Optimal Header design for 484 FE without shock towers.

[hrtatk1]

Hello All,
I have a Shelby Aluminum 484 with Keith Craft CNC stage II edelbrock 6008 heads and edelbrock victor efi 4500 intake. I was wondering if anyone has suggestions on primary header tube diameter and length as well as the collector style, diameter and length or is step design better?
Does anyone know someone that makes custom headers if I decide not to do them myself?
This is a Hydraulic roller motor with FAST XFI 2.0 with ITC. This is going in 67 Fairlane 500 with C4 auto and gear vendors coupled to a 9' 3.70:1 35sp Detroit locker rearend.
When on the Dyno with the smaller Wilson 4150 throttle body and large dyno headers, the engine made 553HP @ 5600 and 555TQ @ 4900, and with FPA headers made 540HP @4600 and 547TQ @4900. I expected the HP to be over 600 for this build. I am hoping with the upgraded intake and throttle body (4500) as well as good flowing headers, I can get to 620HP or so. Cam was installed 110 @ 2 degrees advanced on timing set. Duration on cam @0.050 was 242/248, lift is 0.643/0.637, lobe sep. 113.
Intake/Exhaust valve size is 2.19/1.75" with port volume of 165/130cc and 76cc chamber. Posted head flow numbers at 0.3 lift is 219/163, 0.4 278/196, 0.5 311/220, 0.6 324/240, and at 0.7 335/253. Please let me know if you have any suggestions or need any more info. This is a 4.255 bore, 4.25" stroke motor at ~10.6:1 compression. I will probably install cutouts immediately after header if you believe that will help performance.
Thanks, Josh

[My427stang]

A couple of comments as your build is very, very close to mine

- The Victor, if unported, is leaving some power on the table, especially on a big inch motor
- I'd be surprised if those stage 2 heads flow anywhere near there.  I had a very similar flow table from KC when I bought mine, sent them back for other reasons and more porting and the next chart was less, but on a local table was about 40 cfm lighter.  This was 2006, and I can't say I know what KC does up there, but that was my experience.

So if you want a big jump, you may consider having someone else port them, it took us quite a bit of work to get in the 320s after I decided to have someone else to do them.  Again this was 2006, I haven't had any KC Stage 2s in my hand since then, but it could be something to consider.  Those are relatively big numbers for an Edelbrock head, maybe Joe or Brent can comment on what they have seen with KC Stage 2s more recently

I don't know any header builders, but I'd assume if you stick a screwdriver in the exhaust port and look at the overall direction the port travels, you'll see the direction the primary pipe needs to go, combine that with delaying the turn as long as you can for fitment. 

If you want to get serious with size and length based on engine characteristics, look for a program called PipeMax, it's cheap and has a good reputation for taking advantage of exhaust pulses for additional cylinder fill with primary pipe sizing and length

I am not a big cutout fan, but if you want them, they can reduce backpressure, especially if your exhaust is marginal.  That being said, put them well after the O2 sensor, I'd recommend 18 inches, just to be sure the EFI doesn't get any funky feedback and try to adjust it out

Overall I think you will really like the engine, should be very happy on the street

[Joe-JDC]

I have had 3 sets of the Keith Craft II CNC heads on my flow bench in the last couple of years, and all three sets flow in the mid 330cfm range @ .750".  As for headers, call REF in Kingman AZ, 928-692-0111.  They make some of the best custom headers for race cars available.  Not cheap.  Joe-JDC

[blykins]

Those numbers are pretty similar to what I've seen when I've flowed them.

I responded to your post on Club Cobra.  From what I've experienced on the dyno with similar combos, your hp and torque are pretty much "in the spot" for your build.  I highly doubt you'll pick up 70 hp with a throttle body and header swap...it will take a lot more than that.

[My427stang]

Awesome, thanks guys, he must have changed something in last 9 years LOL

That's why I hoped you'd chime in. 

[hrtatk1]

Thanks for all the suggestions. 
This build was nearly identical to one that KC did for a cobra other than the fact that the cobra had stack injection.
This build yielded "654HP@6000 and 633TQ@4400". I didn't expect my numbers to be as good as stack injection, but I did expect them to be over 600HP.
Is there a better hydraulic roller cam that could provide the performance I expect and still have decent street manners? I have Erson Roller rockers.
I did this build based on Joe-JDC results with these heads.
Joe, what do you show for the intake and exhaust volume?  I asked KC but they didn't know for sure.  My numbers we based on KC's estimate in another post.
Thanks, Josh



Thanks, josh

[blykins]

Are those xfi cam lobes?  If so, I would take a long hard look at your valvetrain setup and to be honest, I've picked up 25 hp by using milder lobes.

