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Location:
Hobart, Tas
Registered:
May 2002
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Cost of porting&polishing and other engine work?
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Tue, 03 September 2002 13:40
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Just wondering approx. what I should expect to pay for porting&polishing, or OS valves or a head reconditioning.
I realsie this might be a bit like 'how long is a piece of string' but am just trying to get ballpark figures so I can get an idea of things/what is reasonable etc.
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Location:
Perth WA
Registered:
July 2002
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Re: Cost of porting&polishing and other engine work?
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Tue, 03 September 2002 15:19
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yeah it really depends on how radical you want to go, and if you only want to clean up the runners etc its better to do it yourself, just get a good tech book to tell you how, and maybe practice on a stuffed head
bigger valves and so on is always $$$ if you need extensive machining
most of the cost is labour so just ring up some shops and ask thier hourly rate
Cam
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Location:
Wollongong
Registered:
July 2002
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Re: Cost of porting&polishing and other engine work?
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Wed, 04 September 2002 06:27
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I was talking to people just recently, its about $600 for a head reco or a little more, then add more for porting and such. I think just cleaning up the ports a little was only around $150 more but you can spend as much on the head as you can on the rest of your motor if you want it good 'cause thats what makes all your power.
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Location:
Newcastle
Registered:
May 2002
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Re: Cost of porting&polishing and other engine work?
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Wed, 04 September 2002 11:08
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I was told not to have the port polished as it is worse than just having the ports smoothed.
think of it this way. an old paint job on a car the water run off it . a new nice polished painjob the water tends to bead on the paint. not think of the fel in your ports would you rather it flow or bead??? the fuel will atomise better if the ports arent polished.
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Location:
Perth WA
Registered:
July 2002
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Re: Cost of porting&polishing and other engine work?
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Wed, 04 September 2002 16:22
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as i said before, buy a good tuning book..it should tell you how to setup a flow bench ..make one.. get an old f&*ked head ...port it ..flow test it ...simple !!... if you stuff up and its no good start again... in my opinion the pros must have started somewhere so why not figure it out yourself
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Location:
Brisbane, Queensland
Registered:
May 2002
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Re: Cost of porting&polishing and other engine work?
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Wed, 04 September 2002 21:10
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I agree with celica_RA40, I've been told that ultra shiney and smooth is worse, same as adding oxygen to water, you need turbulence, turbulence causes the two subtances to mix., also the longer the turbulence is the better but not too long 
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I supported Toymods
Location:
Berowra-Sydney
Registered:
July 2002
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Re: Cost of porting&polishing and other engine work?
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Thu, 05 September 2002 04:32
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makes sense about the polish bit but wouldn't polish be good for the exhaust chambers?
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Location:
Rocky Mountains, Canada
Registered:
May 2002
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Re: Cost of porting&polishing and other engine work?
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Thu, 05 September 2002 08:16
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Port & Polish is the general term.
Normally it means:
- port matching the head to mainfolds.
- making the inlet & exst ports less restrictive.
- polishing the exst port only.
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Location:
Brisbane
Registered:
May 2002
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Re: Cost of porting&polishing and other engine work?
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Thu, 05 September 2002 08:32
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Turbulence is beneficial on old-school engines with carbies and big cams. On modern port-injected EFI engines, it's completely unnecessary - the high-pressure fuel system does an excellent job of mixing the fuel with the air. Think about where the injectors are compared to the valves - do you really think there's a danger of the fuel dropping out of suspension in that amount of time?
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Location:
Newcastle
Registered:
May 2002
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Re: Cost of porting&polishing and other engine work?
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Thu, 05 September 2002 12:16
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yep i certainly do norbie. this is my opinion so it may not be totally right but if you look at the spray pattern of an injector it is reasonably wide for the size of the port, now when you shoot the injector into the port some of the fuel will touch the sides and bead up, sort of the same as shooting a fine mist of water out of one of those spray pack bottles onto a pane of glass.
in the end it may onlt be 1 kw at the fly but money could be better spent elsewhere.
also i think you would have to be continualy cleaning the exhaust ports if there were any advantage to be obtained from polishing the exhaust as carbon builds up fairly quick.
also wouldnt you have to polish the inside of your exhaust headers to get a performance gain at the same time.
