About to "set to" with the die grinder underneath the car on the exhaust ports (done the headers) but would like to know how much meat I can safely take out without breaking into the water gallery??
Did that once on a mini (sleeved the valve guide hole to get round it )


Cheers

Andy

 

Andy,

are you planning to do this in the car

The swarf will go back into the engine, and errrrr, well that would be bad news.

You can do it with the heads off. This is a precision job that IMHO should only be done properly - and from what I have seen there are very few who can do it.

Personally I would not attempt this myself - even tho like you - I prepped and ported a 12G295 head for my Mini

Trout



[Edited by Trout - 12/29/2002 10:14:33 AM]

 

already though of that !
going to make sure both vales are shut on the one I am doing and then for double protection stuff a lump of rag in there as well.

explain to me the point of porting the headers if I'm not then going to do the head as well.
sounds like I will have wasted my time if I stick it back together without porting the heads

Cheers
Andy

 

Oi Mr Wallis

did you bother with your heads ???????

Andy

 

I did mine, although my engine was in bits. If you are just matching to the manifold/gasket, then I think you would need to be grinding like mad to break through anywhere. The main port is quite large anyway, so just take it easy, you done need to be able to get your hand in there.
IMO a mini head would be a more complex head to port, with the siamese ports and very small ports. The subaru heads look very good to start with. I simply cleaned up and enlarged the valve seat area, and blended it to the port, and opened up to teh gasket line ( or slighlty smaller ). All pretty easy to get at.

 

Why are you doing it ... you will only remove the reversion dam and allow pressure waves back into the heads.

bob

 

what about the turbo inlet then ?

oops...too late

 

Bob,

Rather than me try to explain my reasons badly I thought I would scribble something instead.
first pic being a before
second pic being...if I don't do anything with the heads
third pic being, what I hope to achieve.

I don't see much of a reversion dam in the "as standard form".
I would have made a good one if I left it alone after doing just the headers,
but alas, too late as I've done one port already

I'm back in the house for a cuppa as the toy air compressor I have in the garage threw a wobbly after being run non stop for the last hour or so.
best I give it chance to cool down.


Andy

 

I didnt do my heads.. considered it... Im doing my new heads...

David

 

No what you are trying to achieve is fine in principle, its just that the pressure pulses coming back up the headers would normally be broken up by the lip, also you need to keep a parallel exit from a joint into a tapered flowed entry otherwise gas just expands into the joint and slows ... same when porting the header joints, parallel exit and flowed entry. What you've done to the turbo is good, just make sure the uppipe exit is parallel and preferably the same diameter as the turbo inlet flare.

Edited to add that the middle pic is the correct setup.

[Edited by Bob Rawle - 12/29/2002 7:59:34 PM]

 

cheers Bob

edit to add: the heads are as parallel as I dare make them
now I'm being stung round the neck by shards of ally, grrrrr

see you on the 11th

as for whether what i'm doing is going to make any difference, I'll find out on the 4th.

Andy
<always in it, just the depth that varies >

[Edited by Fuzz - 12/29/2002 8:25:13 PM]

 

Stepped works fine.

Did you measure the gasket on the turbo? I hope it still works!

Save your efforts

Paul.

 

paul,

Up pipe is exactly same size pipe as top gasket,
turbo bellmouthed out to meet full size of up pipe and gasket.
no step at all there
should work well, as the gas ramps up the gentle slope it's speed should increase and hit the turbine with a lot less turbulance than the standard item

all done for tonight but I'm stuck....

need at least three studs for the up pipe, as they would not come out of the old unit.
had the heat on them in the end but they left the threads behind

I got so bored, I dropped the oil out of her, changed the plugs, changed the oil filter and fitted a new centre exhaust section !
off to bramalls in the morn for some new studs.

Andy

 

This should show you how much bigger the new up pipe is and the need to increase the throat of the turbo exhaust inlet to match

 

I'm not sure, so this is a question not a statement.

I thought that the reversion lip is only necassary if your running an aggressive cam that has some intake/exhaust overlap. Otherwise I though you were fine to match the ports to the header, keeping the sidewalls straight at the joint.

 

Anyway, I have some phase 2 heads here (on bench), what was the original question?

Okay, so I read it again and it made sense (scanned through before, duhh).

How much are you intending to remove? As bob says, parallel works for most applications, but a step is generally a good idea. It seems to be one of those things that is worse on a flow bench but better on a dyno, IOW, we don't fully know what's going on.

Paul

[Edited by Pavlo - 12/30/2002 8:20:09 PM]

 

I made the exhaust ports as close as I could to parallel sided to match size of manifold gasket. then tapered manifolds out to meet this gasket too, so no lip.
I did leave more meat on the side of the head with the longest exhaust branch as it would have made a sharper turn into the manifold, tended to play the grinder on inside lip a little instead, to smooth out that bend (requires picture i think !)
I was too impatient to wait for much of an answer and I had done one port when Bob replied, so thought I aught to do the rest at least to match, good or bad .

I seem to see an improvement in throttle response, though that could be the up pipe, I was expecting it to be worse, (with respect to the up-pipe as it's a larger diameter than standard.)
Overall boost threshold is virtually smack on 2500rpm.
Boost now holds at a smidge over 1.1Bar in fifth,(between 1.0-1.1 before).
control is better too, very little spiking round to 1.3 as it did before (only if you come off throttle and back on again ).
exhaust gas temp can now be measured as I finally fitted the boss in the new up-pipe before it went on. the highest I managed to get that was 760oC.
sensor put here FYI

nice growl from the exhaust now too, doesn't sound like there's a banana stuffed up the tail pipe when on full chat anymore.
again this may not be all to do with the porting and up-pipe as I fitted a straight through centre section as well.
Will be nice to see a good improvement on 221BHP from last visit to P station....

Andy
Saturday will tell...

 

The up-pipe looks nice, what is it? looks like it could be H&S.

Was the thermocouple bung welded in by the supplier?

Or did you make it all yourself? As I just remembered you're a welder by trade, so not a difficult job!

Paul

 

Up-pipe it's self, made by Hayward and scott.

Connector welded in by yours truly.

Andy

edit punctuation

[Edited by Fuzz - 12/31/2002 12:32:54 AM]