0110-M-P

iTrader: (10)

So it has been over a year since I last started my FD. I got it tuned a couple of years ago, but it was getting pretty bad ignition breakup past 6500 rpm at 14-15 psi. I was in grad school, so I just parked the car until I could really work on it (pay for it) again. Now that time has come and one of the first things on my list to upgrade is the ignition.

The car is a track car build with the intent of running 93 octane only (maybe water injection too, but maybe not), max of around 15 psi, and looking for the 400-425 rwhp range.

Currently:
Engine has a large street port by djseven
Turbo is a ball bearing T04R with a divided 0.84 A/R turbine housing (might move to a divided 1.00 A/R though)
ECU is a Power FC with Datalogit
Fuel system consists of 550cc primary and 1680cc secondary injectors
Ignition system is stock with BUR9EQ's all around
Power steering and A/C are removed

I had a planned ignition upgrade a few years ago, but am questioning whether or not it is worth the cost now. I am open to any suggestions, but these are currently the options that I was looking at. Costs shown are of core components only...no plug wires, connectors, etc.

CDI Option 1 - Cost: $1045.70
- (2) MSD Digital 6+ Boxes for Leading
- Stock ignitor for Trailing
- (2) MSD 8253 HVC-2 Coils for Leading
- (2) MSD 8207 Blaster SS Coils for Trailing

CDI Option 2 - Cost: $675.70
- (2) MSD 6AL-2 Boxes for Leading
- Stock ingitor for Trailing
- (4) MSD Blaster SS Coils for Leading and Trailing


Inductive Option - Cost: $268.00
- (4) IGN-1A Inductive Coils/Ignitors for Leading and Trailing

Is it really worth double or triple the money to do a CDI setup over something like the IGN-1A coils/ignitors?

Howard Coleman

iTrader: (6)

"until I could really work on it (pay for it)" good move, hard to do.

your turbo makes 60 pounds per minute of air at 15 psi. that is 450 rotary rwhp.

60 pounds of air and at 11.3 AFR that is 5.3 pounds of gasoline.

3180 CC/Minute.

you have 4300 CC/Min of deliverability. to get to net subtract 10% (could be as much as 15%) for lag and another 15% because you shouldn't run your injectors more than 85% due to heat build up in the coils....

so your net deliverability is 3289. i suggest you add a bit more injector as funny things happen on the track, like 17 psi and...

as to ignition, given your wish to be around the 400 level, where you will blow most cars off if yours is setup right, you don't need alot of it. generally the stock ignition works well to 400. alot of FD owners find the HKS TwinPower works well for them. fairly inexpensive, around $400, it juices the elec to the coils. 10 heat range plugs.

finally, i do suggest you install a modest water AI system as 400 is a bunch of hp out of a small displacement engine. keep it simple... there are a bunch of options but i suggest you take a look at Coolingmist.

good luck and have fun ontrack,

howard

C. Ludwig

iTrader: (27)

IGN all the way. Will support way more power than you're looking to make. Less expensive, easier too install, and no possible headaches associated with CDI.

G's 3rd Gen

iTrader: (11)

With your intended goals Howard it right on the mark. I had the same high rpm problems you encountered and the twin power took care of it. Just purchase the plug in adapter and it installs inline tothe ignition harness instantly. I am still using the same ignition set-up at 450 whp and 10's for plugs with zero issues. G

Turbo8

iTrader: (17)

Could you elaborate on possible issues with a CDI system? I am putting together my own ignition system myself for my build and I have planned on using an MSD CDI box, so I am trying to learn about what roadblocks I could run into.

rxspeed7

iTrader: (5)

There's nothing wrong with cdi system. They do Usually provide a stronger spark but are far more expensive to put together and of course have more parts involved

RotaryEvolution

iTrader: (30)

you sure it was actually ignition break up? in my experience i have actually heard detonation occur with the powerFC maps unless they are aggressively scaled back beyond 14psi in the timing tables and split not too aggressive. even with a 10 degree split i was hearing and feeling detonation cycles happen with a moderately conservative fuel tune.

the knock sensor didn't pick up on this at all by the way, still was reading under 60 knock but i heard them with my knock ears clipped to the front rotor housing and felt the light hiccups. once the timing tables were reworked i could then feel the actual breakup from the richness of the tune. i only noticed this recently as i lost about 100 or so maps with my old laptop when it died and the knock ears i put together.

rxspeed7

iTrader: (5)

Knock ears? Copper tube style setup of electronic setup?

