Rarely discussed power producing Ignition tech.

[@jesusisalive3227]

You remind me of my Grandpa, he was a mechanic for 60 years and owned his own shop for 50 of those. He was the most brilliant man I knew and didn't even graduate high-school. He could explain how something worked so anyone could understand it. He was a die hard Ford man and even came up with a couple fixes for common Ford engine problems that I was lucky enough to learn from him. His favorite engine was the 390fe. I miss him, the world lost a lot of hard earned knowledge when he passed.

[@franknukemcomegetsome2744]

Amen brother!

[@yeboscrebo4451]

So what about the 390?

[@matthewmoilanen787]

Fords engines in those days were more dependable than most of the competitors if worked on by knowledgeable mechanics.

[@jesusisalive3227]

@@yeboscrebo4451 What about it? It was my grandpa's favorite engine.

[@marciosilva89]

May he rest in peace 🙏

[@9psi]

Adding resistance increases the duration of the discharge. The inductive cable kills the di/dt which is what causes the emi. It also increases duration. Inductors cannot have instantaneous current change. Fast current edges are the main culprit for EMI/RFI I designed a emi supression kit for points ignition that got it so quiet that it was quieter than modern coil on plug. It was used on fire trucks in the state I live in so the wideband receiver / narrow channel could be used on gas powered trucks

[@irzoro]

I've been sitting here watching your shows for hours, all night actually. David I've bought several of your books and built a 427 BBC motor for my 72 C/10. I'm getting ready to take a 4-bolt 350 to the machine shop and go on and get a crank and stroke it. Those 383's are a strong motor! Thank you David for sharing your expertise!

[@jimmieblue6262]

He reminds me of my shop proffressor he was a warehouse of hard learned knowledge. He taught me a lot.

[@immanutt4442]

Thank you Sir for your tutorials - I have learned so much from your books and now also from your videos . Belated but so sorry for loss of your daughter - one of the hardest things ever for we are not supposed to outlive our children

[@PorscheRacer14]

As someone that used to work with explosives in the oil patch and seen my share of fuel tanks go up, I can easily say fuel burns and doesn't explode. What most people hear (in reality, not the movies) is the pop of air rushing or combustion escaping. A proper explosion doesn't go boom. It sounds like a jet breaking the speed of sound because that's what is happening. I never filmed those ones, because I was being safe, but I have filmed a few good pops haha.

[@th600mike3]

Yeah the pressure wave and flame front don’t move at the same speed. However detonation is a different story… detonation is when the flame front is supersonic… much closer to the pressure front

[@rjsmith7170]

David is a wealth of valuable automotive technology knowledge, and we greatly appreciate him sharing it.

[@lawrenceskrobarczyk4402]

I've ported heads for 30 yrs a big part off my cylinder head no how came from ur books & videos thank u amigo !!!

[@topenddean]

This is such a great series, THANK YOU for putting this all together!

[@Comet-hn3gm]

Thank you Mr.Visard. I am looking forward to the next in this series.

[@TheJagjr4450]

GM fitted an engine with a quartz lens in a cylinder for viewing and took photos of the two colliding flame fronts. The photos are shown in a book about high performance engine design. A domed piston can also cause the problem as the dome can split the air and keep the flame from traveling across the face of the piston.

[@paulzellner9447]

Thank you truly , for sharing you hard earned knowledge with motor heads .🙏

[@Aceman597]

Thank you for your knowledge. Ive noticed big difference using a msd 6a with the e3 spark plugs. Im not an electrical engineer but wonder if looking into using a ferrite for electrical interference.

[@johnnyhonda7576]

Can you discuss your view of plug reading. The carbon ring which few talk or know about. Burn rate on threads and timing on the strap. Steve Morris has a good video. I’d love to see one from you on plug reading

[@nickrodriguez7293]

I like to personally thank you for the videos. Your knowledge is golden. I am engine building and your advice has come in handy and I am building my second 350 Chevy engine 2 bolt main for a 72 Nova.

