ported and polished heads

[Guest SPANKU]

was at my mates house to pick up my overside bored ver8 semi-closed deck and he shown me a head that hes been working.

one of my other mate did it himself and it came out pretty good.

im thinking about getting the AVCS heads done also while its out. worth it? yay or nay?

looks very good.

just some of the photos i got while i was there.

[Stoffa]

I would say its only worth it if its getting properly flow tested while its being ported, everything i've read says its pretty easy to stuff up if you dont know what your up too

[Guest boostcut]

if you knife edge the port divider and just generally clean the casting marks off the surface you will be suprised at the results..

[Guest itsgotgo]

any porting done well is good.

But would have to make sure that the cc,s per runner are resonably even.

As spanku has said,get it flowed and cc,s checked.

[ReubenH]

What kind of price are you looking at to actually get it done properly?

[Guest SPANKU]

my mates that's done this has over 10 years of experience doing head works.

price vary depending on the condition of the heads also this is including a fully rebuild so you pretty much have a fully recon head

I would get all the seals and Seats replace while at it.

[Guest itsgotgo]

 SPANKU']

my mates that's done this has over 10 years of experience doing head works.

price vary depending on the condition of the heads also this is including a fully rebuild so you pretty much have a fully recon head

I would get all the seals and Seats replace while at it.

[quote name='SPANKU said:

my mates that's done this has over 10 years of experience doing head works.

price vary depending on the condition of the heads also this is including a fully rebuild so you pretty much have a fully recon head

I would get all the seals and Seats replace while at it.

Sorry spanku

I quoted you and got the wrong person,my apologies

I have a friend that worked for pro cylinder heads in auckland many moons ago and has 20+years doing heads.

He always flows and cc,s to be sure.

But if your mate is confident as,go for gold

Most blokes with a few years of doing them are good and get to know how far they can go.

[Guest SPANKU]

all good any advice is a good advice

[Guest]

There is good power gains to be had, we had to cars that had pretty much the same specs bar the turbo. one had a holset HX40 with a port and polish, the other had a garrett GT3540. on the same boost the HX40 made 401KW the GT3540 made 360kw. both turbos responded the same and power curves coming on to full boost were the same.

The other result we had was with the 400kw motor was its old T3T4 turbo it made 300kw on 15psi. most only usually make 270kw max

Port matching also helps with intake and exhuast. I'm Currently doing that on my skyline, will be interesting to see what diffence there is on the dyno once its all back together as my cheep exhuast manifold was way off.

Thats is what we have found on the dyno at work, no back to back results as such.

I have talked to mark maholland (pretty well known race engine builder in speedway and other circles) and he has told me the same results as what we have found.

[ReubenH]

Wow.. nice to see some figures. Looks like an easy 30KW to be had out of those big power engines with a good port and polish eh?

[Optical]

 GETLOW said:

one had a holset HX40 with a port and polish, the other had a garrett GT3540. on the same boost the HX40 made 401KW the GT3540 made 360kw.

what size housings on the 35 and hx40? 6 blade hx40 compressor?

[Guest]

both had .63 exhuast housings Garrett housing on the HX40. 7 blade compressor wheel from looking at the oversized.. photos on the website.

power gains are dependant on each motor and the tune and the quality of the porting, as every motor reacts in different ways to mods.

You can go too far with your porting and polishing as it can affect how the air flows in the combustion chamber, from what Mark has explained to me, is that you still need some turbulance

I will hopfully have some Dyno sheets in a couple weeks from my RB25DET once I have put it all back together to show the difference. I'm not so worried about peak power, I'm more interested in picking up some more fat through the midrange

All I will have changed that will affect power is port matched the exhuast manifold to the gasket, smooth the transition in to my turbo as there is a step (EJ20 turbo flange welded on to pipe to T3 flange). port match the intake manifold, and De-shroud the intake valves and possibly the exhuast valves depending on what Mark suggests will give some good results.

If this thread is easy enough to find Ill try remember to post up the results

[Guest]

Finially got the car back together and running and tuned.

I can't say that I made a power gain as we didn't make a noticable jump the engine made its power easier, I think theres somthing else thats now limiting the car..

although the main notes my workmate told me is that wastegate duty cycle is down 15% and it has taken 4degs less ingnition advance to make the same power. so everything is obviously flowing alot smoother.

it does also appear to be making boost a little eariler, 20psi used to come at about 4000rpm. now i have a full 22psi by approx 3700rpm

All I ended up doing, was getting the valves recut and seated, exhuast manifold port matched to the gasket, turbo exhuast housing port matched to the gasket.. I think the collector in my cheep exhuast manifold is now a big flow restricition

I still think this was well worth doing, though as I didn't touch the head porting I have missed out on some bigger gains.

and i can sware that the car revs out easier and faster then before and has a more crisp note to the exhuast..

[subout]

 Optical']

[quote name='GETLOW said:

one had a holset HX40 with a port and polish, the other had a garrett GT3540. on the same boost the HX40 made 401KW the GT3540 made 360kw.

/quote]

what size housings on the 35 and hx40? 6 blade hx40 compressor?

think this may have been my old holset Matt that Ray put the Garret exhaust housing on for me

[Guest keltik]

Looks like a bit of a rough finish to me...compared to another head ive seen

But i am by no means an expert - i honestly have no idea about porting - I just like shiny things.

[Koom]

 keltik said:

Looks like a bit of a rough finish to me...compared to another head ive seen

But i am by no means an expert - i honestly have no idea about porting - I just like shiny things.

You only want a shiny surface in the combustion chamber and in the exhaust ports to prevent carbon deposits from sticking so easily.

A slightly rough surface in the intake ports/runners gives less resistant to flow as it promotes a turbulent boundary layer which gives a better flow profile than if you have perfectly linear flow right across the cross section. Kind of like a dimpled golf ball that flys further than a smooth one. But its more of a rough surface finish that you want, not rough as in lumpy and hatcheted.

[Max Headroom]

 Koom said:

You only want a shiny surface in the combustion chamber and in the exhaust ports to prevent carbon deposits from sticking so easily.

A slightly rough surface in the intake ports/runners gives less resistant to flow as it promotes a turbulent boundary layer which gives a better flow profile than if you have perfectly linear flow right across the cross section. Kind of like a dimpled golf ball that flys further than a smooth one. But its more of a rough surface finish that you want, not rough as in lumpy and hatcheted.

Agreed. Polishing the ports was commonly done in the past, but these days there are more benefits with a slightly rough surface, e.g. it also aids fuel atomisation. The shape of the ports is critical though.

[Guest keltik]

Ah didnt think of that, despite knowing the americas cup boats keep a rough finish on their hull for that exact reason