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post #16 of 35 (permalink) Old 09-24-2012, 07:29 AM
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Re: 351 windsor intake manifold question

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Originally Posted by brihvac View Post

You can have the best of both worlds. Looks like my biggest issue is the single plane intake. Explains why my car always hesitates off throttle unless you really tromp it.
Correct. A single plane intake on a wet manifold type is for HI-RPM usage only. It is meant to flow @ very HI-RPM's. The fuel charge will separate from the air flow @ low RPM. It has no allowance for tip-in or part throttle. It is designed for hard launches and the last time I checked that is not considered street-able.

You may still have trouble with the engine build but at the least this will give you some control.

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post #17 of 35 (permalink) Old 09-24-2012, 08:00 AM
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Re: 351 windsor intake manifold question

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Originally Posted by KULTULZ View Post
Correct. A single plane intake on a wet manifold type is for HI-RPM usage only. It is meant to flow @ very HI-RPM's. The fuel charge will separate from the air flow @ low RPM. It has no allowance for tip-in or part throttle. It is designed for hard launches and the last time I checked that is not considered street-able.

You may still have trouble with the engine build but at the least this will give you some control.
klutz , you need hands on
there are many single plane manifolds used on the street , without any issues
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post #18 of 35 (permalink) Old 09-24-2012, 10:03 AM
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Re: 351 windsor intake manifold question

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klutz , you need hands on
there are many single plane manifolds used on the street , without any issues
+1.......I am running a vic jr on my current engine and before that I ran a wieand Xcellerator single plane on my old 302..Both work very well and definetely do not have any hesitation issues..However they do require a complete package to work well including proper gearing..


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post #19 of 35 (permalink) Old 09-24-2012, 07:50 PM
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Re: 351 windsor intake manifold question

I think you will be pleasantly surprised by how much more responsive the RPM is over the Victor Jr-especially on a mild engine like yours.

The Victor Jr is an excellent intake manifold for the 351w, but it really shines at upper RPM ranges, 5000-7500 is about where it's doing it's best. From about 1000 RPM to about 5000-ish, the RPM absolutely KILLS the victor Jr in responsiveness, fuel economy, and the butt-o-meter dyno. This is speaking from experience.

I like the air-gap myself, but the regular RPM did give me better MPG because the intake ran hotter (which atomized fuel a little better)....BUT, the regular non-airgap style also had a tendancy to boil the fuel in the Edelbrock carburetor.

I can tell you this: Mine was mild. 9.5:1 compression flat tops, iron heads, 750 4 barrel Edelbrock carb, typical headers/exhaust....1.94/1.50 valves in the ported iron heads. Nothing special-probably made max HP about 350 HP and probably around 5500 RPM. Pretty much a turd in my opinion. Originally I built it with a Victor Jr hoping for good top end HP, and the top end was decent. No race car but decent. 5000 to redline (about 6000 RPM max). I traded it for a RPM non air-gap. With the Jr, it would not spin the tires off idle (C6 with 1500 stall speed...about stock). With the RPM, it would spin all the way through first and well into 2nd gear from a dead stop. Overall responsiveness for "street driving" was excellent-it felt like a different engine.

Now if I had kept and and bumped the compression up to about 12:1, put a big solid roller in it and a 4500-5000 converter, the JR would have worked great. But then you get into race car territory....and that wasn't the intended purpose of that old ragged 351. I just happened to have the Jr intake laying around from a previous project that worked better with a super victor.

Real world comparison. I'll say it again-the victor JR is a great intake, it's just not great for a street-type car/truck. Surely someone out there might trade their RPM for your victor jr. I've done this twice-once on a 351w and once on a 302. The 302 with a victor jr (in my case) was a turd, but it woke up with the RPM. Just lost exactly 1 mph on the drag strip, but picked up some ET. And drove 100x better on the street.

Now if you were running methanol, a Jr works great for that....but you're also talking about roughly twice the volume of fuel running through the runners; assuming carburetion. Our stuff is all injected now and it doesn't make that much difference with intake design. Some difference but not night-and-day like on a carb'd motor.

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post #20 of 35 (permalink) Old 09-24-2012, 09:02 PM
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Re: 351 windsor intake manifold question

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BUT, the regular non-airgap style also had a tendancy to boil the fuel in the Edelbrock carburetor.
Interesting observation. My newly learned factoid for the day...

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post #21 of 35 (permalink) Old 09-25-2012, 06:37 AM
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Re: 351 windsor intake manifold question

I have used all the mentioned intakes on my 302 in a 84 Mustang. Had the T5 with a 3.08 rear. Cam was a .536/.548lift heads pocket ported DOOE. Both 650 and 750 Holley carbs used.
The Vr Jr was slightly lower on torq but just enough to make it easyier to drive around town. Mid range and top end was better. I have also flow tested each of these intakes bolted to several SBF heads factory ported and aftermarket ported.
I pulled 24 to 28 MPG highway with the Vr Jr. Dont remember in town. The 750 did well untill a muffler shop doing my exhaust screwed up the tube size going over the rear axle. Had to drop to the 650.
If I had dug into it deeper at the time I would have noticed the Jr port is raised around .1 of an inch over stock location (the Vr EFI is about .285 over stock location). Could turn average of 12.2 in the quarter.
On the bench all of the intakes reached max flow around .500 lift.
Wether the combo works or not mostly depends on selecting all the correct parts. Very important is being able to modify each circuit in the cab to function correctly. Most only change main jets possibly the power valve.
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post #22 of 35 (permalink) Old 09-25-2012, 02:30 PM Thread Starter
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Re: 351 windsor intake manifold question

Thanks for the responses. Seeing I am going to change the manifold anyway, I will be going dual plane. Most likely a RPM AIr Gap. According to Edelbrock Tech, my hesitation while easing the throttle is the manifold. Caused by the large plentum and the exhaust gasses being drawn through the cyl. in the overlaping phase. This causes rough low RPM running. Their words, not mine. They said that when I tromp it (which I get no hesitation) it rushes more air down the cyl not giving the exhaust gases enough time to draw through the cyl. With a dual plane the passages and plentum are smaller and the air going through has more velocity at lower RPM, therefore more low end power and torque.