Also keep in mind that all dynos do not read the same.  There can be and often is 5-10% difference between locations.

I think you can pull a little more out of it with a cam, but 70-100 hp just isn't there unless you make some major changes.

I'll reply here from now on.

[Joe-JDC]

It seems like the 6008 heads have a much larger combustion chamber than the 76 you state.  Unless you milled the heads to get the cc's down, then you don't have as much compression as you think you have.  That would account for some of the loss of power and torque.  The intake volumn is close to 200ccs, but I haven't poured the exhaust on the KC II.  Port matching the intake, and compression are always power builders.  Joe-JDC

[hrtatk1]

The intake was port matched by survival as a 4150 flange.  I just opened it up to accept a 4500 throttle body but haven't run it yet.  I had several people tell me that the plenum was too small and that I needed a larger throttle body and injectors to hit over 600 hp.  I know jay says I should use a larger cam and go solid but if possible I would like to stay hydraulic for now.

[hrtatk1]

On the cylinder head sheet from KC it says
"Mill Heads clear-78cc"
"CNC Work Complete Stage II"
"valve job yes, face and backcut yes-30 deg"
"additional work bowl blend - restrictors 0.070"
"coil bind 0.0800
"Assemble Heights 2.035-2.045 150-155 ?Sut?
"spring pressure 405-410 @ 0.600
Cam shaft is comp cams PN 33-000-9  SN E 7837-14
grind FB 3018R/ 3039R HR113
gross valve lift 0.643/0.637
duration @ 0.006 tappet lift 292/300
valve timing open @ 0.050 int 10 btdc 52 abdc
these specs are for cam installed @ 111.0 intake center line.
Duration @ 0.050 242/248
lobe lift 0.3650/0.3620
lobe separation 113
Barry Said cam installed 110 2 degrees advanced on timing set

[hrtatk1]

Barry confirmed
Chambers were 76cc
The quench was +/-.041  to .043 - we target zero deck

Dyno headers are far from optimum for this engine - 1.750 primaries, 3.5" 4-2-1 collector, +/- 37" length

[blykins]

Ross likes to use the phrase, "too many cooks in the kitchen", so with that phrase in mind, I'll say this:

If Barry did the bottom end and supplied parts (or even built the engine complete), and Keith supplied parts, then I would be giving them a buzz. 

BTW, those are XFI lobes.  Personally, I haven't had much luck with them and have gained power by going to lazier lobes.  Counterintuitive, but it worked for me. 

[hrtatk1]

Thanks, I will consider your CAM comments if/when I change it.

[blykins]

Honestly, I wouldn't get hung up on peak numbers.   Most guys don't understand what a true 550 hp feels like.

[My427stang]

I agree with Brent completely

I'd say work with Barry, and be careful chasing numbers, any place you gain with a change, you will lose somewhere else. 

That looks like a very well thought out EFI build and if your goals have changed, then Barry certainly has the knowledge to help you get there

[Barry_R]

Hi Josh...

I can pretty much "promise around 20HP by moving up to the 4500 throttle body - - I've had to go the opposite way on a rules driven EMC deal and verified it a couple times.  I also modified a Ron's "Flying Toilet" single barrel throttle body to meet the 4150 rule the following year and picked the power right back up.

Your injectors will not be a limit - they are rated at 80% duty cycle and you just want to watch the duty cycle on the data log to see if you're getting close to 100%.  The heads are the biggest opportunity after the throttle body without impacting the driveability.  I did not flow them since you provided them - but I have to imagine that they have more potential than we are at right now with a bit of work.

First effort then is to try the higher flowing throttle body & see how the car runs.  My dyno is historically something of a polygraph and you could pick up "Hollywood Horsepower" at some other places....but the engine ran well and should perform well too.

[Faron]

Cam Is Too Small for HP Expected , Still Great Motor , you cant Hook 500 HP on any street tire , as posted above , Don't get hung up on Numbers , My 475-575 HP Combo is Fun , I love It more is a bragging right that is worthless in practicality IMHO

[Barry_R]

Not really comparable...for other reasons
But my most recent EMC engine made middle 600s at 6500 with 433 cubes with a 236@.050 cam....
Back in the day we'd have called that an RV grind as far as duration goes
Same engine with a 242@.050 cam went over 700..

