Controlling heat with blower housing vents on aclohol

K

Killswitch

New member
When trying to control CHT using the tape method (is there another way?) over the start nut hole what is the target temp? The dyno guys would know I would think. Have any of you guys seen more or less HP at different temps? Is it wise to try to control it? If so what is too cool and what is too hot?
 
There is no too cool.
Try to stay under 380*F
Spikes to 400 are ok but if you consistently run at 425 you will eventually warp the head.
 
Thanks Jimbo, I just see a lot of guys taping off the starter hole with a flapper. They say to keep heat in the motor and looked at me like I had two heads. I don't have CHT just EGT cause I went from 2 stroke to animal so I didn't know.
 
Killswitch said:
Thanks Jimbo, I just see a lot of guys taping off the starter hole with a flapper. They say to keep heat in the motor and looked at me like I had two heads. I don't have CHT just EGT cause I went from 2 stroke to animal so I didn't know.
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very few four cycle people use the EGT. What kind of temps do you see?
 
You can't tune an engine to a egt number.The optimum egt is the one that makes the most horsepower.If that melts parts,or fouls plugs,you need to re-think your combination.
 
Steve Vermeer said:
You can't tune an engine to a egt number.The optimum egt is the one that makes the most horsepower.If that melts parts,or fouls plugs,you need to re-think your combination.
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I can understand that. EGT is not the only tuning tool I use. Plug reading is still king for me, but I don't pull the plug after every heat or race. I will if something feels off, but a quick look at EGT on the Mychron makes me feel better when she's around that temp. When at that temp plug looks just about right.
 
Al
You are right in that most 4 cycle people don't use EGT. The reason being is that (unlike your beloved KT 100) a 4 stroke won't stick the piston if the mixture is not perfect. If you don't have EGT on a KT 100 and know how to use it you run the risk of severe engine damage.
Contrarily, you can have the mixture way off on a Briggs and not have to worry. I have NEVER seen a Briggs destroyed because of a mixture issue.
If the mixture is way off the kart comes off the track and into the pits to be repaired.
I will also add that we have numbered jet kits that put you very close to the correct mixture. Even if you select the wrong jets you won't be so far off that you will damage anything. In fact you will probably be close enough to have a chance of winning the race.
Alcohol is even more forgiving as far as jet selection. You can be a couple of thousands off of the ideal jet and the motor will still make good power.
I'm not saying EGT can,t be helpful. It certainly can but it would be illegal on a LO206 or a World Formula.
It would be legal for a blueprinted WKA Animal.
 
HIYA JIMBO another thing to consider is that the animals use a fixed jet while on track you cannot dial in the mixture like with a 2 stroke. So how are you to know IF you are too lean or too rich ? Both can give a low EGT number.

Been there, (;-) TP
 
Terry
You can use the SWAG method. Ha Ha
Right or wrong that's what most Sat nite racers use.
Yes you can use EGT or O2 sensors but around here in the summer racing season the AD usually doesn't change enough to warrant a jet change on Alcohol.
If the carb is set up properly to begin with people will more than likely get themselves in trouble by making a change.
"I'm not saying EGT can,t be helpful. It certainly can"
 
Jimbo said:
Terry
Yes you can use EGT or O2 sensors but around here in the summer racing season the AD usually doesn't change enough to warrant a change on Alcohol.
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That's very interesting, because in California, the air density changes more in the summer than it does in the winter. In the summer, if we race a late afternoon early evening schedule, the air density will change even more.

From the desk of Al Nunley
Comments compliments criticisms and questions always welcome.
If the data does not support the theory, get a new theory.(Al Nunley
 
When I ran 2-stroke I found that the EGT gauge was quicker to respond but capable of fooling you. One time I spent a whole race trying to keep the engine rich enough to keep from smoking a piston only to learn that the high temp numbers were caused by late ignition timing, not engine temperature. Later in my 2-stroke days I ran BOTH EGT and CHT gauges. When a brake bind caused increased CHT temp the EGT didn't show much change. Over the past few years I've changed from Flathead Modifieds to OHV Modifieds. The Flatheads ran very hot and I had to pay close attention to the temp and mixture, but the newer OHV Modifieds run much cooler. I still turn the CHT gauge on, but I really don't even need it and I rarely adjust the carb. Now an exhaust mixture gauge might be fun...
 
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