"I use the NGK Racing 10.5's or 11.5's at higher boost. From my experience they foul easily and I need a set every few events @ $30 a plug. Ernie told me he has a LOT of sets because of fouling as well."

Hi Anthony,

i have been using the NGK (10.5) 6725s in all four holes for a couple of years and have yet to foul a plug. i daily drive them as well as quite a few dyno pulls. i realize you are running at higher boost as the most i have run so far is 20.. and you are no doubt making more ponies.

you do have me wondering why your plugs are fouling. have you run other types of plugs and do they foul? what ignition do you run?

i run a Jacobs FC3000 amp and a MSD 8253 coil on each lead plug and have yet to have a misfire. when i started my alcohol i was running 9.1 AFR initially and my ignition didn't miss a beat.

i guess the probable answer is that you are just developing alot more combustion chamber pressure.

howard

When I run lower boost I have no issues. Once I went up to 30-35 psi they did not last as long. I am running the complete Electromotive TEC3 system. Keep in mind I take really good care of my plugs, I only use them when the car is warm, I actually start the car on 9s and the swap over to 11.5s when the car is warmed up. I don't let them idle in the staging lanes. When I am done for the day I change them immediately.

I can only tell when they are bad when I am in 3rd or 4th gear, I will have a few "hiccups" and I know it's time to change them. You would never notice on 20psi, it's only on the higher boost levels. A lot of guys in the NE that run higher boost have the same issues. If I know lower the boost to say 20psi, the same plug will be fine.

On another note, for 20-22 psi I use 9's in all 4 corners. I only use the race plugs when I'm running high boost. A few "veteran" racers recommended I clean them with a spark plug cleaner which I am going to try this year.

Anthony

What kinda power do you make @ 20-22psi? I was under the impression a colder plug would bee needed at that boost level (ex 10) I hope to be nearing the 500mark at around that boost level and was thinking 4 9's wouldn't cut it...

Anthony, are you using leaded race gas when you are fouling the plugs?
What kind of deposits are you seeing on the porcelain?

Barry

I made close to 500HP.

Yes leaded gas, VP C116. I never really looked at the porcelain, what do you look for?

Anthony

The lead is one of the contaminants that will "foul" the plug. It makes the porcelain conductive. Using a wire brush will also burnish metal onto the porcelain causing it to become a conductor. If you blast the insulator/ ceramic it would probably be best to use a plastic media that would not cut through the shiny surface. Once the more porous surface below is exposed the plug fouls again quickly.

The lead looks like splatters and tiny balls of metal.

When we cleaned aircraft plugs we would test them in a pressure chamber. We watched the spark as we raised pressure till the spark was “blown out”. The pressure at which this happened was dependent on gap and cleaning.

Barry

i had an interesting conversation w FJO today. it might even relate to this thread:)

FJO worked for a year trying to get max atomisation exclusively with water. since water is much harder to atomise they figured if they could get it w water alcohol would be a breeze.

here's what i found very intrigueing... they now spray water at less than 60 microns. according to them at that dispersion they find that water does significantly cool the IAT! at lessor atomisation they get no IAT cooling.

i have no idea what other competitors are able to do w water. both AQ and CM have solenoids and i'll bet they both have done some homework it would be interesting to find out their micron levels.

what FJO did say was that nozzles really suck (they didn't quite say it that way but did mean something similar). i could go into the details but most already know.

of course the preturbo setup would be different since the compressor is going to do the chop chop.

on another matter... they started testing their system w water and it worked fine. what they found later was when they added 50% alcohol it worked alot more "fine."

how fine?

their in-house car is a 69 camaro street driven twin turbo that has run 7.80 at 175 on 91 octane pump and WINDSHIELD WIPER SOLVENT!!

h c

I have known that water cooled for some time, and 50/50 was great for someone injecting pre turbo with no IC.... but no one believed me. The quality of the jet and the pressure of the injectant are absolutely critical to it working properly.

Aircraft engine manufactures went to town with all this in the last great world war. I don't know about how valid the alcohol water ratio is for vapourization but alcohol was only used because of the temperatures the aircraft operate at,and running a 50/50 water/alcohol ratio was below the lower burn limit of methanol and ethanol at that ratio down to pretty extreme temps. The finer the atomization the greater the latent heat of vapourization with water. I imagine the problem is finding a cost effective pump to flow enough at the higer pressures and to a slightly lesser extent nozzle design.

Dont quote me on this. But isnt this where rice's WI setup takes over, as it doesn't require pump's. His is run on manifold pressure as far as I'm aware.

