I have experienced it in almost everything I applied it to B

The targetAF is just a number more related (in my mind) to cooling capacity V's the incidence of non audible miss fires that reduce the powner noticably (either on graph or seat of the pants)..... the more I can feed into it the more I like basicaly & as a result of this obsession I have figured out that 10.80:1 seems to be the number where things come alive be it a modle 3.5cc methanol/nitromethane engine (yes I have measured the afr and data logged the performance lol) or on our semi meth/water cars or on other full meth cars. Lots of the higher end top power stuff relevant to us is run much richer again just to make it live as a result of having too high a basic compression ratio and too much power being demanded of it.

If the car has a realy high capacity igniton system some times this limit gets lowered to around 10.20:1 but you will still in most cases get a nice gain in power at 10.80:1 ......... if you look at the math your forcing more fuel into the engine and as long as you can burn it all you will make more power but its all tied in with that great variable called BSFC which is why you simply just cant keep on forcing in more and more fuel and expect a gain in power, the balance is near that rich figure I mentioned have a play and see what you experience and see the effect on EGT, but as your power goes up and igniton system startsto get taxed harded and harder you will need to step up to a CDI of some sort to get the jist of what I am saying or otherwise you get misfires and the loss of power and you wont be able to use the figures i am suggesting here.

geeI typed too much i think sorry.

 

my larger-turbined turbos should return friday sep 14 making my next session sep 22.

interesting on the afr's... we will certainly explore running a bit richer. if the larger hotside wheels free up my turbos we will be looking for lots of hp and running in the 10s does help on the risk side.

i can, and have, fired 9.0 AFRs w my ignition with no knock. i have a Jacobs FC3000 amp and a MSD 8253 coil on each of my 6725 10.5 leading plugs.

it will be interesting to see where the instrumentation leads us tuning-wise.

hc

 

while this is off my specific tune i thought it might be beneficial...

the snippets come from turbobuick's AI section which is the single most valuable AI resource IMO. all 200+ pages of threads.

http://www.turbobuick.com/forums/alc...-propane-tech/

the car is a 3600 pound turbo'd buick. eng is a 231 cu in 2 valve V6. fuel is 93 octane pump and two M10 methanol nozzles run by and Alkycontrol AI system. power steering, A-C, stock interior, totally streetcar...

making about 700 rwhp. boost in the mid 20s and 10.8 AFR.

"ok went racing at our local track today .. Russ was playin with the "tune up" and the car was coming around Melissa ran a 10.15 @ 135.57 with a soft 60' ..

stock crank cut 20/20
stock rods

as far as the "tune" .... we tune for no knock thats it ...

My guess in post #46 is probably a little low and could be as much as 150hp worth of fuel. You have to figure that most guys cant go over 125mph at 3600 lbs with a single 340 and no other pump when everything else is in check. She's going 135.5mph. It takes about 150 hp to go from 125mph to 135.5 mph at the same weight. Im figuring her engine is making a click under 700 hp. Thats kicking *** for a stock set of rods and .020 stock crank on a relatively mild build. Proves that if there is no detonation the engine will live."

all of the above on 93 octane and meth... the single reason for inclusion in my thread is the quote from the owner/tuner of the car....

"we just tune for no knock."

consider they are running stock rods and crank! you have knock w that setup and you will be gathering up your engine parts w a basket.

this speaks to what we can accomplish w AI.

also it is interesting that the 10.8 number mirrors what Rice was saying about 10.8 being the magic number.

whether it is or not, i will be following my instruments and knock will be a key item. i note that having read thru the over 200 pages of threads on the buick board that most have tuned w knock at the top of the list.

howard coleman

 

Maybe I have bad hearing but I've never heard a rotary knock and I've blown many many motors.

Are you just using your PFC to monitor knock ? I never trusted the readings my old unit gave me. I've seen some local 10.5 cars get tuned locally and those guys tune straight off power and sound.

