Cylinder Head Temps, My Experience + lessons learned Options

[rwilner]

I drove down to Chris Foley's shop to get his shift linkage installed this weekend. At the charlton plaza on I-90, I stopped to fill up. I usually put premium in the 914 but this time put regular in because it's what I put in my other cars and I was on autopilot. Oh well, I thought...let's see how she runs on 87, maybe I'm wasting my $$ on the good stuff.

Before the fillup, I was running between 300 and 325 F in 5th gear around 70-75 mph.

After the fillup, I was running between 380 and 400! (IMG:style_emoticons/default/ohmy.gif)

I spent the rest of the trip in 4th gear at no less than 3500 rpm to try and keep the head temps down. When I got to Chris' shop, we put the car in the air and drained out 5 gallons. I replaced them with 93 octane before getting on the highway for the ride home. My cyl head temps were back down to 310-350 for the return trip.

Here's what I learned:

• A cylinder head temp sensor and gauge are critical to know what's happening in your engine and should be on everyone's short list. Without it I would never have known of the dangerous operating conditions for the engine. The aircraft spruce gauge/probe are short $$ and a quick install.
• The state of tune has a major impact on running temps (duh). I am still tuning my car with the microsquirt and it's clear I have work to do.
• Higher octane gas makes your car run cooler.

As always YMMV but thought I'd share my experience.
Rich

[jsayre914]

I forgot we need sensors too, so I called Harold @ The Sensor Connection and told him we need a quote on at least 40 CHT sensors 14mm and he also said no problem, he will get back with me tommorow, he also said he was just about to pick up the MGL guages himself, and he will beat whatever price aircraftspruce will quote me on 10pcs....

this is getting interesting....

(IMG:style_emoticons/default/chowtime.gif)

i think i smell a group buy starting tommorow (IMG:style_emoticons/default/biggrin.gif)

[falconfp2001]

I forgot we need sensors too, so I called Harold @ The Sensor Connection and told him we need a quote on at least 40 CHT sensors 14mm and he also said no problem, he will get back with me tommorow, he also said he was just about to pick up the MGL guages himself, and he will beat whatever price aircraftspruce will quote me on 10pcs....

this is getting interesting....

(IMG:style_emoticons/default/chowtime.gif)

i think i smell a group buy starting tommorow (IMG:style_emoticons/default/biggrin.gif)

(IMG:style_emoticons/default/w00t.gif) OK, if you can get this down to about 370 or lower then I think it is a go for a group buy. All vendors welcome to make other offers as I think this has a lot of interest and potential.

[rwilner]

I forgot we need sensors too, so I called Harold @ The Sensor Connection and told him we need a quote on at least 40 CHT sensors 14mm and he also said no problem, he will get back with me tommorow, he also said he was just about to pick up the MGL guages himself, and he will beat whatever price aircraftspruce will quote me on 10pcs....

this is getting interesting....

(IMG:style_emoticons/default/chowtime.gif)

i think i smell a group buy starting tommorow (IMG:style_emoticons/default/biggrin.gif)

(IMG:style_emoticons/default/w00t.gif) OK, if you can get this down to about 370 or lower then I think it is a go for a group buy. All vendors welcome to make other offers as I think this has a lot of interest and potential.

Don't forget we're going to need about 40' of K-type TC wire as well (purple jacket). A complete kit would include the wire, gauge, sensors, and enough terminals / splices to get the job done.

And oh yeah, probably 3 beers.

[ChrisFoley]

Don't forget we're going to need about 40' of K-type TC wire as well (purple jacket). A complete kit would include the wire, gauge, sensors, and enough terminals / splices to get the job done.

And oh yeah, probably 3 beers.

Any connections added to the thermocouple wires may mean the cold junction compensation feature of the instrument won't work. FYI

My 4 channel instrument comes with extended wires on the gauge, so no need for extra wire, but it has no built-in cold junction compensation. If you understand what that compensation does its a minor feature anyway. I put the connectors inside the cockpit where the temp is most stable and closest to the ideal 75F to minimize any inaccuracies.