Opinions on my porting skills

[Templ8e30]

This is the old 2.7eta cylinder head, I have drilled the oil feeds to the previously unused cam bearings and decided to have a play with my porting kit and air powered die grinder.

I've opened out all the ports from the original tiny ones to 325i spec using the gaskets from a 325i and my imagination. Also have mirror polished the combustion chambers and mildly polished the ports.

So what do you think ? good or scrap ?

This took 12 hours + in works time

http://img119.exs.cx/img119/118/pict00049xp.jpg

Cheers,

Iain T

[Jhonno]

you want a mildy rough, not polished finish on the ports as it aids fuel/air mixing

[E30Adam]

you want a mildy rough, not polished finish on the ports as it aids fuel/air mixing

Only on the inlet side, the exhaust ports are best highly polished to aid exit of the exhaust gases.

[craigieeb]

it need's to be slightley swirled a bit, and not pollished up on the inlet side, know what i mean?
and your porting skills seem to be ok, it all looks evan to me

[M3GTR]

Do you want to do another????

[Guest]

Good timing, just doing mine at the moment, yours looks good.

There was an article in Performance Car Mag a couple of months ago on porting (although a bit vague) but the good bit was there were a couple of photos of a 325 race head that Cylinder Head Developments had just done. If anyone's interested I'll try and scan them in and post them.

I've been reading up in various places on the best way to port & polish and judging by what I have read there are lot of different views, the replies so far to this thread also bear this out. It looks like there is no definite answer, in fact some heads that have the best flow rate may not produce the best power as there are other factors like swirl etc. to take into account. Highly technical subject when you look into it!

It's certainly a very cost effective performance mod if you do it yourself (especially if the head has to come off for another reason anyway).

[e30_Turbo]

Has anyone paid to have this done on their m20 head?

I've been quoted Ԛ£285.00 by castle engineering who came highly recommended by a man who races M5's.

They said that they can do quite a bit of work on the head and will def see gains from doing it. The guy also mentioned that the M20 head has lots of economy features built into the design of the head and he can rework it to be much more performance orientated.

[Templ8e30]

OOH please scan those pics, could do with comparing the two.

No i don't want to do another this one took a lot of work and I'm still pulling bits of ally swarf out of my hair and clothes

I think I'll run some emery up the inlet port to 'swirl' it a bit.

What do you guys think of polishing the backs of the valves ?

Cheers,

Iain T

[suave]

Be very carefull because if you get the flow wrong and not equal within 3% over all 6 ports you will end up with hot spots and burnt valves in weeks rather than months, having said that, the finish looks lovely.

[Ant]

polished inlet ports only really cause a problem with carb fed engines , the fuel air mix is drawn in and "condenses" on the port runners.

on the M20 the injector fires on the back of the valve so leave em bling dude, no need to rough em up IMHO.

finely polished exhaust ports are again a good idea, no troughs to trap carbon deposits and soot

with regard to Fozzys post.... hes talking about altering the squish dude, could end up pinking like hell if its not bang on the money.

I can spend your Ԛ£250 more wisely M8

[craigieeb]

Has anyone paid to have this done on their m20 head?

yes, i paid to have my head ported on the 2.0 and it fly's, there is no more flat spots and it pulls like a train, i didn't pay anything like you'v been quoted i actually paid 150, and it has been done properley, the guy who done it for me is a v,good friend of mine and has been porting for quite some time and has done a shed load of diffrent engine's, he's doing my 2.5 at the moment and i cant wait for it to be done, and with the cam in it should be fun : )

[suave]

Placibo.

[craigieeb]

Placibo.

erm.........come again

[suave]

It means the notice of power is in your head and not in the head if that makes sence, there is no real power gains in porting the M20 cylinder head.
2hp at the most without cams.

[craigieeb]

right, ok then, i think were going to have to agree to dis-agree, as the 320i unleashed a lot more than 2/bhp belive me.

[suave]

It isnt possible.

[craigieeb]

yes it is

[suave]

Looks like we disagree then.

[Jhonno]

you want a mildy rough, not polished finish on the ports as it aids fuel/air mixing

Only on the inlet side, the exhaust ports are best highly polished to aid exit of the exhaust gases.

yeah thats what i meant - i assumed ppl would read it ok as i mentioned fuel air mixing

[Jhonno]

It means the notice of power is in your head and not in the head if that makes sence, there is no real power gains in porting the M20 cylinder head.
2hp at the most without cams.

i suspect its more than 2 altho headwork on its own is not gonna produce a monster, headwork goes with cams to give the proper gains from it!

[Ant]

BUT ..............

assuming the head in question was due a refurb anyway the gains felt would be , in some way, atributable(sp?) to zero leakage @ the valve seats when compared to a 100K coked to death head

the same could be argued of cleaned up ports.

Al things are relative, the only true test of tuners claims is a back to back test, new clean minted head, test, then modify to suit then retest.

I can see both sides of this brewing arguement dudes, bottom line is, if you're happy with what you got for the Ԛ£Ã”šÃ‚£ outlaid then its all good

[M3RAGS]

Placibo.

Placebo!

anyway, just from looking at your finished product cannot determine whether you have done a good job or not. DIY porting has seen many people lose power as they haven't got a clue what they are doing.

You can only just on a rolling road of before and after.

Looks like 'before' is going to be difficult

You should leave it to the professionals with flow benches and experience and the CORRECT TOOLS!

Im not cynical or anything

[Jhonno]

Airflow is as important as airspeed is as important as swirl and mixing which is why its so hard to get right!

[suave]

I believe Dave Walker, whom is commonly known as the godfather of head work once took the M20 head and could only manage a 2hp gain in power, this was using a brand new head.
His comments were along the lines of, "up untill now this is one of the best designed heads for application I have tested."
Anyone who knows anything about hardcore mods will know this man knows his stuff.

[Jhonno]

Oh right - never knew he had a pop at it..

In that case 2bhp it is

[Guest]

Must admit when I looked at the ports they didn't look that restrictive and fairly well radiused so it looked to me like there won't be massive gains. I'm just gonna try and copy what they did in the mag article to the beemer head which was basically smooth down the hump leading up to the valve guide, open it up to the gasket diameter, mirror finish the combustion chamber and again smooth down the exhaust port. According to Cylinder Head Developments, Inlet ports are finished to 180 grit and Exhaust ports to only 60 grit as "there's no gains to be had from polishing them further".

It does seem to be a bit of black art but hey if I only get 1bhp gain for Ԛ£30 (cost of the die grinder kit) that ain't bad going

What sort of output do you reckon for the following spec on a 325i?

Zone wild/hot chip (the wildest one)
Zone large bore throttle body
Shrek (sorry Shrick ) 288/288 cam
Ported/polished head (well there's 1bhp )
Tubular exhaust manifold and s/s exhaust (sorry can't be more specific as to the make, custom jobby).

I was thinking 190bhp at the flywheel or is that optimistic?

[suave]

There is a posibility you will end up with 160hp.
The ridge in the head port aids swirl and the lines toward the valve aids squish, changing these can kill power, also the schrick cam is designed to standard head/valve, changing them can lose power.
Custom home made 6 branch manifolds can lose as much as 15hp, i kid you not.
Of course, there is a chance everything goes well in which case 190hp is a posibility.