Distributorless Ignition System

decoupe

decoupe

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Has anyone had any experience with an electrontic Distributorless Ignition System such as the XDI( http://www.racetep.com/electrotechpx.html )? The car has issues with high compression, premium pump gas, a hotter cam, advance and altitude (4,000 - 7,000').

Maybe the longer duration spark combined with a MAP sensor for vacuum advance of the XDI would help. The other alternative is to lower the compression by milling the pistons which would mean a lot of "out of body work".
 
Alternatively, you could drop in a thicker head gasket. Much cheaper than milling the pistons.

Also, rather than halfing and getting the XDI, you could go full standalone DME using MegaSquirt for less than half the cost of the XDI. I have heard of these guys before, a lot of the FI-ed E36 guys use their Tec3 system.
 
Ignition and Compression

Hadn't thought of the thicker head gasket. Any idea as to the range available or who sells them?

We have a WSC tube frame car with a 1.8 Toyota mill, twin 45 DCOE's and the MDI Ignition but it runs on race gas so the issues are different. It is probably overkill for the street but solves several problems and very easy to work with. Timing set with a volt meter.

Does the MEGA Squirt work with carburators - thought it was FI only?
 
Todd at Turbocharging Dynamics could give you some leads as to the gasket. Heck, he'll probably sell you one. I think they make them in thicknesses as high as .140", which drops the CR of the M50 from 10:1 down to about 8:1, if memory serves. These thicker gaskets are also supposed to be much stronger than stock, and not just because of the additional material. I think the main brand name is Cometic.

As for MegaSquirt, considering how the whole thing is very modular, and has a MAP sensor included as part of the system, I can't imagine why it wouldn't work. Try looking in the MegaSquirt forums.
 
Those pistons are forged Arias parts and have flat crowns. The head should not be high compression. It was skimmed but I don't believe it was cut sufficiently to raise the compression ratio significantly. Honestly I don't know what the CR is but I would be surprised if it was higher than 9:1. Is the engine pinging badly? Have you tried retarding the spark?
 
Ignition and Compression

Thanks for the info on the head gaskets - I recall seeing the name. Hopefully I don't need one.

TJ - Good to know about the CR and piston shape. I had the car into a shop with a dynopak 248 and a portable wide band gas analyzer which finally got the jetting sorted out for altitude. As a consequence the car runs very well - closer to what it did at sea level though you can't make up for thin air.

Both power and torque increased very significantly as did mileage (how often does that happen) once the mains were reduced (.130) and the air jets increased( .220). I had installed a simple fuel air meter and was chasing the main jets with the air jet size but was just way to agressive with the mains (.150) given the altitude. I would have got there eventually but I love a quick fix if it can be found.

One thing that was apparent was the advance necessary for the mid to high end power (25 degrees) made the idle and low end to lean. So it is set at 13 degrees at idle which gives a good compromise overall and is very driveable but reduces power in the 4 - 6000 range. I've got some questions about the mechanical advance system you installed I'll email cowpokeracing.com if that's alright with you after I scan the dyno graph's to pdf.

Appreciate the comments, as always.
 
Have you considered using a simple Pertronix unit to get a more prices spark. Also what about a hot coil and P4 bosch plugs? Rique
 
SDI

Malc - you're amazing. These guys are in Calgary, 40 minutes from me and they have a hanger at the same airport as we do.

Unfortunately it looks like the system is fuel and ignition management for EFI only but there is a note about conversion of older carburator engines so I'll talk to them next week just in case. Don't think I'm ready to switch from the Weber's.

Doug
 
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