From the Testing ECZ-B vs Mummert 4V intakes – Round One

thread.







This is a question I too am interested in because I plan on building some headers soon. In addition to the questions above, I have one about stepped headers. Is there a certain length that tends to work well before stepping up the header to the next size?

Is it better to match the shape of the ports? Leave the tubes round at the port? Perhaps the same shape, only slightly larger?


Lawrenceville, GA

Complex things... Here is some theory:

No matter how much additional air is forced into the engine, no additional HP will be made unless additional fuel is also added. The energy that makes HP in an engine comes from the combustion of the fuel, not only the air. In general, every two HP produced requires one pound of fuel per hour. When modifications are performed that increase airflow into the engine, more air is available for the combustion of fuel. The combustion of the additional fuel is what translates into additional HP.

Air flow is not just influenced by the size (area) of the paths it takes into and out of the engine. It is also influenced by the speed at which it moves.

Specific Port Flow (cubic meter/sec) = Flow Velocity (m/s) x Average Path Area (m²)

Whenever an engine modification increases the average area of the airflow paths into and out of an engine, there is a chance the velocity of the flow will decrease. Most of the time the factor of velocity decrease is very small compared to the area increased, so flow is generally increased. If modifications are taken too far, the velocity will decrease more than the area increases, so flow is adversely affected (example - four inch exhaust system on a 1.6 liter engine).

1. A "shortie" or a "block hugger" flows better than a stock manifold, and helps to produce more power than stock. However, it is not technically considered a header. They are easier to install in a stock style exhaust system, which makes them attractive.
2. Bigger diameter primary tubes are NOT better in most street applications.
3. The torque/power boost available from a header will occur at a specific RPM that can be easily determined. The price paid for this boost is likely lower power at other RPMs. All engine design is compromise.
4. Equal primary tube length is very important for tuning and power output, but not to the point of obsessing over it. A regular Tri Y or 4-1 header will work wonders over the stock manifolds.
5. A long and smooth collector is a good thing.
6. Just like header tube size, be reasonable with the size of your exhaust system.

Those "facts" are browsed from internet, not my head.

http://www.fabshopheaders.com/header-facts.html

The more you read, the more you get new ideas...

 Seppo from Järvenpää, Finland
www.hollowheads.net (just click the hole in the head to proceed)

That is too heavy so early in the morning. I think you just gave me a headache...

BOB

Ok, let's make things easy to do Download this and have some more fun...

http://www.otter-ag.ee/files/Header%20design.pdf

That doesn't really answer the question about sizes but it is otherwise interesting to read... I like the trial and error method more friendly for my wallet...

This one has more graphs and runner lengths calculated by rpm range

http://tom.marshall.tripod.com/exhaust.html

And this Merge Collector thing interests me more and more.

http://www.spdexhaust.com/pdfs/02-11_Merge_Collectors.pdf

And this is easy to read. Understanding is another dilemma...

http://www.popularhotrodding.com/tech/0310phr_jack_burns_exhaust_manifold_header_tech/index.html

 Seppo from Järvenpää, Finland
www.hollowheads.net (just click the hole in the head to proceed)

  I built headers for my 57 Custom using 1.5 tubing, there a shorty style all tubes exiting around and above the cross member. Problem with long tubes is ground clearance with the front tubes going underneath the control arm and the collector exiting right into the cross member. I read a header test article with a 400 hp 383 sbc and they used 1.5 to 1.75 tubes and the smaller tubes generally out performed in torque and horsepower on a street driven car. 

DOES ANY ONE MAKE A GOOD HEADER TO FIT A 57 PASSENGER CAR?

  JUST A MIDNIGHT CRUISE DOWN THUNDER ROAD!!! TOM DRUMMOND MIDWEST DIRECTOR 57 FORD INTERNATIONAL

Tom, I don't think anyone builds a "good" header for the 57. Ted's carb test proves that the Reds are only slightly better than stock. The good headers that Ted is using are modified scrubs by JC and RB, but they want fit in a 57 frame. Good headers will have too be custom made. It's time for someone to step up and offer a "GOOD" set for the 57 y block.

Glen Henderson



Freedom is not Free

Letohatchee, AL

And trucks!


Lawrenceville, GA

Thanks Hollow Head for all the tech you posted. I"d like to build some headers also at some point for my trucks. I built a few for a 223 and it sure woke that thing up even with the stock 1bll. carb on it.

Michael

Sandy Valley, NV

When the heads and intake manifold dyno testing is concluded, an extensive exhaust system test is planned.  At this point I have the following exhaust systems on hand in which to test.

 

EMC four tube stepped headers with 3½” X 10” collectors w & w/o mufflers

EMC four tube stepped headers with 3½” X 28” collectors w & w/o mufflers

Fenderwell 1 5/8” four tube headers with 3” collectors

Fenderwell 1¾” four tube headers with 4” collectors

Pickup Tri-Y 1 5/8” headers with 2½”  collector opening.  Lead pipes being considered.

Thunderbird short tube Tri-Y 1¾” headers with 2½” collector opening.  Lead pipes being considered.

Reds/Hedman short tube headers with 4” long 2” diameter lead pipes

Rams horn exhaust manifolds with 4’ long 2½” diameter lead pipes w & w/o mufflers

Stock 1957 exhaust manifolds with 4’ long 2” diameter lead pipes

Four tube 1¾” headers with 3” collectors w& w/o mufflers (built for dyno testing)

Four tube 1¾” headers with 3” collectors (custom for a ’56 Ford racecar)

 

This looks to be a minimum of fifteen different test variables and likely at least 30 dyno pulls on the engine as each variable is normally tested twice.

 

The EMC headers have a 3½” collector but the collectors are now double walled with a 2½” smaller collector inside the larger one which helped the EMC engine.  That same header is currently being used on the 312 dyno mule without any changes from when it was used in the EMC competition.  I’m currently building some new 1 ¾” tube headers for the Y dyno engine with 3” collectors and without the stepped tubes as are currently being run.  There’s also another set of 1¾” tube headers of a slightly different design available that were just built for a ’56 Ford drag car that’s currently going together.

 

It must be remembered that dyno testing is WOT testing and smaller sized headers are not necessarily bad at low rpms and at a cracked open throttle operation.  It’s only when the engine is at full throttle that a larger volume of ingested fuel air mixture must be purged from the engine and that’s where sizing becomes critical as scavenging becomes a major player.  As a general rule, being too large on header tube size is not as detrimental to overall engine performance as being too small.

Lorena, Texas (South of Waco)