Notching the bell housing worth it?
01-12-2012, 05:02 PM
#32
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01-12-2012, 05:47 PM
#34
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Yes true i would have liked that way. however having everything up front is so much easier in every way. If you can install it right it can be clean as well. There are tons of cars bmw for example that have the sensor up front as stock location using 60-2 wheel. Modded how do you have urs mounted? I have mine up front.
01-12-2012, 08:21 PM
#36
Yes true i would have liked that way. however having everything up front is so much easier in every way. If you can install it right it can be clean as well. There are tons of cars bmw for example that have the sensor up front as stock location using 60-2 wheel. Modded how do you have urs mounted? I have mine up front.
01-13-2012, 04:42 AM
#37
Adding sensors at the front of the engine is anything but cleaner than stock.
How does it "make things easier"?
If people have to mess up with their sensors everyday, then there is something wrong with their set ups to begin with.
A sensor at the front of the engine will always be in the way of accessing the belts, and having to remove and reinstall the sensor each time the belts are being accessed means increasing the risk to misadjust it when installing it back.
At the stock location, it is set once, and can be replaced afterwards without having to readjust its height.
How does it "make things easier"?
If people have to mess up with their sensors everyday, then there is something wrong with their set ups to begin with.
A sensor at the front of the engine will always be in the way of accessing the belts, and having to remove and reinstall the sensor each time the belts are being accessed means increasing the risk to misadjust it when installing it back.
At the stock location, it is set once, and can be replaced afterwards without having to readjust its height.
Last edited by Thom; 01-13-2012 at 05:14 AM.
01-13-2012, 09:14 AM
#38
Race Car
Adding sensors at the front of the engine is anything but cleaner than stock.
How does it "make things easier"?
If people have to mess up with their sensors everyday, then there is something wrong with their set ups to begin with.
A sensor at the front of the engine will always be in the way of accessing the belts, and having to remove and reinstall the sensor each time the belts are being accessed means increasing the risk to misadjust it when installing it back.
At the stock location, it is set once, and can be replaced afterwards without having to readjust its height.
How does it "make things easier"?
If people have to mess up with their sensors everyday, then there is something wrong with their set ups to begin with.
A sensor at the front of the engine will always be in the way of accessing the belts, and having to remove and reinstall the sensor each time the belts are being accessed means increasing the risk to misadjust it when installing it back.
At the stock location, it is set once, and can be replaced afterwards without having to readjust its height.
As I said, I'm putting mine in the factory location, and I'm going to manipulate the trigger, rather than the pickup. But if I were not pulling the engine (or specifically, then flywheel), there is no way on earth I would go through that effort just to keep the factory location. I'd be in touch with Chris right away. Probably be stuck trying to figure out something else given my preference for a Ford system (36-1) over the Bosch system (60-2). But I'd rather change that than pull the flywheel.
01-13-2012, 09:39 AM
#39
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I can offer up a technical answer on a couple of things –
There is an optimal crank angle position for the location of a crank sensor – it is just before the maximum ignition timing angle. Typically you don’t want / need to run more the 40 degrees of ignition advance (the Autothority chips run more than 40 degrees off boost timing!), so you would want the crank sensor to use a location signal that is just before that point. With the 60-2 tooth trigger wheel and the Electromotive system the position of the crank sensor should be 11 teeth before TDC (66 degrees). You can change this in the advanced settings if you have some sort of restraint in the mounting, but the 66 degree position is strongly preferred. The Haltech system recommends a position between 60 to 75 degrees.
The front mount trigger wheel that I have is laser cut to fit inside the belt housing, it uses the flange on the ribbed pulley drive to locate it for zero runout and it uses the four bolts to line up the trigger wheel timing to the correct location (66 degrees before TDC with the supplied crank sensor mount).
So it does “make things easier” since the optimum timing location is set up in the design. Yes, it does have to be reset when you mess around with the front end (and to paraphrase a post – “f people have to mess up their front end everyday, then there is something wrong with their set ups to begin with”!)
What about the stock sensors?
The 951 set up uses two sensors (twice the failure rate, twice the replacement cost, and twice the probability of them seizing in place) - one to count the teeth on the starter ring gear (which is not the optimal square tooth pattern – it does not produce a clean square wave signal) and one to count the set screw that is the TDC locator. If you are using a standalone system that allows for use of the stock triggers then you are adding a software based emulator to calculate the crank angle. Hopefully its not Microsoft based (<- humor)!
The 944 S2 based flywheel has the 60-2 tooth design instead of the ring gear system (see – even Porsche upgraded their EMS components!). The problem with the S2 set up is that the flywheel uses a smaller diameter clutch and pressure plate. The size difference is not a problem for clamping ability – but it does mean that you have to replace the whole clutch/pressure plate and flywheel to convert. The other problem is that the S2 flywheel uses a sensor location puts the TDC signal at 20 teeth before TDC – that’s 120 degrees instead of 66. Most engine management systems can compensate for this - but it is less than optimal.