[@hunnybunnysheavymetalmusic6542]

The spark initiates a coronal discharge cloud, which then initiates an electrical cascade in the air and fuel in the range of the corona, and this is where actual flame begins. It starts as a 'candelation point' before there is a flame front propagating.

[@mattgoodmangoodmanlawnmowi2454]

Just started work on a Triumph triple. Hoping to add a little pep. Love this stuff. Instant sub.

[@robertryan2228]

Awesome stuff as usual David. Please keep the 4 valve stuff coming as I am very interested in the approach with the single intake port v's samesed port approach and how to induce twirl v's tumble with the siamesed port shape in conjuction with the polyquad modification. Iam modifying jetski heads these days and this is the closest episode to deal with the cylinder head type. I know most of the typical sigle port flowing priciples still apply but am eager to learn more oabout 4 valve types. i look forward to the polyquad episode and please keep up your great work DV you are a legend 😁

[@JohnDoesItAll]

You've got all my time. Thank you for sharing your knowledge and experience with the masses. 😊

[@bretbradbury5559]

I call it flame propagation. The speed is determined by the fuel, the piston shape and combustion chamber size. One is able to compare flame propagation speeds by the required timing advance required to satisfy each engine. In-cylinder pressure sensors show pressure peaks at some 8 degrees ATDC.

[@robv.o.1777]

NGK and Sumitomo Love my Whitaker's 😊

[@johnw5242]

@6:09 May have already been mentioned, but the answer here is Denso, or at the time, Nippon Denso.

[@NorthPoleJeff]

Explaining the DELAY. When the spark plug discharges, because of the extreme turbulence in combustion chamber, the tiny lit portion of the fuel breaks up and becomes a whole bunch of tiny burning spots in the chamber. I once have read that this was called, "Fulguration: emitting flashes of lightning." As these spots grow larger, their surface area becomes much larger and the overall burn rate suddenly increases in speed. This is where the MSD ignitions come in to make a lot more power as they make a whole lot more of these little burning spots at the time of ignition and therefore the delay should be less. Also, I've always thought that the noise that was heard from preignition was the increase of piston slap and hammering of the bearings. I'm not sure if that's true, but it sure makes sense. I sure love your show.

[@DANTHETUBEMAN]

Piston slap sounds like a good cause of the knock sound, 🤔

[@tonyschiffiler4816]

I want more spark power, little more power never hurts. Thank you David!

[@brianbrigg57]

I can tell you've never touched a live wire.

[@yomanspray]

​@@bigboreracing356 if you upgrade the coil pack under the distrubutor cap wouldn't you do the opposite and open the gap up aliitle bit

[@ChrisS-oo6fl]

Multi-Fire are the absolute best insulated plug wire/cable on the market...Period. Unfortunately they are very costly and hard to get as they are hand made. I didn’t believe they could be that much better until I bought a set. Only other Problem is that you can’t get a clip on timing light to work with them lol. In order to set timing I have to put a single MSD wire on.

[@TheJagjr4450]

GM fitted and engine with a quartz lens in a cylinder for viewing and took photos of the two colliding flame fronts. The photos are shown in a book about high performance engine design.

[@charlessmoak]

Always learn here and I have know creatures that set a number if class and track records. This man is a genius.

[@cdeprima1209]

Knock is a sonic boom at approx. 750 mph and is an explosion as far as engine is concerned because the shock wave causes high resonance of piston rings which will break the top ring seats, very bad. The maximum burn rate for longevity is just below this. Computer cars can constantly tune the engine for a burn rate just below this; they automatically adjust for different octanes which is their main advantage. Older ignition systems had to be tuned manually to the octane gas being used and they worked well.

[@neps4th]

I purchased a set of forged, flat top "L - Ring" pistons/rings about 1975. They were 4.060" for a 327 Chev. Intended for a turbo application. At that time, I figured to wait a few years for aftermarket turbos to become more perfected and cheaper.

[@bisbopjefferys9622]

Thank you Sir for a the care. And all the teachings from a lifetime. All the props😅

[@waynecera4422]

In Australia in the late 70s Chrysler moved the top ring up to reduce hydrocarbon emissions. It was a way to reduce emissions & increase power with no additional cost for machining. Win Win. They got something for nothing.

