lsjion

I would assume a gmr is slightly smaller, than this port. Remembering back to my flow bench numbers. Few years back, iirc it flowed roughly 10 Cfm less on a pretty small port.
This port generally drops 3-4 lbs of boost also

JapEatr

iTrader: (9)

Josh is correct there is no need to hog the port out when in fact you will loose power

zrated89

iTrader: (15)

when my head was ported by joe this is exactly what we did. To big youll disrupt velocity and lose power

RooTBeeR

iTrader: (4)

i like that sound of that!

hmm, once i pull this engine...not sure if should fully build it, or just do head port...or just leave it alone

mrbelvedere

iTrader: (3)

tell that to infra

Area47

increasing cfm while maintaining and/or increasing port velocity.

hogging increases cfm, but tanks the velocity.

mrbelvedere

iTrader: (3)

when your forcing velocity dosent matter as much

Area47

lsjion

Will a larger port make more power? yes, in some cases. However not everyone can utilize a larger power. Without the proper setup a car can lose power, and down low performance, due to lack of velocity

lsjion

larger port* not power.
for some reason I don't have the ability to edit my posts

mrbelvedere

iTrader: (3)

as soon as the ex port is opened up bottom end is lost and and power is shifted up velocity is more important on a n/a engine

RooTBeeR

iTrader: (4)

All I want is down low performance. Need that off the line/idle grunt...so much that if I lose some top end power I don't mind

mrbelvedere

iTrader: (3)

then leave it alone

armcclure

iTrader: (2)

I agree to a point. Velocity is still important, but not as mush as n/a. On na the scavenging is more important.
Now I am NOT saying to hell with velocity!
Just simply observing that we have boost shoving fresh air in, without the restrictin of a turbo

RooTBeeR

iTrader: (4)

I need to advance the cam/s too, peak power by 6k with a stump pulling tq band

lsjion

I disagree that you lose low end performance when opening up the port, That's like saying.....oh I put a ported head and header/3" exhaust now my car has no power down low.
Now, if you put a huge port, and 3" exhaust on a stock pulley car, it will suffer down low, that's why I said, it must be utilized.
Throttle response is also imporoved by very little port work

lsjion

On my ex's redline, I had a head I did some experienting on and went a little overboard with, when her car busted pistons...tune related, we swapped a that head onto it, it ran as well as a gmstg2 car, but suffered some down low power. After we added a 2.9 to it, it woke it up pretty well, but still wasn't as snappy down low as it could have been from a smaller port, it really came aline around 4000 rpm though.

Also, mr. b had a HOGGED out head on his car and after swapping to a less aggressive port that I did for it, it gained 20 hp on the dyno.
It all depends on what your mods are and how well you can use it.

Vander Nars

iTrader: (5)

im have to get me a spare head as some point so I can get u to port it, u seem to really know what ur doing.

RooTBeeR

iTrader: (4)

Hmmm, Zzp stg2 cams + GMT can gears + advanced cams = funky powers lol

lsjion

I've been doing it for a few years now, and all of my friends have ran one, or will in the very near future. I've seem to have lost count of how many are out there.

I really need one of those nifty sig's
Any takers?

RooTBeeR

iTrader: (4)

So a tvs w/2.9" on 91 could surely take advantage of exhaust porting

lsjion

Any lsj can benefit from porting, the amount of port work needed is dependant.
The most gains from a ported head will be seen from say a 2.9 tvs then switching to a ported head.
My 2.8 tvs and ported head setup was nasty

lsjion

The more boost that is present,,,, like a 2.6 m62 could greatly benefit from a ported head, Especially with the drop in boost

Bluelightning

iTrader: (8)

I'm definitely looking forward to the drop in boost

RooTBeeR

iTrader: (4)

"Lowered boost" yields a better efficiency range
Might just stick with the 3.15 and crank some timing into it...
2.9 though, all the extra boost coming on sooner should give me more of The tq im looking for...want/ need a custom long tube or maybe even tri-y.