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