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Location:
Canberra
Registered:
May 2002
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Re: Cost of porting&polishing and other engine work?
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Thu, 05 September 2002 12:41
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I agree Celica_RA40. keeping the fuel mixture suspended in the intake air is just as important with efi.
An EFI injector may have a very nice spray pattern in 'calm' air, but consider that they are not placed in the middle of the stream of air, they are more often quite close to the top/side/bottom of each intake runner, and with the high velocity of air rushing past, its quite easy to see how the fuel could contact the walls of the intake manifold. Then put 15psi or so of boost pressure through those same intake runners, and the situation escalates further.
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Location:
Melbourne
Registered:
May 2002
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 Re: Cost of porting&polishing and other engine work?
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Thu, 05 September 2002 13:04
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raSkaS,
so what do your books say about setting up a flow bench?
Does anyone know of a workshop in Melbourne that has one?
David
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Location:
Hobart, Tas
Registered:
May 2002
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Location:
Brisbane
Registered:
May 2002
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Re: Cost of porting&polishing and other engine work?
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Thu, 05 September 2002 23:39
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If you have high velocity air rushing through the ports, this is only going to reduce the chances of fuel touching the port walls. And when I say high velocity, on many engines the intake velocity can approach the speed of sound! If any fuel contacts the port walls under those conditions, you have serious problems that can't be fixed by a rough wall surface...
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I supported Toymods
Location:
I renounced punctuation
Registered:
May 2002
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Re: Cost of porting&polishing and other engine work?
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Fri, 06 September 2002 01:20
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Cost of head work will depend on how far you want to go. Obviously 4 cylinders costs less than a V8. Cleaning out of casting dags and match porting will be much cheaper than extracting every last cfm of flow (usually involves sectioning a spare head) and fitting bigger valves.
Port finish is a contentious issue. Generally, a slightly rough finish is desired for street and track work. As Norbie has stated, this is probably less important with fuel injected cars and fuel being deposited so close to the inlet valve. The ultimate extension of this would be direct fuel injection (EGA 2JZFSE) where the fuel is injected directly into the cylinder. The need for fuel droplets to be kept in suspension here have been abolished, so a highly polished port finish would be ideal. I haven't seen any randomized controlled trials which demonstrate any difference in fuel suspension or any which show a difference in major end points (eg power/torque). One must remember the origins of this dogma - carbed engines of yesteryear. Nevertheless, polishing is generally only recommended for drag cars.....huge flows, wide open throttle, run for 4-10 seconds.
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Location:
Eskilstuna, Sweden
Registered:
May 2002
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Re: Cost of porting&polishing and other engine work?
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Fri, 06 September 2002 02:33
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Has anyone found a place that uses the extrude hone technique in OZ
http://www.extrudehone.com/
This process offers a good slightly course and dag free finish.
Nice footer gianttomato........ 
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Location:
Brisbane
Registered:
May 2002
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Re: Cost of porting&polishing and other engine work?
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Fri, 06 September 2002 03:35
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Extrude Hone is not recommended for cylinder heads because you have no direct control over what gets removed. It's great for manifolds though, although a little too expensive for anything less than a race engine IMO.
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Location:
Mentone
Registered:
May 2002
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Re: Cost of porting&polishing and other engine work?
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Sat, 07 September 2002 14:11
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Theres a place in lovely Ballarat that has developed a similar systme to the extrudehone system. Zoom did an article on it a couple of months ago. Ill look for a number for you if you want. They are not far from me during the week.
Brad
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Location:
Montrose, VIC
Registered:
May 2002
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Re: Cost of porting&polishing and other engine work?
