Crank Triggers And Rb Possibilities .

[PSI086]

Very basic set up I did for my RB30. 3 slots in the balancer @ 120deg intervals (works out to 1 tooth per cylinder) and a Honeywell GT101 sensor. Have not had a single issue with it and cost me about $60 for the sensor

[DVS JEZ]

Very nice, What did u run as the cam sensor?

[discopotato03]

Yes interesting idea thanks for that pic . For those of us that haven't had much to do with RB crank pulleys is that a modified RB25 one and do you have any pics of the back of it ?

I'm all for simple mods particularly to std components and if the notches don't damage the belt that's probably as simple as it gets to be .

The thing I'd like to know is does having more notches make the tuning results any better . I've read about toothed wheels having different numbers of teeth based around dividing into 360 ie 36 30 24 for 10 12 and 15 crank degrees .

Someone thats really into the electronic side would know if its necessary (for some computers) to have the tooth/notch count divisible by the number of cylinders as well .

Compared with rocking up to Nissan and being bitten $1300 for a new CAS this is lookng really good IMO .

Cheers A .

[rob82]

Yes interesting idea thanks for that pic . For those of us that haven't had much to do with RB crank pulleys is that a modified RB25 one and do you have any pics of the back of it ?

I'm all for simple mods particularly to std components and if the notches don't damage the belt that's probably as simple as it gets to be .

The thing I'd like to know is does having more notches make the tuning results any better . I've read about toothed wheels having different numbers of teeth based around dividing into 360 ie 36 30 24 for 10 12 and 15 crank degrees .

Someone thats really into the electronic side would know if its necessary (for some computers) to have the tooth/notch count divisible by the number of cylinders as well .

Compared with rocking up to Nissan and being bitten $1300 for a new CAS this is lookng really good IMO .

Cheers A .

More teeth gives you a better ability to resolve smaller crank angles so in reality you should gain accuracy of the estimated crank angle. However it is dependent upon software and how the crank angle is calculated.

[r33_racer]

If you have too many teeth won't some ecu's lose resolution? As in too many teeth spinning past the sensor and it can lose track of their position?

[rob82]

If you have too many teeth won't some ecu's lose resolution? As in too many teeth spinning past the sensor and it can lose track of their position?

If you miss a tooth your your in a world of hurt as your ignition event will then be (360/total number of teeth) out. The issues I've seen with too many teeth is when there is a bit of crank/cam flex which causes the triggering edge of the cam sensor to move past the triggering edge of the crank sensor. Have seen this issue on motronic 60-2 triggers where your cam triggering event only has a 6degree window.

[GTSBoy]

There are problems both ways.

You can try to get away with the barest minimum number of trigger events per cycle. That way you only have to look for 1 event every so often and do what you have to do at that time. But if you have to do something at some other time that lies between your sparsely scattered triggers, then you have to start interpolating between them to estimate. My following discussion uses angles that I've just made up that have no specific relationship to any real events. They're just for examlpe.

Let's say you have a trigger event 50° before you want to do something but there are no other trigger events between that one and the thing you want to do (such as fire a spark). Because you know from your last 2 revolutions what the rpm is, you can wait a certain number of milliseconds until that 50° has passed and then do your thing. But if the rpm is changing during that revolution (and on hipo motors it can change an appreciable amount in each revolution) then your event will be done at the wrong engine position.

So the thing that any reasonable engineer would do is then put in more trigger events so that you can keep track of what position the engine is at. So let's say you put in 4 times as many trigger events. Now you'd probably still keep one major event per rev to keep track of whole revolutions and give a simple way to get rpm, but with the extra events you may well have one or more of these extra events occur between your actual trigger (50° before your spark say) and the spark. Now you can monitor these extra events and keep track of teh rate of change of engine position and do a better job of getting your spark event to occur at the right position.

So you can continue this until you have gone to a fair extreme, like Nissan did with 360 slots. Now you can notionally know where the engine is to the degree, which is probably over the top. But this is where you start to have other problems. Like someone else said above, if you are relying on seeing every single one of those events, and you start missing them, then you are in a world of hurt. So again, any sensible engineer would make sure that they do not rely on seeing all of those slots. You have to have, at the very least, a single event per rev to keep you on track, and if you were smart, you'd probably also have a smaller number (like 1 per cylinder) to keep track of critical engine positions. That way if you miss a single degree slot, you don't get in strife. But it could get worse. If you have belt harmonics or some other craziness going on, it may be possible to see any given slot more than once (ie if its edge flickers back and forth past the optical detector). This would be just as bad as missing a slot.

I think this is probably where the Nissan system falls down. All those things people talk about (stiff valve springs, stretchy cam belts, etc) are probably all at least partially true and partially responsible for some of the failure to work properly that we see on these engines when we start to modify them a long way away from stock. If it were me designing it, I would have gone for 3 sets of triggers instead of just 2. And probably put at least the main engine position trigger on the crank instead of on the valvetrain.

[PSI086]

Very nice, What did u run as the cam sensor?

