DLIDFIS myth?
 

well guys. i dyno'ed my little n/a 12a today. pretty happy with the results. hit 137hp and 95 trq. i actually dyno'ed it twice. first 3 pulls with the dlidfis system and the last 3 with the stock system. been woundering if it actually does any good except bypassing the dizzy. well, NOW WE KNOW!

https://www.rx7club.com/attachment.p...id=74218&stc=1

That's an awesome result. Only mod is the DLIDFIS?

What kinda mods do you have besides dlidfis? I see that dlidfis didn't add any extra power. Mabey all it does is increase throttle response and smooth out the idle.

no. the dlidfis was the first 3 pulls, and stock ignition the last 3 pulls. no difference between them. but my car has plenty mods from a street port to the holley.

At the bottom of your sheet, are those the A/F ratios? Looks like there is a little difference in their curves. I've done the FC coil mod and I would think it is virtually the same but without even dyno'ing it I have felt a difference in acceleration, noise reduction, and slightly better gas mileage. Of course my engine is still stock and so is the carb though all emissions stuff has been removed (before FC coil mod). Maybe with all the mods you've done on your car, it just isn't as significant of a difference as it is on a totally stock engine?

^ doubtfull

Is that on your '80? What components does your setup consist of?

yeah. on my 80. with 84 ignitors and coils. all stock parts.

you only have 95 tq. coming out from that streetport??

isn't one of the benefits of dlidfis a smoother idle and smoother all around running motor? i'd consider that a huge benefit, even if it doesn't net a lot of power, at least its not expensive... i wonder if there would be any power differences with a msd system or bosch etc.... or maybe a jacobs pack... wish i had a running motor to test that on, i got a jacobs rotary pro pack sitting in my drawer...

next round stock vs MSD. some1 give the man an MSD box!!

carl.

w/ the mods he has, i don't think he will need the MSD box... as of yet

i've had personal driving experience and scrutiny behind wackyracer's theory about the box and no box. his bro in law w/ SA isn't using the box but is utilizing direct fire w/ blaster2 coils. his FB uses it, but you can't really tell the difference. 12a and 13b had both aggressive streetports that idles almost like a bridgeport

maybe if his ports were bigger and his car fully tuned will direct fire show up on the charts

Supports what I said recently:

https://www.rx7club.com/forum/showpo...3&postcount=10

"I'm not a fan of ignition upgrades. They are a usually terrible investment in terms of cost/benefit. All the "new" stuff is really rehashed tricks from back in the day and there is a reason the "knowledge" was lost...no real gains. Just get some good plug wires and fresh plugs periodically and you will be better off in the long run while saving you money to spend on more worthwhile upgrades."

A few years ago, I raised the issue with Rob Golden of Pineapple Racing, back when the hype started about direct fire mods. He laughed and said, "yeah, we tried that way back when...almost everything has been done and what sounds new is just stuff that didn't work so well." It's not that it's "bad", per se, but just not worth the trouble or expense. Another such mod that has been reinvented is the "secondary bridgeport"...sure it's not all bad, but a proper "rally" streetport gives just as much performance and a real bridgeport blows it away. Anyway, if something sounds totally new, you can bet it's been tried and abandoned. This is not to say there are no innovations, but things tend to be more evolutionary than revolutionary.

good point. but if that was the case, why did mazda switchover to a direct fire system on the introduction of the FC and FD.

if it's good for the upperclass rx7s, then it must be good for my Fb right ;)

well, i didn't notice any difference in idle or acceleration between the two today. and for my ports....... never know. stage2 street on primary and race on secondaries with holley 600 that is pretty well tuned now. headers to glasspacks to straight through muffler. just maybe the dlidfis is good for some kind of set up............. i will still use it cause it stops the chance of killing the rotor and cap. but for power increase and acceleration, well the graph tells that one. just sharing the findings for today.

Capacitive Discharge systems have negligible benefit on rotary engines; the stock inductive system is superior, or at least not inferior. Anyway, all you can ask of an ignition is to reliably ignite the fuel/air mixture. Once it's "lit", the combustion takes care of itself. Timing if the ignition, however, is a very, very big deal!

I've dyno'd with and without an MSD and found no additional power whatsoever. And, then, the MSD died and left me with significantly less power (running on trailings alone). Bypassing it revived the beast. I think it lasted all of two weeks before dying.