(really rice should comment, Im only speculating on what I know of rice's system)

Yeah rice's kit works well because its a simple design so there is less that can go wrong with electronics and pumps etc. The nozzle is an air atomizing nozzle so it atomizes the water very well without high pressures. And then after being run through the compressor is super atomized.

I did a lot of reading on his kits, as well as some other similar kits the guys down under are running. This is actually the route I'm going with my WI build up, and will have information this week on how my home made preturbo injection works for me. Although I'm still running my intercooler. I think if i was to get rid of it like Brian I would go with at least some alcohol.
Heres the link to my preturbo WI for anyone curious. https://www.rx7club.com/auxiliary-injection-173/going-make-my-own-wi-kit-807016/

Unfortunately I don't think rice is on this forum anymore, (sometimes i have the suspicion he is, but in disguise) but his old old posts have a lot of good information.

Brain any plans for a alcohol/water mix experiment?

Hey Brent,

No plans to do a mix. I'm sticking with alcohol and probably post-turbo.

Today I made a new map and adjusted the ratio from 75/25 to 70/30. I ran 22-23psi on high boost in 3rd gear with AFR's from 9.9:1 to about 10.40:1 (normally about 10 flat:1) and saw something peculiar: The EGT's from 4800 to 6500 (when I shift) were flat across between 1625-1635*F. Car ran the same. Also I advanced the Lead at that boost from 7* to 9* but added 1 degree of split (from 8* to 9*). IAT's at 22-23psi were 90-92*F. Ambient air temps were low 70's today.

B

That's about 50* cooler EGT then you were getting right? I have a pretty good feeling it was the added alcohol that really contributed to the lower egt. I wonder if you took some fuel out of the base map to make the AFR's closer to upper 10's if the egt's would stay about where they are. I also think a bit of water mixed in might get those egt's even lower, but as it is right now you're right where you should be EGT wise. Good work with everything, this has been a very revealing thread.

I think you're right, Brent.

Here's the datalog if anyone wants to see it. Spare A/D to EGT -- 4.51VDC = 1624*F and 4.53VDC = 1631*F.

http://bdc.cyberosity.com/d/14216-1/bdcha36-1.jpg

http://bdc.cyberosity.com/d/14218-1/bdcha36-2.jpg

http://bdc.cyberosity.com/d/14220-1/bdcha36-3.jpg

It's a good 90-100*F cooler surprisingly. I'll have a chance tomorrow to goof with it plus I may try your suggestion and see what happens.

As far as the EGT question goes, the more I screw with this the more I'm marching away from it and instead looking more at using pure knock to tune. Adjusting all of this alcohol/gas ratio is throwing things off. The thing about alcohols is they're oxygenated; they're adding O2 that's being read by the wideband and therefore shifting its AFR output conversion from lambda off. So, every time I add or remove fuel /alcohol I have to re-do some of this.

B

Ok so when you change the alcohol mix you alter the lambda settings in your wideband a bit to compensate for the shift? Or do you leave them the same then compensate by tuning to a different AFR?

Wouldn't a properly tuned alcohol injection system display leaner due to the extra oxygen? So if you tune for 11.1 on straight pump fuel and then add 20% alcohol you might now be tuning for something like 12.1 AFR's with no other changes made to the wideband settings? Thats just an example, and a guess out of no where. I'm sure there is a mathematical way to do it. stoich for gasoline is 14.7 and for methanol is like 6ish if i recall correctly. I can see how this would get even more complicated with a variable AI control.

while you certainly have flattened your EGTs there's still more work to do.

your most recent dataset was generated from two significant changes... timing and alcohol mix.

!. at 5200 you are at 9 degrees advance V 15 in the prior run.

2. your base fuel duty cycle was 42% at 21.3 psi V 36% at 14.1 psi. a 17% increase in fuel V a 51% increase in boost. lots less gas.

i assume lots more alcohol since you were at approx similar AFRs.

so more alcohol and less timing...

maybe that's the answer... or not.

maybe it is more alcohol and not less timing or the reverse.

i still say that eventually each system's backpressure will call the tune as to where the music stops on the EGT meter.

one system w really low EBP might be able to run 11.7 AFR without getting into trouble whereas another w higher EBP might have to settle for 10s.

another interesting piece of data is your IAT... you flattened your EGT march inspite of 95 IATs V 64 degrees in the prior run.

nice work.

hc

The wideband reads in lambda, we convert the number to the type of fuel that we are using. Since we are comfortable with the gas numbers i.e. rich =10.5, lean =15.3, stoich =14.7 continue using the lambda in this familiar form. Rice explains this well in a thread on this.

