kooks 1 7/8 x 3" or kooks 2"x3"

[n0speedlimit]

which are better? pros and cons? I'm a 14 zl1

[Bigtime53]

Great question. I hope someone answers this. I would like to know also.

[Travis104]

I went with 1 7/8. I am pretty sure I read somewhere that below 650rwhp 1 7/8 was fine, but janetty did a test that showed no loss in low end torque with with 2", but a gain in power in the higher RPM's.

[jayno20]

You can't go wrong with either one, but 2" is going to yield slightly higher HP in the higher end of RPM.

[ZO6 Bryan]

I have never seen the need in 2" primary tubes when the exhaust port in the head is only 1 3/4". The sudden jump in diameter from 1 3/4" to 2" will cause a drop in the velocity of the exhaust gases as they exit the head. Different story if you've ported the heads and the exh port is much bigger.
But this is exactly why I got the stepped Kooks headers. The first 6" of pipe is 1 3/4 just like the exhaust port. Then increases to 1 7/8" for the rest of the primary tube until it hits the collector and dia. changes to 3". This maintains higher velocity of the exhaust charge. Then the merge collector is designed to "pinch" the diameter so you don't lose velocity in that area.
And for those that don't know...Velocity = Torque This is also true in the intake track.

2" headers MAY provide a tiny bit more power at WOT on the very top end, But will result in less torque everywhere else. Especially idle to part throttle and mid range RPM.

[n0speedlimit]

Originally Posted by ZO6 Bryan

I have never seen the need in 2" primary tubes when the exhaust port in the head is only 1 3/4". The sudden jump in diameter from 1 3/4" to 2" will cause a drop in the velocity of the exhaust gases as they exit the head. Different story if you've ported the heads and the exh port is much bigger.
But this is exactly why I got the stepped Kooks headers. The first 6" of pipe is 1 3/4 just like the exhaust port. Then increases to 1 7/8" for the rest of the primary tube until it hits the collector and dia. changes to 3". This maintains higher velocity of the exhaust charge. Then the merge collector is designed to "pinch" the diameter so you don't lose velocity in that area.
And for those that don't know...Velocity = Torque This is also true in the intake track.

2" headers MAY provide a tiny bit more power at WOT on the very top end, But will result in less torque everywhere else. Especially idle to part throttle and mid range RPM.

great info provided seems like you wouldn't noticeably feel a difference between the two and as far as common sizes i think the 1 7/8 would be a better choice, not taking anything away from the 2" tho.

[Stephen12ZL1]

General rule is <650rwhp go with 1 7/8". >650rwhp 2".

[rjs2010SS]

Anything will yeild more power by getting rid of the manifolds. If you plan on building your car over 650HP just get the 2" to start off with and save the money. And I have seen more then just one tuner do dyno comparisons with a gain in touque and HP( its been a while cause I seen them when I ordered mine last year), with no loses. Not to mention these cars were all around 600hp. Just saying facts is facts... I wouldn't look to much into the scientific side of it as the numbers are around here to back it up.

[rjs2010SS]

Here is Jannetty's test... http://www.camaro5.com/forums/showth...y+headers+test

[owhite3003]

Quote:
Originally Posted by towmoe
Ted,

I don't understand how the 1 7/8 is "best all around header" in your opinion if the 2" headers had better average and peak numbers. Could you please explain? Thanks.

A few Reasons, the additional cost does not justify the gains.
They are a Tighter fit.
They are Heavier
Most manufacturers offer a 1 7/8 headers so they are easier to get.
The biggest gains from headers are in the middle of the curve where you drive most and you can't tell the difference between 1 7/8 and 2 inch, on the dyno graph or in the car.

Unless your Racing you won't miss the 5 HP at 6300 RPM, your not there enough to use it on the street.

Hope this Helps.
__________________

[JDP Sales]

Originally Posted by owhite3003

Quote:
Originally Posted by towmoe
Ted,

I don't understand how the 1 7/8 is "best all around header" in your opinion if the 2" headers had better average and peak numbers. Could you please explain? Thanks.

A few Reasons, the additional cost does not justify the gains.
They are a Tighter fit.
They are Heavier
Most manufacturers offer a 1 7/8 headers so they are easier to get.
The biggest gains from headers are in the middle of the curve where you drive most and you can't tell the difference between 1 7/8 and 2 inch, on the dyno graph or in the car.

Unless your Racing you won't miss the 5 HP at 6300 RPM, your not there enough to use it on the street.

Hope this Helps.
__________________

I'm with him. If you are making over 1,000 HP or something crazy like that then I could maybe see the need for 2" but for the Majority of us, 1 7/8" is more than enough.

All the best,

Jared Royce
801.545.4215

[TXsilvy]

I love reading regurgitated internet bullshit with zero proof or backup. nobody has even asked what the future looked like for this build.

OP, do you ever plan to install a blower, or nitrous? and by nitrous, I don't mean a dinky 200 shot or less. do you plan a 250 shot or larger at any point down the road?

[ZO6 Bryan]

Originally Posted by TXsilvy

I love reading regurgitated internet bullshit with zero proof or backup. nobody has even asked what the future looked like for this build.

OP, do you ever plan to install a blower, or nitrous? and by nitrous, I don't mean a dinky 200 shot or less. do you plan a 250 shot or larger at any point down the road?

Pay attention. He already has a blower.

[KaBoom1701]