Slant Six Forum :: Where to put EFI coolant temp sensor?

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Where to put EFI coolant temp sensor? https://slantsix.org/forum/viewtopic.php?t=18602	Page 1 of 1

Author:	Sam Powell [ Sun Jul 16, 2006 7:02 pm ]
Post subject:	Where to put EFI coolant temp sensor?
This is a question for anyone who has put any kind of efi on a slant. Where did you put your coolant temp sensor, and why? How is the cold start drivability? What is your opinion of the choice between the head temp sender location, and the block drain plug. I have run mine both ways, and it seems that with the sensor in the head, because the head heats faster then the engine, the enrichement table was a little out of sync with the actual condition of the engine. Tell us what kind of ECU you are using as well. Is it GM,. Mega Squirt, or some other after market? I'll share a little more after we get some feedback. Thanks guys. Sam

Author:	Greg Ondayko [ Sun Jul 16, 2006 7:19 pm ]
Post subject:
Sam I never messed with any EFI , but at carlisle I saw the early valiant with the temp sensor near the Temp Gauge Senting unit. There was another hole drilled in the head for it. Another option is to run your sensor After the Thermosat housing on the head. - If you check out a late seventies / Early eighties smog head you will see what I mean. The coolant i guess would remain a lot colder there until the stat opens. Greg

Author:	VE Safari [ Sun Jul 16, 2006 7:35 pm ]
Post subject:
I drilled and tapped a hole in the front of the cylinder head, close to where the factory temp sensor is.

Author:	Pierre [ Sun Jul 16, 2006 7:51 pm ]
Post subject:
You do NOT want to run your efi sensor after the thermostat, in the housing. This will only show you true engine temp after the thermostat has opend, and not as the engine warms up, negating any cold start measurments. I run my sensor to megasquirt through the stock location, and put an aftermarket temp gauge in car as well. That sensor is the one in the thermostat housing, since its not critical to see engine temp warming up there its only for an indicaiton of what max temp is to see if your overheating. The block drain can be used for the sensor but you will have to offset calibrations by ~20 degrees because water at that location hasn't been heated by the head yet. Cold start drivability is completely dependent on tune. Its really tricky tuning cold start - all other parameters must be tuned first, then it will take several cold starts and experimentation to get them right. Megasquirt has several parameters to tune in this respect - cold acceleration enrichment, cranking pulsewidths, afterstart enrichment, warmup enrichment - once all are in synch with the engine, it should start up and drive like a modern engine.

Author:	Al T [ Sun Jul 16, 2006 8:16 pm ]
Post subject:	Temp reading
here's where I put mine - I used the front hole behind the thermostat on a 76 head http://www.projectplato.com/cars/Images ... engbay.jpg

Author:	Sam Powell [ Mon Jul 17, 2006 1:38 pm ]
Post subject:
Pierre, If I am reading your right, in the end it would not make any real difference between having the sensor in the stock location, and having the sensor at the drain plug, as long as you tune appropriately. Is that correct? I currently have the temp guage sending unit in the stock location and the computer ECT sending unit in the drain plug. It is simpler just to leave it all where it is, if you t hink this can be tuned OK. Leaving it where its is means not having to drain the block and it also eliminates a pair of wires running down the length of the engine. Whatcha think? Sam

Author:	Pierre [ Mon Jul 17, 2006 10:09 pm ]
Post subject:
Sam, in theory yes that is the case. My personal opinion - I would rahter put the efi sensor in the stock spot so tuning becomes slightly less of a hassle. Then for the gauge sender - thermostat housing for "correct" readings, or block for offset readings.

Author:	Sam Powell [ Tue Jul 18, 2006 5:44 am ]
Post subject:
On your suggestion then, I guess I will swap the two senders and re-rout the line for the gauge. The gauge I use is a mechanical one with a long thrmo coupling between the sending unit and the gauge. I can bury the ECT line in the harness I am currently building for all this. It comes with a stock Cheby V-8 harness, which is pretty much completely wrong for a real engine like the slant. So I have torn off all the convolute tubing, and am measuring, and cutting and splicing to make it all fall into place on a slant. Thanks for the advice. Sam

Author:	Dart270 [ Tue Jul 18, 2006 6:48 am ]
Post subject:
I have both my cars running off the sensor in the block plug. My thinking is that this spot heats up more slowly, matching more closely the heating of the intake/TB and cylinders/pistons. The head location is the hottest spot on the engine, and heats up much more quickly than the rest of the engine (except exhaust). You want the time constant of the temp sensor heat-up to match the time constant of the engine parts that most affect mixture needs - like intake/TB, pistons/cyls... Lou

Author:	Sam Powell [ Tue Jul 18, 2006 11:08 am ]
Post subject:
Gosh, Lou, now I have to re-think that. That was my reason for putting it in the block in the first place. Maybe that was your suggestion. You think? I guess I will leave it where it is for the time being; give the current set up a try. Sam,.

Author:	Dart270 [ Tue Jul 18, 2006 1:18 pm ]
Post subject:
I think either location should work fine given sufficient tuning. Lou

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