Currently using the factory cas with the sync wire hooked up on the trigger pin and a single slot in the chopper disc. I've bought another GT101 sensor though which I'm going to trigger with a stud off the cam. Engine is a RB30 running 6 LS2 coils but you would be able to do the same thing with a twin cam head off the exhaust cam

[discopotato03]

GTSboy I tink you've put the picture across pretty well and highlighted the point of enough trigger events to track rapid engine transients but not too many possibly causing "overlapping" crank/sync issues .

I did a bit of searching at Evomnet because I remembered David Buschur and some mob in the US doing a crank trigger plate for Evo 4G63Ts with more teeth . Std they use a pressed steel disc with two long teeth so to speak and a Hall sensor , it's clamped to the front of the crank by the lower timing belt drive wheel and I think acts as a guide for the balance shaft belt . AFAIK they run a cam reference or sync Hall trigger and use a waste spark ignition system .

I had a link to a mob called something like triggerdisc and interestingly they mentioned that Hall sensors are supposed to be more accurate and reliable that photo optic ones , not sure if there's anything in that .

The more I search the better the Ross system seems to look and I intend to contact them to see what a minimal kit costs ATM .

I have a link to a thread here where Piggas (Sp ?) used an early Ross system on his engine .

http://www.skylinesa...s-with-results/

http://blog.rossperf...am-trigger-kit/

Ross has optional bits for their RB system like the dry sump pump cog and an alternative drive/sensor/housing for the cam trigger but Mr Piggas used a std looking CAS , and I don't need the oil pump drive . I'm curious to know what a basic system of crank pulley and Hall sensor/mount costs and I also like the idea of retaining the std CAS .

For Mr PIS086 yours would be the simplest cheapest option but the one downfall could be if the outer or pulley section started to creep on the rubber dampening material . I don't know if RB pulleys do this and doing a new one is probably good insurance . Also if it had six notches it would double its resolution . I'm not insulting your idea at all because its so simple .

Will speak to Ross soon , cheers Adrian .

Edited January 5, 2013 by discopotato03

[brad 110]

Despite what many people on the forum say, Ross is a great guy. I run his full trigger kit on my race car and turn it past 9000, the Motec trigger trace is a perfect line, even with a brand new complete cas the log would look like a saw tooth over 6800 rpm, increasing valve spring pressures only aggravated the problem. The Dyno graphs showed measurable gains at high rpm. If anyone is interested I can post the screen capture of the pre and post logs.

[GTR_JOEY]

Despite what many people on the forum say, Ross is a great guy. I run his full trigger kit on my race car and turn it past 9000, the Motec trigger trace is a perfect line, even with a brand new complete cas the log would look like a saw tooth over 6800 rpm, increasing valve spring pressures only aggravated the problem. The Dyno graphs showed measurable gains at high rpm. If anyone is interested I can post the screen capture of the pre and post logs.

id be interested in seeing it Brad

[Piggaz]

The more I search the better the Ross system seems to look and I intend to contact them to see what a minimal kit costs ATM .

I have a link to a thread here where Piggas (Sp ?) used an early Ross system on his engine .

http://www.skylinesa...s-with-results/

My kit is the final finish product with the 34 - 2 tooth "chopper wheel". You have the option to either keep the OEM CAS or use a blanking plate. I kept it for ease of starting. The first versions had 12 teeth without a missing tooth.

[brad 110]

I will post it tomorrow, might have to be a photo of laptop screen unless someone can tell me how to capture screen view so I can attach to post. Cheers brad

[GTR_JOEY]

I will post it tomorrow, might have to be a photo of laptop screen unless someone can tell me how to capture screen view so I can attach to post. Cheers brad

The print screen button on the key board "Prtsc"

[brad 110]

Thank you ill post tomorrow, if you want the logs joe pm me you email address. You can run them if you grab i2. Ill post capture anyway, cheers

[GTR_JOEY]

Yep ill PM you now mate.. I've seen Piggaz results with the crank trigger, I also have a crank trigger so I would like to see how much difference there is in your case

[discopotato03]

Thanks everyone for the feedback particularly on the Ross kit . It is interesting that using a brand new OE CAS just for the cylinder reference pulse still made the signals saw tooth like . My guess for what its worth is the belt drive and optical pickup system .

I suppose if someone really wanted to use a std appearing CAS they could gut it and possibly rig a Hall sensor to read off the original discs anchor pin but its still fiddly work and costs money .

I guess the question to ask with the full Ross kit is does it take a few more crank revs to fire up initially , and if so is that a problem ?

Cheers Adrian .

[brad 110]

Answer to number of rotations to sync up and start no difference, in regards to the cas causing the saw tooth, there was no crank trigger on it at the time at all. The cas was responsible for trigger and home signal. I will post are a couple of screen captures of engine with brand new CAS v,s Ross trigger kit

[Piggaz]

It starts like a factory car with the Ross trigger kit.

[GTRNUR]

Starting speed will be determined by the ECU that is being used. Some will require a full 720 degree rotation to count the 6 sync and one reference before fuel and ignition will be enabled. Others will wait for the reference pulse and start fuel and ignition from there.