Ride B Red

I think im starting to have a minor valve problem w clicking and stuff, have any of u ported and polished your heads or replace w larger valves?? I've wanted to do this for a while, thanx

kingrye

i was wondering this also port and polsish is suposed to give u good power increases right

ChrisCheezer

if you can find a place that will port the intake (VG) YES you will get about 5 hp maybe more....

maxima_dumby

oh yeah you will get a couple more hp
but you will also be wasting more gas
not worth it

mykizism

ok so whats the point of putting on intake and exhaust, you`ll be wasting more gas that way too.. is it still not worth it?

maxima_dumby

intake and exhuaust frees up the engine so the engine wouldn't have to work as hard to produce power. Hence it actually saves gas. But for a port and polish you're making your cylinder bigger hence using more gas. I wouldn't do it, if i was going to use the car as my normal grocery getter.

Jeff92se

iTrader: (82)

Your last 2-3 posts in this thread made absolutely no sense at all. Actually most of the posts in this thread don't make sense. How does one know how much a "port & polish" LOL job will make? Exactly why NOT make the engine more efficent for a grocery getter??(other than cost which hasn't been addressed yet)

NismoRacer83

Indeed, is making the the engine run smoother a bad thing? The hosepower gain isnt too much, and the amount of xtra gas you waste is minor.

Jeff92se

iTrader: (82)

UGH. If you make the engine more efficent, it uses LESS gas for a given hp.

DanNY

iTrader: (14)

think of it this way...

you drinking a milk shake throught a tiny straw...(coffee stirers..looks like a tiny straw).
it takes a lot of work for you to actually get the milk shake into your mouth..because of the tiny straw.

now if you have a bigger straw for the milkshake...(something like a slurpee straw)...you get more milkshake with less energy...u don't have to suck so hard to get the milk shake in your mouth (keep it clean you pervs).

ok...now there's a point of diminshing returns....
instead of the slurpee straw..you have a straw that's a inch wide....
you'll be huffing and puffing to get the milkshake in your mouth because there's a huge area of the straw to fill before the milk shake hits your mouth.

how does this relate to port and polish...
your engine is currently breathing w/ the small straw...you have to use a lot of energy to get the air in (gas)..hence gas wasted

mild porting...now u have a slurpee straw. things flows much better...less energy for the engine to get in air..(higher MPG).

incorrectly porting job...now the straw is a inch wide...plenty of space in the intakes and etc...but now the velocity of the air is going much slower...(one inch straw). it takes longer to fill the combustion chambers.

hence on a NA car..you must pay careful attention to what material to take off and where.

ok that's my take on it...any one else want to comment?

oh and dumby...it doesn't use more gas...that only happens because after a port and polish the driver tends to gas the car more. no one does the port and polish to make the engine look nice inside..it's to make it go faster and work more efficienty. but for comparision...mile for mile the port and polish saves gas in the long run.

Evil Yak

ya know, I think i read this exactly word for word out of some
magazine.. i could be wrong

DanNY

iTrader: (14)

oh...i guess me and some magazine writer have the same idea.

OptimusPrime

i think MaximaDumby was referring to boring, not port and polish

rcrdps

One small note: If you port and polish, don't go with the "common" mods afterward. Most of the mods out there enhance low to mid range power.....like CAI, 2.5 inch exhaust and y-pipe. The port and polish will generally tune for high rpms. Things like porting the intake manifold and exhaust manifold and running 3 inch y-pipe and ehaust will probably actually be good after you port and polish the head. I think probably in the past when others were testing those things and didn't get any gains, they were probably using it with other things that enhance low end. Most people tend to like low end power....especially considering we drive these things to work or school. Just depends on what you want.

