Member
Don't bash on hightower too much you can make the ports smaller to increase velocity, it's not always going to help you though. But having bigger ports wont always help you either. Think about it with the exhaust pipe. A .5" diameter exhaust pipe is not going to do you any good, but neither will a 12" diameter exhaust. Somewhere in between is the perfect size for a perfect rpm range, but it's never going to be perfect, or perfectly designed straight from the factory.
Enthusiast
They probably are smarter but the cost/budgeting is the problem. The intake manifold is usually a cast piece and most designs aren't optimized for maximum performance. Ridges and uneven transition points from throttle body to intake manifold to cylinder head, can all upset the flow of air. Port polishing is meant to remove/smooth these obstructions. Smoother air is faster air.Originally Posted by h00t_h00t
I can't see how smaller diameter intake tubes would be better? Many advanced engines use butterfly valves to shorten and lengthen the intake runner to achieve best length for specific engine speed. Making the intake progressively smaller could benefit from the venturi effect, as air speeds up as it's forced through a smaller space but unless it's done just right it'll probably just create a bottleneck.
**Pic: basic concept of port/polish. "A" has a transition that upsets the flow. You need to remove the shaded in "B" to achieve the desired flow of "C".
"Racing improves the breed" ~Sochiro Honda
Enthusiast
firstly I would like to say sorry for a typo when I wrote body filler I meant to write epoxy (I wrote the post very quickly and I couldn't quiet get the word)
I used epoxy to do the work on my engine
all of you are misunderstanding what I wrote.
I said that I used the epoxy to get rid of dead space in the intake and exaust ports. Nowhere did i say that I reduced the size of the port openings to the manifold or the valves. In fact the port opening that mates with the manifold was slightly polished to match the manifold. For the valve side opening I cut a 3 angle cut into it.
to explain what I did and why it works so well will probably not be understood by many people here because most of you see the Otto cycle as having only 4 stages... in reality there are 8 that need to be taken into account if you want to extract the most power from the engine.
(Another interesting note: the 47.2hp i got was a happy thing and I assumed that the increase in velocity had somehow increased flow but when I had the head flow metered it flowed 3% less than stock!)
I make a super quick paint picture to explain what i did not why it works!
the red areas in the picture at the bottom is where I put epoxy (rough sketch) these are supposed to look like intake ports. the exaust port tuning is slightly differant because the point is to achieve supersonic speeds in the exaust (because when the exaust goes that fast it will actually pull the piston up lowering pumping losses!) also the thick black line is the choke point this is what needs to be smaller on almost all engines!
Power, whether measured as HP, PS, or KW is what accelerates cars and gets it up to top speed. Power also determines how far you take a wall when you hit it
Engine torque is an illusion.
Enthusiast
That's exactly the result I mentioned early (faster but less mix in the chamber).
So this extra 42.7hp are as a direct result of only modifing the intake runners? or did you also do other mods? I'm suspecting that the power curve would have shifted and you attained this extra power lower in the rev range (compared to the original peak). But I'm also suspecting that you actually lost power on the higher range. did you? How was the torque affected?
Zag when they Zig
Enthusiast
wrong an engine would be hard pressed to make so much more power out of less fuel and air. When I put it on the flow bench it showed 3% less but this is not what happens when it is on the engine. The extra velocity means that air is stuffed into the engine slightly longer and that the flow doesn't deteriate as quickly due to the higher velocities involved. Most of the power is due to an effective increase in flow seen by the engine.
The 47.2hp is the max gain at about 4500rpm and that is after I fixed the intake and the exaust ports this includes matching the ports to the manifolds and using the epoxy. Over the whole RPM range the gains are between 20 and 40 with the 47.2 max differance. Torque wise the curve got alot flatter with a max increase of 49 ft.lbs. at about 2000rpm the engine got alot more torque down low and smaller gains in the higher end.
the stock peak for torque is 2300rpm and peak HP at 5000
after tune peak torque happens at 2000-2200 and peak HP is at 5500rpm (31hp gain at peak)
Power, whether measured as HP, PS, or KW is what accelerates cars and gets it up to top speed. Power also determines how far you take a wall when you hit it
Engine torque is an illusion.
Enthusiast
What percentage gain are we talking about here? a 47.2 hp gain starting out of 500 hp is not that much, but out of 250hp is a lot...
How much did you reduce the diameter of the runners?
Zag when they Zig
Enthusiast
I am still finding it hard to believe Ford didn't spend $50 extra on there cars to do what you claim.
Enthusiast
Ditto.
~50 Horsepower from fine tuning intake manifold seems too optimistic. Unless, of course, there was a dead mouse in there for the base readings.
"Racing improves the breed" ~Sochiro Honda
Enthusiast
it was about 50$ for me to do it but it would cost ford several million to change the casting molds and machining programs to make the runners smaller. Also keep in mind that Ford is conservative so they don't like saying that the assumed facts are wrong.
the 3.8L V6 started at 152hp peak and 210 ft.lbs.torque peak pretty low for the capacity.
the choke point was reduced to 4/5 the diameter of the valve opening
Last edited by hightower99; 02-01-2006 at 12:56 AM.
Power, whether measured as HP, PS, or KW is what accelerates cars and gets it up to top speed. Power also determines how far you take a wall when you hit it
Engine torque is an illusion.
Fanatic
not necessairly, if you stroke/bore, it doesn't really change the weight of the engine, the only weight difference would come from the difference between the stock and new parts. And also, a 6 litre LS2 is smaller and lighter than the 5.4 BOSS
Enthusiast
They wouldn't need to change it, Ford invest massive amounts of money into engine development. They would have known already.
Enthusiast
The gains you describe are way too good to be aqcuired with just some porting and some filling. In fact they are on the same league as forced induction systems worth thousands.
So, either you are becoming a millionaire fast or you are following the steps of Korean and Norwegan scientists... good luck!
Last edited by magracer; 02-01-2006 at 09:52 PM.
Zag when they Zig
Rookie
What are the 8 stages?
"In theory, theory and practice are the same. In practice, they are not."
Enthusiast
I assure you that the money being invested in development did not come anywhere near my 3.8L V6 it has some nasty flaws that when corrected translate into massive power gains. Mine is running just fine right now with the port treatment a small whipple twinscrew supercharger a homemade exaust and intake track and a revamped stand alone computer controling Ignition timing and fuel delivery (I upgraded the injectors as well)
all that adds up to 320hp peak and 360ft.lbs. peak.
I only get 18mpg though!
Power, whether measured as HP, PS, or KW is what accelerates cars and gets it up to top speed. Power also determines how far you take a wall when you hit it
Engine torque is an illusion.
Super Moderator
Have you had all these parts checked individually??
I am the Stig
There are currently 1 users browsing this thread. (0 members and 1 guests)
Posting Permissions
Reply With Quote
