What do you consider a necessity, besides a fuel gauge?

Porsche obviously felt an oil temp gauge was important in the 914, and a pressure/temp in the 911. I know Jake Raby likes the cyl head temp gauge, but Porsche didn't seem to think it was as important. Now that I think about it, Rich Bontempi's race car has all three, plus exhaust temp on all 4 exhaust ports....

necessary for what ?

for engine development and front-row of the grid performance tuning, you need all that stuff and a 5-gas exhaust analyzer.

for driving a street car once the engine is developed, gas gauge (or odometer), oil pressure warning light, high-beam indicator. just like my '53 ...

Oil temp and head temp. Even more so than oil pressure!

Head temp keep engines alive.

so, instead of removing my clock for a oil press. gauge, I should go for a cyl. temp? is the oil-press light good enough?

oh yeah - and an alternator light! (on a /6, it indicates cooling system failure...)

For a street car running an engine that is known to not have problems:
-Tach
-Fuel gauge
-Oil & alt warning lights
-High beam indicator (legally required in CA!)

...All others are "nice to have".


For a street car with an engine of unknown reliability:
-Tach
-Fuel gauge
-Oil & alt warning lights
-High beam indicator
-CHT
-Oil temp

...Any others are "nice to have".


For a race car:
-Tach
-Oil & alt warning lights
-CHT (1 per cylinder)
-Oil temp

...and any other stuff is a distraction.

--DD

Porsche didn't want you to see that your head temps can range 200 degrees over a single mile and spike to 400F when you hit a hill...

I cannot think of any car that had a CHT from the factory... Just aircraft..

The oil temp is worthless from the factory.

Buy a CHT, best tool you can invest in.

Great advice. What CHT ranges should we be looking at in a stock set-up? Which cylinder runs hottest?

Tim

What is required to install the headtemp gauge?

with stock cooling #3 is typically 40 degrees hotter than any other cylinder.. use it and MOUNT THE THERMOCOUPLE UNDER THE SPARK PLUG AND NO WHERE ELSE!


Heads should run 325-350 at cruise and hit 400 on a hill and no more..

You will soon see how 5th gear and hills get along, and how not going fast enough for 5th is a bad thing in a teener... all load and no fan speed.

If I had only one gage it it would oil pressure. If you over heat, the oil pressure will drop, and if you loose oil, the oil pressure will also drop. If you have an oil temp gage, it may stay somewhat cool even with loss of oil pressure (eventually it will heat up, but by them the engine bearings are probably toast) Head temp tells nothing really about the oil (until it is too late)

In my car all three are used, great monitoring on the engine. The volt meter is nice, but really not needed in my opinion.

order of nessesity:

oil press., oil temp, head temp.

dave

PS the head temp will let you see the effect of lugging the engine, it heats up real quick as soon as there is load, and not enought fan speed.

Can't agree with that one!

As long as I have my idiot lights my first gauge I want is an oil temp, 2nd would be CHT.

I've ran bugs for years without an oil pressure gauge, the idiot light (really I use a pro-light in the bug) is very fast to react, faster than most gauges. I also don't like the dual pressure sensor/idiot light senders. I may put a pressure gauge in my teen sometime, but I will keep the stock idiot light sender.

If you lose oil pressure- The engine is already munched...

If you see heads spike to 410 and you back out of it, you have just saved the engine.

Like I have said before, the CHT is a tool more than an instrument.... You can dial your engine in with it, and coupled with EGT you can do it almost as good as I can on a dyno.

If you really want to get picky about it in terms of NECESSITY:

One light to tell you when you're low on gas.
One light to tell you to pull over (oil press, oil temp, cht, whatever, is out of the usual range)

Nothing else is really necessary (except for obscure legal reasons you'll never be called on). I've certainly spent enough time behind the wheel of various cars with a non-working speedo to know that not having one is only a minor annoyance, at least in any urban setting.

However...

Since engines are never really in "known good condition" (how many people have had freshly rebuilt engines explode?) and since it's far cheaper to have a few gauges warn you of potential problems before they cause the engine to start smoking or spluttering, esp. when, like me, you're used to listening for bad noises and would really like to KNOW if that noise or smoke or spluttering is something really serious, or something you can wait to fix until you get somewhere comfortable, then having as many gauges or other indicators as you can afford and cram into the dash can be very handy.

This goes double if you've sunk a substantial sum into the engine.

Having at least a CHT gauge on the hot cylinder gives some mental relief, and it seems to function as something of a mixture guide (useful for carb setups). I'm reasonably happy with the idea of the oil pressure light doing its thing, as long as I know it works (and I'm not sure mine does, never lights up even key on/engine off). However, a pressure gauge also functions as a loose temp gauge, since pressure is higher when cold, lower when hot, so at least you know when the oil is up to temperature.

A voltmeter has manged to solve a couple of puzzling problems for me in the past, and I think they're nice additions (cheap and easy to install, too). On an Alfa I had a few years ago, oil got onto the alt drive belt and caused it to slip noiselessly, esp. when the engine was cold, and the voltmeter caught that even though the alt light didn't (volts stayed at 12v with the engine running, rather than running up to 13-14v as it should). Could have had a nicely dead battery and no idea why otherwise.

Certainly having CHT and EGT on every cylinder is overkill except for serious tuning situations, or for those who really push the envelope on engine builds.

early 911's don't even have an oil pressure idiot light; i suspect no matter how low they dialed them down (and i've seen some down as low as 2,0 psi) the lights would come on at hot idle and scare people...

the car does have a pressure gauge and as long as you're seeing about 10 psi per thousand rpm (hot) it's no -real- cause for alarm... it's got the obligatory alternator light, and if that comes on cruise and you switch off right away you'll probably save the engine -- air-cooled cars don't last long with no cooling fan !

So, where is the best place to buy a CHT? How much can I look at spending, what do I need (what size of thermocouple, etc), and who has the best price?

www.westach.com

aircooled.net has probably the best price for the VDO CHT gauge, but Westach can sell you a dual gauge in the standard 2" round size if you want to keep an eye on both banks, or even a quad gauge in a larger package if you want to do all four.

Thanks Jake. What size of thermocouple do we need for a TIV? I think I might order one right now.

14mm

After reading the posts I've decided to go wild and get oil pressure, voltmeter and CHT gauges to add to the console. Was looking online for info on prices and such and found that VDO makes about a dozen different sending units for 0-80 oil pressure gauges, with all kinds of different thread sizes. Anybody know what thread size the stock oil pressure sender uses? I'd like to avoid having to take the air cleaner housing off twice - once to measure so I can order the sender and again to install the new one. It would be really great if someone knew the VDO part number for the dual sender (gauge and light), but having the thread size would be a big leg up. Thanks.

Bill,

Great minds think alike! I am going to get CHT and oil pressure gauges as well. I'd be very interested in what you find out and where you get the stuff. I will post any info I get regarding the dual sender, etc.

Chris H.

me, I'm pulling my voltmeter and clock for CHT and oil press. the volt idiot light is enough

pelican has the dual oilpressure sender and gauge...