I also once spent probably $300 on a cold air intake setup for my 89 GTU-S. This was a cone filter, custom cold air box and a FEED "fresh air" headlight cover. I picked up exactly 1rwhp on the dyno. Maybe it would have been more if I were driving in the real world, but the benefits were really minimal at best. The Racing Beat downpipe and precilencer got me 23rwhp and cost $100 used! Which was the better cost/benefit mod?

maybe I am a bit confused on the subject but isnt the point of direct fire just to give you a stronger spark so that you can increase your fuel intake? So if that being true, there would be no noticable increase in HP but it would allow for more dump, right?

Again, it's not "bad"; just not a good investment. Mazda did it because they needed better ignition timing (ECU controlled, rather than a distributor) and it certainly had favorable results on emissions....much, much more important than performance to an OEM! Oh, and perhaps they saved a few cents per unit.

If you want to do it, go right ahead. It's just probably not a good investment if you consider what else you might be able to spend the time/money on. But, try this: after you live with it for a few weeks, disable it and drive around for a day. The butt dyno is far more accurate when reverting than when eagerly anticipating gains from a new mod.

yeah but if you have a better fuel intake and more dump. you should have more hp. cause the faster and more fuel goes through, the faster the engine should spin, so the hp should be more. but it's not.

Right on, didnt realised that you put more fuel to it for the run, my bad. Thanks for doing the dyno for us BTW

I'm afraid you are confused...and I have no idea what you mean by "dump". Air and fuel must be mixed in proportion to burn effectively. All you can hope is to have the right proportion (slightly richer than stoich, so that every oxygen molecule reliably has a fuel molecule mate) and to ignite it at the right time. A "hotter" spark does nothing. Doesn't help; doesn't hurt. The timing of the spark is about a million times more important than the strength, so long at the mixture lights reliably. Adding fuel does not increase power unless there is proportionally more oxygen, which won't happen without increasing Volumetric Efficiency...something totally outside the control of the ignition system. And, burning the air/fuel mixture will not be affected by the "strength" of the spark.

Back in my Army days, I was a Combat Engineer specializing in demolitions. Demolitions require a primary ignition source to initiate a secondary charge of much greater strength. The secondary charge, usually, was C4 or TNT and the primary charge was a blasting cap. Using a bigger blasting cap or multiple blasting caps didn't make for a bigger explosion because the magnitude of the explosion was completely a matter of the quantity of the secondary charge. Same thing for combustion in an internal combustion engine. The air/fuel mix is the secondary charge and all we have to do it set it off with the spark.

I think the main objective of my DLIDFIS article was to present a way to get the benefits of direct fire on an older pre '86 rotary without having to spend an arm and a leg on an MSD box. I tried the MSD based on what I read on Paul Yaw's website and realised it wasn't worth the money. Since MSD was the only game in town, I decided to 'help' the online rotary community by presenting a much cheaper option which just so happened to work better for me.

For better or for worse, I was using my REPU as a test vehicle. It was always down on power so I was looking for anything short of a port job (I couldn't afford an engine rebuild). Ignition seemed like the least expensive route. Mind you this all took place back in '00 and '01. It wasn't untill late last year and earlier this year that I finally discovered the reasons why the old REPU was so gutless, but I won't get into that here. At least the problem wasn't ignition related, if you were wondering. Heh. :D

Anyway, with each progressive step in trying different ignition mods, DLIDFIS seemed the best overall in power vs cost and reliability, not to mention less exhaust smell to cling to my clothes. It also changed the actual sound of the engine so I knew it was doing something.

I've never done any dyno testing because I never really cared to. Am I wrong to not care about such things? I've often questioned myself as to why I've never had a dyno test, then I shrug it off and think about something else.

Hey, speaking of Rob Golden, he even said that if your air fuel mixtures were perfect all of the time, a direct fire ignition system does not improve the power output of the engine. This says nothing about the idle quality, emissions, mileage etc. Even the R26B's late trailing plugs only improved fuel mileage at the cost of some compression with no net power increase.

As for perfectly stoich mixtures, our 20+ year old carbs were only kinda close to perfect maybe most of the time when new. What about after 100k or so miles?

I think I've realised something within the last month or so. It doesn't matter which route to direct fire you take as long as both leading plugs spark together every 180º. That late leading spark is what actually improves how the engine runs moreso than how much electrical power gets to the plugs, how much money was spent to achieve it, or how much power it can produce on a dyno. Perhaps the recent popularity of 2GCDFIS and all the positive words the owners have to say about it is more important?

