VWDiesel.net The IDI, TDI, and mTDI source.
Engine Specific Info and Questions => IDI Engine => Topic started by: Jetmugg on May 29, 2013, 07:55:43 am
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Yesterday, I had a "brain flash" that I would like to share, and take feedback.
I'm building a 1.5 VW diesel for a land speed record attempt. I do not need or want a vacuum pump on this engine. I'm thinking of putting a conventional gasser distributor in its place, and using the spark signal from the coil to trigger a tachometer.
Any thoughts on this idea? It would use factory parts, requiring nothing to be welded to the crank pulley and would not need fabricated brackets to hold a magnetic sensor.
Why not?
Steve.
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I may be remembering wrong but I believe the helical gear on the diesels is cut in the opposite direction to the gassers as the IM shaft spins the opposite way, but the oil pump still turns the same way.
There is factory hardware out there to delete the vacuum pump, though it is not particularly common. These diesels were used in some generator or marine applications where a vacuum pump wasn't needed.
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Further to that, one of the most elegant way of triggering a tach I've seen so far is using a sensor attached to the timing belt cover pointed at the cam or IP pulley, and then a couple of marks or magnets (depending on sensor type) attached to the pulley.
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Yea the diesel intermediate shaft spins the opposite direction, its probably easiest for you to use a dakota digital converter with the dodge cluster and a vw alternator with w terminal or an aftermarket diesel tach, although it is hard to find one that goes to 6k
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I know a lot of folks prefer analog tachs but I installed a "tiny-tach" which uses the pulse from one of the steel injector lines - flawless. No moving parts, and several other functions as well. I believe you can even set an alarm. I don't know the upper RPM limit offhand but I'm sure its well over 6,000
OK - here's a link http://tinytach.com/diesel.php (http://tinytach.com/diesel.php)
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jett... they made factory non vac pump parts, oil pump, gear and cap...
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I know a lot of folks prefer analog tachs but I installed a "tiny-tach" which uses the pulse from one of the steel injector lines - flawless. No moving parts, and several other functions as well. I believe you can even set an alarm. I don't know the upper RPM limit offhand but I'm sure its well over 6,000
OK - here's a link http://tinytach.com/diesel.php (http://tinytach.com/diesel.php)
I think those things are sweet. I like the ford magnetic pick up style kevin made too
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I think you MIGHT be able to press the distributer gear off and press the vacuum gear onto it and run it just as you say. I don't know what you would have to run for power to it, or if it would just run off the pickup, or would the tach need to see spark?
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One nice feature of the Tiny Tach is it will record and save your highest RPM - something that may be of interest to you at the end of your run.
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http://www.vwdiesel.net/forum/index.php?topic=30442.0 (http://www.vwdiesel.net/forum/index.php?topic=30442.0)
this works great with better tachs, doesnt work with a stock mk2 tach tho..
it drove my Autometer tach like it was nobody's business..
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I'm looking at buying a tiny-tach, I'd love to have an accurate RPM measurment for idle and road rpms. I don't need a fancy analog tach.
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Good choice - accurate to 1 RPM (I think) and saves you'r highest rev.
Too bad it's twice as much as the gasser version - still well worth it though.
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Yeah, trying to find a deal on one. I like fabbing things up, but I don't trust a sensor that close to the tbelt...you never know...
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If you mount something on the belt cover measuring off the cam, ip or im pulley it can be set up without necessarily needing to weld anything and can be mounted well clear of the belt.
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If you mount something on the belt cover measuring off the cam, ip or im pulley it can be set up without necessarily needing to weld anything and can be mounted well clear of the belt.
:)
What exactly are you measuring on those pulleys?
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Kooky is right. You would also need to add an ignition coil and power it for it to work.
Not true if he used a sensor on the distributor rotor and ground off three of the four lobes. I don't think he was planning on using a distributor with points. He would still need a way to convert the signal from the sensor into a valid number though.
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I have come to the realization that the idea is too Kooky to be practical. I would have gladly run an electronic distributor and coil, just for the purposes of triggering a tach signal.
I'm building a dedicated race truck that will see very few miles.
The Ford (or equivalent) magnetic sensor looks like a pretty solid idea.
The optical sensor measuring at the cam sprocket seems OK, too.
Right now, I'm seriously thinking about buying one of those digital tiny tachs.
Steve.
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There was someone on here who used an optical sensor and a couple of white marks on the IP pulley - the sensor had its own light source and picked up the reflections. You could also mount a couple of magnets to the IP pulley quite easily if you wanted to go the magnetic route.
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http://www.4crawler.com/Diesel/CheapTricks/Tachometer/index.shtml
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http://www.4crawler.com/Diesel/CheapTricks/Tachometer/index.shtml
Bingo. That is exactly the setup I was thinking about.
Sent from my HTC One X using Tapatalk 2
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I have come to the realization that the idea is too Kooky to be practical. I would have gladly run an electronic distributor and coil, just for the purposes of triggering a tach signal.
I'm building a dedicated race truck that will see very few miles.
The Ford (or equivalent) magnetic sensor looks like a pretty solid idea.
The optical sensor measuring at the cam sprocket seems OK, too.
Right now, I'm seriously thinking about buying one of those digital tiny tachs.
Steve.
i dont like having the sensor that close to my timing belt. ive already had one sensor come apart on me, i dont want it to be able to come apart, and break my timing belt..
getting the reading directly from the crank with an external sensor is a little less prone to failure, if you ask me.."
my crank trigger tach idea was based off the photo-electric tach.. but highly modified..
all i had to do, was tach 2 nuts on my crank pulley, build a bracket for the sensor, and run wiring..
plus, you can use this method to drive almost any gasser 4 cylinder tach..
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racer.... libby help me...
i know for one snap on sold a contraption you inerted in the glow plug hole... to run a timming light.. a normal old school timming light.. old early 80s tech.. only seen used 1 time...
why libby... i know he is using something like this for a timming light... you no need 4 glowplugs on a racer... install the tool as a tach signal you can also use to set ideal pump timming...