There's always more to it than meets the eye
And some old ideas tend to die hard..

[blykins]

Well, back in the day, we didn't have 370 cfm heads.  A well performing head works without a monster cam. 

[hrtatk1]

Hello Barry,
Should know shortly how the 4500 performs. 
With all of your experience, what do you think the best header design to optimize the performance would be.  If I am going to build them, I only want to do it once.  without the shock towers, I can hopefully follow the port roof straight for a fair distance before turning down.  I had one header shop tell me 2-1/8 x 34 to 36" with not more than 2" straight pipe off of head with 3.5"merge collector. I might be wrong, but I would think you would loose to much velocity with that size tube.
Thanks, Josh

[Barry_R]

I think I would go no more than a 2" tube coming off the head myself...

[hrtatk1]

Hello Barry,
Thanks for the response.
Do you recommend a certain length primary tube? what type of collector and diameter? How long should you keep the header tube straight off the head before you turn down?

Hello Faron,
I know your are correct. I will have more than enough power as proven by Barry on the Dyno.  I just want to optimize the configuration before the final install. 
I hope with aluminum motor, triangulated 4 link, 285/40/18's and intelligent traction control, I will be able to put most of the power to the ground in a controlled fashion.  I figure if the GT500 hooks pretty well on these tires considering the weight, the Fairlane will have a decent chance as well.  Only time will tell.

Thanks everyone for your comments and suggestions.  I really appreciate it.

[My427stang]

I plugged your data into Pipemax, checks with Barry's recommendations

Primary pipe size (numbers rounded)
1.75 - 1.875 for low end torque
1.875 - 1.95 for mid and upper end

Primary pipe length (Actual numbers)
34.4 - 37.2 inches, with 34.4 considered optimum.

Collector diameter and length
3.25 - 3.50 diameter, 9.7 or 19.3 inches long (either works for the harmonic) but sort of a moot point with an exhaust behind it, but shows you big diameter exhaust is good

It's just a program, but it's generally accepted as a cool and useful program  

Seeing you are working this one pretty carefully, I'd try to hit the primary length close and likely use a 1 7/8 or 2 inch primary, whichever was easiest to source and/or fit the flanges. 

[hrtatk1]

Hello My427stang,
Thanks for taking the time to generate those numbers.
I really appreciate it.
Your numbers sound more like I expected.
Based on your experience is there a point I can drop down to 3" or smaller exhaust without a penalty on performance or would a x-pipe at the end of the 9.7 or 19.3 long collector be helpful or is it best to keep 3.25" or 3.5" exhaust all the way out?
Thanks, josh

[My427stang]

Interesting that you bring that up, because my tune has changed over time

Guys used to say that the gas cooled further down the pipe, so you could go smaller.  I never bought that, and still don't

However, I have seen quite a few dyno tests that prove you CAN go smaller further back and have been chasing data on why that is true.  The best explanation I have found so far is that at some point, the exhaust pulse rise and fall is dissipated so much, that there is no longer a need for the large pipe, just a pipe large enough to handle overall steady flow.

I'd say a 3 inch mandrel bent exhaust with an H pipe would be good all the way back on your motor, with the reduction from collector size as far back as it can be, and as gradual as it can be for the room you have.  Some of the circle track companies have gradual reducers if you have room to run them back 18 inches or so after the collector

In the end, my hunch is we are talking single digit differences, so likely just a 3 inch exhaust without much concern for anything else will be real good, but if you wanted to try to sneak every bit out of it, delay reduction as far back as you can

FWIW, I run almost the same engine with 1 3/4 inch headers and 3 inch exhaust and although I think there is a little more power to be had, it fits so nice I can't get myself to change it and it sure runs strong.

