Spinny 3ngls

just out of curiosity has anyone installed a multi-spark capacitive discharge ignition system(like Jacobs or MSD) yet? If yes which one and how much? If not is it even possible with the unique nature of the rotary? Thanks in advance for any insight.

NAVILESRX8

iTrader: (1)

You can use MSD type ignitions in a Rotary, just on the leading ignition though. I don't know much about the renesis, and how it would benefit, though.

rotarygod

You could use them on PAST rotaries ('86- until Renesis) because the leading plugs in both chambers always fired at the same time as the other. This was referred to as wasted spark mode since the additional firing by the plugs was on the exhaust side of the apex seals. The MSD box (or any other) was fed a signal from the leading output of the ignition system. The MSD box fired a pair of coils simultaneously to the leading plugs. In order to fire the trailing plugs off of an MSD, 2 more boxes were needed for a total of 3 ignition boxes! Since the trailing plugs fire independently of the other one, they can not be run off of the same box as each other. Neither trailing plug fires at the same time as the leading plugs either. The created the need for 3 boxes to fire at 3 independent times. On the old distributer equipped RX-7's, 1 box could be used before the distributer since the distributer seperates the firing sequence internally. Those cars could also be converted to the later system by picking up the leading plugs signal before the ignitor in the ditributer. This signal could be run to an MSD box and then directly to 2 leading coils. The leading coils ran off of the MSD and the trailing plugs still fired off of 1 coil through the distributer. This is how I run my 1st gen RX-7 and it is superior to the distributer system. This now takes us to the RX-8.

At this time I have not heard of anyone using an MSD or equivalent on the Renesis. There are some main problems which make it harder on this car than on the previous rotaries. First of all, the coils are very small and get very hot. A few people have already burned them out just playing with spark duration. We aren't even talking about running more juice through them. They would probably not live very long. It is my opinion that new aftermarket coils should be used if an MSD type of system is to be used. The next problem is that all 4 plugs fire independently of each other. No more wasted spark mode. This means that we either need 2 boxes for only the leading plugs or 4 boxes total if we want to boost the entire system. We also need 4 new coils. I don't know where anyone is going to fit all of this under the hood yet alone be willing to pay for it. I'm fairly sure it can be done but it would not be cheap and would be a big hassle. A hotter spark may help the poor little trailing plugs light off the engine faster and help the flooding issues some.

I hope that shed some light on the subject.

RX-8 friend

Have a look under the intake rubber tube from the air filter to the MAF. You will see four small ignition coils. You would need to replace these with four MSDs complete with coils. Just for everyone's info. the output from the ECU is +3V 4mS pulse to fire the coil. The stock coils are not just coils, they are also transistor amplifiers. Hence, you need an electronic box and coil to replace each one.

Also, a warning. If you feel the need to do this, be aware that a truly better ignition spark will have the effect of "leaning" the mixture, as it will burn more quickly and more completely. IF you were on the edge of detonation, it would put you over that edge.

Spinny 3ngls

I thinking a maximum gain of about 10 hp (optimintically speaking) with a total setup price of at least $1000.00 it sounds like the $6900 turbo kit is a better bang for the buck. thanks alot guys.

Stic

at the risk of sounding really stupid, can' t you just use a different ignition by MSD, perhaps one that is used on a piston engine (for example a v-8 or v-6) that way you won't need so many boxes to do the same thing? I'm guessing not b/c no one else has brought it up.......and i know next to nothing about ignition systems..just throwing something out there.

Stic

hmm well that isn't my name..but oh well. it's supposed to read army_rx8. don't you love technology

Japan8

Do a search guys.... Maniac has setup an E-manage and MSD box on his 8. He's got wiring diagrams and all for you.

RX-8 Friend, so what happens if you get a better ignition spark and run Stage 1.1?