Mid length vs. long tube headers for lowered SC

S

Scott Long

Registered User
I'm looking at buying a set of Kooks headers since my car is going to need a better flowing exhaust than my current setup (cat-less down pipes into a Flowmaster Force 2 system) when I get the new setup (blower, heads, cam, etc)

The car is lowered with eibach springs and sits pretty low (rubs resonator on speed bumps in parking lots). I'm wondering if the extra $100 for the long tube headers would be well spent or if it would just cause problems with rubbing and ground clearance?

Would the mid lengths flow just as good with 2.5" downtubes, no cats into a custom exhaust system?

Car is staying low. Handles amazing and looks great.
 
Stick with the mid-lengths Scott, you'll be fine. I would however do something with the ball and socket connection. I had mine cut off, added 2" of stainless tubing and then added a v-band clamp. I think DLF added a 3-bolt flange to his. You can see pictures of both on the site.
 
I found the article where Dave Dalke flow tested the different headers and manifolds and notice the mac mustang headers flow almost identical to the Kooks at 1/3 the price. So... where can I get a set of those? Might as well use them even if I have to re-weld or bang the driver side header to clear the steering shaft. For $500 less.... yeah I'll deal with it buy injectors with the money I save and still have money left.
 

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The thing is to optimize scavenging as much as possible. Dave's flow test was just that; a flow test (which he has stated.) Scavenging depends on how long the primary tubes are, which to reduce it, you'll need longer primaries. The length and size of tubing depend on the volume and VE of the cylinder. If the primaries are too small, you suffer from lack of flow. If they're too big, you will lose power from lack of backpressure that provides the cylinder with air during overlap events. Just as long as the tubes are long enough and have good enough volume, they'll work well. If you put exhaust on headers, you effectively shorten the needed length of the primaries. An open header motor will need longer primaries than mid-lengths.

These are general concepts. I didn't wanna bore anyone with a physics lecture.:)
 
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Scott Long said:
Found some I think these are the right ones:

http://www.stangmods.com/MAC-Short-Tube-Headers-1994-1997-V6-Mustang-p/00178.htm

and here they are ceramic coated, if these are correct and have 2.5" collector I'm going to order them:

http://www.stangmods.com/MAC-Ceramic-Coated-Shorty-Headers-for-94-97-V6-p/00639.htm
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If you want my Macs cheap you can have them, $75. With downtubes. Later you can go bigger if you need to. They aren't the prettiest but still work, they are not coated, paint does not stick to them for long.
 
If sticking with a positive displacement blower, then I don't see a need to worry about primary length or size. The blowers have enough power instantly that you simply shouldn't see a difference.

Look for exhaust that has low variance port to port and flows reasonably well. I made over 400rwhp on stock cast manifolds. The Mac headers are probably fine for the job.

It's really a question of what you will use the car for. If you're chasing tenths of a second on a 1/4 track, then every little bit can help but you need to include your heads, cam, blower into your exhaust decisions. (do you want to help low rpm power, or high rpm breathing or split the difference)
 
CMac89 said:
The thing is to optimize scavenging as much as possible. Dave's flow test was just that; a flow test (which he has stated.) Scavenging depends on how long the primary tubes are, which to reduce it, you'll need longer primaries. The length and size of tubing depend on the volume and VE of the cylinder. If the primaries are too small, you suffer from lack of flow. If they're too big, you will lose power from lack of backpressure that provides the cylinder with air during overlap events. Just as long as the tubes are long enough and have good enough volume, they'll work well. If you put exhaust on headers, you effectively shorten the needed length of the primaries. An open header motor will need longer primaries than mid-lengths.

These are general concepts. I didn't wanna bore anyone with a physics lecture.:)
Click to expand...

I was under the impression that in a boosted car header scavenging was not a factor due to the air charge that comes in is under pressure. What I hear you saying is the headers do make a diffrence on a blower, or turbo, car. Guess you can now do that boring physics lecture;)

Ken
 
ricardoa1 said:
If you want my Macs cheap you can have them, $75. With downtubes. Later you can go bigger if you need to. They aren't the prettiest but still work, they are not coated, paint does not stick to them for long.
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what do u need to do to make the macs fit the sc ?
 
I have worked with Kooks on some custom headers within the past year so different collector options are available if anyone wishes to custom order a set.

The V6 mid-headers have a ball/socket on them while the 2V and 4V V8 Tbird/Cougar/Mark VIII headers have the flat 3-bolt flange on them.

I don't know why Kooks initially made each this way but that is what Super Coupe Performance has been offering for some time now.

Working with Kooks I have made the V6 mids with a flat 3-bolt flange and the also made the ball/sockets on the V8 headers for customers who had specific likes and dislikes on each one.

Since most everyone here is a SC guy, should we continue to offer the ball/socket type collector on the mid-length headers or go with the flat 3-bolt flange? Kooks can also do a V-band clamp too.
 
If doing it over, I'd get a set of stainless mid length Kooks headers with extended collectors and a 2.5" V-Band connection, instead of the Jet hot coated longtube Kooks headers with 3" collectors and 3 bolt flange.

The Longtube headers are a very tight fit and at least one header has to be unbolted from the motor/head before the transmission can be removed. The steering shaft also had some clearance issues. They look real cool, but didn't make any more power than the mid length headers I had, and required retuning to get the A/F ratio back where it was supposed to be.

Now that I've got a 4.2 motor and a bigger supercharger, they might be helping some, but I suspect I could make the same power with a set of mid length headers.

David
 
As far as flange type since I went to 1/2" SS carriage head bolts I've had no problems with my ball/socket loosening up.
 
bowez said:
As far as flange type since I went to 1/2" SS carriage head bolts I've had no problems with my ball/socket loosening up.
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On my car, the ball on the mid length headers were getting deformed from engine movement, not loose fasteners. Mainly from racing it with nitrous.

David
 
I like the 3 bolt flanges. They are cheap and if you use a dead soft aluminum gasket, they don't leak. V-bands have their own issues and are not perfect solutions either.
 
XxSlowpokexX said:
The ball on my midlenghts deformed due to overtightening. Thin metal, bad idea
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I had the same problem with the kooks midlength. Bill told me, the new midlengths he offers are stainless steel instead of mild steel. Stainless is much stronger and wont deform. I probably over tightend mine because they were leaking, and eventually would do the same thing to stainless(maybe).

I still say the best connection is to use are v-band connections. They work great and absolutely wont leak. Make sure you use a high quality set, i've seen some of the cheaper thin-walled ones break over time. Worst thing that can happen is breaking the clamp, as long as you can find he correct replacement your fine. I found that to be a bit of an issue without buying a new kit though

chris
 
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