Any real header hp# on stock motor.
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Any real header hp# on stock motor.
I am going to buy headers but they is a huge difference in price. I can get coated pace setters for $380 or QTP for $1200. If the difference in horsepower is minimal then it really isn't worth spending an Extra $800 for equal length headers. Here is an example. Everyone claims that freer flowing exhaust equates to more power but thats not true. I have raced cars for 15 years and I have subscribed to every hot magazine since 1990. I have seen severals test where 2.25 exhaust outperformed 3 in exhaust. Back pressure is a big factor in pruducing torque, which is the most important of the two. I have also seen build ups where they compare1 5/8 and 1 3/4 headers and found that the smaller header made significantly more torque and gave up only one horsepower. In the end if I can get 35 lbs of torque and 30 hp from the pace setters or 45 lbs and 40 hp from the QTP, I am actually paying $800 dollars for 10 ponies. Is that a smart move? Or should I spend the extra $800 on a wet kit. Now I got 150 hp for $800.
Really, I would like to know the difference in power so that I can decide if its worth spending the extra cash. Also, in a few years I would like to put a ZO6 cam and head in my car but I am not sure. I may go blower or NOS.
Really, I would like to know the difference in power so that I can decide if its worth spending the extra cash. Also, in a few years I would like to put a ZO6 cam and head in my car but I am not sure. I may go blower or NOS.
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Re: Any real header hp# on stock motor.
I haven't seen the pace setters so i can't comment on them. The economics favor less expensive headers if you aren't going to build a max effort NA motor and will buy nitrous. However, if you will eventually go heads and cam, or especially a blower, you'll probably want the best headers too.
Everyone claims that freer flowing exhaust equates to more power but thats not true. I have raced cars for 15 years and I have subscribed to every hot magazine since 1990. I have seen severals test where 2.25 exhaust outperformed 3 in exhaust. Back pressure is a big factor in pruducing torque, which is the most important of the two.
The object of headers is to help get spent gas out of the cylinder; back pressure does not help acheive that goal and back pressure does NOT increase torque. Smaller tubes increase exhaust gas velocity at lower RPM and thus often produce more low end torque. If a car runs better with back pressure (i.e after improving exhaust flow it gains nothing), it is because it was tuned from the factory based upon the back pressure being present. Update the tuning and the extra power will be there.
I agree on header tubing size that going to big can hurt low end and midrange power. Again, that is generally due to a loss in exhaust gas velocity and resulting loss in scavenging.
Everyone claims that freer flowing exhaust equates to more power but thats not true. I have raced cars for 15 years and I have subscribed to every hot magazine since 1990. I have seen severals test where 2.25 exhaust outperformed 3 in exhaust. Back pressure is a big factor in pruducing torque, which is the most important of the two.
I agree on header tubing size that going to big can hurt low end and midrange power. Again, that is generally due to a loss in exhaust gas velocity and resulting loss in scavenging.
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Re: Any real header hp# on stock motor.
Any time you have smaller tubes the engine need to move gases faster throught the smaller tube. Because the tube is smaller and having to move faster to achieve the same end as a larger tube, there will be a certain amount of back pressure compared to the larger tube header.
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Re: Any real header hp# on stock motor.
your taling about low end torque, in the midrange and upper rpm's, lt's will make more torque. As for the pace setters they are not coated which will cost you another 250 dollars. Plus the pacesetter y-pipe i saw had one of the worst y pipe designs, while the qtp's used a flowmaster y, one of the best y's.
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Re: Any real header hp# on stock motor.
Any time you have smaller tubes the engine need to move gases faster throught the smaller tube. Because the tube is smaller and having to move faster to achieve the same end as a larger tube, there will be a certain amount of back pressure compared to the larger tube header.
With an optimal designed system, the higher velocity creates scavenging. the scavenging produces a pressure drop behind the wave pulse and helps suck out the spent gas. That's the whole point of keeping the velocity high. That's also why headers are built to maximize performance over a certain rpm range; you can't optimize the velocity and wave pulse accross a 6,000 rpm wide band. Backpresure only causes some of the burned gases to remain in the cylinder and thus crowds out space for incoming fresh air and fuel. Power is made from burning gas which needs the fresh supply of Oxygen.
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Re: Any real header hp# on stock motor.
your taling about low end torque, in the midrange and upper rpm's, lt's will make more torque. As for the pace setters they are not coated which will cost you another 250 dollars. Plus the pacesetter y-pipe i saw had one of the worst y pipe designs, while the qtp's used a flowmaster y, one of the best y's.