Ported Intake Manifold ??
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From: Central Valley, CA
Ported Intake Manifold ?? Are there any real performance gains to be had by porting the intake on a 383? I am torn between porting it and running a 58mm or jsut leaving it stock and running a 52mm. How much horsepower are we really talking about here?
when I did my LE2 heads Lloyd said you could expect to gain 10hp out of a full clean up by him with his head. This is not much but what really counts is he said it would smooth out the power curve.
I look at it this way, will ported heads make more power than stock, of course they will. And a ported intake and 58mm tb will make more hp/tq than a stock intake and 52mm tb, how much more who knows but I would say maybe 10-20 hp more.
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From looking at your SIG I would suggest some head work first. Gains with a ported intake vary. You could potentially loose HP from a ported intake...especially if it is done poorly. There was a thread just like this one not to long ago. A fellow member lost a decent amount of HP from a ported intake. At best if it went in your favor w/o head work would be a few extra ponies. Get yourself some LE or AI heads and decide from on it from there. 
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sorry I should have put a link to my build thread or at least updated my sig I am building a 383 with some Trickflow heads but I am running out of money and I am trying to see where I can cut a corner or two without costing too much power and would be able to easily access to change it later if the mood strikes. The intake seems like a pretty good spot but that would limit me to buying a 52 mm throttle body now and then having to sell it and go with a 58 after the intake is ported so I am trying to make a decision on what to do. The rear end is going to be a big hit to the pocketbook and most likely necessary after the stroker and t56 so I am trying to save a few bucks where I can.
From looking at your SIG I would suggest some head work first. Gains with a ported intake vary. You could potentially loose HP from a ported intake...especially if it is done poorly. There was a thread just like this one not to long ago. A fellow member lost a decent amount of HP from a ported intake. At best if it went in your favor w/o head work would be a few extra ponies. Get yourself some LE or AI heads and decide from on it from there.
Too large of an intake port results in a slower port velocity and can cause a loss in power at all RPMs.
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From: Arkansas
Making the runs to large which them leads to too much air going in. I myself know of a local guy that ported his intake by a source on here I choose not to name and after his install of JUST the ported intake, the car drove like crap. He took it off and we put on a factory unported and it ran perfect. We had another local builder take a look at it and he agreed that it was indeed the ported intake being the cause of the problem.
not sure what it weighs but theres a decent amount of weight reduction, shifting at 6300ish and going through the traps at 6500. that was on a 1.62 60' so it definitely has low 11s in it with a 1.5x 60'
Would the porting hurt if you port-matched it to the heads that already have work done to them? Or is our LT1 intake port bigger than most ported heads to match them up and open the runners up? How much are most people taking off the intake runners that give good numbers?
sorry I should have put a link to my build thread or at least updated my sig I am building a 383 with some Trickflow heads but I am running out of money and I am trying to see where I can cut a corner or two without costing too much power and would be able to easily access to change it later if the mood strikes. The intake seems like a pretty good spot but that would limit me to buying a 52 mm throttle body now and then having to sell it and go with a 58 after the intake is ported so I am trying to make a decision on what to do. The rear end is going to be a big hit to the pocketbook and most likely necessary after the stroker and t56 so I am trying to save a few bucks where I can.
like said above, the runner size really has nothing to do with the heads them self unless the port and runner has a vast size differance that would disturbe the air flow. even then they will port match but no open the runner up at the top. It has more to do with the Cam and head and valve train combo. For N/A engines the smaller the cam and rpm the smaller the runner is what someone said to me, otherwise you kill the torque curve. there is a point in wich you need to flow the air through the intake faster and that is ussually if you turn High RPM's. When you turn high rpms due to a cam and head setup, you have to flow so much air to feed the engine at those points where the cam makes the power. For most at say 5500 to 6500 you don't need to have that big of runner because you are at the end of where the cam makes it's power. Cleaning them up and smoothing the runners out helps more than opening them up. This is the way it was explained to me.