Gene

Bob91se

Ok, I have actually had the heads off my vg, and did a gasket match on the intake side of the head (didn't do exhaust cause I got sick of it).... if you have a small block chevy then porting the heads will make a large difference in the top end, however modern heads (yes even those on the vg) don't leave much for improvement and getting success here requires a little more knowledge than just making them bigger. On top of all this, nissan didn't leave all that much material between the port and the coolant and oil passages, and unless you know where these are you could possibly cut into them . So my take is if you really want to mess with things, go ahead and gasket match the ports (once all that junk is out you might as well match the runners too) and call it good.

by the way, I was gonna do a big port job too, and couldn't find any info on how much you can take off before hitting the water jacket, so I left mine at a gasket match.

Jeff92se

iTrader: (82)

FINALLY! Someone who understands what the hell is going on! Read and learn folks. You should see the heads on the VE. Very, very smooth and clean.

Shadow1198

iTrader: (1)

I was just curious what some of the veterans hear thought of this? The way I always thought about it, port/polish isn't too noticeable or doesn't give very much of a gain until you do other mods (i/y/etc) and especially if you added something like a turbo. Then, say you add a turbo, you'd get a few more HP out of the port/polish job due to the increased efficiency. I'm not an expert and just wanted to see if my way of thinking was right.

Scott Fife

I've read every article I can my hands on regarding this subject and I've come to the same conclusions. I gasket match port, I polish the ports and then I remove the casting flashing in the bowl area under the valves. No reshaping, just take out the sharp edges. It's probably only worth 1 hp. Why do I do it? It's more productive than watching the trash on television.

Shugarhi

iTrader: (1)

i think skymax ported/polished his blue max... but i doubt he'll talk about it.

Matt93SE

iTrader: (44)

you can get some good gains if you know what you're doing.

good head shops also have equipment to check the thickness of the walls- just so they don't grind through on a head they're not intimately familiar with.

Depending on how much you want to pay and how crazy you are, you can do a gasket- match and clean up the casting flash (worth a couple hp at most), up to a crazy, high-RPM only job. it's all governed by your lunacy and checkbook.

Jeff92se

iTrader: (82)

Just a note. There is about zero casting flash on Nissan VE heads or any Japanese heads in general. If one is really good, I think some gains are possible. But it's not like grinding on a set of Chevy 350 or Ford 351 V8 heads.

Matt93SE

iTrader: (44)

there was some on the VG manifolds I tore into last weekend. I'll get pics of them up sometime.. probably next week. I took several while I had the valve covers and stuff off too..
but there's some flash in the VG intake manifold. removed that and dia few other small airflow improvement mods.. he said he noticed quite a bit of improvement.
(but he also changed his 30k+ mile plugs at the same time)

kaleb

Geez some people really don't know what they are talking about.

I'll be doing a "clean up" job on the ports of the heads from the engine I'm building. Nothing major. Just a wee bit on the intake side, maybe a bit more on the exhaust side (turbo power!). Our intakes are naaaasssty w/ flash (VG of course). The water jackets on the head and block are horrible, but there's not much I can do about that.

Anyway, I'll try to take pics and post them within the next two months. Porting and polishing increase the size of the cylinder.... oh man that takes the cake.

-Kaleb

Nismo87SE

Hogging out the port isn't the correct way. I had my VG heads ported and a valve job done. My advice for the DIY is to make the intake/exhaust ports as smooth as possible. Also you blend the perpendicular side of the valve seat into the intake/exhaust port. In the end the port isn't really any bigger but it flows air alot better. You should be able to run your finger from the intake port where the gasket goes to the valve seat without noticing any rough surface and it should be very very smooth. Ported VG heads + cams have been known to gain from 10-30whp on the dyno. I'm betting VE's would see a simular gain.

JC93SE

What are the areas around the valve guides like? I haven't seen the inside of a VE head, but wondered if the bosses could be smoothed out like most other heads. Maybe a bowl blend to the seats too?

MrGone

iTrader: (30)

http://mrgone.homeip.net/photos/ported/index.html

http://mrgone.homeip.net/photos/veapart/index.html




I'll get around to it sometime.