To some people (mostly racers and track addicts) the ease of replacement of any mission critical sensor is a plus. I cannot imagine changing an old stock crank sensor at the track (and I have replaced head gaskets at the track!). More than half of the stock crank sensors I have had to replace had to be destroyed to remove them. And since you mentioned setting the sensor height….yeah, that’s fun (and accurate) system….not! On the front mount set up I can set that to a couple of thousandths in a minute – without loosing any skin on the back of my hand!
Here is a pic of an S2 flywheel for those of you that have not seen one –
And a pic of what the cool racers use….
There is an optimal crank angle position for the location of a crank sensor – it is just before the maximum ignition timing angle. Typically you don’t want / need to run more the 40 degrees of ignition advance (the Autothority chips run more than 40 degrees off boost timing!), so you would want the crank sensor to use a location signal that is just before that point. With the 60-2 tooth trigger wheel and the Electromotive system the position of the crank sensor should be 11 teeth before TDC (66 degrees). You can change this in the advanced settings if you have some sort of restraint in the mounting, but the 66 degree position is strongly preferred. The Haltech system recommends a position between 60 to 75 degrees.
The front mount trigger wheel that I have is laser cut to fit inside the belt housing, it uses the flange on the ribbed pulley drive to locate it for zero runout and it uses the four bolts to line up the trigger wheel timing to the correct location (66 degrees before TDC with the supplied crank sensor mount).
So it does “make things easier” since the optimum timing location is set up in the design. Yes, it does have to be reset when you mess around with the front end (and to paraphrase a post – “f people have to mess up their front end everyday, then there is something wrong with their set ups to begin with”!)
What about the stock sensors?
The 951 set up uses two sensors (twice the failure rate, twice the replacement cost, and twice the probability of them seizing in place) - one to count the teeth on the starter ring gear (which is not the optimal square tooth pattern – it does not produce a clean square wave signal) and one to count the set screw that is the TDC locator. If you are using a standalone system that allows for use of the stock triggers then you are adding a software based emulator to calculate the crank angle. Hopefully its not Microsoft based (<- humor)!
The 944 S2 based flywheel has the 60-2 tooth design instead of the ring gear system (see – even Porsche upgraded their EMS components!). The problem with the S2 set up is that the flywheel uses a smaller diameter clutch and pressure plate. The size difference is not a problem for clamping ability – but it does mean that you have to replace the whole clutch/pressure plate and flywheel to convert. The other problem is that the S2 flywheel uses a sensor location puts the TDC signal at 20 teeth before TDC – that’s 120 degrees instead of 66. Most engine management systems can compensate for this - but it is less than optimal.
To some people (mostly racers and track addicts) the ease of replacement of any mission critical sensor is a plus. I cannot imagine changing an old stock crank sensor at the track (and I have replaced head gaskets at the track!). More than half of the stock crank sensors I have had to replace had to be destroyed to remove them. And since you mentioned setting the sensor height….yeah, that’s fun (and accurate) system….not! On the front mount set up I can set that to a couple of thousandths in a minute – without loosing any skin on the back of my hand!
Here is a pic of an S2 flywheel for those of you that have not seen one –
And a pic of what the cool racers use….
01-13-2012, 10:44 AM
#42
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Chris, We discussed this subject here.
A 132 teeth gear allows more speed resolution than a 60-2 unit, out of the box.
A 132 teeth gear allows more speed resolution than a 60-2 unit, out of the box.
Here is a little math for you – with a 132 tooth gear at 7000rpm the time between teeth is .065 milliseconds. Is your system calculating the position, speed and change in speed every .065ms? Or is it using a software emulator to calculate the position? BTW - .065ms is 15,400 position calculations per second. While a decent CPU would not have a problem most emulators reduce the complexity of the signal quite a bit – and that gives up any benefit of more teeth!
BTW – there are some systems out there that calculate engine speed once a revolution. They can use all 132 teeth to do that, but in the end they are just counting teeth to figure out when the engine has made one revolution and then the ECU figures out the timing. That lowers the resolution from 132 teeth impulses to 1 revolution signal. Hopefully those type systems are fading out…but they are still out there!
01-13-2012, 01:39 PM
#44
Nordschleife Master
In all fairness Chris, I have met one or two 944 owners that have hands MUCH smaller than yours... I'm sure they could just reach right in there to the rear mount sensors...
01-13-2012, 01:46 PM
#45
While I have no doubt that most modern ECUs can handle all teeth, can the now-dated factory Motronic also count them all?