I have bought the kits before and made my own, but my question is, why do they have to be angled? Why couldn`t they be installed straight in with no cut on the pipe? Just curious. It seems the same to me.

i believe that the angle causes more of a vaccum affect than just having them mounted straight on the header and taking a chance on creating pressure in the engine

I was just wondering. I have seen some drag racers do some crazy things before like a pipe coming in with the tubes inthe center of the tubes, into the collector just past where the tubes meet.

if i understand you correctly, they use all of the exhaust in the header by putting it just past the collector and using the speed of the exhaust to create a even greater vaccum

http://www.reddogracing.com/id18.htm

Something i started and never finished on the website. Some very very good engine builders coments are saved there. Read until your sick of hearing about header evacs.

thers alot of good information in there.thats why i was asking instead of cutting the pipe and angleing it in the collector cud i just put the pipe straight in the side and leave the pipe uncut. i see no difference. to me i thought it wud be the same concept as a vacuum port on a carb.

The problem that i see with installing them straight in, is that you have very little room for error. As you can see from the red lines, a very slight angle would allow exhaust to pressurize your engine versus vaccum.

Look at teh bottom of image. Installing at an angle, your room for error is greater, so it will be harder for air flow to pressurize.

I always cut pipe at angle and install at angle. And error to the side toward the engine, which means i would rather have more angle then less.

Now to really confuse things, if you have a chock point in the header/exhaust design, you could install a straight pipe, as you would then be working on venturi principle of increase velocity decrease pressure, just like a good old fasion carburator.

But I digress.

Don't run them unless they are put in and tested to make sure you have vacuum on them and it is not pressurizing the crank case. Usually they are not worth the effort to install.

James

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