Dyno runs on Furious at 154,000 miles showed a 13.0:1 average all the way to 7200 rpm...carb has never been rebuilt.....and isn't there supposed to be a different tune-up regarding advances and splits when you go down the dark path of Jeff20B?

hey now. i'm still going to use it cause it gets rid of the rotor and cap on the leading side. thats a plus. how many times have you had a crappy running car cause the cap and rotor were coroded? i've just been woundering about the power it might give. so i spent some money to find out. it's and awsome setup. good for alot of things. looks real cool too.

Words of Wisdom. :bigthumb:

Carl! C'mon! There's an explosion and then there's a controlled burn....the two are an apples and oranges comparison! How many times have you heard of a C4 explosion suffering lossed efficiencies from detonation? That is, the explosion being started from somewhere else besides the primary ignition source? It doesn't happen because that C4 event is a real explosion...an almost all-at-once uncontrolled consumption of the fuel source. What happens in a combustion chamber is a controlled burn that is heating the air ingested to provide the mechanical push to turn the rotor. IT IS NOT AN EXPLOSION OF ANY KIND. The comparison is only vaguely useful...

Actually it is an explosion. And they are both controlled explosions. You only use what you need. He's not gonna use 5lbs of C4 to take out an ant hill, nor you're not going to use a 1/4 gallon of gas, and 400 cu. ft. of air to run your engine. Your carb, or FI is made to mix the gas at or close to a 14.7:1 ratio, or stoich. Controlled. If you've seen the high speed heat cameras inside piston engines (yes, the same shit happens inside those and rotaries) the result of the air/fuel mixture and spark is a quite violent explosion in itself. It has to be, there's no other way to turn that rotor, or push that piston around, or down without quite a bit of force behind it.

Glad to see you back Mario! Where have you been?

I was more referring to his first paragraph in that post. Most of the ign products on the market dont do shit, you know that. Like plug wires with capacitors in them :rolleyes:

Isn't this the same guy selling the useless little inserts for secondary port sleeves at $50 each?

Not entirely true, engines experience misfires all of the time where the mixture isn't ignited either because of reasons of flow or local mixture. A higher energy spark is more likely to start a flame kernel because of an increased introduction of energy. To start the flame kernel, the mixture must first have an introduction of energy at least as high as the activation energy.

kettleman, I remember when you mentioned to me that you had gone and done an ignition mod on your '80 (at the BBQ last month), but I don't remembr you saying if it made any difference in engine power. Your dyno test shows that it didn't make a difference on your engine.

Does your engine start up faster than before? How is the idle quality? Mileage? Emissions (can you walk behind your car when it's running and not have smelly clothes for hours)?

its suppose to run rich...my co-workers love my new cologne "smell of unburnt gas"

useless? useless that nets 4-5hp? i think thats worth 49 bux for 2 inserts.

I used to always were that cologne untill I upgraded the ignition. Three years of the same cologne was getting really old. Besides, cologne is supposed to help attract people to you, most of the time. :)

I'd try the inserts if I was into 6 port engines.

i've gotta answer no to those queations. my engine is just a year old and starts up every time unless i flood it or the started screws up. the idle has not changed at all, i switched it while hooked up to the dyno. there were no changes in idle at all on the car or on the machine. when you'r running a holley 600 with 65 primary jets and a #10 plate in the secondaries. not much can change the mileage...... and emissions? well, i wouldn't stand behind my car for very long. ha ha ha.

Talking out of your ass, apparently. The reality is that explosives are *extremely* controlled burns, and are spec'd in feet per minute burn rates. Sure, it's about 20,000 feet per minute for det cord, but we still had to tie the knots to suit the direction of the burn. Anyway, this was just an example of a similar primary/secondary ignition system. It wasn't meant to prove anything but, rather, illustrate a rather well-known relationship between ignition and burn. Both require a primary ignition source and, once that has caused ignition, the secondary "charge" is entirely responsible for the "work".

Think of it like this: If you build a very tall tower of bricks that is very finely balanced, then you push it over with your finger, your finger is NOT responsible for anything but initiating the release of potential energy stored by the construction. Arguing that a stronger finger will cause it to fall faster or land harder is ludicrous. Same thing with initiating combustion with a spark! The results of the burn are *entirely* the result of the potential energy of the secondary charge being converted to kinetic energy.