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Sat, 07 September 2002 14:18
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Specialised Power Porting 03 5341 8028
The guy's an absolute champ, happy to talk freely and honestly about all kinds of stuff and give you plenty of ideas
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Location:
Brisbane / Gold Coast
Registered:
May 2002
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Re: Cost of porting&polishing and other engine work?
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Sun, 08 September 2002 01:23
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Take two tubes, one with polished inner walls and the other with a carefully roughened surface, and blow air through them.
If you carefully measure the airflow, the one with the roughened surface will always flow more air - This is because the carefully roughened surface tends to make the boundary layer of the air touching the walls of the tube stick to the walls better, and so effectively make the tube a bigger diameter than the smooth walled one.
It's an easily repeatable test done around the world.
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Banned member
Location:
Brisbane
Registered:
May 2002
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Re: Cost of porting&polishing and other engine work?
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Sun, 08 September 2002 03:34
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Bill Sherwood.....no offense on the idea but how can you expect to 'breathe' the same amount of air at the same speed on both pipes ??
As for head work, a smooth finish on the intake ports and as mirror as possible on the exhaust ports. You want that fuel/air to spin on the way in, and get out after it's burned. If you can get some 'vortex' action happening in the intake, it'll work like making a whirlpool when you drain the dishwater out of your sink. When you create a vortex, or helix, you increase not only the velocity which slightly compresses the air, but also vacuum at the top of the vortex which sucks MORE air down with it. Think of it like a free turbo. Note that the intake ports curve into the cumbustion chamber and the exhaust just goes straight out. That's how you want to approach the porting. You want that exhaust gas to vacate ASAP after burning, so make sure it has NO resistance and not only will it exit faster, but the smooth walls will be less prone to trapping carbon particles and such. ...I'm thinking this (from experience) would broaden the powerband all the way across, more poop per puff.
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I supported Toymods
Location:
Berowra-Sydney
Registered:
July 2002
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Re: Cost of porting&polishing and other engine work?
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Sun, 08 September 2002 04:30
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like the design inside a rifle's barrel?
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Location:
Brisbane / Gold Coast
Registered:
May 2002
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Re: Cost of porting&polishing and other engine work?
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Sun, 08 September 2002 06:36
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Bill Sherwood.....no offense on the idea but how can you expect to 'breathe' the same amount of air at the same speed on both pipes ??
I didn't write that, I wrote that the boundary layer on the rougher tube will be thinner, and so the effective diameter of that tube will larger and so it'll pass a little more air.
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Location:
Canberra
Registered:
May 2002
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Re: Cost of porting&polishing and other engine work?
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Sun, 08 September 2002 09:24
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Hey Bill
A bit of aviation influence coming out there?? Laminar & non laminar flows & the like? makes sense to me, but i still dont understand why people recommend a polished surface on exhaust ports, surely this would be offset by carbon buildup within a few thousand kays of operation?? Is it really worth the effort?
Phil
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Location:
Sydney, Australia
Registered:
May 2002
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Re: Cost of porting&polishing and other engine work?
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Sun, 08 September 2002 09:36
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Simple. Why has a Golf ball got dimples on it and is not flat. Try hitting a smooth golf ball and see how far it goes (unless yr like me and cant get it to go more than 10 feet anyway).
rgrds
sam
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Banned member
Location:
Brisbane
Registered:
May 2002
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Re: Cost of porting&polishing and other engine work?
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Sun, 08 September 2002 10:43
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well everyones own opinion
ive heard everything on these forums now...
* stock air filters are better than ones which flow more air
* 2.5 inch exhaust is 'better' than a 3 inch exhaust
* you dont need to port and polish an engine just cos all the racing and performance guys do it for extra power, they dont know what they're talking about
* oh and stick a 1g-gte in it, whatever 'it' is, thats really the only 'mod' thats recommended
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I supported Toymods
Location:
Berowra-Sydney
Registered:
July 2002
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Re: Cost of porting&polishing and other engine work?
