm, but let me just address it here. Admittedly that’s a bit snarky of a reply, but honestly it wasn’t my intent to be disrespectful. I don’t even quite recollect posting it, but had just finished a banzai 2600 mile solo round trip picking up a car out of state and towing it back. So perhaps my mind wasn’t so clear at that moment.

So let’s back up and summarize some. You chose those RX8 sensors back in 2012, but the RX8 ceased production in 2011. The first RX8 rolled off the assembly line in 2003 and so that sensor design is likely older still. So coming up on what; about 20 years maybe? So it was determined a long time ago on the Renesis that the knock sensor was often inhibiting performance by pulling back timing unnecessarily; i.e. the conditions were such that no knock was, or even could have been, occurring. Now maybe it’s possible that Mazda; as a automotive engineering and manufacturing firm, didn’t get the software right. Equally, maybe they were using the sensor in a way or for a particular purpose different than your own.

So this just started off with me asking how it was actually determined that it was legitimately recording actual ignition knock and not other noise. Which is an entirely valid question to ask about any sensor. Because in this particular case of it being a knock sensor; if it’s picking up noise rather than actual ignition knock, what does that in turn mean? Well the most obvious reality is that the timing settings being determined using it our always likely to be more conservative than necessary. So you’re not blowing up engines and calling that a success, which on one hand I suppose it is, but if it’s keeping the engine back from additional timing that can be put to good use, then is it really a success? That’s the gist of what I’m getting at.

Perhaps I misinterpreted your words, but my take on your prior post is that after changing ecu’s and now seeing different readings that suggest knock is taking place, but by your own understanding of the conditions; knock isn’t possible. Which mirrors what I relayed as the Renesis experience with them. So you’ll have to forgive me because some of the things you’re saying in words don’t actually mean anything strictly from a true technical assessment of what an actual knock ping is and whether the sensor can accurately differentiate if properly from anything else it’s picking up.

A hammer ping is a hammer ping, but is it the same as an actual knock ping on a rotary engine, particularly when it’s running under load and generating other signals? When you started using the sensor, or for how long, or your perception of gathering results that matched your expectation, aren’t a true answer to the actual question. Especially considering that now with a different ecu/software the latest results aren’t matching up to the prior ones. On one hand I get how a Renesis seems so similar to a previous 13B, but it’s my belief that the rotary community as a whole is still by and large is in the dark about how different the two actually are to each other. Regardless, it’s not any validation for the sensor.

So I see this sort of thing often; just so we’re clear, from myself too, where we take data that aligns with what we were expecting that might not be a correct assessment. Because maybe we didn’t ask the right question(s), or consider all the possibilities, and maybe jumped to a false conclusion, etc. due to the results matching are expectation.

I’m not claiming you did any of that, but am only asking the question for the reasons stated. Yet I feel like I’m not really receiving an answer to the actual question about how do you really know if it accurately detects and responds solely to ignition knock on a rotary application using a highly knock resistant fuel type. More over, you seem highly resistant to even consider the possibility at all.

Maybe I’m just flat out wrong and somebody needs to slap me down with some truth. In which case I’ll hopefully learn something new. On the other hand, and again I know this from my own personal experience, as hard as it may be to have believed something for so long, and led others down the same path, the last thing to do is to compound upon it keeping on a false path rather than face and admit the truth. I’m just not sure either way.

All I’m trying to do is figure out if the sensor actually serves a productive purpose in terms of actually defining true rotary engine ignition knock, or not.
.

 

i appreciate you are asking a valid question. other than anecdotal, i have no answer.

on one hand i have higher knock readings, and they are just where they should be in relation to real knock, around peak torque. on the other, i have run timing all over the normal span, i have used a variety of fuels, spark plugs, AI, AFRs boost levels etc and there has been zero effect on the knock readings. in addition, last week i did a compression check and it is up 8% from the prior month so my engine is doing it's usual thing, breaking in and gaining compression. real knock collapses corner seal springs which should maintain a free height of .18. as corner seals collapse compression decreases. no compression decrease, no corner seal collapse, no knock.

as to the RX8 and timing being pulled, that is interesting. i am building a new block motor ATM and may do a re-visit as to knock sensors. i do think that since they worked perfectly for me w my V88 that my issue is w my new ECU. it is probably much more sensitive as to input. i would probably be smart to listen to the people who engineered my ECU. they are telling me it is a totally new knock system and not to compare absolute readings between the two ECUs. i have been blown away as to how awesome my Link G4X Extreme is in every aspect so it wouldn't surprise me as to differing knock readings.

i will be running a new block CPR motor at the Oct Texas Mile and it will be on E85. a recent Borg Warner presentation by Brian Rheinhardt at the Deal's Gap Rotary Rally included the warning that EFR turbos should not be run at EGTs any higher than 950 C which is 1742 F! something about the titanium-aluminide turbine wheel material "changing state." that didn't sound good to me. when i did 205 on the dyno, 8650 in fifth, my top egt was 1430 on E85.. so, for this event, i will be doing E85. my 2021 plan was to run race gas and meth AI but there is no way my egt would be below 1740 after 30 seconds at 575 rwhp. easy w E85.