[@MrMightyytau]

WOW I have learnt so much with this, I will have to go back and watch the other and the future vids.

[@portedhead7164]

Thanks!

[@michellatour150]

NGK and perhaps Nippon Denso?

[@jamest.5001]

On my last engine I went about overkill, you could not run a stock rotor with it, a friend borrowed my coil and cap, with a stock rotor, it lasted about a day, about 25-30 miles before melting the rotor, and arcing to the shaft!

[@automan1223]

The MSD multi spark (3) firings on 8 cylinder engines dropped to 1 after 3000 rpm. I owned a sun scope with 12 cylinder trace and snap on counselor.

[@hunnybunnysheavymetalmusic6542]

I have only driven AC Delco HEI distributors, because they were factory original on the cars I got with them [ Cadillacs ], but they tended to burn out, right at the center electrode a lot. I tended to get rid of them and replace them with Holley ignition towers.

[@benwingo6675]

Gm had great ignition back then they were almost too good the coil energy would burn through the rotor button and ground itself out on the distributor shaft all you need is better wires and lower residence plugs. Great system.

[@deankay4434]

@@benwingo6675 As a tech who spent hours over decades staring at scopes secondary activity, everything effects the amount to voltage needed to jump the spark plugs gap, meaning, it only produces enough energy needed to overcome air, fuel, compression and rich / lean fuel mixtures. No manufacture is going to use the worse plugs, wires, cap or rotor they can find! The inductive wire wound plug wires these use now are on subject to excessive heat when installed incorrectly or cheap plugs. DK, ASE master tech since 78

[@benwingo6675]

Gm had a stock piston used back in the seventy that was dish with the top ring land beveled down to about twenty thousand of a inch from the top ring this piston was found in the police performance engines, boy did they make some power.

[@u.e.u.e.]

I think the biggest and most important progress in ignition technology over the last 150 years had been achieved by outphasing interruptors/points and the introduction of electronics! That was revolutionary. Everything different was just evolutionary improvement.

[@alext8828]

I remember the Sun Analyzer very well. Even saw one go onto Pawn Stars and nobody cared about it. Using that in about '62 was the first time I had heard of dwell and dwell time. All the other things it could pick out were great too. And it gave you a graphic image just like an oscilloscope would. It was the best. Of course, today's cars are so different. Coil on Plug, computer everything. I had to pull into a parking lot to try and change the radio station this morning. Someone screamed, "Whataya doing, grandpa??" I yelled, "I'm looking for Cousin Brucie on this thing." He screamed, "He's not on now."

[@anvilsvs]

In 1970 I was the only guy in the local Cad/Olds/Datsun dealership who knew how to use the Sun. Just out of Army, considerable electronics training so I could use a scope. Found several problems that the old guys in the shop had no clue about such as bent distributor shafts, ungrounded point plates, etc.

[@automan1223]

Jacobs ignition was some of the best stuff sadly they were absorbed by Accel and that was the end of that .

[@chevelleib]

Nice agin here from Denmark this is the ultimative best explain og All time 🙏😉

[@terryheimerl8674]

Thank you David. A bit more technical but that is what I like. Interesting facts about the top ring and its affect on torque/HP.

[@AJBlues]

Just pondering the pinging or detonation knock and was considering the possibility that it could be caused by cavitation bubbles in the combustion charge

[@ChengDIY]

Thanks for precious knowledge sir David . Keep on going helping some Children and other people needs suport , hoping you live more years . Only thing i can say is what we need Right now it the Lord Jesus Christ ❤ keep inspiring . Lord bless you good heart brother

[@g0fvt]

David, the RFI issues are initially created (ironically) due to DV/DT, IE a voltage with a fast attack. The inductive leads prevent the current in the leads following that curve and the current climbs more slowly than the voltage. The resistive solution achieves a similar effect since the resistor in association with stray capacitance slows the "attack time". Many years ago I used copper leads but with a much higher value resistor than you did, I used a 4700 ohm resistor. (they are manufactured in values called the E12 series) I wanted about 5000 ohms. Modern spark plugs often have integral resistors for a similar reason. The RFI is related to a Fourier transform, it has a lot of relevance in mechanical parts too. Sorry if this is badly worded, counter intuitively the choice of lead should be able to increase spark duration. Two leads laying parallel to each other will be subject to crosstalk, partially due to distributed capacitance and partly due to magnetic effects. These effects are more severe at high frequencies. Sorry if this is redundant info, as an aside it might be interesting to incorporate a magnet in a sparkplug, you should be able to bend or spin the arc...

