Stock ports too big?

[Levi05]

I've been doing lots of research on cylinder head porting and i know the 2.3l duratec head flows well and typical port work may make you lose power . So what im wondering is:are the ports too big?

There is porting technique commonly called "velocity porting", where u actually fill the ports to make them smaller. The goal is to increase intake velocity for better cylinder filling when the piston is trying to push air back out on the compression stroke (the intake valve is still open for a little bit).

Any thoughts on doing this kind of "port work"?

[Sponsor]

[felixthecat]

Originally Posted by Levi05

I've been doing lots of research on cylinder head porting and i know the 2.3l duratec head flows well and typical port work may make you lose power . So what im wondering is:are the ports too big?

There is porting technique commonly called "velocity porting", where u actually fill the ports to make them smaller. The goal is to increase intake velocity for better cylinder filling when the piston is trying to push air back out on the compression stroke (the intake valve is still open for a little bit).

Any thoughts on doing this kind of "port work"?

The 23 has a 3.70'' stroke w/ a 6.094'' rod Which makes it a 1.64 rod to stroke ratio, so w/ the 3.70'' your going to have great port velocity & having 4 valve head w/ two 35mm int & two 30mm exh, helps a lot. And having a shorter rod to stroke ratio similar to a 454 chev= 1.53 your going to get flow vs say a sb chrysler 273/318/340 which has a 6.123'' rod & a 3.31'' stroke-= to a 1.85 rod to stroke ratio & with that you'll have a longer dwell at top dead center, which gives you more mid range torque. Shorter rod to stroke ratio motors can get a way w/ more cam duration. Leave the head alone. If you want to do something add a set of cams.And of course you have a header & a 2.5'' exhaust system.

[elsolo]

One easy example of different sized intake ports used on a very popular engine is the big block chevy. They had "peanut ports", oval ports, and resctangle port heads. Intake runner volumes from 260 cc to 320 cc, that's a big cross sectional difference.

The big rectangle port heads were the factory hi-perf heads on 396, 427, 454 motors. Nowadays, people make more power on those motors with the smaller port heads and extensive porting work. You can buy aftermarket heads with runners from 260 cc to 385 cc, it takes a big motor turning a lot of RPM to need the huge runners.

If you put a stock 2.3 head on a flowbench, it's probably the best flowing dtec head. If a cylinder head guy spend a god awful amount of time porting, flowing, and dyno testing with the smaller port heads, he could probably get a 2.0 head to outflow it with better velocity. This kind of work is far from cheap.

I think the "tumble flap" intake helps keep the port velocity high at lower rpms, it effectively reduces the cross sectional area just before the port.

[Levi05]

Thanks for the good info. Felix, which ratio creates more torque? Sorry, got a little confused.
And im not too familiar with the V8s so the comparisons dont mean much to me. Have any motorcycle engines you can compare? Haha.
Ive found that sportbike racers and atv guys fill their ports on the port floor to create a better short-turn radius and it creates higher velocity flows to combat reversion on the compression stroke. Hence better cylinder filling and improved power across the rpm range.

My car is a DD so i need the fattest midrange possible (2500-5500rpm) so i think anything to increase velocity would help. I dont need massive volume at 7000rpm.

[felixthecat]

The bigger rod to stroke gives you more mid range torque. But its not like you can mix & match rod lenghts & cranks, like say from 5.7'' sbc rod to a 6'' rod & have a few different crank strokes to choice from. You got what you got w/ the mzr/dura-tec motor. You can modify it viva a turbo kit or a set of cams/header & intake. Hayabusa= turbo!

[Levi05]

As much as i love turbo's, i wanna keep this car n/a and explore its potential. I also have to pass safety and emission testing so ill need to be selective in mods or get creative with them!

To those that have sent me PM's, my (stupid) smart phone doesnt appear to be sending my replies so ill respond when i get on a real computer. But thanks!

[1turbofocus]

Got your PM , sent one back

Tom

[Outlaw5.0]

Port size and shape depends on the c.i.d and rpm range needed. Now are the stock 2.0L ports too big, no they are not. The same goes for the 2.3L ports, they are not too big for the 2.3. Filling the intake ports will not get you want you want.

The late model 454 had peanut port heads because it made peak power in the 3750-4500 rpm range, it was a pig plain and simple. The 454SS pickup only had 255hp at 4000 rpms and 405ftlbs torque at 2400 rpms.