Author Topic: Cylinder Head Temperature  (Read 4568 times)

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Offline LandSpeed-DSM

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Cylinder Head Temperature
« on: June 12, 2013, 10:54:56 AM »
Has anyone with liquid cooled aluminum heads used CHTs in their program?

Recently picked up a Cylinder Head Temperature Gauge/Sensor kit (VDO). The thermocouple ring slides over the threads of the spark plug and is then clamped between the hex section and the head.

A search here turned up nothing directly related.

Doing this in the hopes of dialing in cylinder fuel trims individually, as well as monitoring heat in general.

This is in addition to pre- and post- turbine EGTs.

Who else has taken a similar approach? For anyone familiar, this is going to be done on a 4g63 in a DSM with standard intake/throttle orientation by #4.. Any cylinder consistently hotter than the others?

Curious to see what I find, and trying to determine what a safe Full-Load temperature is for extended periods.. as in upwards of two minutes under load.

Thinking I will aim for max of ~320-330*f in 4th and 5th gear at WOT, keeping an eye on plugs and EGTs for trouble. Some cursory research has suggested T6 aluminum heat treatment will be destroyed with regular or sustained temperature beyond that. I am trying to find a definitive answer, but it seems reasonable for the 4G63s aluminum head to be T6 treated.

I would be interested on anyone's input in that regard as well.
Chris

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Offline Dean Los Angeles

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Re: Cylinder Head Temperature
« Reply #1 on: June 12, 2013, 11:42:55 AM »
EGT give you the almost instantaneous reading of exhaust temperatures. A good indicator of fuel mixture.

Coolant temperature gives you the long term picture of heat removal.

Cylinder head temperature gives you the in between picture of heat soak close to the piston. The actual value depends on head design and coolant passages.

This is such a short run that heat treat won't be affected. Best use for a CHT is differences between cylinders. You can't have too much information.
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Offline rouse

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Re: Cylinder Head Temperature
« Reply #2 on: June 12, 2013, 12:04:47 PM »
What dean said.

Every cylinder could need a different number based on a whole lot of factors, or they could even be the same, every engine type will need it's own numbers.

I'm thinking 330 is up there for a WCE, I'd sneak up on that if I were you.

I ran HT at the plug sensors years ago on Gokarts, some engines needed 380 at the plug to be right, some would put the piston in the pipes at 320.

Rouse
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Offline LandSpeed-DSM

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Re: Cylinder Head Temperature
« Reply #3 on: June 13, 2013, 09:59:13 AM »
Thanks guys.

The plan was to try and see where the head gets hottest, then first try and even out each cylinders individual fuel trim. After that was sorted I wanted to use the CHT to determine what part of the head needs coolant the most and manipulate the feed and return holes at the deck to get it there.

The 330*F figure was more of an absolute max, the approach will be conservative for sure.

There are plans for individual EGTs as well. Individual widebands would be nice, but those funds are being put towards safety equipment first.
Chris

HX52 fed 2.0L on E85/Water Injection

"Frustra fit per plura quod potest fieri per pauciora" - Summa Totius Logicae

Offline fordboy628

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Re: Cylinder Head Temperature
« Reply #4 on: June 14, 2013, 07:55:58 AM »
EGT give you the almost instantaneous reading of exhaust temperatures. A good indicator of fuel mixture.

Coolant temperature gives you the long term picture of heat removal.

Cylinder head temperature gives you the in between picture of heat soak close to the piston. The actual value depends on head design and coolant passages.

This is such a short run that heat treat won't be affected. Best use for a CHT is differences between cylinders. You can't have too much information.

All of the above are great advice.   Data that you don't record, CAN NOT be analyzed at a later time.   I ALWAYS want as much information as I can get . . . AND I ALWAYS want more . . . . . .
 :cheers:
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Offline Milwaukee Midget

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Re: Cylinder Head Temperature
« Reply #5 on: June 14, 2013, 09:15:15 AM »
EGT give you the almost instantaneous reading of exhaust temperatures. A good indicator of fuel mixture.

Coolant temperature gives you the long term picture of heat removal.

Cylinder head temperature gives you the in between picture of heat soak close to the piston. The actual value depends on head design and coolant passages.

This is such a short run that heat treat won't be affected. Best use for a CHT is differences between cylinders. You can't have too much information.

All of the above are great advice.   Data that you don't record, CAN NOT be analyzed at a later time.   I ALWAYS want as much information as I can get . . . AND I ALWAYS want more . . . . . .
 :cheers:
Fordboy

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Offline Ron Clevenger

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Re: Cylinder Head Temperature
« Reply #6 on: July 22, 2013, 11:54:41 PM »
EGT's are not the end all for tuning. Lots of factor can change them. For the most reliable tuning aid learn to read the plugs. When you go thru the timer click it off clean and read the plugs. There an eye witness to the combustion event.

Blessings......Ron C

Offline JimL

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Re: Cylinder Head Temperature
« Reply #7 on: July 26, 2013, 09:39:48 PM »
Just food for thought.  The inline fours (at least JPN types) are designed to run two different flow patterns based on water pump flow rate.  At low rpm they typically flow end to end through the head.  At highway speed this transitions into a spiral type flow.  That is the reason for the arced side passages in the head gaskets.  If you can get access to earlier Camry New Car Features training manuals, you can see the diagrams in the engine section.  I think it was '92 or '97 when they first showed us.

Once we saw that, we began to understand why replacement head gaskets for older vehicles were suddenly being redesigned!

Once this characteristic was discovered, a lot of development went into headgasket passage/water port arrangements.  Without this planning, cold weather engines would have emissions problems at idle and a few other problems.  Water pump position was also optimized, and thermostats moved to the inlet side to accomodate the improvements, which also helped minimize hysterisis in coolant temp.

I suggest caution when trying to change flow geometry.  I would be tempted to run electric water pump and stay in the spiral/rotary flow rate area.  I use a Dedenbear Sprint Car water pump (remote type) on my motorcycle engines.  These engines also exhibit the "odd" coolant passages through the head gasket.

Perhaps this will give you some ideas on what to investigate next.  Often, when I was struggling with some supposed complaint, that I couldnt find, my friend Nels would walk over to my stall, look at it, and say, "Jim, if it aint broke, you cant fix it!"

Regards, JimL