[@1magnit]

To simplify what you said, a square wave has an infinite number of odd harmonics. Adding inductance rounds off the wave and reduces the harmonics. Particularly in the upper frequencies.

[@g0fvt]

@@1magnit that sounds like a reasonable summary, it is difficult to produce a quick answer in a comment box.

[@Thumper68]

@@1magnitto simply it even more. stop clipping

[@bryanst.martin7134]

The one thing missing in that test was turbulence, aka Swirl. Ford's HSC series played a lot with that. I appreciate Smokey. My late step father Ted Haywood worked a while in his shop. Started by pushing brooms and worked his way to building engines in the "Trophy Room". Ted built his 289 to push 504hp @ 9Krpm. In a '67 Shelby GT 350 it time qualed with 167.86 mph lap, and 210 on back straight. He was the 1st to "Stand on the go pedal" in the turns because the reverse rotation planted the inboard wheel instead of lifting it. Black flagged and proven legal.

[@mrman1536]

One of the biggest changes to a point distributor is to eliminate point bounce . The best spark ive ever seen has come from a kit i built called a capacitor discharge that spark ate everything.

[@keithtobin5369]

Thank you DV. I'm a poor boy racer. What's up know about you long time ago. I got a bunch of books you put me in victory circle.

[@yvandurocher2750]

Awesome podcast David, I appreciate and thank you for your immense knowledge in the internal combustion engine. BRAVO! I am curious as to why I haven't seen any podcast illustrate and explain why exhaust valves are concave and not convex? Wouldn't a convex shape increase the flow coming out? A response would be great! Have a great day.

[@rogerpatton]

Raising The ring land eliminates carbon build up. Also. Around ring land

[@reltub20001]

You are right about detonation. It is not 2 flamefronts meeting. And easy way to prove that is by listening to a dual plug engine. If it was 2 flame fronts meeting, these engine would be in cositant detonation at all times

[@michaelblacktree]

It's been awhile since I last touched a distributer. And honestly, I don't miss them.

[@methanial73]

The advantage with spiral wound wires is they shield the spark, which suppresses the interference.

[@anvilsvs]

Detonation, if it could be controlled and the engine could stand it, could improve efficiency by increasing BMEP.

[@Akya2120]

I've always thought the sound accompanying detonation/knock was actually the piston/engine fighting preignition. The rattle being the connecting rod either at the wrist pin or the crank.

[@josephverdone7099]

1970 we bought a Sun analyzer for our dealership. I was 12 years old learning how to build hotrods, dragster and funny Car.

[@1magnit]

The difference between normal combustion and detonation is the flame speed. When the flame speed is slower than the speed of sound it's "normal" and when it exceeds the speed of sound it's "detonation" or an explosion. When the flame speed is below the speed of sound, the shockwave (pressure wave) is always ahead of the flame front but once faster than the speed of sound, the flame is ahead of the shockwave, which piles up on it's self. No different from a plane going through the sound barrier.

[@1magnit]

Don't even mention no 13, it was all faked. I've read the report which makes no sense at all due to all of the errors.

[@1magnit]

@@bigboreracing356 no. Use water injection to slow the flame

[@jeremylastname873]

The knock (ping) is likely to be the resultant “sonic boom.”

[@NCmtnDweller]

Do u have any videos covering any performance tips for running dual point distributors with high output coils etc ? Thanks

[@pmd7771969]

On an early hemi you can use 2 plugs if you drill and tap another hole.

[@joe-hp4nk]

Is non resistor plugs worth better spark versus resistor plugs?