[hrtatk1]

Ross,
Thanks for the suggestions.
Did you run your exhaust out the back?
I will see what I can fit with the Heidts suspension. The IFS and triangulated 4 link reduce clearance especially above my 9".
Thanks, Josh

[jayb]

My latest foray into header design isn't perfectly relevant here, but I thought I would share it just to shed a little more light on this subject.  On my big SOHC engine (950+ HP), my original header design was a stepped primary, 2-1/8 to 2-1/4 to 2-3/8, into a merge collector with a 3.25" choke and a 4" outlet diameter.  This was a little smaller than Pipemax's recommended size; they recommended a 2.3" first primary tube, going all the way up to 2.5" for the third stage, and a 4.5" collector diameter.  Since I built those headers, I've had some input from two Engine Masters builders who I respect, Mark Dahlquist at Throttles Performance, and Blair Patrick.  They both say that the primaries are too big, even at 2-1/8", going in the opposite direction of the Pipemax recommendations.  They are saying I should go to a 2" first primary size, and size all the pipes down from there.  I'm in the process of starting up my new headers, to try out their suggestion.  In addition, I'm going to be using two different merge collectors, one with a 3" choke (my choice) and one with a smaller choke (Blair's choice; Blair is getting me the collectors).  When I'm done with this, and the engine is back together, I will have the original set of headers, plus the new set with two different merge collectors, to try out on the dyno.  Should be a very interesting test.  I wonder if Barry has any thoughts on this...

[Joe-JDC]

 I have flowed many of the designs on my flow bench with a head mounted backwards so the headers can be mounted and flowed through the exhaust port into the header.  The headers get so hot on the flow bench that you can't touch them for several minutes after flowing them.  If the exhuast port is a good flowing port without a tube, any size header will help pick up the flow unless it has a sharp bend immediately after the port opening.  Every angle that is welded into the tube will cut flow some, and turns/bends that are smooth do not.  You can build engines to make close to 800hp with 1 3/4 header primaries if the collector is merged correctly.  Stepped headers should have the primary tube volumn for first step of at least the cubic inch of that cylinder before the next step up in tube size, and so should the second step, etc.  A street car will always run better on the street with a smaller header primary tube size than most folks think is appropriate. 

Factory exhausts had the exhaust pipes after the mufflers smaller for a reason.  It has been a proven fact that the exhaust cools enough back to the mufflers under normal driving conditions to allow the use of a smaller exhaust after the muffler and keep velocity up in the pipes on the street.  Also, think of the jet engines with the afterburner, for them to speed up the exhuast and make more power, they squeeze the exhaust down considerable to aid in acceleration.  And as the power comes up, they open in stages to keep the velocity at its peak.  Automobiles don't have adjustable exhaust pipes, but squeezing the pipes down after the primaries with a merge collector does the same thing.  Smaller exhaust tubing after the muffler is a similiar affect.  Joe-JDC

[My427stang]

I have flowed many of the designs on my flow bench with a head mounted backwards so the headers can be mounted and flowed through the exhaust port into the header.  The headers get so hot on the flow bench that you can't touch them for several minutes after flowing them.  If the exhuast port is a good flowing port without a tube, any size header will help pick up the flow unless it has a sharp bend immediately after the port opening.  Every angle that is welded into the tube will cut flow some, and turns/bends that are smooth do not.  You can build engines to make close to 800hp with 1 3/4 header primaries if the collector is merged correctly.  Stepped headers should have the primary tube volumn for first step of at least the cubic inch of that cylinder before the next step up in tube size, and so should the second step, etc.  A street car will always run better on the street with a smaller header primary tube size than most folks think is appropriate. 

Factory exhausts had the exhaust pipes after the mufflers smaller for a reason.  It has been a proven fact that the exhaust cools enough back to the mufflers under normal driving conditions to allow the use of a smaller exhaust after the muffler and keep velocity up in the pipes on the street.  Also, think of the jet engines with the afterburner, for them to speed up the exhuast and make more power, they squeeze the exhaust down considerable to aid in acceleration.  And as the power comes up, they open in stages to keep the velocity at its peak.  Automobiles don't have adjustable exhaust pipes, but squeezing the pipes down after the primaries with a merge collector does the same thing.  Smaller exhaust tubing after the muffler is a similiar affect.  Joe-JDC

Joe, I agree you CAN use smaller pipes out back, but I have not found where cooling was a "proven fact" and certainly haven't seen any proof that large tailpipes hurt other than noise control.  Primaries being too big, yes, collectors being too short or too big with open exhaust, yes, but not diameter further back.

Matter of fact, I would say the cooling theory is only theory based on interpretation of what we both agree we see with smaller pipes.  My personal opinion is that it isn't based on cooling, if it was, eventually you could have an exhaust long enough, maybe an ice cooled 5/8 heater hose, but no matter how cool it was, I don't see that 5/8 tube flowing enough.