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Sun, 08 September 2002 10:43
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golf ball design is completly different, dimples in it are for creating spin so that way it kind pulls itself upward or downwards when a certain direction of spin is placed on the ball kinda hard to explain but learnt it in physics.
as for the polishing the exhaust outlets, well surley a polished outlet will get less carbon build up then a rough outlet as the roughness will just help catch more carbon, also by being polished and therefore having less friction it gives the carbon less to hold on to.
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Location:
Brisbane / Gold Coast
Registered:
May 2002
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Re: Cost of porting&polishing and other engine work?
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Sun, 08 September 2002 10:47
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No, not aviation, but the guy that used to build engines for Moffat & Ford in the 60's & 70's - John Wynne.
he said that Ford Aus & Ford US did a lot of testing on such things, and the two tubes experiment that I mentioned above works just like I wrote it.
Not sure about the fine finish on the exhaust ports, I agree with the carbon build-up negating any great effort there.
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Banned member
Location:
Brisbane
Registered:
May 2002
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Re: Cost of porting&polishing and other engine work?
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Sun, 08 September 2002 11:00
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polishing helps prevent carbon build up thats why it is polished to mirror standard
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Location:
Newcastle
Registered:
May 2002
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Re: Cost of porting&polishing and other engine work?
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Sun, 08 September 2002 13:12
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i think even if it is polished there will always still be very minor even microscopic dimples in the surface and over a few thousand kays carbon will build up in these and then more carbon will grab a hold of it and cause to layer up just like an unpolished surface.
saying that when i re did the head of my 18R-GEU the carbon in the exhaust port wasnt caked on or anyhting it was just a very fine coating.
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Location:
tallahassee FL usOFa
Registered:
May 2002
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Re: Cost of porting&polishing and other engine work?
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Sun, 08 September 2002 13:38
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polish the exhaust from the valve head to muffler tip as much as you want. it'll be great the first 20 seconds or less.
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Location:
Eskilstuna, Sweden
Registered:
May 2002
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Location:
Montrose, VIC
Registered:
May 2002
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Re: Cost of porting&polishing and other engine work?
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Sun, 08 September 2002 22:25
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ahhhhhh... 2 strokes! They're a entire book, er, 26 volume encyclopedia in themselves. Reading 2 stroke theory can be fascinating stuff though.
I'm gonna dig out my 1st year thermodynamics book again tonight - I think there were a few relevant pages in there.
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Club President
I supported Toymods
Location:
Sydney
Registered:
May 2002
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Re: Cost of porting&polishing and other engine work?
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Tue, 10 September 2002 04:22
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Celicamad 85,
Just to reference you post !
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ive heard everything on these forums now...
* stock air filters are better than ones which flow more air
* 2.5 inch exhaust is 'better' than a 3 inch exhaust
* you dont need to port and polish an engine just cos all the racing and performance guys do it for extra power, they dont know what they're talking about
* oh and stick a 1g-gte in it, whatever 'it' is, thats really the only 'mod' thats recommended
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Thats because people come here to discuss idea's and opinions. They key to the whole experience being worthwhile is actually listing to what other people suggest and the reserch all the options and make your own final decision. You have to be prepared to take the advice of those people who know more than you do 
Back to the topic tho. On the Polishing of exhaust ports I cannot add worthwhile comment. It is however not uncommon to mirror polish the bottom of the valves to deter carbon buildup. Yes it will still hold carbon but in theory not as much and definatly not as quickly. If the anchor point is only small it will support a smaller amount of carbon against the flow of air thru the head. The better (read Bigger) grip the carbon has the more it can resist the head flow to be blown/sucked into the exhaust.
As for the Boundy Layer this is indeed a consideration for Both EFI and carby vehicles so whilst the benifit and requirement to maintain particle suspension can be debated it doe not change the fact that the smaller boundy layer (read thinner) is a good thing.
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