I noticed it's an option on "cardomain" menu.....what do you port? I know you can polish just about anything....

 

Reference to porting out the intake and exhaust ports on the heads, or intake manifold. This effectively makes them larger. Then you polish them to smooth out in inperfections in the surfaces that you port out. All in the sake of more power.

S

 

smooth runners = higher air velocity = better breathing for VQ =

 

Has anyone ever done it? What gains? How much should one expect to pay?

 

i had my intake manifold and throttle body ported cost 100$ notices alittle better throttle responce and top end but i dont have any dyno results

 

on a VG or VE??

 

Veeeeeeeeeee

 

By porting the heads, specifically the intake and exhaust ports, you increase the the diameter of the inlets leading to the combustion chamber allowing more air and fuel to mix creating more horsepower. Typically, when having this procedure done, you increase the compression ratio which will require a higher octane fuel being used in the vehicle. I am not sure how often this is done on 4 and 6 cyl engines, but is a very common modification that is done on V-8 engines creating impressive increases in HP levels.

 

yes my friend has a 302 mustang and extensively ported his TB, intake manifold and heads and it slashed .4 second off his 1/4 mile time and droped him into the 12s. he already had alot of boltons like full header back exhaust, intake, ignition, injectors, pulleys etc and said it made a bigger diference than any of those mods except the exhaust

now the only thing is i think nissan did a much much better job designing all our engine components than ford or chevy so theres not as much to be gained + we have 4 valves per cylinder where as they only have 2

 

heres pics of my porting







the guy couldnt go very far into the top intake runners with his tool but took alot off of the throttle body area and lower manifold

 

I belive Mr.Gone has done his intake manifold.

As far as porting the manifold, I personally say its better to just work out any rough surfaces & polish it up. That will increase the air velocity, but there is a downside. The VQ's are pretty much efficient & there isnt much power to free up. Unlike 5.0's and most v8's there isnt much to be gained unless your boosted in some way.

If you pay attention to the porting job of subs1000w's manifold, you'll realize for the most part, its still a bottle neck. I dont think there is much to be gaing with porting & polishing the manifold on the VQ's at all.

As far as the heads go, there is only a fine line you can go up to. IF you go too far your going to lose a considerable amount of low end. Yeah your top half is going to pull pretty well, but if you have wider ports & not enough air velocity running though them ( thats why I said boosted ) then its just going to bog down til the air velocity picks up.

 

dude, bijan, next time just ask us in OT

 

................whats OT?

 

Off Topic



Well....either forum works - I got the answer

 

about how expensive is a port and polish?

all i know is it is like $5000 on Gran Truismo 3!

 

Compression ratio will still remain the same, that is static, that cant be changed by a port and polish. Only way to change that is headgasket thickness or different piston heads.

Dixit

 

I remember I looked into it for ***** and giggles and it can be a lil expensive. I don't remember the web-site but you'd have to send off your heads and there wasa 2-3 week down time. There are different stages of porting and polishing all yeild different HP gains. I personally would go with a stage 2 or 3 about 30-45 HP I belive...it's been awhile...Also go with boring and resleeving the block for the low end power...why not?

 

Haha not on a maxima. Resleeving and boring the block haha. Tell me how much that costs. Port and polish usually refers to the heads of a car. You port the intake and exhaust ports on the heads of a car.

 

the most effective area of porting is the valve seat areas. not the actual intake and exhaust ports. if you're going to do this, take it to a pro using a flow-bench. doing it yourself will often do more harm than good. polishing is practically useless and is a catchy word thrown around. does not gain anything. and costs way more. OEM rough surfaces promote full atomization of fuel-air mixture.

 

You handicapper! Boreing and resleeving the block is the lower end of the engine. It would yeild some gains how much, unknown. Not a lot of people do that. Bore it out maybe toa 3.2 at the most and get newer bigger pistons and sleeves....wish i had those damned sites!

 

I know Kevin did the ExtrudeHone on his IM a while back and saw like a 5-10 hp gain on the upper end. Somebody else I know did it too and saw virtually no increase. True porting might be a better value.

 

good info....thanks guys

 

Check out my webpage and I have pics of my ported TB and upper and lower intake. I was able to port the entire lower intake and removed the injector bumps. I could only go a few inches on the upper intake.

I do not recommend just anybody doing this. It's easy to mess it up. I lost noticable low end and gained noticable top end. All in all, I didn't get any faster in the 1/4 mile with just porting the manifolds. But porting my TB I think shaved one tenth in the 1/4 mile.