That being said, I spent a ton of time researching it, with no solid answer....but we agree that you CAN go smaller.  Knowing there is a relatively violent exhaust pressure spike and then negative spike that decays over distance, my interpretation is that is why the tailpipes can be smaller because that spike and recovery minimizes. After that it is just an area calculation, however even then the exhaust experts don't agree completely on anything and I haven't found a definitive answer.

I'll also go one step farther and agree with the exact words you used..."in normal driving"   I can probably buy into the fact at light throttle there isn't much heat back there, but when your foot is in it for a continuous period, racing or pulling a hill, I think things stay pretty hot all the way to the tail pipe exit.

However, I agree on what you said about sizing and hp requirements and the fact that many people use too big of a primary pipe. 

hrtatk1 - I run my pipes all the way back and turn down in basically stock location at the back valance

[Barry_R]

My thoughts on headers is approaching the ones I have on cams.  The more experience I get the more likely I am to just try stuff & see what happens.  So far I can say that something of at least a short straight run out of the port definitely helps - and is nigh unto impossible in a shock tower car.

My stuff has proven to be MUCH more sensitive to collector length and design than it is to primary features - as long you are in the general rational realm of sizing.  I am also pretty well convinced that some characteristics that show up good on the dyno are not going to be optimal in a car.  The difference is one of running against a load that controls acceleration rate (dyno) compared to running against a variable load while trying to maximize acceleration (car).  Blair has more experience than I do in race car optimization and I would tend to follow his lead there - I've seen some stunningly small choke diameters in use.

[Joe-JDC]

I am just repeating what I was taught in my college courses and what I have experienced working with a factory sponsored race team that did all the porting for a  GTP race series.  When the new for '86 Mustang GT/LXs came out with dual exhausts, Ford made the statement about the pipes not needing to be the same size after the mufflers.  I believed them then, and I still think it works best for street.   I have seen Fox mustangs run in the 10's with 1 5/8" headers, and 8's with 1 3/4" headers, and I have seen them use 2" headers to run 8's NA.  Sometimes we over think the whole process, but some header designs always seem to come out on top when compared to others of the same family.  You can move a header pipe around on the exhaust port as much as 1/8", and pick up 10cfm in some instances.  Getting it to fit the shock tower car is where the problem arises for optimum shape with a FE.  I still think REF in Kingman AZ has as good a handle on what works as anyone for the FE.  Some folks think that it is simpler to multiply the exhaust valve diameter x 1.25% and use that for header sizing.  I ask you how that works out when a 1.600" exhaust on the D-3 Motorsports head flows 300cfm, but we struggle to get 250cfm with a 1.750" exhuast valve on the FE heads?  Cubic inch size has to be taken into account somewhere in the factoring of header tube sizing for optimum efficiency.    Joe-JDC

[jayb]

My thoughts on headers is approaching the ones I have on cams.  The more experience I get the more likely I am to just try stuff & see what happens.  So far I can say that something of at least a short straight run out of the port definitely helps - and is nigh unto impossible in a shock tower car.

My stuff has proven to be MUCH more sensitive to collector length and design than it is to primary features - as long you are in the general rational realm of sizing.  I am also pretty well convinced that some characteristics that show up good on the dyno are not going to be optimal in a car.  The difference is one of running against a load that controls acceleration rate (dyno) compared to running against a variable load while trying to maximize acceleration (car).  Blair has more experience than I do in race car optimization and I would tend to follow his lead there - I've seen some stunningly small choke diameters in use.

Your comments on primary and collector length pretty much repeat what is in David Vizards book; he says on a normal V8 engine (one with a standard crank, not a flat plane crank), the exhaust pulses on the primary are a little fuzzy because of the two cylinders on each bank that fire in succession (4-2 on the right bank, 7-8 on the left).  His claim is that this tends to defeat the purpose of sizing the primary pipe length, and the result is that if all the primaries are in the 30-40 inch range, they will work just as well as if they are all the same length.  On the other hand, he says that normal V8 engines are very sensitive to collector lengths, and that people should spend a fair amount of time and effort playing with those, because there is significant power to be gained there.  Of course, if you attach an exhaust system there is less sensitivity to the collector length.

I'm considering making two new sets of headers for my engine, one where the bends are minimized and the lengths are all in the 30-40 inch range, and one where I keep all the primary lengths at about 33 inches (which will require more and tighter bends), and test them out to see which works better.  I'm also looking forward to trying a "collector comparo" at the track...

