Heat and Semiconductors
I believe the stated 6,500rpm limit refers to V8 engines, therefore it would be 13,000 for our engines. I rev mine to up to 8,000 regularly and never experience any sort of ignition break down.
Thanks Rob, that was what I was asking as I couldn't find reference for 4,6,8 . . . cylinder settings in the Crane unit but as you confirm you sail past 6,500 and get 8,000 on your unit without issue so that's now irrelevent. I can't comment on why the current dizzy would be an issue if the internals are stripped out other than Willy's wrench guy was struggling.
As to the RPM issue, according to VAS, the 6500 limit is intended for V8 engines, so in theory it should be able to handle 13,000 in a 4-cyl. They say that the limit is actually lower but the coil will be the weakest link when trying to push crazy RPMs.
Willy
I'm glad you didn't run the white flag up and persisted with the optical unit you have at hand now the 6,500 query has been answered. Rob has already noted the coil to use that works the wrong coil often cooks the electronics so consider wisely. If you come unstuck with that dizzy and go a different direction I hope this link below helps discipher what fits, whilst the engine is still out plan and add whatever grommets/holes and wire trees you are going to need whilst you have access to the engine bay, or is that motor back in already? IMHO keep the ignition trigger loom away from the existing wiring looms or at least shield the trigger wires.
LUMENITION OPTRONIC AND PERFORMANCE IGNITION FITTING KIT IDENTIFICATION
http://www.bccp.nl/techdocs/Fittingkits.pdf
Tony
You may need to get 'around' a little more widely Papa Tony. In all seriousnes we need to ensure apples are compared with apples. The Old Pertronix has spread from Ignitor, Ignitor II and now Ignitor III systems, makes it hard to give a blanket recommendation later ones got smarter with adaptive dwell but would I buy one - No. PerTronix did buy Spyke that do stuff for VW and Harley's perhaps the new gear has evolved, I'm not too confident about that as Spyke made Compufire ( still magnetic drop in modules AFAIK). If the acquisition didn't get them any good patents there is better stuff around ( the unit type Willy is fitting being one of them ), choose optical over a magnetic dizzy triggers if you can. If you are talking crank angle sensors (CAS) on a pulley or flywheel where the resolution is better knock yourself out with a magnetic CAS but if the drop in dizzy module relies on little magnets on a disk proceed with caution. I have seen a Kombi on three cylinders because one of the magnets went walkies. Steve mentioned Lumenition. They do both kinds (Country & Western ! ?) they have Magnetronic ignition as well. I was a less than enthusiastic fan of their Optronic system because the shutter I saw was like a plastic fan with big blades corresponding to the number of cyl. If we are going to use the infrared spectrum as a dizzy trigger on an engine capable of over 8,000 RPM I'd like a rigid disk with as small a trigger slot as I can have to initiate the timing event. For example they guarantee accuracy to be +/-1° crank at 3000 rpm, what happens at 9,000 is that a linear or exponential error rate? For sure hands down they are superior to points that float at high RPM and for NA that's probably fine but EFI and high boost I get uneasy.
With any of these points replacement systems one thing a lot of folks forget is they still have to worry about the rotor button, is it clean and in good order - buy a good quality one. Choose a cheap Chinese knock off and your asking for trouble. The other issue with all these pickup systems is they still use the original old dizzy which is probably shagged. A cheap poorly made rotor button with the usual modern "mix" seen in the injection molding which often contains more carbon blacking so is more conductive. Combine this with the rivet which holds the brass inlay strip into the molding which can be slightly longer than the original, it is now probably too close to the spring clip in the shaft hole. Whammo !! The improved high tension current, probably 30,000 volts, seeks out the easiest route to earth and shorts out from the tip of the overlength rivet, through the reduced thickness of more conductive plastic and the spring clip on the underside of the rotor arm, straight to earth down the distributor shaft.
Result - missfire with no spark at the plugs.
Folks wrongly blame the points replacement kit and scratch their heads as they trouble shoot in their garage as the problem often rectifies itself on cooling, but then re-occurs with increasing frequency until the rotor permanently short circuits. Never in their wildest dreams do they make the mental leap that it is not the '****ty electronic kit' but a crappy rotor button that is not part of the solid state nature of the kit. So buy a good rotor button at step one. Two if you gotta keep the dizzy is it floppy and need re-bushing?