20B10AE

iTrader: (14)

For ease of installation and cost, I vote IGN-1A. I just installed these on my car. I'm still in the process of tuning fuel, but I've had no problems with a couple of severely rich instances. I'll provide more input as I can.

0110-M-P

iTrader: (10)

Yes, very hard to do...now I have a lot to take care of before driving it again.

I was honestly a little worried about the condition of my stock 550cc injectors (have 90k miles on them)....probably wouldn't be a bad idea to get the factory 850's sent off and flow tested, then throw those in place of the 550's. Should give me enough headroom then.

I was originally considering this, but if I can have a better inductive ignition setup (IGN-1A's) at a lower price, would that not be a better idea? The rewiring/custom mounting doesn't bother me much if it will be a more robust/stronger setup.

I'll definitely look into it because the more I think about it, the more I want to push it towards the 450whp mark.

Thanks

Thanks for the input. This is honestly the route that I would like to go (mostly for the cost), but don't want to do it unless it is a proven solution.

0110-M-P

iTrader: (10)

I am almost positive it was ignition break-up. I tried tuning my first engine, but it popped (posted my maps here and the general consensus was that it should have been a safe tune, just trying to get too much power out of a stock engine with 90k miles on it), so for this engine I took it to Bryan at Rotorsports Racing (Kannapolis, NC) and he handed it back over to me with this top-end ignition breakup. With as much rotary experience as he has, I really hope he can differentiate between detonation and ignition breakup.

fritts

iTrader: (5)

Just made 500 WHP on E85 with my IGN-1A's. Only break up I had was during initial tuning when I was in low 9's at high rpm. Cleans up as soon as you get to a reasonable AFR.

C. Ludwig

iTrader: (27)

The IGN coils are well proven. RXTASY57 is using them to 30 psi on his half bridge engine running E85. We've done a number of 400-500 whp setups with these coils with consistently good results. In the piston world, there are a number of guys making over 200 hp per hole with them.

The IGN-1A will make around 115mj spark energy at 3ms charge time. That's similar to the energy developed my the LS truck coil at 6 ms charge. The MSD 6 boxes, and most "street" capable CDIs are in that 105-130mj output range as well. We've run the IGN coils up to 4.5ms of charge time full time without issues. They can be run up to 6.0ms for short durations and will develop around 250mj output with that amount of dwell. You will damage them if you dwell them that long all the time though. So you'll need an ECU capable of throttling the coil dwell in order to completely maximize their potential. The PFC allows you to setup dwell versus RPM.

Another upside to a good inductive coil versus the CDI option is the longer spark duration of the inductive coil. Same spark energy that lasts longer is a benefit. This is why CDI ignitions employ a multiple spark strategy. One short duration burst, no matter how hot, has trouble properly igniting the mixture, especially in the less than ideal environments of the rotary combustion chamber.

Only issues with CDI are encountered during installation. MSD especially is bad about emitting EMI. Make sure to take care to place the box itself or it's power leads that run to the battery well clear of the ECU, crank trigger, and signal lines. Common sense really, but if not done correctly will play havoc with everything.

CDI has a place and can work very well. But at the power level the OP is looking for, there simply isn't the need for the complexity or expense of a CDI system.

0110-M-P

iTrader: (10)

So the IGN-1A's are sounding very promising. It just seems like they can't be beat for the price.

Anyone have any other thoughts?

KNONFS

iTrader: (14)

Can a HKS twinpower be used in conjuctionwith the IGN-1As?

RotaryEvolution

iTrader: (30)

electronic, did a writeup in the 2nd gen section for anyone who wanted to try them out for themselves.
https://www.rx7club.com/2nd-generation-specific-1986-1992-17/diy-knock-ears-980837/

kind of ghetto but they work decently. i do need to get some better cable for the mic extension as it does pick up a bit of electrical static noise with the CAT5 cable(all i could find for shielded cable in Fry's).

C. Ludwig

iTrader: (27)

No.

XLR8

iTrader: (52)

With your power level....

The Twin Power is a nice unit that works quite well. My power is in my sig and it works flawlessly on all 9 plugs. Takes 5 min to install and I purchased it for less than $400.

As far as OEM coils go, the stock location is terrible and contributes to much of their failure and weakness. I relocated mine just below the steering arm.

Another great option with the Twin Power is the LSX coils. I will probably switch to these as I turn up the boost with AI. Dale Clark had a simple write-up on installing them. I think it is a great setup for relatively little cost.

KNONFS

iTrader: (14)

MSD 6A or equivalent?

