ScottS

iTrader: (2)

I searched for porting and found only 2 threads on porting. Nissan has done such a good job on the head, there are no gains to be had doing, gasket matching, port work, chamber, valve jobs?

nismology

iTrader: (8)

Head work costs too much money to be justifiable by most of the members here. Most people stick to bolt-ons or boosting the stock motor. With that said, there are definitely gains to be had with headwork. VQ heads are far from perfect. VQ30 heads need porting to try to match stock VQ35 head flow (at least on the intake side) yet VQ30 heads have a more compact and efficient combustion chamber. So to answer your question, no.

DasYears

if you can do it yourself its worth it

ScottS

iTrader: (2)

How about a url or Pic of the chamber?

doublea

iTrader: (7)

I just finished the port & polish on the upper & lower intake manifold on my VQ30DE-K ( 2001 ). I was surprise at the amount of shaving I was able to perform on both UIM & LIM, I was also able to port match them perfectly.

There is still some room for improvement on the heads, yesterday I've install LIM on the heads to see what kind of shaving I can do on the head to match the LIM and there is a good amount of material that can be removed. I think it's going to make the head less restrictive with a much better flowing. I wouldn't pay 1200$ for someone to do it but if you can do it yourself I'm pretty shure if well done the gains will be there.

I dont know for shure how much HP it's going to give me, but with all the work on the engine it's an all around thing just not the work on the heads. As an improvement I'll be swapping the VQ35 cam in with Stephen's max cam adaptor along with new HR spring and double shim this should make this engine able to rev-up to 7500 rpm.

I'll post some pics later tonight so you can draw your own conclusion.


Cheers

AA

i30krab

iTrader: (1)

Gasket matching & porting & polishing the intake & exhaust manifolds will improve airflow in & out.
If you're doing a good size project with forced induction etc., All work will add power in small increments. If done right they all add up. Done sporatically with no master plan they are usually not worth doing.

nismology

iTrader: (8)

Effective head porting is not DIY unless you have tons of throwaway heads to practice on before coming across an improvement over stock. Valve jobs are DEFINITELY not DIY.


Just so we're clear folks, the OP was asking about HEAD work, not manifolds.

NmexMAX

iTrader: (22)

I've seen a few too many people actually lose power when DIY'ing their own headwork. When opening any motor to do cams/headwork, IMO, that's the last place to use pocket change on.

DandyMax

iTrader: (7)

Port matching the upper to the lower manifold and the lower manifold to the head will provide a little benefit by reducing some turbulence, and is worth doing if you've got everything apart since all the little things add up in the end, but in the grand scheme of things, is not a large improvement and not really what I consider head porting. You're usually only talking about a mm or 2 of wall intrusion, in an area that is at the edge of the velocity profile, so the effect is minor.

The key area is inside the head itself, through the transition past the valve guide to the bowl and the seat area. And doing this properly is not a DIY job for 99.99% of most of us. In 4 valve, divided port heads like we're talking about you can screw up flow paths/velocities in a big hurry by removing material/hogging things out if you don't know exactly what your doing and have the right tools to do it. Also, balancing the ports evenly is tricky without templates, port moulds etc. There are many many cases of DIY head porting that turn out performing worse than stock for this reason.

BTW doublea, what's the end of the cam timing story?

doublea

iTrader: (7)

There is a lot of moron out there who doesn't know how to do thing properly. I'm a graduated mecanics, this is my first japanese build but over the last 25 years I've build many american muscle car and I've had not a single failure, many bogs and problem that we end up resolving over time. That doesn't garanty me that everything will go perfectly but I couldn't care less, I mean I does this kind of stuff because I have the ability and so far I didn't screw up anything so lets wait and see.

ScottS

iTrader: (2)

I agree whole heartly with porting not being DIY. I as well have seen attempts, even heads done by people who thought they knew what they were doing, end up being worse than stock.

doublea

iTrader: (7)

I understand the entire issues with porting heads, I'm not going to tell I know everything cuz I dont, but I'm not affraid to try things then if things goes wrong it's no big deal, I will just have learn a lesson and will try again until it work to my satisfaction. So my goals is just to make them breath a little better and port match with the LIM since I already port match the LIM with UIM. I dont expect big gain and honestly I'm having a blast in my garage every evening so if I scrap a set of VQ30DE-K heads then I dont give a shiat I picked up a set for 75$ at the local junk yard.

I'm only concern by P&P the ports itself, like someone said Nissan already made a some how very good job on that.

It's sound like when 20 years ago I started my business, every single person I knew would tell me to do this or that or go pick a job instead. Well, 20 years later my biz is doing awesomely well. Now everyone is telling I'm a visionary, it's all BS I just had the ball to do it.

doublea

iTrader: (7)

The few good shop that I contacted charge anything between 850 -1500$

I've read so many good write up about P&P, I've also tested my skills on multiple occasions, it's not like I never did the work before ( first time on a VQ30DE-K but not the first engine I'm building ) I know I can do some good work, but I'm not saying it's going to give me this or that, I'm willing to live with the end result and this is enough for me to at least give it a try otherwise what life is made for ? If not to try and learn.

I'd say go for it and have fun, if that doesn't work all the way you want anyway the stuff was free so who care, see what I mean.

A+

KRRZ350

iTrader: (29)

I've got to agree and technically disagree.

There is a big difference between removing material/increasing diam./changing agles VS a basic clean-up of the casting flaws. Stop being so stubborn.


That's why the basic cleanup must remain just that. I've done some pretty complex port timing changes using calculated time/area target's on two-strokes, it's like cam's for a 2-stroke, and I've been "that guy"

Clean-up= Remove all the horrid casting flaws, leave a rough finish on the intake, & a smooth mirror finish on the exhaust to reduce carbon buildup. But I geuss the later doesn't become a benefit as much on a 4-stroke until WAY down the road

NmexMAX

iTrader: (22)

I guess that was my sign to STFU.

ScottS

iTrader: (2)

I guess we do not have any good community porters around then, eh? Are the Max valves already back cut and have a multi angle valve job?

nismology

iTrader: (8)

I'll pretend the "stubborn" comment was a joke and ignore it.


Which flaws in particular are you referring to?