[@moparmanjames]

I believe NGK and Denso were the two Japanese wire manufacturers

[@pmd7771969]

You can piggy back external coils.

[@jimgee2676]

hello , what do you think of taking out the points and adding a pertronix ignitor into your distributor ?.......

[@t.s.racing]

You're probably looking for D.V. to respond, but I am a Engineer with almost as many years of Dyno/Engine Builder Experience. That being said, there's 3 levels of Pertronix ignition so you would have to be more specific. BASICALLY now, level 1 just eliminates the breaker points. Level 2 eliminates the points and has a little hotter spark - more energy than the level 1. Level 3 gives you all that plus the ability for a multi spark throughout the r.p.m. range and a adjustable rev limiter. None of these will help a distributor with worn shaft bushings and or a worn or sticky mechanical advance unit. Food for thought is with a GOOD points distributor, use this in conjunction with the analog MSD 6A or 6AL box. This gives you the best of old and new technologies and the ability to literally change a set of points on the side of the road with nothing more than a screwdriver and a piece of box top cardboard to set the gap enough to get home. Try that with any electronic ignition module. You get this plus the multiple spark discharge and the rev limiter feature with the L box. T.S. RACING

[@jimgee2676]

Its the pertronix 1 And i use platinim spark plugs in a 1970 small block la chrysler motor that is stock no mods

[@t.s.racing]

@@jimgee2676 Pertronix 1and the Platinum plugs are a good choice for a stock engine, you should be happy. A good set of LOWER OHM spark plug wires would or should be next. Pertronix spark plug wires are fine for a stock engine as you have. Also a often overlooked part of ANY Auto electrical system is a good ground from the engine to the frame or body. I like the flexible braided type cable as the engine moves within the motor mounts as it's running. It's a ground cable so it doesn't need insulation or a coating. They are very inexpensive and you should be able to find a bolt or threaded hole on the cylinder head or intake manifold somewhere. Do not use a head bolt though. Clean both surfaces from paint or grease before bolting the cable down. Good luck 👍 T.S. RACING

[@jimgee2676]

@@t.s.racing my car actualy has a ground from my neg battery cable to the radiator suport os that ok ? As for spark plug wires i use united motor products 7807 I did a test last night and i found it to be quite interesting I took a set of autolite 66 put it in engine Warmed it up then shut it off I waited 2 minutes and turned the key ..it cranked for 2 seconds amd fired up I did the same test with nkg platinum and when i turned the key starter didnt even have time to turn and the engine fired up I did the same test 5 times on each plug and the reulsts were the same With copper plugs ut cranked a few sexonds and fired up and the platinums fired up as soon as i turned the key

[@rubenlempens1121]

I love your video's but i am personally more interested in more modern non us engines and i was wondering if you maybe also have information about jdm or german 4 valve heads and how to port these ones?

[@jonellwanger7258]

😂

[@floordford1717]

Agreed. He has good info for 1970 but we've had DOHC engines and coil on plug engines for a very long time now.

[@howdareyu]

This guy is a lost art and a treasure! Get a real car! 😂😂. Just joshin ya, mate

[@Fulcrum205]

He has mentioned the 24 valve 4.6 and the 2.3 ecoboost. I'm sure he's taken a look at those heads

[@steveconnolly7129]

The e3 plugs,are they really a better plug for flame,and power output,what are the chances of melting pistons with e3s compared to the splitfire champ plug,if e3s have a more powerful burn then maybe that would help with a older engine that has wear and looseness in it,the guides leak a bit i think

[@robertoliver7088]

Sumitomo made spiral wound plug wires for Honda in the early 80's.

[@cdeprima1209]

This way you get the maximum cylinder pressure and maximum efficiency from a gas IC engine. Happy tuning! :)

[@yamajastytha3386]

Thanks o g. We love u for this!