I have an unistalled HKS twin power, but I am liking what I'm reading about the IGN setup

C. Ludwig

iTrader: (27)

There are several versions of the Mercury coils. The IGN-1A has a built-in ignitor (AEM calls their rebadged version a "smart" coil). Because of that, it won't work with a CDI.

There is also the Mercury IGN, without internal ignitor (AEM calls it the "dumb" coil). This coil can work with CDI, but it is designed to be used in inductive applications. This is the same coil Electromotive has used with their direct-fire systems for years.

There is an IGN-CD coil. The windings of this coil are specifically designed for use with CDI. It's the same case as the other IGN coils, just wound with a lower internal resistance. Not available through AEM. Only place I know to source these is through Lance Nist of Pantera EFI.

The other option for CDI is the Mercury Thunderbolt coil. This is what M&W offers and we supply with their systems. Very low internal resistance for great results with CDI boxes.

All things are relative, and there are a lot of variables that play into it. But IMO, for anything 25 psi and under (boost pressure being the easiest generalization to use), I wouldn't consider anything other than the IGN-1A coils. They do the job as well as anything else, are less expensive than CDI, and a little easier to install. Over that and the M&W boxes are a great, one box, 4-channel solution for the rotary engine.

The IGN coil will require a minimum of a 20 amp ignitor (hard to find!) to achieve it's full potential, and with the lack of knowledge of how the Twin Power actually works, I wouldn't use the two together and actually expect it to work well.

Trots*88TII-AE*

iTrader: (11)

To the OP, not to sway your decision either way, but I have exactly what you need as far as MSD parts for sale right now in my thread. If you do decide to go CDI and want to save almost 1/2 the price, hit me up and we can work something out...

0110-M-P

iTrader: (10)

I'm sold. Thanks for all the information.

I actually saw that before posting this thread because it aligned with my original plan from a few years ago. Then I posted this thread to see other options and now I'm sold on the IGN-1A setup due to its simplicity and robustness.

Jobro

iTrader: (2)

FWIW Ludwig's comments and the mention of the 'Huber Mustang' convinced me to buy a set of IGN-1A's. My Level of tune is 124mph down the 1/4 mile not 100% sorted.

Anyway I'm a strong believer in pre turbo water injection but I've been too lazy to setup my new water injection valve for ages (like over a year).

I had been using cheap pump E85 all for about 15months, the whole time minimum 17psi on a 9.4:1 motor. What I did was disable the water injection and remove the oil cap whenever I'm at the track. I also changed over from BUR7EQ and BUR9EQ to R7420-9 and R7420-105.

My missfire problems have not reared their head even hitting 22psi lately and that is using 100% factory FC3S ignition system and cheap leads from a good local parts shop.

I'm not having miss fire problems but I'm pretty sure I will once I start using the water again, and then I will retest with 100% sequential ignition and the IGN-1As.

BLUE TII

iTrader: (9)

The bad-

Besides initial cost of CDI unit(s) is the cost of constantly replacing plugs.

I turned multistrike off on my Crane HI6 to LX92 coil for each of the leading plugs and still have to constantly change plugs because the electrode has worn out (stock style surface discharge) or the ground strap is worn out (standard style iridium plugs). Its about once a month.

If your CDI box has a boost input so it only increased spark with boost onset I imagine plugs would last much longer.

My Crane HI6 is also a bad option because it requires an external 12V jumper to fire 4cyl or it will start firing 8cyl. Another point of failure.

Took me a while to find that the body shop had neglected to plug one of these jumpers in when they put the front bumper back on...

The good is-

When I had my car tuned it made a little bit of power leaning from low 10s to 11:1AFR and then no power leaning past 11:1AFR.
I believe most the power people get from leaning out turbo rotaries is from eliminating misfire events. High EGTs are also a result of these misfires.

The AFR read at the exhaust pipe is the waste gasses of all the chamber, not just the parts that contributed to combustion.

Think of all the cold spots and combustion ineffieciencies of the rotary compared to a piston engine and look at best power AFRs on turbo piston engine cars. Shouldn't we be running quite a bit "richer".

Jobro

iTrader: (2)

Lambda sensors work by measuring the amount of remaining oxygen in the tailpipe. If you have bad cycles the mixture will read leaner than it should rather than richer. It is a common misconception in most of the tuning circles on the internet.

With non-oxygenated petrol in theory the power should keep going up until you hit 12.5:1 mixture. I know for sure people are tuning boosted road pistons on pump fuel at mixtures 11.5-11.8 even 12.0 12.2:1. They can make them survive and work so they do it.

I tried the leaning it out thing and I also came to the conclusion my mixture was right.