[machoneman]

Long ago.....Mickey Thompson swore by and made the Super Scavenger header where, as shown in a linked pic, the unequal length primaries ended up stuffed into a rather large square shaped collector where the pulses allegedly evened out. They were a pretty popular header but I never saw any back-to-back test, track or dyno, that verified his published tests.

 http://forums.hotrod.com/car-craft/70/9646431/car-engine/headers/

What's interesting too is what the Fab Shop makes these days ala' the heavily tapered 4-hole merge collector. Yet, the pics do not show some of the wilder collector extentions (2 into 1) some of the Pro teams run.

http://www.fabshopheaders.com/pro-comp-headers.html

[hrtatk1]

I was actually going have the FAB shop build my headers, but after I sent pictures and he realized I had inner fender panels, he said he wouldn't.
His recommendation was 2-1/8" X 34-36" primary not more than 2" straight off the head with a merge collector with 3-1/2" outlet.
I also called REF and he said 2 to 2-1/8" primary.

[1968galaxie]

Not really comparable...for other reasons
But my most recent EMC engine made middle 600s at 6500 with 433 cubes with a 236@.050 cam....
Back in the day we'd have called that an RV grind as far as duration goes
Same engine with a 242@.050 cam went over 700..

There's always more to it than meets the eye
And some old ideas tend to die hard..

hello Barry,

How on earth can you compare the low duration (0.050" numbers) EMC camshaft with a typical low duration RV grind?
Not really the same are they?
Any extreme camshaft lobe profile (which any low duration EMC build is) coupled with high lift does not make for a long maintenance free lifetime. I am sure you will agree. Hydraulic rollers set up like a solid roller, and solid roller type valve spring pressures.
Not a comparison in my opinion.

I would much rather have a little longer duration with a reasonable lobe design than an EMC type lobe.

[Barry_R]

You can't - - and I said that.

At the same time the point is that you also cannot simply state that something "will not happen" with a set of cam specs unless the rest of the combination is way, way out to lunch.  Five years ago anybody on the internet would have called me out for claiming that I could go to 7000 RPM or approach 700 HP with 236@ .050 - - now its accepted as factual "with a disclaimer".  A good set of heads changes the entire scheme of things.

[900HP]

My thoughts on headers is approaching the ones I have on cams.  The more experience I get the more likely I am to just try stuff & see what happens.  So far I can say that something of at least a short straight run out of the port definitely helps - and is nigh unto impossible in a shock tower car.

My stuff has proven to be MUCH more sensitive to collector length and design than it is to primary features - as long you are in the general rational realm of sizing.  I am also pretty well convinced that some characteristics that show up good on the dyno are not going to be optimal in a car.  The difference is one of running against a load that controls acceleration rate (dyno) compared to running against a variable load while trying to maximize acceleration (car).  Blair has more experience than I do in race car optimization and I would tend to follow his lead there - I've seen some stunningly small choke diameters in use.

Your comments on primary and collector length pretty much repeat what is in David Vizards book; he says on a normal V8 engine (one with a standard crank, not a flat plane crank), the exhaust pulses on the primary are a little fuzzy because of the two cylinders on each bank that fire in succession (4-2 on the right bank, 7-8 on the left).  His claim is that this tends to defeat the purpose of sizing the primary pipe length, and the result is that if all the primaries are in the 30-40 inch range, they will work just as well as if they are all the same length.  On the other hand, he says that normal V8 engines are very sensitive to collector lengths, and that people should spend a fair amount of time and effort playing with those, because there is significant power to be gained there.  Of course, if you attach an exhaust system there is less sensitivity to the collector length.

I'm considering making two new sets of headers for my engine, one where the bends are minimized and the lengths are all in the 30-40 inch range, and one where I keep all the primary lengths at about 33 inches (which will require more and tighter bends), and test them out to see which works better.  I'm also looking forward to trying a "collector comparo" at the track...

Bring that Mustang up here once the engine's done and I'll help you build a REAL set of headers.

[900HP]

On the header thing, please read:  http://www.exhausting101.com/
                                          and:  http://www.speedtalk.com/forum/viewtopic.php?f=1&t=41836
                                          and:  http://www.speedtalk.com/forum/viewtopic.php?f=1&t=36702

A couple of things about header design:

1) most are too big with too restrictive of bends

2) The header tube does not need to be any larger AREA wise (and often smaller) than the exhaust port it's attached to, at least to start out with.  The primary should start with the same AREA as the exhaust port and then step from there depending on power/rpm/etc

3) 4-2-1's will allow a broader powerband with no loss of peak (when designed correctly) and are easier to package and offer more ground clearance.

