Taping side vents

[Jalenward14]

Should I tape the vents on my box stock predator? Some people tell me yes, some say no, some say sometimes. I'm new to racing so any tips or information helps, even if it's not about that.
Thanks, Jalen

 

[alvin l nunley]

I wonder if you could measure the horsepower difference, taped or un-taped?

One thing I'm pretty sure of, it makes the engine run hotter, so you have to run it richer and I'm pretty sure that hurts the horsepower.

Most really worry about the temperature under the spark plug, I worry about the temperature in the engine. If the outside of the engine is cold (colder) you should be able to run it leaner because it can get rid of more heat. There is a limit of course, but I'm pretty sure that limit cannot be reached as long as the outside of the engine is hot. Detonation, that thing most responsible for lost horsepower, is caused by excessive heat and/or pressure.

 

[youngengines]

Taping up the blower housing will usually pick power up about .5 .... it makes the difference in higher rpms. If it runs cool taped up, go for it

 

[Jalenward14]

Taping up the blower housing will usually pick power up about .5 .... it makes the difference in higher rpms. If it runs cool taped up, go for it

Ohh okay, thanks I appreciate it! Will do

 

[Jalenward14]

I wonder if you could measure the horsepower difference, taped or un-taped?

One thing I'm pretty sure of, it makes the engine run hotter, so you have to run it richer and I'm pretty sure that hurts the horsepower.

Most really worry about the temperature under the spark plug, I worry about the temperature in the engine. If the outside of the engine is cold (colder) you should be able to run it leaner because it can get rid of more heat. There is a limit of course, but I'm pretty sure that limit cannot be reached as long as the outside of the engine is hot. Detonation, that thing most responsible for lost horsepower, is caused by excessive heat and/or pressure.

Thanks for the useful information, as I said, any little thing helps.

 

[alvin l nunley]

Taping up the blower housing will usually pick power up about .5 .... it makes the difference in higher rpms. If it runs cool taped up, go for it

Getting your engine hotter, so it will run right, with the tune you already have on it, seems to be backwards to me. When tuned right, an engine will run stronger in cooler air versus hotter air. This is even more true with an air cooled engine.

Years ago, the carburetors on cars had automatic chokes, they did this because with a cold engine the engine needed a richer mixer to run right. Once the engine warmed up, the engine no longer needed the rich mixture and the automatic choke would open up.

On a cold day, your kart engine is no different. Cooler air is almost always denser (heavier) and you need to mix more fuel with it to keep the mixture ratio right. Another important reason for the air density gauge.

 

[Racergirl143]

Getting your engine hotter, so it will run right, with the tune you already have on it, seems to be backwards to me. When tuned right, an engine will run stronger in cooler air versus hotter air. This is even more true with an air cooled engine.

Years ago, the carburetors on cars had automatic chokes, they did this because with a cold engine the engine needed a richer mixer to run right. Once the engine warmed up, the engine no longer needed the rich mixture and the automatic choke would open up.

On a cold day, your kart engine is no different. Cooler air is almost always denser (heavier) and you need to mix more fuel with it to keep the mixture ratio right. Another important reason for the air density gauge.

Taping the sidecover is not done necessarily to make heat, it's too reduce the amount of aerodynamic drag at the flywheel. That's where the extra hp comes from on the Dyno along with a quicker acceleration time. When we tested it on the Dyno, we used our normal procedure in bringing the temperature up to 200 degrees then loaded the engine till 300 degrees and then made the pull taking engine temp (cht) out of the equation.

 

[alvin l nunley]

Taping the sidecover is not done necessarily to make heat, it's too reduce the amount of aerodynamic drag at the flywheel. That's where the extra hp comes from on the Dyno along with a quicker acceleration time. When we tested it on the Dyno, we used our normal procedure in bringing the temperature up to 200 degrees then loaded the engine till 300 degrees and then made the pull taking engine temp (cht) out of the equation.

I'm a little confused. Hard to explain. If the engine was 300? with wind blowing on it, and then 300? with no wind blowing on it, how could you consider those two tests the same? I have to believe that the CHT would reach 300? much faster with no wind blowing on the engine. I'm not saying that the fan doesn't use up some horsepower, I'm only questioning how much.

I'm wondering about something else, if there's no air coming through the shroud, and the fan is spinning in a vacuum, is the rest of the shroud completely sealed off, you know, around the edges? Is there no way for air to get into the shroud? You know the atmospheric pressure is 15 psi and if there's any way for air to get in there, it will get in there!!

Now if you had had an EGT, and the EGT was reading the same on both tests, then the difference, if any, in horsepower, would be much more believable to me.

