You've got to be a member but the young man goes into detail
Is your exhaust port small enough?

So I recently had the opportunity to build some headers for a Ford Coyote FSS/_ car. I built a 421 header mainly because It is a 310" (I think) motor and uses a 3 speed automatic transmission. So from my point of view it needs all the help it can get at the bottom of the power band. Most people would be suprised to know the average rpm of a run with a automatic transmission. (Your RacPac can tell you that)

As many of you many know I will always determine the area of the exhaust port I am presented with from the Engine builder/head porter. I was surprised to find that the exhaust port at the flange was not ported (or at least did not appear to have been. Since it was a SS engine I would be sure that a lot of work probably was done inside but that does not affect me,) and measured 1.480" round. This was as the factory made it. I am sure several folks here on Speed Talk will calculate the valve area/Curtain area data and everything but to say the least I was shocked at how small and round it was. I was impressed and upon learning the engine is capable of around 750hp! I was giddy. Holy S___! this was even off my charts! Ha!

I had run into Coyote motors back in 08ish? I think at multi-matic and Elan Motorsports and the port were not round, they were WIDE and rather large. (not unusual). So I have to say Ford has done some work and made the exhaust ports SMALLER! a lot smaller! and this is something to note. OK?

So for anyone who has taken my tube size/horsepower range chart to heart, ah... a 1.625" tube off the head can handle 750 hp.

Calvin ElstonElston ExhaustMatthews, NC 28104346-704-4430Blog: www.exhausting101

 

Totally opposite of what was said and seen thru testing.
As long as you don't go smaller than the exhaust port hole.

 

A friend of mine wore me out over going to a smaller tube header on our motor. Said the same thing about the port size. We were running 2" Kooks at the time. So I picked up a set of Hooker super comp 1 3/4 long tubes. We lost 3.5 tenths off our all motor run. Tried everything tuning wise to bring back the time and got no improvement at all. That included several different length tuner pipes too. Needless to say the 2" Kooks are back on. Could not find a 1 3/4 stepped to 1 7/8ths or I would have tried that too but no one makes them. They do make them for open wheeled modified dirt cars though. Just no street cars for some reason and I called every manufacturer. Schoenfeld said they would make us a set but I had to bring the car to them so they can map out the exit route. **** that. WTF, no one has a freakin 93-97 camaro around there. But at least they were willing to do that I guess. Lol. Thinking about trying the 2" to 2 1/8th" Kooks on the next build.

At least that is what I've found on the LS subject. Another friend of mine did the same thing on his 434 SBC that had 2" Schoenfeld's, he found a set of stepped 1 3/4 to 1 7/8ths Hooker Super Comps for his 3rd gen. He, on the other hand, picked up 5 tenths on his motor pass. That's huge for just a header change. His motor loved those headers on spray too. We were all shocked at the outcome on our motor. Apparently these LS motors like to get the air out just as much as in. Which makes no sense with the size of the exhaust ports on the heads.

We ended up playing with tuner pipes different diameters and lengths too. Found a bad *** expander you use a impact on to expand the pipe. Works unbelievably good. Did 3" stainless to 3.5" no sweat. Sweet spot for us was 3.5" straight off the collector with a 3.5" mandrel bent turn out, to get the air out from under the car, at 24" total length.

 

Best Example of a great Header is.... .

who I tried my best to imitate (just smaller). John B. Go take a look and the reason for my investigation. That quote was from a 19+ page thread and it F"ed me up on size of the 1 step. What I seen John do made sense and a bit of research made it even more logical. Yrs later became a member of Speedtalk, read what a top End exhaust header specialist had to say and his thoughts on the subject of a Header.

Reference back to John...

 

I think the one thing is the tube size and the size of exhaust port and what Corona said on not blocking it. The Dart LS7 heads measures 1.80 wide x 1.6 tall and the TFS head is 1.72 x 1.47 and I think my Brodix 100 cc port was like 1.75 x 1.55. And they are D shaped but I would say a wide shaped D so a round pipe (based on the widest part) would cut the corners off a little at the 10 and 2 o'clock positions. Here is a photo of my Brodix heads done by AI. A 1.75 OD tube is like 1.65 ID so they would need to be shaped/stretched in the flange a little. A 1 7/8 should clear. I have ARH 1 7/8 headers and I think in the flange area they are like (inside dimensions) 1.85 across and 1.58 high. You need to have some extra as not all the holes line up perfect every time. The OEM exhaust port is like 87 cc so if the head is like a 100-104 cc the exit hole (Archangel is 99cc) is probably bigger and the header alignment/size should be looked at.

 

My thought is for anyone to Copy John's idea...
purchase a 2 step header and add the last step.. Way cheaper than a 3 step header by a professional.

 

Flow area is just one detail to consider. Size and length of the primary tubes sets the harmonic wave tuning.

For most, you bolt on the headers that are made for your car and hope for the best.

 

Mirek, happy for you. Sounds like a fantastic set up!


Your car has come a long, long way from the old MTI 222/222 Hammer Cam days

 

Yeah man, I have been trying to get the mods to give my old account back !!

I am like a 20 YEAR member, I lost my PW a few years back but have my same exact car.

My previous handle was “Mirek” hence my new handle “Mirek Again”

Mods if you see this help a brotha out

 

That is probably true. In this case, it's similar to the old adage that the bigger an engine is, the more cam it can handle. In this case, with 434 cubes, a 1-7/8" header may be a bit restrictive at the top end. A 1-7/8" set of LTs on a 5.3 would probably be way too big, unless maybe it was an 8,500rpm drag car. What's too big on a 5.3, or 5.7, is probably just right for a 402. I'd say, and only my .02, a stepped set of LTs, or 2" the entire length, may be just right.......

 

There is a good Engine Masters episode on this very thing. Cliffs Notes, back pressure is bad.

 

Oops.... I forgot this is 2023. Sorry for waking a dead thread