Port And Polish

[R31Nismoid]

Note: Little off track

Did you save that $1500?

What about the new ic piping, oil and water lines, most people require a new exhaust manifold (You were lucky and has the GTS-R manifold), maybe an ext. wastegate, etc.  When you add all these up, just to acheive a similar figure, how much are you really saving, you'll probably find you are actually spending more 

Lets not forget all the hidden costs:

- More boost=less reliablity

- EPA:  You mods stuck out and were obvious, the officer will really have to know his stuff to pick up on my mods. B)

a little, my car was EPA defectable because of the way it was complied...

More boost doesnt equal reliablity at all. If the motor is tuned right both will last equally as long.

I also didnt make the car as 200's one... into the 300's was the plan

[lwells]

Al: What was the actual cost of the port?

Re: polishing, my understanding is that you want to leave some roughness to aid fuel atomisation on a street car.

[Al]

now now - lets settle it down girls

let's agree that port and polishing is a good thing - but only when it's justified, and I mean in terms of cost and desired performance

Let's also agree that  to REALLY see the benefits - you need the other supporting mods, EG exhaust, dumps, AFMs CAMS and the list goes on

My opinion is that once these other mods ARE done - that you will see better results if the proper prep work has also been done

I also ggree - $1500 is a lot of beer (or scotch in my case )

<{POST_SNAPBACK}>

itbmils: Don't worry too much about Ash (R31Nismoid) or myself, we're pretty cool and i haven't seen anything that offends. Just two guys discussing different opinions.

As previously mentioned, i too beleive that porting and cams should be one of the final performance mods.

lwells: The porting and full head service/reco costed about $1700. That included the 24 valve seals at $13ea. Porting was completed by a person that has been porting heads for racing teams, such as V8 Supercars, for many years.

[R31Nismoid]

Yeah, we friends, all tis good, fear not

[mr_crust]

i didnt get the a port n polish i jsut got the head shaved and thats it. But im lookin for a decent cooler as we speak.

[Abo Bob]

I am getting my engine rebuilt as we speak. I have a highflowed R34 turbo like Al's and some Tomei 260 Poncams going in. I have allowed $600 for head reco.

What could I get done at this stage? I mean, is there a jump between something you get for $600 and $1700 or are there incremental things to do, like say polishing but not porting?

[R31Nismoid]

$600 will be mild porting... nothing else

$1700 will get all the stuff replaced inside the head & porting also.

your head should be A-1 condition, my RB25 one was excellent.

So no need

[Mik]

$600 will be mild porting... nothing else

$1700 will get all the stuff replaced inside the head & porting also.

your head should be A-1 condition, my RB25 one was excellent.

So no need

<{POST_SNAPBACK}>

With solid lifters, $600 probably won't get you any more than a head service.

[Al]

My head internals were in excellant condition and were not replaced.

The only things replaced (not including the valve springs or cams, as they were a seperate expense) were the valve seals (something like that). Clearances were checked and adjusted, as necessary. I got the "race port", there were two other cheaper options but i decided to do the job properly. Be carefull who you trust to do your porting. Even though boost tends to hide a poor port job, the differance between a good head port and a poor one can be huge, especially when you consider off boost driving/response.

Abo Bob: Reconsider polishing your head, especially the intake side, i was advised against it by my porter. At the end of the day he could have said; "Yep, no prob., for polish it will cost you $### much extra.....", but instead advised me not to do it. Something to do with the fuel injection.

[Al]

WARNING:

A good porter may not take out the most material from a head, but will know what needs to be taken out and what should not be touched.

My port job may be considered by some to be "expensive", but experience is priceless .

[Cubes]

Just a heads up.

Its cheaper to buy the VRS kit than it is to buy just the valve stem seals..

$275 for the VRS kit, $330 for the valve stem seals. lol.

[Al]

What is a VRS kit?

and........

Now you tell me :lol:

[Cubes]

VRS kit contains all top end gaskets.

Thats head, rocker cover, inlet manifold, exhaust manifold, plenum, valve stem seals, cam seals and I've probably missed a few.

[hungry6]

Ok going by my limitted experience, on the same motor same tune same fuel, even same dyno driver, haha.

before port/polish/combustion chamber modification to promote a more efficient-complete burn of fuel mixture.

Before head works approx max power 570 rwhp with full boost by 4650rpm (5.9 sec) to develop full power

After head works, almost broke 600hp max power with full boost by around 3700rpm and (4.2 sec) to develop full power.

So the gains with head works wasn't just in outright power, but in the time it took to develop full power.

Which a good racehead porter would look for and the additional power is just a by product.

Please understand, this is just going by my experience and may vary from other ppls results.

[Cubes]

Almost 1000rpm.. Is that really possible?

I'm a little sceptical to be honest, 1000rpm is a big jump in spool.

Thats the same as increasing displacement by approx 750cc.

Exactly what was done to the combustion chamber? This would have no doubt dropped the comp ratio?

[RB30-POWER]

Head porting even though you may make the ports larger can actually decrease performance as well. Bigger isn't really always better. Its all about the correct angles and so forth to the valves to acheive the correct gas velocity etc etc

In the book 21st Century Performance it makes it very clear that with good 4 valve per cylinder heads its far easier to actually bugger the ports up then gain extra performance.

So make sure the guy that ports it, has done numerous RB heads before and have been proven on drag/track cars.

You dont just want some hack job, where they are bigger but it hasn't helped torque or whatever it is that you actually want the porting to acheive.

Its a little like bigger valves, bigger valves can actually impede gas flow rather help it.

The factory isn't dumb, they are the ones who have paid millions of dollars in research and CAD design to come out with the best compromise . More so then the average joe blow performance guy has anyway.

Just to think your gunna open the ports and gain power is dead set crazy!

Thats why the people who do know how to gain real performance from porting will charge huge dollars, because they have destroyed and tested numerous heads for research into what works and what doesn't.

[Al]

VRS kit contains all top end gaskets.

Thats head, rocker cover, inlet manifold, exhaust manifold, plenum, valve stem seals, cam seals and I've probably missed a few.

<{POST_SNAPBACK}>

Is that Kit, Genuine Nissan Parts?

[Cubes]

It is genuine.

[Al]

Damn it.............

Will have a chat to my mechanic about that... I paid seperate prices for each of those gaskets and seals

[R31Nismoid]

VRS kits are complete = cheap

ive used before.

1000rpm in just porting... i agree Cubes, skeptical am i