 

VWH

i don't believe i have ever stated anything about listening for knock. as i stated and you repeat above.... "i will be following my instruments." i have published knock metrics from my various road and dyno runs throughout this thread.

yes i use Power FC numbers. i respect the Power FC as well as other ECUs. i also run a late model J&S knock system that employs a Bosch knock sensor and it parallels the PFC readings.

as to your experience w people tuning off power and sound... i don't know exactly what that means. i use a dyno so that would qualify for power. sound? great. go for it.

i have never indicated that there was but one method of tuning. i am merely sharing my journey here which includes hopefully learning a few things along the way.

i will be running another EMS next year but i hold the Power FC/DL combo in high esteem.

howard

 

Yeah, I was just curious how you were monitoring knock. I probably shouldn't even be quoting mustang results/techniques since those are a completely different breed.

 

howard, lots of good information.. thank you

 

There is a certain exhaust note when you getting close to reaching detonation, more easily noted with wide open exhaust or an open wastegate dump. Same with the powerband, once you start feeling the torque curve drop off, you're usually headed for trouble.

 

I am calling BS, you can hear it when you are approaching detonation? "same with powerband once you feel the tourqe curve falling off" so everytime you put the engine above the tourqe curve you detonate? Please enlighten us.

 

The torque curve doesn't drop sharply after peak torque...

I'm not going to say anymore, you're as usual trying to start a fight...

 

Man, you are way off base, I am not trying to start a fight, I am not going to back down from one, however I am asking you to explain. You make statments like "I am running 9afrs and 5 degrees of advance across the board and running good power" should I link to azrx7 where you said this? I am not all knowing I learn every day so I am just looking to learn how your theories work.

 

I disagree. There doesn't seem to be any "gray" area inbetween when the engine is running perfectly and then all of the sudden knocking. It just happens. I like to think of it as a thin line between the two. Btw, it doesn't have to be detonation. That's one branch of a larger condition - knock.

B

 

Huh? You know very well I can't view whats on that forum. Sounds like you're pulling something way out of context that I might have said years ago. Why on earth would you be trying to learn from someone who tunes like that anyhow? You may have people who don't know you fooled, but I know what you're trying to do.

 

That hasn't been my experience. The first time I learned the difference in tone was on an engine with RA apex seals, not only myself, but the owner too could call out right before it was going to detonate. Just like when a motor is running too fat the exhaust note is very lazy, or when you have the timing too retarded that also changes the sound.

Thats just been my experience, its not like I'm writing a bible or anything. Just amazes me at how worked up people get at impersonal comments posted on the internet.

 

You dont know me. You have read my posts and may have met me once. I am not trying to do anything. I dont believe in being able to hear detonation before it happens, if that was true no one would detonate because they could get out of it before it happens, I could be wrong but I dont believe it is true, so I was asking you to elaberate.

That is all Elliot, so next time I question what you say it is to understand what you are saying. I dont believe half of what you say, so to be fair I was giving you room to explain, this is a forum, I am not going to believe everything I read nore is anyone else, so we ask for explanation.

Oh and if you check out my posts I question others as well, I am not after you.

 

Any updates from Howard or BDC as to your progress? Have you guys switched over to HD AI systems that have tuneable pulse widths for the AI like the ones in Howard's thread?

Earlier in the thread, I believe Howard was tuning to a calculated AFR using the stoich values for meth and gasoline.

http://forum.teamfc3s.org/showthread.php?t=50684

That made sense to me, but later, Howard kept pulling fuel and now I'm guessing is shooting for the 10.8:1 AFR as Rice mentioned. So are you guys tuning for the same AFRs as you would gasoline (hypothetically) regardless of meth/gasoline ratio?