4) Primary length is about #7 on the list of importance in header design.  As long as it's in the ballpark it's close enough, the reason for this is that unless you have a 500 rpm powerband, one pipe "tuning" at 100 rpm less than another really doesn't matter.

5) the most important part of the header is the port-match and the bend radius off of the cylinder head.

6) When the area increases the exhaust releases energy as it slows down, this can be seen as heat.  This is why collectors and tight bends are always the hot spots, you are giving up exhaust energy.  Once it's gone you can't ever get it back either. This is why header for header stainless steel will make more power.  It 1) keeps it hotter and 2) doesn't rust so the inside stays smoother. 

7) Anti-reversion steps/valves work very well but most put them at the wrong spot.  The cylinder head is the wrong spot, the end of the system is the correct spot


No header is going to get the op the power he wants.  #1, the lobe separation is too wide, especially considering the compression.  #2, th duration is fine, I just built a 464 inch Buick with 230/236 duration and it peaks at 5900-6000 rpm @ 598 hp.  It has heads that are done nicely (hint hint).  #3) if you need to run that wide of LSA because of your efi system, you need a different efi system.  There is power to be had in electronics too, proper injector size (much bigger than you'd think) injector timing, throttle body size, etc, etc, etc.

[900HP]

Are those xfi cam lobes?  If so, I would take a long hard look at your valvetrain setup and to be honest, I've picked up 25 hp by using milder lobes.

Thinking more on this.................................... OP, WHAT LIFTERS ARE YOU USING?  I haven't had an issue with XFI lobes, they aren't as aggressive as some think however, if you aren't using the GOOD lifters you are leaving a LOT on the table.  What's the point of having a hot camshaft if the lifter can't keep up with it?

[hrtatk1]

Survival provided the complete custom Hyd. Roller Cam/Lifters so I would have to defer to Barry on the brand of lifters.

[machoneman]

On "optimal" headers, I'll go out on a limb here. If our poster (or anyone for that matter) runs a full length exhaust with mufflers, I don't believe one set of headers makes a big difference, minimal at best. That assumes a fairy well-designed yet off-the-shelf header with appropriate sized primary, collector, exhaust pipe and free flowing mufflers.

Yet, an open header engine, on any track, does make for testing various designs. I'm reminded of some old pals running Comp/Elim and Pro Stock cars who used to have a ton of various headers that were constantly swapped for real on-track testing in hopes of gaining provable, yet often minimal e.t. reductions. Heck, they had more invested in headers than any complete drag car I ever ran! And yes, Stock (where allowed) and SS cars also benefit by particular designs that do show solid, if not major, e.t. reduction.

But once again streeters that are mufflered-up are in a whole different world. Flame on!   

[900HP]

Survival provided the complete custom Hyd. Roller Cam/Lifters so I would have to defer to Barry on the brand of lifters.

If you got the lifters from Barry they are Morel and they are fine.  I was just thinking out loud...........

[900HP]

On "optimal" headers, I'll go out on a limb here. If our poster (or anyone for that matter) runs a full length exhaust with mufflers, I don't believe one set of headers makes a big difference, minimal at best. That assumes a fairy well-designed yet off-the-shelf header with appropriate sized primary, collector, exhaust pipe and free flowing mufflers.

I don't agree with you on this.  IF the headers are designed correctly they can be made to "ignore" the exhaust system behind them as long as it flows well enough.  It can be as simple as an A/R valve at the collector which is the biggest mistake that I personally made at Engine Master's this year.  Last year we had a nice A/R valve and the engine wasn't affected by the dyno exhaust.  This year there was no A/R valve and the exhaust behind the header drastically affected power. 

Also, a 4-2-1 header properly designed will out-perform a 4-1 header at every rpm you are likely to use.  As rpm band narrows and goes up (think comp eliminator) the advantages of the 4-2-1 become less and less significant.  One more thing about the 4-2-1 header is you will have MUCH better part-throttle drivability and response if it's designed correctly.  Too many people build a 4-2-1 header like a 4-1 header with a different collector and that is not the right way to do it.

Please read the links I previously posted, there is an incredible amount of good exhaust information contained in them.