[@Crysmatic]

fuel never detonates. even "low speed pre-ignition" is a misnomer. You still have 70% of the fuel just after TDC and if it autoignites it liberates quite a lot of energy in a few degrees of crank rotation. As of SAE WCX 2019, PhD don't know why it happens, and it's such a rare occurrence (1 in 20k cycles) that it takes a huge amount of data collection to find it, and autoignition tends to break whatever pressure sensors are being used. Oil with a high calcium can cause knock, which can be overcome with good fuel. Darrin Morgin says that lean pockets cause knock, and I agree that the faster the burn rate, the better. That's why 11.8:1 AFR is "safe", because the flame speed peaks there.

[@kevindouglas2060]

The rate of burn in a very high rpm motorcycle engine would be perceived as detonation in something like a tractor engine.

[@eweunkettles8207]

how do you rate the old magneto ign systems the polar inductor aero mags were very efficient against coil systems at the time

[@StefanRügamer]

when two flamefronts meet how it works with the quenching of the unburned mixture like in an ( two spark plug per cylinder ) engine ?

[@sorshiaemms5959]

I use FORD DURA SPARK SYSTEM AND WORKS GOOD WHEN RECURVED

[@jimthomas1989]

I run Taylor 10mm sparkplug wires , Accel plugs , HEI distributor with a 80,000 volt coil on my built 327 On my other 327 it has MSD distributor, muli -spark box ,8mm Accel plug wires , AC Delco R44TS plugs , My other 327 has HEI distributor , HI performance wires ,AC Delco R45 plugs , And all these engines run just fine , all have 11 inch clutch and 4 speed trans and 12 bolt posi rear ends

[@victoryfirst2878]

Could someone tell me what happened with SMOKEYS engine that was going to change the worlds fuel consumption ??? Nice video Sir. Also, may Jacque rest in peace with the angels too..... vf

[@speedmaverick]

Just makes sense that as a flame is created in the chamber, it starts slow and the expansion of the combustion gas accelerates the flame front as pressure increases behind it until combustion cycle is complete. If the fuel exploded, there would be no need for timing advance. Hydrogen injection has shown the explosive nature of that fuel required retarded timing vs gasoline.

[@jeffreydurham5342]

Thanks for all you do!

[@gmcnelly2468]

the difference on those three spark pictures is directly related to difference in amperage (think electric arc welding).

[@Hitman-ds1ei]

One thing that is seldom discussed or even realised is the ability of high tension energy to be delayed due to cylinder pressure and solid core cables more so, would like yo hear your views and experience with this phenomenon of cables acting like a capacitor until cylinder pressure drops or mixture richens to match plug gap without engine misfiring

[@flinch622]

I think he said what was needed regarding inter-element capacitance: space cables minimum 1/8" apart. Researchers could say more, but for a builder, I think that will suffice. DC has a knack for developing interference issues, but being low current ignition systems don't get too crazy. Main thing is high power cables should not run parallel with sensitive things. So don't zip tie that TPS sensor cable to a plug wire to "tidy up" is one advice. Craziest thing I ever had to sort was spacing a communications cable up [because there was no other routing option] about 18" from cabling that served up 1100 amps with anywhere from 150-750volts dc: the interference problem went away after that - it was a motor load with poor power factor and reflected power was guaranteed.

[@bertramlrezenet9311]

A video could be made about plug gap ionization. As you know, there are variables...

[@MoparMissileDivision]

Just found your channel and subscribed after an all night binge of watching your videos! In the late 1960's I remember my dad pulling into the gas station in his '65 Buick Electra 225 with the 455ci BB and saying "fill her up with Ethyl". I was too young to know what he was talking about so when I was old enough to start understanding, he explained about leaded gasoline and it's anti-detonation properties. Those were the good old days when gas was .29 cents per gallon and if you filled up you got a free hot wheels car for your child. God I wish I could go back to those good old days, even if I had just known then what I now know and had kept all of the classic cars I have owned over the last 50+ years, I would have been rich and would have kept several rare and highly sought after vehicles.

[@steffybael1245]

isure would like to get my hands on some of that good ole "tetra ethyl lead" please dont ask me why!!!

[@ericneilson1198]

If you have a small general aviation airport nearby, they still sell leaded 110 octane avgas.