 

i just received my updated New Generation FJO controller module friday and now that the holiday is over and i am back from the lake will be installing it today. the dyno thread will resume very soon.

yes, you tune for whatever AFRs work w gasoline. once you reach that vicinity you tune for knock. i am currently in the mid elevens and if i am fortunate enough to get into the 500++ area i will richen it a tad...

but knock is the key on tuning.

stay tuned as things will start rolling again on Beyond Redline's eddy current dyno in Green Bay.

howard

 

Howdy,

I'm back in the game with mine. I don't have any plans to switch to a more sophisticated unit. This is where (and probably the only place) Howard and I disagree. I'm staying with the Alkycontrol unit as I've had great success with it. It does the job and can replicate a flat fuel curve. The caveat to using a system like this one, however, is to keep in mind that since it's irrespective of RPM and only of boost, fuel from the EFI end needs to be removed once past torque peak (as best as I can tell).

I am not aiming for any 10.8:1 AFR because, quite frankly, I'm not convinced it's some magic number. I'm trying to keep in mind that with the amount of alcohol that Howard and I are using (as much as 30% of total fuel output) we need an ever-increasingly stronger ignition system on the back-end to fire it. I'm going to go for low-mid 11's myself but one change I'm making is not running quite as much advance.

Here's my progress:
http://forum.teamfc3s.org/showthread...=50682&page=21

B

 

Howard you mentioned that your J&S knock sensor system readings paralleled those of the stock knock sensor. So is the stock knock sensor a good/accurate reading to tune off of?

BDC if I recall correctly, you are monitoring 1 EGT sensor post turbo. What sort of post turbo EGT readings are you shooting for? Are you confident that your EGT readings for each rotor are somewhat even?


How exactly are you guys determining the meth/gasoline ratio (80/20, 70/30)? Is it by how much gasoline you are pulling from your baseline gasoline tuned maps?

Is there an ideal ratio? I'm guessing you'd want to inject the most meth around peak torque, but why not 60/40, 50/50, etc?

 

Apparently so.

It was post turbo but now I've moved it into the manifold. The probe is acting up (pegging at +5VDC) but so is the EGT gauge. I think the wiring to them (shared) is screwed up somewhere so I can't get an accurate reading yet.

I'm shooting for nothing over 1550*F pre-turbo at 1.5+bar.

[QUOTE]How exactly are you guys determining the meth/gasoline ratio (80/20, 70/30)? Is it by how much gasoline you are pulling from your baseline gasoline tuned maps? [QUOTE]

The way I do it is by establishing an all, 100% pump-gas map up to about 14-15psi of boost and then at that load bar, in all RPM's, I removed a given percentage (I did 28% this time with a 2% slop for more spark advance on the alcohol map) and then re-tune the fuel curve w/ the system to match the same air/fuel ratio that the 100% pump-gas only map was doing. That make sense?

We don't know. That's the million dollar question. Seems to me, however, that while the rotary engine is under big boost and load, the more alcohol the better. The guy who does Alkycontrol recommends 15-20% replacement of fuel with alcohol for his system but he's a piston guy. Howard and I instead opted for 25-30% and lean towards the benefits of alcohol for the engine based upon the premise that the RE, compared to piston motors, creates much more heat for its comparative displacement. In Howard and I's cases, the ~30% (or 70/30 ratio) is at 15psi and above. It's much thinner below 15psi and ultimately no alcohol at around 4-5psi and below into vacuum.

B

 

last year i was attempting to solve a knock problem and switched out 3 OEM knock sensors. interestingly. they all read the same so i remain postively impressed w the factory setup.

i look for 1550 before the turbo and tune using knock.

i now have the latest FJO setup and should be on the dyno in a matter of days.

hc

 

Good luck guys.

I look forward to your future posts.

 

any updates here?

 

I started tuning on my setup a few weeks back just to have a problem with the transmission. Turns out the transmission might not be bad; may be something else that's problematic on the car as I've put a 2nd known-good tranny in there just to have the same problem.

I'm already back up to 21psi of boost, same ratio of fuel/alcohol, with the stock top mounted intercooler. Once I get the numbers on this setup, for reasons of both plumbing as well as experimentation, I'm going hot-air.

B

 

What's the "trany" problem you're having?

-J