Now, P&P the heads, that's a different story. First off, Nissan doesn't have any casting flaws like domestics do. So it won't do AS much as other domestics. But it should help noticable top end.

Check out the z31 VG guys. There are many of them that have cams and headwork and they got a very nice gain.

 

Or even mill down the heads has been done.

We also like to do flow match so everything flow evenly.

 

or, do a web search

 

hehehe.

This is on my VE:




I'm not done yet, almost
http://mrgone.homeip.net/images/ported/9.jpg

Polishing is really just making the runners smoother.
Porting is taking off more material.
Port Matching is making the the 2 surfaces match perfectly
and Gasket Matching is opening up the runners to match the gaskets.

I am gasket matching my upper and lower intake, and am probably going to work my heads alittle bit. I also have a spare motor. I'm not really going to focus on polishing that much. The main thing is to watch out around the injectors. I also have a spare throttle body I'm going to bore out, and will make a new butterfly plate.

Also you can gain lowend back by making your intake runners longer.


Another thing I've done is worked on our 1998 Durango. We have a 318ci motor (5.2l Magnum), and it needs to breath more. It looses power after 3300rpms. I ported the throttle body abit on it and extended the power range upto 3600rpms and gained massive low end and throttle response. I'm not done though, I need to make some new butterfly plates for it so I can bore it out more. Also I am going to cut about 1" (triangular notch, its hard to explain, i'll take pictures) off the bottom of the intake runners so I can make it pull hard to redline. With this specific motor I wont loose any low end, infact I might gain some, but I will gain all my high end back.

before:
http://mrgone.homeip.net/images/tb/1.jpg
after:
http://mrgone.homeip.net/images/tb/6.jpg

Also after I finish up that I'm going to run a bead around the Maxima's headers and then port them. When they are made they have a nice restriction in them, but with out reinforcing the welds and part of the pipe, you will just damage them if you try to port them. I'll try to grab pics of what i'm talking about.

 

Since I know people are just as lazy as me on this forum, I will just post some of my pics. I have many more on my webpage if anybody is interested.

This is my throttle body and matched intake




This is my upper intake


Here's my lower intake before and after:




Everything was done with a 1/4" shank electric rotary grinder and the deluxe standard abrasives kit. Also, Dykem (a blue paint used for porting) and a scribe were use to really be precise. Sand paper cartridge rolls work by FAR the best. The Standard Abrasives kit had all the bits you needed. Check out summit racing for the product.

MrGone, what did you use to port your runners? They really need to be smooth out a little better. It looks like you used something like a carbide bit. It's VERY easy for air to get disturbed by little waves in the runner walls. All it takes is one bump or two and you will have severe turbulence entering the heads. Be careful when you port the heads. They are WAY more sensitive. If you accidentally take out a little too much metal, then you will lose HP. I looked at the intake ports on the heads and there is no room for improvement other than polishing it. So I just cleaned the carbon build up out of my heads. And of course, the closer you get to the cylinder, the cleaner it should appear. So I didn't have to clean very far in the heads.

 

Aaron, I just used some sanding drums that came with my die grinder, I still need to get some sanding rolls so I can smooth it out because like you noticed their are some 'ripples' or waves/etc in the runners right now just because of the drums.

 

Yeah, that aluminum is so soft, it doesn't take much for a rough sanding drum to really dig into it. I used a very course one and a carbide bit to really shave the metal first, then I smoothed it out with a 80 grit cartridge roll. The closer you get to the injector, the more you want to pay attention to fuel atomozation. (sp?) So polishing and shining it up won't allow the fuel to mix as good as it does stock with all those little casting bumps. But 80 grit is as smooth as I would go for lower intake. When i was all done with my porting... minus the TB port job, I'd say it took 30 actual hours on the grinder. I was hunched over an aweful lot after work each day trying to get my car all back up and running.

And since air does almost all of it's flowing on the long side radius', you don't have to really be picky about short side radius'. Just keep feeling with your finger until you know there are no ripples or waves. And try to think about how water would flow through this... you'll see it really hugs the outside. You know what I'm talking about.

 

500 bucks full port and polish on the VE - no pics since the cars not back yet...

 

Gentlemen - fill me in with barbecue sauce cuz I'm dumb as hell






Thanks again fellazz

 

Can you tell me what exactly you had ported and polished? Did they extrude hone the upper intake manifold or just do a gasket match? What about the lower intake, did they gasket match all the way through? What about the intake ports on the heads? I hope they didn't gasket match that. That would be a LOT of metal removed. What about the exhaust ports on the heads?