jdm kooks longtube dyno, before and after

[jonas]

Ok here goes.

I have an 03 cobra with a kb at 17 psi
I have every supporting bolton. i.e. catted x-pipe, catback, throttle body, cai and whatnot

The only diff between the 2 runs is one has the stock exhaust manifold and magnaflow catted x, one has the kooks and catted h-pipe.

Can you tell which is what?

Shoulda used the money for a live axle :nonono:

 

[redaddiction]

Did you have it tuned after the headers ?

 

[jonas]

yes, I also added a bap. The a/f ratio is dead on 11.8 both times with it rising to 12.2 at the very end.

I didnt get the a/f charts unfortunately

 

[JKD COBRA]

so you had 584, then a month or so later, you put on the headers and went down to 566? Thats pretty suprising, what was your a/f like? How much boost did you lose? Are you going to put the stock manifolds back on? If so, you should dyno again and see if you gained the power back.

 

[PhillyCobra]

That blip at the end of the blue run is artifact. Discard that and the curves are essentially the same-- no loss with headers, no gain. Why does the blue curve start so late? Would like to see if headers gave up power at low revs.

 

[Juiced-03]

Wow thats very hard to believe with your KB!! You'd think you would gain a crapload of power with LT's! Well sorry to hear about that though. Does it feel any different on the street?

 

[jonas]

dont go by the numbers, go by the graphs. The blip to 584 is just that. happens on alot of runs when you get off suddenly. The lines mirror each other before and after the kooks. I bet the restriction now is the exhaust port flow. maybe its time for cams.

Just a heads up for you guys. Maybe other cars responded differently. Felt like sharing some hard emperical evidence. We knew they did little to no gains with the eaton cars and assumed the restriction was the eaton itself and here is me and my kb.

Ill do a before and after with a pro-m maf im planning on purchasing as well. I'll have socal diablo do the same and lay the graphs on top of each other

 

[JKD COBRA]

thanks for posting your graphs Jonas, I am sorry you didn't gain anything. Like juiced asked, does it at least feel faster?

 

[sambandit]

Well crap, look like I blew 1600 bucks with install on these things. At least it sounds good. Why don't the headers work on our cars? Makes no sense. Maybe it's not a dyno mod but it show up at the track. At least that's what I keep telling myself.

 

[flyn high again]

Could the stock exhaust manifolds be flowing as well as headers? Can anyone test the flow through manifolds and headers?

 

[SVTdubs]

I have said since this car has come out but noone listens, these cars need a certain amount of backpressure. Headers are a waste of money. If you want sound, take off the cats and run a straight pipe where the mufflers are but this car needs backpressure. Maybe some day someone will listen. hehe, Im not busting your balls, Im just talking out loud. If anything, go with a shorty header and stay smog legal but still it is waste of money for the install.

 

[jonas]

it sounds badass!!

 

[JKD COBRA]

maybe it has something to do with our blowers making power under load. Like dubs said, maybe we need some backpressure to put some load on the motor so the blower will make power. Does anyone agree, or is that not right?

Its like when our cars run awsome times at the track even though we bog off the line. Sometimes thats the best way to do it because when the car bogs, the rpm's go down and that puts a lot of load on the motor. But I could be going in the wrong direction with this. What do you guys think?

 

[HIGH ROLLER]

When i had my 99L i added shorty headers and my 01L i put longtubes on and gains were minimal at best and not long ago i added JBA headers to my 03 cobra and at best i picked up around 7HP with them. I feel why we are not seeing better gains is because when you add headers most of us will lose at least 1 pound of boost i know i did. To be fair about it if we added that loss of boost back in we would see a decent gain from them.Before my header install i was seeing 15 pounds of boost and now i barely see 14 pounds of boost but my car did run slightly faster at the track after install even after loosing that 1 pound of boost. Just a thought :read:

 

[sambandit]

High Roller, like the sounds of that! Makes me feel better. My boost is completely f-ed up given my elevation anyway. I see a peak at about 14.5 lbs even given my setup.

 

[SVTdubs]

you will lose the boost but not lose that much power. The headers free up backpressure on the motor hense making it run more efficiently and with less effort. I might do headers just to put less strain on my motor but no means would I be looking for or expecting any gains. Highroller is right, you will see gains at SOTP up top where the HP is but the loss of backpressure will usually result in a loss of low end torque which is what gets these bricks moving. Sam, with that much boost, I would DEFINATELY be running some sort of headers. You made a great choice! Your motor is not working nearly as hard as it would have been with the stock manifolds running that much boost!

 

[RedfireVenom]

I'm not trying to be a smart ass, but did you do any research on them before you bought them. I remember reading several posts stating that no gains were achieved from LT headers.

 

[PhillyCobra]

Could it be that the cats on your car are the point of most resistance now? It's like putting in a better H or X pipe without changing the stock cat back-- no real gain as the cat back is still the most restrictive point in the exhaust.

Some people claim benefit with LT headers, but a lot of them don't run cats. Could that be the answer? Not to say that I condone running without cats on the street.


Also have read of many melted cats on high power engines. Might be worth looking at your cats.

 

[sambandit]

Problem is, I bought them last March before they were really proven. One of the 1st steps for me with a new hotrod is always LT's anyway. Like I said, maybe I bought 1600 bucks worth of sound, oh well.

 

[SVTdubs]

Originally posted by RedfireVenom
I'm not trying to be a smart ass, but did you do any research on them before you bought them. I remember reading several posts stating that no gains were achieved from LT headers.

at least the vert guys do some research and stick together:lol:

jk:beer: :beer: