C9OX intake reprise

69gmachine · Feb 17, 2008

For reference, here is a link to our earlier discussion on this intake:http://forums.stangnet.com/showthread.php?t=718046&highlight=shelby+intake+351

I found a guy selling an SCCA legal 69 Mach 1 on e-bay (pic below). As you can see, he's using the C9OX intake and claims to make 400 Ft. lbs and 395 HP @ 5600 with his stock stroke 351W. I'm almost certain the SCCA requires the stock iron heads as well, but allows headers.

Eventually I'm going to have to try one to see what it'll do compared to the Torker II on a 408.

The early magazine tests certainly didn't do it justice.

bnickel · Feb 18, 2008

i have one of those myself that will be going on the 69 cougar, which i finally paid off this weekend and will hopefully be bringing home next weekend, weather permitting. i've heard many rumors that ford had some kind of 400hp variant of the 351w in the works and this intake was a derivative of that program but for whatever reason the project was cancelled but the intake lived on in the Ford Muscle Parts program and on the 69 (and 70) GT350. whether this is actually true or not i have no idea but i've heard this from more than one source so maybe it is.

i would recommend carefully checking the casting for flaws though, mine has a pretty rough looking plenum area but the ports and the outer surfaces of the intake are fine and it's definitely a casting flaw. that's alright since i plan on smoothing the interior surfaces of the plenum and port matching the intake anyway but if i wasn't going to do that i would have been upset.

69gmachine · Feb 18, 2008

I hope you're going to install a nice set of aftermarket heads, a strong cam and headers to go with it. Let us know how it runs when you get it all together.

bnickel · Feb 19, 2008

a set of GT40-X aluminum heads (that's the plan) a fairly mild retro roller but with a set of 1.7 cobra roller rockers and either some shorty headers or a set of ported 351w or hi-po 289 manifolds. i'm not looking for an all out performance monster out of this one mainly more power than stock, reliability, longevity and decent mileage. it's also going to get a long rod conversion as well using 400 rods and KB pistons

69gmachine · Feb 19, 2008

bnickel said:
a set of GT40-X aluminum heads (that's the plan) a fairly mild retro roller but with a set of 1.7 cobra roller rockers and either some shorty headers or a set of ported 351w or hi-po 289 manifolds. i'm not looking for an all out performance monster out of this one mainly more power than stock, reliability, longevity and decent mileage. it's also going to get a long rod conversion as well using 400 rods and KB pistons

The only thing that looks out of place to me would be either of the stock manifolds. If you're taking a vote, cast one for the shorties.

bnickel · Feb 19, 2008

69gmachine said:
The only thing that looks out of place to me would be either of the stock manifolds. If you're taking a vote, cast one for the shorties.

yeah i know but headers would give away the total sleeper image i'm going for with this thing. it may not be a barnstormer but i'm still hoping for 375-400hp so maintaining that stock look is important to me.

CraigMBA · Feb 19, 2008

My dad had a '46 Willys jeep he used to sand drag back in the late '60's with a 289. His buddy bought a brand new '68 Bronco. My dad's rig ate it's lunch. In a big way.

His buddy added an intake and a four barrel. No faster.
His buddy added a cam. No faster.
His buddy ported the heads. No faster.
His buddy added headers. It was instantly faster, not as fast as my dad's deal (pops had more cam) but close enough where the ribbing stopped.

If you HAVE to use manifolds, can you use the ones off a pickup or something?

Rusty67 · Feb 19, 2008

CraigMBA said:
My dad had a '46 Willys jeep he used to sand drag back in the late '60's with a 289. His buddy bought a brand new '68 Bronco. My dad's rig ate it's lunch. In a big way.

His buddy added an intake and a four barrel. No faster.
His buddy added a cam. No faster.
His buddy ported the heads. No faster.
His buddy added headers. It was instantly faster, not as fast as my dad's deal (pops had more cam) but close enough where the ribbing stopped.

If you HAVE to use manifolds, can you use the ones off a pickup or something?

The Hi-Po 289 manifolds flow a lot better then the regular ones. Properly ported 69/70 351w manifolds flow as good as most headers do. Now I know you are going to call bull**** on this but thats why I said PROPERLY. A friend of mine use to circle track race with ported 351w manifolds (they weren't supposed to be ported but who knew ?) and he use to crank well above 7000 rpms all day. I've got a set he ported for me but I've got no use for them since he ended up making me some sweet custom tri-ys to clear my clutch cable. My exhaust wasn't cheap.....

bnickel · Feb 19, 2008

Rusty67 said:
The Hi-Po 289 manifolds flow a lot better then the regular ones. Properly ported 69/70 351w manifolds flow as good as most headers do. Now I know you are going to call bull**** on this but thats why I said PROPERLY. A friend of mine use to circle track race with ported 351w manifolds (they weren't supposed to be ported but who knew ?) and he use to crank well above 7000 rpms all day. I've got a set he ported for me but I've got no use for them since he ended up making me some sweet custom tri-ys to clear my clutch cable. My exhaust wasn't cheap.....

what are you going to do with that set you have no use for? wanna sell 'em or something

CraigMBA · Feb 19, 2008

Rusty67 said:
Now I know you are going to call bull**** on this but thats why I said PROPERLY. QUOTE]

Back when street racing was a real hobby in the late 1980's, I knew a guy with a beat mustang II with a "stock" 302. This car retained all the smog equipment and even the hubcaps. He had a 'properly' ported set of heads and a 'properly' ported set of manifolds. I saw the bill for those two and it was just short of $10K.

I know, it was excessive, but this car was a work of sleeper art. If you looked close, the rim screws gave it away. Then you'd notice the cheaterslicks and the glued on white letter Futura sidewalls.

It ran like a 10.80 the first pass at LACR and they kicked him off forever.

I guess my point is you can absolutely make it work, but you ought to be prepared to get your wallet out.

FWIW, we used to cheat like crazy on my buddy's dirt track car. After porting the heads, we would shot peen them to put the pattern back in. Always passed tech.......but it wasn't cheap when we kept getting claimed.

Rusty67 · Feb 19, 2008

Porting heads, that is expensive. Porting a set of exhaust manifolds... well that is fairly affordable. I think that for the money spent for performance gained if you are using the right manifolds and have them ported correctly then you will definately get your money's worth.

69gmachine · Feb 19, 2008

I just don't think there are any manifold castings that are large enough to really let a healthy 351 breathe. I could see a highly ported set of Hipo or 351W manifolds working well on a 302 but on a 351? All the comparisons I've seen in the mags have used off the shelf manifolds and they give up a lot to a 351 with headers; even shorty headers. I have no idea how much you could get back with porting, but unless you can get that used set for a deal, I think it would just be easier to use headers.

bnickel · Feb 20, 2008

shorty headers are not out of the question but the manifolds will help keep the stock look of the engine. until i get the stang sold and have a little more budget to work with i think all i'm going to do to the 351 for now are install the worked C90x intake, a 4100 autolite carb and a set of ported manifolds with 2 1/4" exhaust. for now the engine will remain stock otherwise but later i'm going to do a long rod, roller cam, aluminum head motor and will likely go with the shorty headers then, i'll just have them ceramic coated in cast gray.

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