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DLIDFIS myth?

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Old 09-18-04, 10:54 PM
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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!

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Old 09-18-04, 11:05 PM
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That's an awesome result. Only mod is the DLIDFIS?
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Old 09-18-04, 11:06 PM
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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.
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Old 09-18-04, 11:08 PM
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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.
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Old 09-18-04, 11:16 PM
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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?
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Old 09-18-04, 11:48 PM
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^ doubtfull
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Old 09-18-04, 11:55 PM
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Is that on your '80? What components does your setup consist of?
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Old 09-19-04, 12:35 AM
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yeah. on my 80. with 84 ignitors and coils. all stock parts.
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Old 09-19-04, 12:36 AM
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you only have 95 tq. coming out from that streetport??
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Old 09-19-04, 12:44 AM
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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...
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Old 09-19-04, 12:57 AM
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next round stock vs MSD. some1 give the man an MSD box!!

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Old 09-19-04, 01:01 AM
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Lightbulb

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
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Old 09-19-04, 01:15 AM
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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.
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Old 09-19-04, 01:18 AM
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Originally Posted by Blake
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
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Old 09-19-04, 01:23 AM
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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.
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Old 09-19-04, 01:30 AM
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Originally Posted by CarlRx7
next round stock vs MSD. some1 give the man an MSD box!!
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?
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Old 09-19-04, 01:44 AM
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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?
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Old 09-19-04, 01:46 AM
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Originally Posted by d0 Luck
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
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.
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Old 09-19-04, 01:51 AM
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Originally Posted by DarkCyDE
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?
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.
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Old 09-19-04, 01:55 AM
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Right on, didnt realised that you put more fuel to it for the run, my bad. Thanks for doing the dyno for us BTW
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Old 09-19-04, 02:06 AM
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Originally Posted by DarkCyDE
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?
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.
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Old 09-19-04, 03:57 AM
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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.

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 180. 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?

Last edited by Jeff20B; 09-19-04 at 04:03 AM.
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Old 09-19-04, 09:47 AM
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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?
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Old 09-19-04, 09:57 AM
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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.
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Old 09-19-04, 10:31 AM
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Originally Posted by Blake
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.


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