Brian you are still too rich. It is really going to take off at 10.5 max AFR and 8000 rpm.

Barry

Barry is correct.... you tune using the usual gas numbers. forget about alcohol stoich at 6.

hc

I can do a before and after today but I think I'm right about this.

B

After reading all about lambda and stoich for different fuels, and multiple articles that made the relationship between all of this clear as mud, I found this thread that really helped clear things up for me.

http://www.innovatemotorsports.com/f...ghlight=lambda

Basically, the wideband reads in lambda. In simple terms this is the amount of oxygen left in the exhaust after a combustion cycle. Lambda does NOT change between fuels. It doesn't know or care what fuel is being used. 1 lambda is 1 lambda both for gasoline and for methanol.

The wideband then converts Lambda into a number we understand. Most of us will use the multiplier for gasoline because it's something we understand. If we see 9.1 we immediately think that's too rich.

Ok so we all understand gasoline scales right? we know 14.7:1 is the "stoich" or perfect burn for gasoline. Methanol's perfect burn or "stoich" is 6.3:1, but trying to figure out what is rich or lean from there would be confusing for us. Most of us are not familiar with this scale.

But if we use the same multipler for gasoline(because we understand it) the perfect burn for alcohol will show up as 14.7 AFR. Even though technically the AIR to FUEL ratio is 6.3 lbs of air to 1 fuel. The important thing is to understand what you are seeing. 14.7 makes sense to me, 6.3 does not.

In a nutshell. If you're used to tuning for gasoline, and used to those scales like most of us are, then don't change a damn thing in the wideband and tune for the numbers you're used to regardless of fuel. For me 10 is rich, 12.xx is best power, 14.7 is stoich and 16 is lean. That's my scale in my brain and I will use that scale for gasoline, alcohol, and every blend in between and it will always come out correct.

I hope that helps some people.

what he said

All of that however hinges on two things:

1) The oxygenated alcohols not adding O2 to the overall lambda reading
2) the "Best for power" AFR's for the percentage of methanol being the exact same, proportionally, to gasoline.

On #1, I think it is throwing the lambda off. And on #2, I don't think the calculated equivalent of whatever low 11's:1 for gasoline is ideal for alcohols. That's why I'm default to a point richer.

B

I would think any extra oxygen in methanol would be burned along with the mixture as a whole, and therefore any remaining oxygen would be read by the wideband sensor. Whether the oxygen came from the methanol or the turbo shouldn't make a difference. It still needs X amount of fuel for X amount of air for maximum power, safety or fuel economy. (depending what the tuning goals are)

As I understand it, Stoichiometry or stoich (perfect burn) is still lambda 1 for both methanol and gasoline, but it requires more then twice the methanol to = stoich compared to gasoline. I would think that stoich rich for best power would still be close for the 2 fuels especially if 70% of the fuel is still gasoline.

One effect of methanol I discovered in my recent readings is that the power doesn't drop off as much when you run richer mixtures compared to gasoline. So going from 11.1 w/ gasoline to 10.1 might drop power 40HP, and with alcohol only 20HP. (just random numbers to illustrate a point)

But, since a large majority of the map is still gasoline, I think the effect is less. Even if it was 100% methanol I feel leaner mixtures will still produce more power then richer mixtures, while actually being safer then the same lean mixture on gasoline due to the knock deterring effects of the methanol.

With "stoich" being lambda 1 for BOTH gasoline and methanol I would think the same basic tuning principles would apply in both situations, and if still using the multiplier for gasoline in your wideband (recommended) then shooting for the same numbers you would on gasoline seems logical to me.

Remember too, in a rotary we are forced to run much richer then our 12.5 afr for best power. We aim for numbers closer to 11-11.5 which reduces power but adds safety. With methanol we are already increasing the safety margin. So we shouldn't have to go for even richer afr's when the same 11-11.5AFR is already safer on meth, and probably our optimum performance afr is more attainable with still a good margin of safety.
Whether the new maximun power AFR is 12.5, 12, 11 or maybe a higher 13, is limited to discovery on the dyno. I think its still close to the same as gasoline though.(12.5 AFR) The only evidence I have of this is instinct though, so who knows haha.

lambda and petrol AFR are the same thing :icon_tup:

its the number scale familiarity that is important as RICE said all so long ago :lol:

You can put in Yak semen or 100 NITRO it makes no difference :)