Again, as long as the combustable mixture lights reliably, there are no ignition improvements other that the precision of timing. Certainly, combustion can sometimes be incomplete and a second ignition can be benefitial, but we're talking *way* after the initial burn has been completed; a totally new combustion event. It won't add any usefull power, though. More spark energy may be required in certain situations to reliably ignite a combustible mixture, but unless you have the problem there is no need to "solve" it. Mazda's OEM ignition systems are very, very good, so there is no need to fix what isn't broken in 99% of the cases. I ran a peripheral port 13B with Weber 51IDA up to 11,000 rpm on the dyno using the stock distributor and experienced no ignition problems, so I find it hard to believe that any NA owner would have problems unrelated to simple maintenance.

As someone else said, I think that's missing the point of a direct fire ignition, with the wasted spark and the MSD "multiple spark" that I think only applies to the first 1500 or 2000 rpm on a rotary.

*Peak* power might not be improved, but idling, cold starting, and resistance to misfires is. I wouldn't be surprised if *average* power was up a few percent, especially if you could measure it from idle on up.

Proof? I don't want to go off topic of this thread too much, but we've covered these little things before and there is no flow benefit to them.

Nice attempt to hit below the belt. It really shows your true colors that you would try to assasinate the character of a respected vendor to discredit my well-founded statements. I suppose you mean "useless" in some other context than performance, where they are proven to have benefits.

Put down the book and show me all these misfires. Most people doing ignition upgrades are not having the problem you describe! I, personally, have run some very extreme setups (PP13B to 11,000rpm, etc.) using stock ingition systems without any problems whatsoever. And, again, everything I said clearly stated that once you get reliable ignition, there are no further gains to be had...I never said that there were no instances where a stock ignition was inadequate, just that the situations are rare and that a "hotter" spark than necessary wouldn't make more power. The best you can hope for is to find power you were losing; not gains something that was never there.

I got my masters degree studying engines at the University of Wisconsin Small Engine Laboratory. I've run a few experiments myself.

Oh, really? I would be interested to hear how you came to that conclusion. Also, how do you account for the very real improvements in quarter mile trap speed (indicative of HP) and power indicated on dyno sheets. No, I don't have them in front of me, but I've seen them personally.

Even just on a logical standpoint of evaluation, how can you even imagine there are no flow benefits to radiusing the port ends? What basis in theory do you have that contradicts everything known to me about fluid dynamics; that turning a column of air efficiently requires a consistent cross-section. And, what about fuel droplets, heavier than the air molecules, which have a hard time changing direction? Certainly, you can see the benefit of placing a wall against which they must turn with the airflow?

I don't know what you have against Pineapple Racing, but why try to invent issues. If you have a legitimate beef, at least stick to the facts and not get "creative" in your character assasination attempts.

Well, that's just great. Show me all these misfires on rotary engines and where ignition upgrades resulted in more power. Certainly, there are a few cases in very extreme setups, but the vast majority of rotary owners have no need to upgrade. Once the fuse is "lit", there is nothing more for the igntion to do. Do you dissagree?

I've never encountered a DLIDFIS install that didn't improve at least one aspect of the engine's runability. This is a first for me. :)

As for improving only one or possibly two aspects, neither of which include engine power, I recently hooked up DLIDFIS with two GM HEI ignitors on my friend's 7" supercharged '77 REPU. The engine is on its way out (bad seals in an S4 6 port, which will be replaced by an S5 T2 in a month). Anyway, the idle was choppy before and didn't improve after the upgrade. We don't think the power was improved since the Holley carb always seems to be mistuned and runs pretty rough most of the time. The '86 clutch fan is starting to suck more and more power and wearing the black anodized coating from the Atkins serpentine waterpump pulley (it screaches pretty badly under acceleration, and the belt is properly tensioned). The engine's side and oil seals are not sealing as they should which is evidenced by all the exhaust and oil spray that can be seen flowing from the breather line hooked to the oil filler tube. It sounds a little bit like it's got late leading sparks, but it runs so poorly/choppy that it's hard to notice it unless directly compared to his 5" supercharged '81 which still has a stock FB ignition system and a healthy engine. The exhaust smell (cologne) has diminished some, which is good.