This subject is a bit like Oil/Tyre threads on the Web, I have had ding dong arguments with 'old timers' some who were under 30yrs who tried whatever 'new system' it was and got all grumpy when they couldn't get it to work and said points were superior and less trouble ( faceplant ). I try and help but give up easily now and leave them to it. Turned out that one bozo left the ignition on for 30 minutes with the optical switch assembly disconnected whilst he was 'trouble shooting'= toasted it. I guess the reason I prefer systems like the Allsion/Crane is that they keep the pick up separate from the amplifier/electronics and the one Willy is struggling with looks like it has generous casing to hold the 'brains'. Heat is a solid state chip killer whilst I liked Bob's ICM conversion, as its pretty neat, I get shivvers about containing an ignition module in an enclosed space. If you ever get the chance where a ignition module is accessible in an engine bay, go for a high speed run pop the bonnet and feel how 'warm' those suckers can get. On a sports sedan I was asked to look at the "intermittent missfire". It was a heat issue and it wasn't intermittent after I asked some questions as it often happened when ambient temp was high and the driver was drafting. Once the tight engine bay warmed up the module had no way of getting rid of a ton of heat and was breaking down. You could have fried an egg on it, 10 mins with a Dewalt drill, hacksaw, a bit of 1/8 alloy sheet and some heat sink compound = problem solved. Lesson there was if you are going to use a heat sink use thermal compound on the backside of the module, heat transfer is dramatically improved. For me its free airflow, away from heat / moisture and bolted to a big FAT heatsink with heat conductive paste. I smother exposed spades in a product like Dow Corning 732 non drying silicone to keep the moisture away, even under the little booties these ignition modules have on their OEM plugs. Look it up it's 'the shizz'(as the young fella says - whatever that means), for stopping wiring from shorting. He likes driving thru rivers for some unknown reason, people invented bridges for that a long time ago, but whatever makes him happy.
Once upon a time we used big hot round metal cased transitors to switch current and that has moved on to MOSFET chips. Gate oxide layers (which are shrinking along with gate length) are now only several atoms thick, and leakage current management has become a large problem in electronics. IMHO gate oxides thinner than one atom are improbable but I am a nosey parker and this is one of the first things I look at, I have openned up casings if a vendor can't tell me whats in it. Depends on the type of FET or MOSFET but are they big enough, well heat sinked, a good brand with history or some hobbled together bit that was cheap.
I was having a VERY heated discussion with someone who should have known better about solid state memory modules and how heat you and I would find very uncomfortable walking around in was detrimental to their life. For example most folks think a SD memory cards lasts forever - nope. Defined read/write life is decades if treated well but life at over 60 deg Celsius its sh0ckingly poor. Papa Tony this is all a very abstract concept but heat is the enemy of reliable electronics, keeping those components out of harms way is a good step. Bernice mentioned some luminaries at Fairchild some time ago at the link you will find one of their white papers. Pour some sippin' mash and skim most of it but start to focus on where it starts at
5.6. Drain-Source Breakdown Voltage (BVDS Breakdown Voltage Temperature)
www.fairchildsemi.com/an/AN/AN-9010.pdf
Summary if you like (I know you like summaries)
when these chips get too hot avalanche breakdown appears = bad ju ju. The avalanche current from the drain-body diode activates the parasitic bipolar transistor. This causes the MOSFET to fail. Keep these cool and they last longer, ever been in a computer server farm? They have some pretty heavy duty air conditioning, an old school buddy who is in IT management has some pretty convincing arguments as to why we should move ALL the big server farms to the Arctic, the amount of energy that goes into cooling versus pushing electrons (data) is interesting. Will never happen but you don't need aircon where there's ice n snow on the ground.
Sorry waffling again. . . .
If anyone does run a Pertronix keep an eagle eye on the coil condition and the voltage specs of what its feed, it will last longer. The ones that I see dead are usually because they were just 'slapped' into the engine bay. No attention to battery condition or how to offer the solid state components any respect.
The old original Pertronix kits were okay in their day and I did have some success with a VW beetle engine as a kid. Of the old Pertronix I was told of low volts on extended cranking often being the suspect by an automotive electrician whom has done some pretty fancy work. If the packaging says it won't like a range of say 9 to 15 volts choose something else, for example modern programmable gear will have tables to allow you to compensate for low volts on cranking to 'see' the crank sensor. I'd avoid anything that can generate EMF where other options exist, or shield the bejesus out of it. That VW motor and the one you describe Tony are both low RPM engines, the Alison/Crane would probably be a good choice but the Lampredi SOHC spins past 6,500 RPM where all the fun starts - that's what peaked my interest in Willy's situation. Thanks to Rob we know that it indeed goes to 8,000 in real life, he seems happy with it so that is good enough a recommendation for me to go the Crane over a Pertronix.
So Sorry if I caused unnecessary anxiety
Sandy
