Ported/Polished lower intake manifold

[stmitch]

Just wanted to post some before and after pics incase anyone was interested. I gasket matched the ports as deep as I could, and focused on smoothing and straightening the truns as much as I could. I took some measurements, and the round intake ports were increasaed in area 15%, while the rectangular exhaust ports were increased 29%!

 

[Airmaster]

Damn, nice looking job! Have you put them back on the rig yet? And if so... hows it feel?

Wish I has time to take apart my engine like that, alas its my work truck in addition to being my fun truck.

 

[James86]

Did you take this off of your truck or did you get a second one form a junkyard so you could keep driving the truck? I'm pondering the second route but still looking into porting and polishing and not sure if I want to attempt this yet.

 

[Rearanger]

Ok, so this can't hurt, but what is it's real value? The openings at the gasket mounting have been enlarged but if you look down the passages they narrow by design which means their flow ability has not changed. Getting rid of the port entrance edges and polishing will reduce flow turbulence (which is good) but will that mean anything when the flow requirements are the same. If the rpm of the engine were to be increased and/or larger pistons installed where a larger flow rate (cfm) was created I might buy this as a good mod. To do this when the manifolds are off anyway is OK, but to tear into the engine just to do this seems a waste. I accept better flow ability is good but what is the science behind doing this on this engine?

 

[James86]

Thats why I had asked if it was a second one he bought. If I were ever to do this, I'd grab a JY manifold and a second set of heads before I tear into a functioning motor. Allegedly, the biggest flaw of the 3.0 (besides a torque peak about 3750rpm) is it doesn't breathe well, which I would assume would mean casting imperfections like the 2.3 HSC's in tempo/topaz's which have also been ported and polished to some success. I'll withhold negative commentary until we see some dyno results or get some feedback when they're on the truck.


Incidentally, if anyone is wanting to get rid of a 3.0 FFV block......lol

 

[stmitch]

I used a spare manifold for the job. The ports were enlarged somewhat all the way through, not just near the outer edges. They don't narrow as much as they change shape, going from circular intake ports to rectangular exhaust ports. I also focused on making the passage as straight as I could so it will flow more air, and the smoother laminar air flow is a plus. It's possible that Ford kept the passages small in order to keep the velocity of the air up. I wasn't too concerned with that though. It's going to be mounted under my whipple supercharger and force fed as much air as it can take, so I wanted to let the thing breathe as much as possible.

 

[Rearanger]

It's going to be mounted under my whipple supercharger and force fed as much air as it can take,

Pressure differential will compensate for a lot of flow weakness.

 

[stmitch]

It's really just about efficiency. It's easier to flow air through a smoother, larger opening than a rough, smaller one. The ported lower intake may drop the boost from the supercharger a little, but I can always increase the boost with a smaller pulley. So, a 2.75 inch supercharger pulley, that makes 10 lbs of boost on an otherwise stock engine, may only make 8lbs with this intake. But, while the amount of air the stock manifold can pass would have been close to maxed out at 10 lbs, the ported intake has a much higher threshold, and will produce much larger gains at 10 lbs than the stock engine at 10 lbs. Basically, ported intake and headers at 10 lbs of boost is closely equivalent to maybe 14lbs on a stock motor (as far as the amount of air flow) and puts much less strain on the engine. My goal is to make as much power as I can, at the lowest possible amount of boost.

 

[Mutant Pony]

Looks good, nice work. Did you remember to keep the openings slightly smaller than the gasket to account for squish of the gasket so that the gasket doesn't impede flow when bolted down?
I have a bunch of junk valves laying around that I can use to keep all the round ports the same while porting. On rectanguar ports, I trim out a piece of sheet metal to match the shape of the gasket opening then use it to match all the ports while porting. You also need to keep a gasket handy so that you don't end up off center.

 

[James86]

So how much would this help a N/A engine? Along with P/P heads and manifolds perhaps? The u-pull is really cheap so this sorta has my interest piqued....

 

[stmitch]

Engines make their power in the cylinder heads and top end. Increasing the airflow into, through, and out of the heads should help quite a bit. If the heads have as much unnecessary material as the lower intake, I'd expect sizeable gains. You may not see the same gains as a forced induction engine, but it's definitley not going to hurt. So if you can get a deal on the parts, and you've got the patience to do the work, I say go for it!