In other words, it's a tired engine and we didn't feel a difference after DLIDFIS was installed. However, there is one point of interest that I hadn't even noticed untill my friend pointed it out to me. He's got a Camden air fuel mixture guage which consists of LEDs ranging from lean to rich and runs off of an O2 sensor. It used to always fluctuate around the rich ride of stoich. After DLIDFIS, only one LED is lit and I think it was either the 14.7 one, or the one just one tick to the rich side (I'll have to ask him which LED it is). Heh, he even questioned if I had accidentally unhooked it or something because it had never been that rock-solid before. :) Anyway, if nothing else, DLIDFIS has vastly improved the burning of the fuel, and I thought superchargers were supposed to cover for mistuned carbs lol! I can't wait to see how the freshly rebuilt S5 and a good clutch fan will work in that truck. He might even bring it the next BBQ. :D

https://www.rx7club.com/showthread.p...ight=pineapple

https://www.rx7club.com/showthread.p...&highlight=yaw

I don't have anything against Pineapple Racing. I've never dealt with them at all. It's just that the sleeve inserts don't do anything.

It's lighting the fuse that the more powerful ignition does more reliably.

And, as I said a dozen times, once you have reliable ignition, that's all you need. The stock systems are very, very reliable so "upgrades" are pointless in those instances where you are not having misfires. All I'm saying (again) is that you shouldn't waste time and money fixing what's usually not broken. If you experience a problem, worry about it then; not sooner. Anyway, the upgrades like direct fire and wasted spark do little or nothing to increase spark energy. Ignition boxes may do so, but capacitive discarge has proven no better than inductive discharge...perhaps because the ignition is already past the threshhold of being reliable. About the one thing that I can see benefit to (again, presuming you are actually experiencing misfires) are better coils. More energy and faster rise times are the way I'd go if facing an ignition misfire traced to inadequate spark energy.

I've played around with all sorts of ignition setups and never found any objective improvements. Money wasted, but at least it's educational, so I don't begrudge anyone wanting to experiment. However, very little is new under the sun and it might just be better to stop reinventing square wheels and move on to more promising frontiers of the performance envelope. Just my opinion.

All those threads show is that you are the lone voice making this claim and trying to convince people by flashing your degree in front of them. I've seen dyno sheets. I've seen 1/4 mile time slips with higher MPH. You're just bashing the product on a *theory* that they *shouldn't* work; not evidence that they don't. When theory and practice conflict, it's the theory that must be thrown out. You're like the engineer who tried to convince me Evans NPG coolant couldn't possibly work. Sure it has higher specific heat and falls short of plain water in many other ways, but it happens to work better because, unlike water or EG/W, it doesn't boil into a vapor insulation on hot spots. The real world triumphs over theory...again.

If you're an engineer, I bet you are a very young engineer...just knowlegable enough to be dangerous. How old are you? When did you graduate? What are your rotary engine porting credentials?

i'm gonna be getting them when i can afford them(no job still)

Actually, I think you are all right.

If you expose more of the mixture molecules to instantaneous spark, complete combustion should, in theory, happen faster, and hence more potential energy is converted in a shoter time window. But I would expect that if the timing was left alone after upgrading the ignition system to do this, that no gain would be seen at all, hence the dyno results. Was the timing adjusted between the swap? Upgrading the ignition system shouldn't add anything unless, like everything else on engines, tuning is done to optimize it. And at higher RPM's where the time windows are smaller, I think it could be of SOME benefit if you know what you are doing with tuning.

As far as the brick wall analogy, if F=MA, I think a bigger finger (or other larger appenage of choice) would get it moving on it's own a little quicker. ;)

I think that any potential gains would not be worth the $$$ for the average 7 owner, however.

R

As a man of science I would have thought you would be more curious. BTW sorry for the hijack. I read your response in the thread and Yaws quote. Tell me, at what depression was he flowing them at? That makes all the difference trust me. I have many hours on my flowbench and truth is he may be right, or maybe not. I'll agree with you on one point and disagree with Blake (sorry dude). While Blakes theory holds water in a technical sense, air doesnt always flow like we think it should, and some really bad looking stuff aero wise outflows what "should" work. Unfortunately, subsonic aerodynamics research seems to have gone the way of the dinosaour. Pitty, we could learn much more with our current technology.

Also a dry flow test doesnt take into account all the other factors in effect in such a dynamic environment, so just because Yaw says they dont work, doesnt make it so. Dyno sheets and time slips will tell you more about a combo that works then anything else.

Now you can both hate and flame me. :D