speedb

Hi all, I have a '94 with some blown coils. Since I'm not too interested in spending $300+ on a new pair, I thought I'd take a closer look at COPs, since they seem to run without issue on 94-95.5 cars.
I'm leaning towards R8 coils, but it seems like very few have chosen to install them, despite units from reputable manufacturers being more powerful and half the price of the toyota COPs on RA.
I'm wondering if anyone other than vendors have tried to install these coils on a stock ECU?
Vendors for pre-made assemblies claim that the current draw is too high for all but the most expensive standalone ECUs, but I wonder if using a high-powered resistor on the 12V input will be enough to solve the problem?

SpartanSV

Get a used pair of OEM coils for $60 shipped on ebay if you're certain your coils are bad. They're very reliable and handle far more than stock rods if you use good plugs and gap them properly.

Read about dwell. Once we you understand it you'll realize how stupid it is to try to run any aftermarket coil on a stock ecu.

speedb

Dwell-related problems are mostly relegated to NBs. There are people on this forum and miata.net who have been running toyota COPs on their NAs for years, with stock ECUs.

In addition, the design of the R8 coils (using a heat sink that runs along the boot) and their ability to run with a longer dwell setting would suggest a lower risk of failure. On top of this, using a resistor to reduce current draw would logically reduce the energy going to the coil, causing a small reduction in spark energy and further reducing thermal energy in the system.

where on ebay do you see OEM coils for $60? Everything there is in excess of 150$ when shipping is taken into account. A new set of NGK R8 coils from rockauto, as well as the resistor and wiring harness will be around half the price.

SpartanSV

https://www.ebay.com/itm/37293418678...temCondition=4

$60 shipped as I stated before.

I don't know what your point is about NB dwell issues? Are you saying people who ran Toyota cops on NBs are the only ones with issues? I'm aware people have done Toyota cops on stock ecu. I stand by my statement that it's a stupid thing to do.

My point about dwell is that appropriate dwell is going to depend on the coils being used. Not enough dwell and you have weak spark. To much and you overheat the coils. Have you compared R8 coil dwell times to a Miata?
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The current requirement issue on R8 coils is on the signal wire. I haven't looked into the design of a smart coil but if it's just a MOSFET being triggered by the ecu then adding a resistor is probably going to cause the MOSFET to turn on to slowly and generate a ton of heat. Also probably messes with required dwell time.