Re: Oval port or rectangular port intake???
 

If you can rough the match porting in using a bridgeport and cone cutter it will save you many hours of grinding. Then just finish it with the hand grinder.

Re: Oval port or rectangular port intake???
 

I roughed in all the ports today. I may be finished by tomorrow. I'll post a picture when done.

Re: Oval port or rectangular port intake???
 

. . .But transition is not and inch in. . . an intake runner to be effective needs gradual transistion to maintain port velocity. Random expansions in straight areas of the port are not good ideas.

Chris

Re: Oval port or rectangular port intake???
 

While I was working on the ports, I made what i believe to be a smooth transition. I had to go into the port a good 3" to achieve it.

Re: Oval port or rectangular port intake???
 

My eyes don't like mismatches either mcollinstn. Truth is we don't know what exactly happens to the fuel when it hits that obstacle. When you trip up the flow like that I see it as waves crashing over a seawall during a hurricane. In my opinion there will always be a wet spot there no matter the RPM. That not withstanding the biggest disruption of fuel atomization if the sudden opening of the throttle blades. All of the fuel that once was suspended is now on the floor of the intake trying to get pulled in every direction. With the injector atomizing fuel it is already in the port where velocity is high being rushed in ONE direction to the combustion chamber.

Roby

Re: Oval port or rectangular port intake???
 

God bless injectors...

Re: Oval port or rectangular port intake???
 

I finished the manifold today. Thats as far in the runner as I can reach to smooth the transition. It feels real smooth, I hope it works.

Re: Oval port or rectangular port intake???
 

Checkmate, as Paul Harvey used to say... let's hear The Rest of the Story.
How did your work end up on the dyno? What result did this intake work have on your torque curve? Do you have and before/after comparison numbers?

I've read this thread a couple of times and discussed the topic with my engine builder yesterday. There are some interesting ideas here, ones that I'm also trying to accomplish. Torque (long and flat) is my goal.

First, some background: I started with a pair of HP500's, and last winter I had the lower end freshened up,(now 509's) and added a set of Pro Action 320 aluminum heads with 119cc chambers. I stayed with 2mm dome pistons, so my CR is still right around 9:1, maybe slightly lower. We did some mild port work on the heads, they now flow 365 @.600 intake, and 255 @.600 exhaust. Running Ferea 2.25 intake and 1.88 exhaust valves. For the most part, the rest is stock HP500 (cams, carbs, Dart rect port intake). They currently dyno at 523hp @5250, and 562lbs @4500.

My focus for this winter is cams and carbs, and I'm trying to get my torque numbers to come in high under 4000, and stay flat as possible through 5500. I'm having custom cams ground, and the numbers aren't set yet, but ballpark is .600 lift on intake and .615 on exhaust, hydraulic roller lifters. I'll be going with a pair of Pro Systems 4150 carbs @950 cfm, with custom fuel curves based on flow numbers and cam data.

So now this thread is making me question what to do with my intake. My Dart rect port manifold is a decent piece, with good torque performance, and I could possibly benefit with the added runner length of a Brodix. But this oval port concept flared to match rect head ports has me intrigued.

Net, net, $350 or so x2 for the intakes, plus $200 or so x2 for port work puts me at $1200 for an end result that I haven't seen yet. If I gain 10-15lbs, it might not be worth the return on my investment, but if I'm looking at 30-40lbs, it's a different story.

Overall, I'm running a relatively small displacement motor (as compared to the Big Iron on this board), so port velocity of smaller intake runners might get me the torque numbers I'm looking for. In the end, I'd like to see peak torque around 625.

What's the scoop? I'd like to hear some "real world" data.

Thanks,
Brian

Re: Oval port or rectangular port intake???
 

Brian,

I wish I could answer the question about rectangular port vs oval port with real data for both manifolds. But, I can't. I only dynoed the blended and port matched oval manifold.
I dug up this old thread I started with my dyno results. I hope it can help you answer a few questions.

http://www.offshoreonly.com/forums/s...540+dyno+today

Re: Oval port or rectangular port intake???
 

Those are indeed some impressive dyno results.

Other than cubes, we're close on a number of things... yet even with the smaller oval port intake sizes, you're still feeding it with a 1050. Hmmm. And your cam numbers are smaller than I was thinking, but I'm leaving that equation up to Sterling. Good information, thanks.

So... can we attribute your torque numbers to velocity on the intake side? Did you do anything else out of the ordinary? Did you message the heads any more than the cnc work? I'm sure the work Nickerson did on your Dominators helped a lot.

Just trying to decide on whether to dive in to the intakes on my project.

Thanks again,
Brian