1965 Falcon, 351W, 4spd Toploader, 9" 4:11 with Detroit Locker
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post #23 of 35 (permalink) Old 09-25-2012, 04:57 PM
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Re: 351 windsor intake manifold question

The real issue might be the port volume of the heads. If they are too large the air velosity is screwed causing poor filling of the cylinders. The cam selection can aggrivate the issue. Split lift and overlap the big contributor.
Many of my builds have higher dynamic compression than static. This is because of more effective filling of the cylinders. A dual plane will possibly in most cases bandaid your issue.

But then you will have what I concider a cammed motor which most manifold companies condone

Last edited by turbo2256b; 09-25-2012 at 06:52 PM.
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post #24 of 35 (permalink) Old 09-25-2012, 06:37 PM
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Re: 351 windsor intake manifold question

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Originally Posted by brihvac View Post
Thanks for the responses. Seeing I am going to change the manifold anyway, I will be going dual plane. Most likely a RPM AIr Gap. According to Edelbrock Tech, my hesitation while easing the throttle is the manifold. Caused by the large plentum and the exhaust gasses being drawn through the cyl. in the overlaping phase. This causes rough low RPM running. Their words, not mine. They said that when I tromp it (which I get no hesitation) it rushes more air down the cyl not giving the exhaust gases enough time to draw through the cyl. With a dual plane the passages and plentum are smaller and the air going through has more velocity at lower RPM, therefore more low end power and torque.

The tech got it right. A single plane CAN be streetable..depending on your personal interpratation of streetable...Generally speaking, it's not a low RPM performer.
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post #25 of 35 (permalink) Old 09-25-2012, 07:15 PM
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Re: 351 windsor intake manifold question

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Originally Posted by turbo2256b View Post
The real issue might be the port volume of the heads. If they are too large the air velosity is screwed causing poor filling of the cylinders. The cam selection can aggrivate the issue. Split lift and overlap the big contributor.
Many of my builds have higher dynamic compression than static. This is because of more effective filling of the cylinders. A dual plane will possibly in most cases bandaid your issue.

But then you will have what I concider a cammed motor which most manifold companies condone
imposible to have higher dynamic c/r than static .
filling the cylinders is different than ratio's

I know what your saying ,

YES , an engine can have Higher cyl. psi at 10/1 cr that one with 12/0cr
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post #26 of 35 (permalink) Old 09-25-2012, 07:19 PM
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Re: 351 windsor intake manifold question

Quote:
Originally Posted by brihvac View Post
Thanks for the responses. Seeing I am going to change the manifold anyway, I will be going dual plane. Most likely a RPM AIr Gap. According to Edelbrock Tech, my hesitation while easing the throttle is the manifold. Caused by the large plentum and the exhaust gasses being drawn through the cyl. in the overlaping phase. This causes rough low RPM running. Their words, not mine. They said that when I tromp it (which I get no hesitation) it rushes more air down the cyl not giving the exhaust gases enough time to draw through the cyl. With a dual plane the passages and plentum are smaller and the air going through has more velocity at lower RPM, therefore more low end power and torque.
edel. tech is half right , know what that means for the other half
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post #27 of 35 (permalink) Old 09-25-2012, 08:34 PM
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Re: 351 windsor intake manifold question

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imposible to have higher dynamic c/r than static .
filling the cylinders is different than ratio's
Nope. DCR "can" be higher than static. intake manifold pressure also affects DCR-in a big way. In the wallace racing calculator, put in 30 psi boost and see what the DCR goes up to. I've seen them upward of 35:1 DCR-but we're talking 2000+ HP boosted engines.

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post #28 of 35 (permalink) Old 09-25-2012, 08:38 PM
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Re: 351 windsor intake manifold question

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Originally Posted by mavman View Post
Nope. DCR "can" be higher than static. intake manifold pressure also affects DCR-in a big way. In the wallace racing calculator, put in 30 psi boost and see what the DCR goes up to. I've seen them upward of 35:1 DCR-but we're talking 2000+ HP boosted engines.
nope , DCR , isn't PSI . .DCR is just a ratio , that's what the R stands for
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post #29 of 35 (permalink) Old 09-25-2012, 08:49 PM
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Re: 351 windsor intake manifold question

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nope , DCR , isn't PSI . .DCR is just a ratio , that's what the R stands for
ADD ...comp. ratio plus adding boost factor is just a equivalent number if the engine had a higher N/A C/R
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post #30 of 35 (permalink) Old 09-26-2012, 07:08 PM
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Re: 351 windsor intake manifold question

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Originally Posted by DanH View Post
ADD ...comp. ratio plus adding boost factor is just a equivalent number if the engine had a higher N/A C/R

In simple terms, yes. But intake manifold pressure still has a direct effect on DCR.

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