Another thing, during the length of the test, wouldn't one engine heat up much faster, and more, than the other? If not, I wonder what that tells you about the effectiveness of taping the shroud. (See previous comment)

I love this sort of thing, I wish I could see the data. I commend anybody who does this sort of thing because, the more data you have, the greater your knowledge and the greater your understanding.

 

[jimmysapp]

Taping up the the recoil holes does increase horspower, especially top end. It is very noticable on the dyno. I like to completely tape it up for qualifying and remove a little for the race. The trick is to figure out the correct amount without getting the engine too hot. Test it out during practice will give you an idea how much.

 

[youngengines]

Taping up the the recoil holes does increase horspower, especially top end. It is very noticable on the dyno. I like to completely tape it up for qualifying and remove a little for the race. The trick is to figure out the correct amount without getting the engine too hot. Test it out during practice will give you an idea how much.

^^Exactly.

 

[alvin l nunley]

Taping up the the recoil holes does increase horspower, especially top end. It is very noticable on the dyno.

I would love to see the data. I could be convinced. You could put this thing to rest.

 

[95 shaw]

A little barnyard logic may help.
These are industrial engines designed to sit stationary at a fixed rpm for prolonged periods in all kinds of weather. The cooling fan and sheet metal are necessary to prevent overheating.
An aircooled motorcycle or karting engine are designed to be cooled by the air flowing around them from the motion of the vehicle.
The industrial engines could also be cooled in this manner. Class rules require the fan and sheet metal be there. For our application, way more cooling is available than necessary. Although a vacuum would be most effective in reducing the power loss, it is not practical.
We are not really operating the engine at a higher temp than it was designed for. We are merely regulating the temp to be in the most efficient range, similar to the thermostat in your car. As a bonus, we are able to recoup some of the power lost by not allowing as much air to get to fan.

 

[Racergirl143]

I'm a little confused. Hard to explain. If the engine was 300? with wind blowing on it, and then 300? with no wind blowing on it, how could you consider those two tests the same? I have to believe that the CHT would reach 300? much faster with no wind blowing on the engine. I'm not saying that the fan doesn't use up some horsepower, I'm only questioning how much.

I'm wondering about something else, if there's no air coming through the shroud, and the fan is spinning in a vacuum, is the rest of the shroud completely sealed off, you know, around the edges? Is there no way for air to get into the shroud? You know the atmospheric pressure is 15 psi and if there's any way for air to get in there, it will get in there!!

Now if you had had an EGT, and the EGT was reading the same on both tests, then the difference, if any, in horsepower, would be much more believable to me.

Another thing, during the length of the test, wouldn't one engine heat up much faster, and more, than the other? If not, I wonder what that tells you about the effectiveness of taping the shroud. (See previous comment)

I love this sort of thing, I wish I could see the data. I commend anybody who does this sort of thing because, the more data you have, the greater your knowledge and the greater your understanding.

It's not a goal of mine to convince you of anything, I was only trying to give the results we seen in testing. We very seldom use egt anymore personally as we use wide band hegos to get our air/fuel ratio data. The air/fuel ratio doesn't change with tape and anyone with common sense understands that the blower housing it's not completely sealed off and working in a vacuum. We're only reducing the amount of air available. Put a towel over the back of a house fan and see if there's any change. This will be my last comment here as I have no desire to drag down this thread or be drawn into a useless argument our discussion that you seem to be good at creating. It gets pretty old honestly...

 

[alvin l nunley]

It's not a goal of mine to convince you of anything, I was only trying to give the results we seen in testing. We very seldom use egt anymore personally as we use wide band hegos to get our air/fuel ratio data. The air/fuel ratio doesn't change with tape and anyone with common sense understands that the blower housing it's not completely sealed off and working in a vacuum. We're only reducing the amount of air available. Put a towel over the back of a house fan and see if there's any change. This will be my last comment here as I have no desire to drag down this thread or be drawn into a useless argument our discussion that you seem to be good at creating. It gets pretty old honestly...

It's a shame that when difficult questions are asked, people get upset.

 

[rebsfan4]

It's a shame that when difficult questions are asked, people get upset.

It's also a shame you feel the people, who do this stuff on a daily basis, should have the need to prove things to you that you can't understand do to simple lack of experience. It really has nothing to do with people getting upset at a difficult question. It has more to do primarily with someone (you) feeling the need to constantly debate with people about things you have no first hand knowledge of. It's really no different than you getting upset when people tell you you don't know what your talking about.

I really don't mean for this to be derogatory. It's just, there were once times when people could come this site, discuss things, agree on some, disagree on others and in the end simply agree to disagree without having someone always trying to tell to try and prove them wrong about stuff. Really wish those days would return.