Hey Guys,
I've recently been dealing with a bit of idle surge and part throttle surge.

I've check all the obvious potential vacuum leak spots, and have now found a small crack in my 7 year old Kooks 1 & 7/8s inch headers, in the cone. If you stand under the car while it's running, the exhaust leak is quite audible.

First, do you agree this is the probable surge culprit, and second, since the headers have long since done their job, would you upgrade to the 2" headers, or just repair the old ones...
Lastly, do you see a decent gain with the 2" on a 800 RWHP setup?

Thanks in advance!!

 

Exhaust leaks will cause the surge your having, personally I'd just replace with new headers.
Never had any luck with repairing headers that were old, you just end up chasing the crack.

 

You will see gains, do it.

 

Thinking of swapping an 1 7/8th F1X car over to 2" right now but, not sure myself at moment.

 

Sounds like good advice... even a relatively small exhaust leak will cause the surge???

Care to guess how much?

Hopefully this thread will help BOTH of us decide.

 

Let me know if you wanna sell those 1 7/8s. I have seen great gains on the ctsv swapping from 1 7/8 to 2 at 600hp levels the swap yielded 15rwhp 18tq.

 

If I upgrade, I'd be happy to sell them to you at a very fair price. One side will obviously need a bit of welding to seal it up...

Since I already run 3" exhaust all the way back, with hollow cats, you'd say the 2" headers will help a bit?

 

At 800hp I would say you pick up at least 15-20rwhp

 

Any low rpm torque loss with 2 inch headers? Not that we race there, but curious for the street.

 

I'd go with 2" ARH's.

 

None that I have seen from the Dyno Graphs I have done on FI cars. On a NA car it was down a bit till about 5k then picked up 10. On the Spray it was up by 4k. This is from my first hand experiance

 

Tough choice man, depends on the condition of what you have! I would just weld what you have, but 2in headers is always sweet and more HP gain !But at a big cost

 

I gained a ton of power from 4k up changing pulleys and to 2" headers. If I had to guess from the header change alone, (from 1-3/4 to 2"), I gained 75RWHP.
You'll need a retune after the header change to take full advantage of the increased flow.

The surge can be from the exhaust leak. If that doesn't fix it, cap off the blower and hit the brake boost line with your air compressor and I wouldn't be too surprised to hear that you found a vacuum leak

 

What kind of injectors you have?

 

dont know how bad is crack, but i just welded a 3" crack on my SW stainless works headers, we have 220v miller welder is just too nice came out pretty good, i sanded and painted with header paint charcoal color...looks new now.

 

I have Kooks now, and can probably get a pretty decent deal on a kooks 2"
I know ARHs are very good, but do you think there's a big difference between the two?

Not sure on the cost yet, find out tomorrow...
My current set has been heat cycled at least 100,000 times in the last 7+ years! They've paid the price.

That's a ton of power from just the Headers! I'm not looking to change pullies, too complicated with my setup...
We would certainly get back on the dyno if I go 2".

We have checked the Vacuum line to the brakebooster, are saying that we may find a leak inside, say the diapham?


I've got siemen 83s, with a Magnafuel pump.

 

I have had a couple of sets of ARH's. Very nice.

 

Is most of the modding moving the AC lines??
I don't have any of them...

While they are nice, Kooks has me me a nice deal on the 2" headers, and I pulled the trigger today!!

 

I installed some kooks 1 7/8 stepped to 2". They are 2" before they get to the ac line. I wrapped my headers and "massaged" my stock ac line. My AC is still working great 6 months later. It was pretty tight down there and will probably come down to the welder/fitter and your car though.

 

AC lines= easiest thing to manipulate.