[@ricomaicofan4388]

Here in France, I use Pulstar's spark plugs on my old VW Polo converted superethanol. So much low end torque on daily driving. But the most amazing result, is on my 2 stroke motorcycle Suzuki TS 200 R and Maico 500 GME. Better everywhere !!!

[@gregbrown9011]

Hello I have a pair of trick flow heads before they were trick flow cast iron 202's and 190 on the exhaust now what you going to tell me

[@user-so2qj4xx6b]

My "assumption" of the knock / rattle metal on metal ping sound is relevant to the pressure increase exceeding the ability of oil to lubricate. Metal on metal is like hammer on hammer. Isnt that why it makes the sound it does, because it "is". My two cents (mechanic of 20yrs). Oh by the way love your videos. First one I watched I thought you were going to get taken down by youtube due to releasing well kept secrets. We are all very blessed to have this opportunity. Matt B

[@benwingo6675]

Spark power is the result of secondary coil energy to residence this can be calculated with voltage of secondary coil by the number of wire turns in relation to the primary windings. The best example of residence is think back to when you were a kid running and jumping over small Creek banks when you came to a bank that you were not sure of you stop for a moment and back up and got a running start and release all you had and jumped the creek the same with electrical energy. That what the resistor does with the electrical energy ,the RF is reduction is a good side affect of residence.

[@GadgetmanKentuckiana]

residednce?

[@daviddroescher]

Detention vs burning. As you said the total charge is at/above flash point ge phase change from lquid to gas is completed allowing temperature to spike above ignition. Atomised fuel is the making of small droplets of fuel that are phase changing on there surfaces. Vapor pressure is responsible for restricted rate of evaporation keeping flame rate below supper sonic ( above is explosive below is burn, speed of sound is dramatically affected by pressure and density).Lquid fuel dose not burn due to insufficient O² infusion, phase change is absorbing massave amounts of heat and allowing the vapor to mix with O² then burn at a controlled rate based on temperature. Detonation happens when the cooling effects of phase change is used up, causing the temp to spike the liquid is now all gas at spontaneous combustion temperature where all is consumed at or above the speed of sound. I think the rattles are sonic booms in cylinder. MSD is 20° of spark shrinking volume from idle to 3000 ( if i remember correctly its been 20yrs) 20°becomes too short of time at higher rpms for multiple sparks ( coil saturation time limmits i think) so it is a continuous spark for 20° above the set point.

[@chevy6794]

DV The 503 rotax a 2 stroke snowmobile/ultralight engine uses a ring that fills the gap in the upper land. I’m guessing it’s for the very reason you speak of? I also noticed on your chart showing the power gains of a higher land there was a drop in Tq and hp at 3000 and 4500. I’m guessing that’s just the characteristics of the engine and or the tune? If someone is building a low revving street engine for better performance and economy such as a 5.2 magnum would this be advantageous? Thanks.

[@eweunkettles8207]

thats called a dykes section ring pioneered by greeves motorcycles that is designed to twist and give a point contact due to it tapering

[@chevy6794]

@@eweunkettles8207 interesting. Thanks.

[@danawilkes6174]

The GM HEI distributors tended to burn right through at the center of the rotor. Went to Bills Hays Ignition, to see what his thoughts were back in the late 1970's on this. He showed me on his distributor machine on what happened when running the .070" plus clearance on plug gaps. Using a clear distributor cap and with the lights out. You could see the ion storm inside the cap, and as the rpm climbed, the eight points firing at the plugs became erratic. Once the plug gap was reduced to around .040" - .045" problem solved, and the ion storm was gone. No more (from that point on) did we have problems with the burn through on the rotors when running the closer plug gap on HEI's.

[@raoulcruz4404]

Interesting. Had two rotor burn through when retro fitting hei to an older car.

[@johnshackelford6965]

I enjoy watching David Vizard. I drained the tank the delay time the neighbor hears.

[@christophersmithsonian3350]

Autolite Black metal copper core plugs are Great in every make American,German, ECT 🏁

[@Bristolcentaurus]

Detonation - the explanation put to me at Tech was almost spontaneous combustion and resultant pressure wave driving the piston and rod down against the rod journal - that is the oil film could no longer support the piston and rod and metal and metal contact results.

[@pauljanssen7594]

Sort of a good diagram but if your spark plug is too hot or the plug is too hot you have preordination other words spark plug doesn't cool down.

[@OkkiMoeljadi]

Thank you very much Mr. David Vizard. I have learned a lot from you. I have some of your books since 90's. Respect and best Regards, Okki Moeljadi

[@RHBTurbochargers]

12:28 A detonation, or "explosion" - in your words, is when the flame front exceeds the local speed of sound. It's a bit of math to find the speed of sound inside a cylinder

[@stickman-1]

My understanding is detonation is the near complete burning of available fuel before TDC. Basically the rapid expansion pushes down on a piston that essentially has no place to go. If the mixture is rich enough that extra fuel provides a buffer for the expansion of the burn. A time buffer. That's why over advancing the ignition timing can make detonation worse. The majority of the pressure is before TDC. So you have a lean condition that causes detonation and an over advancing of the timing of the spark that causes detonation. That's why if you are overly rich you can get away with a lot more timing. Also that burn is a chain reaction. As the burn starts the pressure in the chamber increases. Which makes the rest of the fuel burn faster. So if you have excess fuel it provides a buffer to that over expansion. In both cases it's a timing issue. Ie, when does the majority of the pressure occur? Before TDC that's deonation, a little after TDC that's a good burn. At least that's how I have always understood detonation.

[@codylapoint]

That is very similar to my understanding of it. When compression or hot spots ignite the fuel early enough before top dead center that the force of the combustion process has to be overcome by the rotating inertia of the crankshaft and flywheel. So you end up with 1 or more cylinders that are essentially trying to run the engine backwards. Hence the reason higher octane (slower burning) fuels can help prevent it from happening. Or like you said a lot more (scientifically than I could) about adding more fuel helping to prevent detonation. This i believe helps for two reasons, one being because deviating further from the optimal stoichiometric ratio will cause the flame propagation to move slower across the cylinder giving the piston more time to reach TDC before cylinder pressure spikes from combustion. And to a lesser degree the cooling effect that the fuel charge provides inside the chamber. More fuel will be more able to cool hotspots inside the combustion chamber which can help reduce pre ignition.

[@383mazda]

What you're describing is called pre- ignition: when the air fuel mixture ignites before the spark plug fires. (Spark plugs fire before TDC normally but the way) Pre-ignition can melt a hole in a piston in just one or two events due to what you described - piston moving up the cylinder while combustion is trying to push it down!

[@hunnybunnysheavymetalmusic6542]

The flame front is only one molecule thick under static combustion, and usually not more than 50 molecules thick under peak turbulent combustion, but up to a hundred meters thick at detonation.

[@j.williams4030]

Like a nuclear detonation?

[@chiappettamark]

GM HEI has the variable dwell chip inside for best spark quality vs rpm p to the HEI build limit (mech, some elec). Pickup and chip can run rather high rpm yet the total assy with ground wire to block, low (3-10) ohm button, tight rotor-post gap and phased with rpm, and just about any wire is not as good as a coaxial aircraft wire-plug deal with quad GND spark posts gaped oh say 0.040-0.045" for N/A high compression. I do a side-gap for the 0.045". The big hp/compr/boost folks may want a tighter gap, that which i dunno.

[@andrewforster4974]

Hello David I have a question regarding I just got a motorcraft 4180 carb used and was wondering if you know of a book about the rebuild and modification of that carburetor when it comes time for me to go through it thanks

[@broke_dongle]

H.O. Motorsports on You Tube has several videos.

[@Dr_Reason]

How do we have internal combustion engines with combustion chambers and yet people say the mixture explodes.

[@franklinford9875]

The knock...instantaneous fuel burned at 35 degrees before TDC= KNOCK. The sound is the explosion of fuel and air being compressed as the piston comes to TDC in an over pressure condition almost hydraulic in nature.

[@93xcr440]

Thank you sir 👍 I always make time for your videos great job as always