I just wanted to say, i would suggest doing this if you like to do free mods
I know its been said before, but I'm just so pleased with the results that i thought that id post it again just for the hell of it.
I removed airpump on my S5, and the 5/6ports and port matched the lim, extm and uim, along with the TB mod and the results are just GREAT. That **** really pulls nicely for an NA in the high RPM, especially in 3rd gear. I just want to lay on the gas pedal and redline 3rd but Ill get owned by the police in my area so ill have to wait. if you decide to do this be very carful and dont let anything fall into your intake.
man i love my car.

 

Probably slower than it could be however since your VDI is now non-functional.

 

why the hell would my VDI be non functional?

 

Back to FSM for you. The VDI AND aux ports are powered by the air pump on a s5!

 

Porting anything gives a nice gain on the rotaries. Nice job. You know you want to port the engine now, too.

 

lol

 

read my sig !

 

Might want to try using s4 parts for the upper manifold.

 

why use s4 parts ofr teh upper manifold? bigger?

 

IIRC, it's the other way around. S5 upper on a s4 nets a better result.

 

hey dude i thought u were gonna post pics of your vert after you cut all those metal and stuff

 

S4 intakes are thicker also and have more area for gains in flow.

 

S4 intakes lack VDI!

 

The thread title says "ported intake results" when all we've learned are ported intake opinions. Any before and after dyno numbers for us?

 

probably not, hey, do you think there would be any gains on a Turbo II S4 intake? A large streetported Turbo II.

 

I did already

 

Well, first of all VDI won't matter much on a ported motor. It's tuned for stock ports and you really aren't stock anymore once you've ported. I do believe the S4 mani flows better. I don't have anything to prove it, but this is what I have heard.

 

um wrong. the tuned aspect of the vdi is related to the length of the intake runners (long for low rpm, short for high rpm) the
while a larger port might slightly affect the maximum resomance point for each length runner, it will certainly not negate it. ANY 13b with the vdi manifold will be loosing a significant chunk of its powerband if the vdi valve is non-functional.

 

Definately, it will show gains on turbo and non turbo. The more flow the better

 

i guess things should really liven up once i fix my vdi

 

if you JUST open up the ports some and don't change the timing then you'll be fine. Once you change the timing, though, the VDI can't do its job very effectively anymore.

but really, only the dyno will tell. I know for certain that once you bridgeport its time to chunk the whole stock manifold altogether. The s4 one is the lesser of 2 evils in that case though.

 

i still think you are wrong. vdi still increases power in engines that have the aux ports stuck closed. actualy with the vdi working and the 6-ports stuck close, you can still get decent (tho not the normal amount of) power until redline, while with both closed, the engine is just wheazing over 5k. makes NO power.

oppening the aux ports essentaily changes the timing, as would a larger port. so your theory is still off. its the length of the runners, NOT the size of the port that causes the resonance/natural supercharging effect.

 

its a combination of both. There for a given port timing, there is a certain runner lenth that gives MAXIMUM power at a certain RPM.

Here's what we have:

ports opening and closing creating pressure waves

waves travelling at a certain speed

the wave has to travel the length of the runner and back. This is why runner lengths are so important.

we want to end up with a high pressure wave when the port is opening. this way we have air being shoved into the engine.

if the runner is too long or too short, you won't get that desired effect.

note this is RPM dependant, because the ports are going to open faster or slower depending on the RPM. The waves travel at the same speed.

this is why we have VDI. Different runner lengths for different RPM's

the lemans motor and the RX-8 6 port motor take advantage of this further by having variable length runners. optimal runner length at any given time.

Now, if we make the port open earlier then our runners need to be smaller to take advantage of the effect at the same RPM. what happens when we port and don't change it is that the effective VDI moment ends up getting moved up. But the vdi is still actuating at the same time. we are not able to take advantage of the VDI effect for as long.

this is also why stock manifolds don't like 6PI bridges. once you bridge those the stock runner length is no longer any good for the remaining ports. (its still good for the other ports if you don't bridge them though.)

 

what kind of power gains will this give? what range? will it rob low rpm power? ... is it worth it?

 

Yes, then you just tune it to open later or sooner, wherever it gives you better power (Just do a dyno run to find out!)

VDI = Good