[hrtatk1]

What does everyone familiar with the FPA-Tri-Y headers think would happen if I was to take my set and modify them with a longer tube straight off of the head flange and then a gradual curve into the existing header, thereby eliminating the tight turn normally there for fitment in cars with shock towers? Would they be adequate for my engine combo?

Barry tried both my FPA's and his Dyno Header on my engine and the results are as follows:

FPA's=540HP@5600,  547TQ@4900

Dyno=553HP@5600,  555TQ@4900

[jayb]

There is no doubt that the near right angle bend at the port of the FPA headers, and other FE headers for shock tower cars, has a significant effect on power.  I think if you re-did the first 6-8 inches of the FPA headers they would work really well.

[900HP]

What does everyone familiar with the FPA-Tri-Y headers think would happen if I was to take my set and modify them with a longer tube straight off of the head flange and then a gradual curve into the existing header, thereby eliminating the tight turn normally there for fitment in cars with shock towers? Would they be adequate for my engine combo?

Barry tried both my FPA's and his Dyno Header on my engine and the results are as follows:

FPA's=540HP@5600,  547TQ@4900

Dyno=553HP@5600,  555TQ@4900

I looked on FPA's website and I can see why they are down on power to the dyno headers, what an awful design.  You are not going to pick up large amounts of power with a header change.  Building the correct header you will make more power everywhere but you aren't going to pick up 50hp.  REAL 4-2-1 headers should look like this:


Or this:

[ScotiaFE]

If you have all this really high end gear and cut the towers out of the Lane
why would you buy what some would consider the crappiest pipes out there.
Even an old set of Hookers would help here.
REF makes some pretty nice Lane pipes also. Those SS guys can get up on it.

Nice looking pipe Mark.
How much? 

[hrtatk1]

Mark,
What would you charge to build a set of headers for this combo?  Looks like you use Stainless? Do you wrap them to reduce engine compartment heat? What do you wrap them with?
Thanks, josh

[900HP]

Mark,
What would you charge to build a set of headers for this combo?  Looks like you use Stainless? Do you wrap them to reduce engine compartment heat? What do you wrap them with?
Thanks, josh

You probably don't want to go down the route of custom stainless headers as the cost vs. benefit for a street car just isn't there.  It's a whole other story if you are class racing or have a car that you simply can't buy headers for.

That being said for a set of custom stainless 4-2-1 headers be prepared to spend $3500 parts and labor.  I wouldn't wrap them, it just decreases tube life, even with stainless.  If it was a turbo car with lots of heat you'd use 321 or Inconel and wrap them at that point.

[hrtatk1]

Mark,
Since my heads have rectangular exhaust ports which measure 1.375  X  1.937, would there be any benefit to running rectangular tube a certain distance before transitioning to a round tube or are you better to transition to round immediately?
Based on the exhaust port size would you use the slightly larger 1-7/8" or smaller 1-3/4" or do you use thicker wall 1-7/8" to get area similar until first step?

[garyv]

Josh,
Unless you can build these headers yourself or have $4K to spend on a custom made set, your best bet
is to call REF and have them make your headers.
At the HP level you are at REF's will be more than adequate for what you need
I talked with them and they built the headers for my 465 TP that's right at 700HP now and will be over that when completed.
It's on the next page of this forum and you can read about it if you want.
my 2 cents
garyv

[ScotiaFE]

Not sure if these are the "Optimal"
but they look great.
And they obviously worked pretty good.

 

[jayb]

Those are cool, are they from back in the day Howie?  Like '68 or '69?

[ScotiaFE]

Yes they where the headers for the 68 Torino that David won the Championship with.
The 68 cars had a "non stock" front clip.

[900HP]

Mark,
Since my heads have rectangular exhaust ports which measure 1.375  X  1.937, would there be any benefit to running rectangular tube a certain distance before transitioning to a round tube or are you better to transition to round immediately?
Based on the exhaust port size would you use the slightly larger 1-7/8" or smaller 1-3/4" or do you use thicker wall 1-7/8" to get area similar until first step?

The area of 18gauge 1.875" (1 7/8") tube is going to be really close to your port after you subtract the area of your corner radius.  For STREET use I would do 1 3/4" step to 1 7/8" primary tube.  For RACING use I would do 1 7/8" no-step or possibly 1 7/8" step to 2" even though that's getting on the big side.  Keep the collector at 3" though.