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  #1  
Old 21-10-2010, 10:27 PM
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Default Porting & Polishing

Dropped the heads off to be serviced today and was having a discussion about porting my heads.

After a lengthy discussion it was made clear to me that unless you're trying to squeeze every last drop of potential power out of your vehicle or essentially hooking in a field where every single piece of equipment has to honed and engineered there's no real point having this done.

Basic overview of conversation would be I can go through and see if there are any irregularities and smoothen everything out, but there are better things you can do with your money to get better performance out of your vehicle 'potentially might be able to get an extra 10% more performance out of the motor', and basically stated that porting is more beneficial for naturally aspirated motors.

Having a look at some of the work he had in his factory at that time, and checking out his RX5 Rotary I have no issues in taking his word.

My question is then, for something that can be quite expensive why do members on this forum get the work undertaken.

'this is not a because I can type question, I'm interested in your thought process behind getting it done'.

Personally for what its worth I've decided against it.

Polishing is apparently not something that will give any real gains either 'and note I am not an engineer in thermodynamics, but it was made mentioned that a courser finish allows everything to mix better.

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Old 22-10-2010, 07:08 AM
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its not that difficult, the expensive part is when you need to do flowbenching and comparisons. but to hit something up with a carbide bit and take off the lumps and smooth out the casting marks is relatively cheap.
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Old 22-10-2010, 09:42 AM
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What heads have you got? And what cams?

As initially, I was wondering if I should as well, but now, with the plan being bigger cams, larger valves etc, its required to give everything the room and function. Where are you getting the work done? Costs? (I'm just interested for comparo).

Feel free to shoot me a PM if you like.

And good to see we are all gonna be finishing 'soonish' ! You, me, Joe and Mark should all recover from 'hard-parkers' to 'drivers' again! As the bug fraternity has taken a bit of a hit lately... (No pun intended to some).

Brent.
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Old 22-10-2010, 09:54 AM
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I'm with Stace.. just spend a bit of money and clean the heads up, rather than doing more extensive porting and polishing.. if you're only chasing 350-400HP max (at the hubs), then you're not going to see the benefits of $5k worth of head work.

As far as spending money goes, when it came to do mine, I gave the head shop a budget and they stuck to it.. wasn't cheap, but not over the top either.. I can't tell you the exact cost of porting because it was included in my cam install (had to set clearances as the aftermarket cams had a slightly different base circle), head service, x-raying, crack testing, etc.

I got my ports cleaned up and deburred, a simple port grind (enlargement) throughout and polished, and the port splitters have been shaped and polished... thats about as extensive as I was going to go in my budget..

As soon as you start getting ports reshaped, valve stem areas smoothed out, valve seat work, combustion chamber reshaping, etc, it blows out massively.. you can purge $5k very easily just on head work.

Agree with Brent also.. can't wait to see all the bugs back on the road! We should organise a cruise or something
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Old 22-10-2010, 09:57 AM
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Quote:
Originally Posted by sleepR View Post

And good to see we are all gonna be finishing 'soonish' ! You, me, Joe and Mark should all recover from 'hard-parkers' to 'drivers' again! As the bug fraternity has taken a bit of a hit lately... (No pun intended to some).

Brent.
True that Brent been driving around in the outback haven't spotted a bugeye yet my bug should be finnished late next week will be getting final paint today and reassembly next week + professional detail
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Old 22-10-2010, 10:00 AM
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I am up for a bug cruise sounds like a plan
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Old 22-10-2010, 07:43 PM
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Quote:
Originally Posted by BALISTC View Post
I'm with Stace.. just spend a bit of money and clean the heads up, rather than doing more extensive porting and polishing..

As far as spending money goes, when it came to do mine, had to set clearances as the aftermarket cams had a slightly different base circle, head service, x-raying, crack testing, etc. <== (that's me in a nutshell)

Agree with Brent also.. can't wait to see all the bugs back on the road! We should organise a cruise or something
Agreed, agreed and agreed

Quote:
Originally Posted by BALISTC View Post
As soon as you start getting ports reshaped, valve stem areas smoothed out, valve seat work, combustion chamber reshaping, etc, it blows out massively.. you can purge $5k very easily just on head work.
One thing that was made mention to me when dropping mine off was to be careful of people selling components (still in the box), extremely cheap over the internet etc (people whom bought the components retail and decided not to fit them).

One of his clients was put in a position where the parts he sourced for his head work were EXTREMELY cheap, but when he was informed of all the work needed to get them to fit and function correctly, it was soon made clear why the parts were on the market at such a reduced rate.

Quote:
Originally Posted by tuna View Post
its not that difficult, the expensive part is when you need to do flowbenching and comparisons. but to hit something up with a carbide bit and take off the lumps and smooth out the casting marks is relatively cheap.
He's going to have a look for me and see if there's anything worth flattening out.
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Last edited by mARC; 22-10-2010 at 07:51 PM.
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Old 22-10-2010, 07:50 PM
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Standard heads/cams usually max out at around 280kw atw

I wouldnt bother with any porting or anything of the sort unless you are planning to go over 250kw atw.
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Old 23-12-2011, 10:43 PM
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Thread dig up.

Guys just wondered if anyone could recommend a reputable proven Subaru head shop in W.A?

As some will know I am building a 2.35 stroker combined with a GT35R sized turbo & 272 cams. I have recently got a quote from Headtorque in Ozzy Park, for crack testing, reshaping & porting, fitment of double row springs, 1mm over sized valves & Ti retainers, complete with flow bench testing.

Headtorque does seem very competent, but I am just looking for other proven companies to compare the pricing too. Or can anyone give me feedback of work they may have had completed there?
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Old 23-12-2011, 11:07 PM
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Try John nastis, did my heads and knows his stuff!!
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