Posted by Padreic (pooh-fighter@bruce-lee.com) on September 27, 1998 at 02:24:51:
While I was porting away at my cousins D head from his Si....I remembered seeing and ad for Extrude hone that "a set of heads for 600USD" wouldn't this method of "porting" be better than what is offered out there?
I mean the material reaches inside the port where I can't with my carbide burrs. And hell for 600USD it's a lot cheaper than the DPR even PYR heads out there....wouldn't this be better?? but hell what do I know??
Thanks again Nitro!
Posted by NITRO on September 27, 1998 at 14:29:13:
In Reply to: Hey Nitro..wouldn' t this be
better? posted by body on September 27, 1998 at 02:24:51:
No. The extrude hone method is fine for manifolds and other large and complex pieces, but it errodes the aluminum at a far greater rate than the seat inserts, and the seat shape combined with the aluminum approach is the most critical part of head porting, assuming that you ARE looking for gains.
Posted by Padreic (pooh-fighter@bruce-lee.com)
on September 27, 1998 at 17:49:39:
In Reply to: Re: Hey Nitro..wouldn' t this
be better? posted by body on September 27, 1998 at 14:29:13:
dun mean to question your knowledge..just trying to get things into my brain right.....(difficult task)
anyway...I thought that extrude hone has different "puttys" that are of different abrasiveness....
so if they used a putty that wasn't as abrasive wouldn't be better?? or would the pressure pushing the stuff through still mess it up good?
Is it really worth it to have intake manifolds extrude honed? oh and BTW, would it be of any benefit to extrude a header....going my the theory of anything that is exhaust should be nice and shiny deal......
Posted by NITRO on September 27, 1998 at 18:32:01:
In Reply to: But I thought.....
posted by body on September 27, 1998 at 17:49:39:
I'd advise that you call the local extrude hone outfit and ask them
if they can mask certain areas that you do not want material removed from
in the ports. If so mask the "delicate areas" and pump away.
Unless they can mask, you might try a little experiment. Take a piece
of aluminum plate and drill&tap some holes in it. Screw some grade
8 bolts into the plate until they are absolutely flush with one side. Now
take a sanding block with 60 grit paper and sand the area that the bolts
are in. Feel the surface, Is it flat or can you detect the blots with your
finger? Sand it with finer grit paper, and feel the surface again. Is it
all flush?
The point of the experiment is: different materials have different
hardnesses, and it doesn't matter what medium is used, the harder parts
will not be eroded at the same rate as the softer material. Hopefully they
can protect the aluminum on the ST radius and approaching the seats, if
not you've got a gleaming piece of junk. If extrude honing was so good,
why do you think we and many others purchased $millions on CNC equipment
simply for doing heads, and we also do some phases by hand as well. Hell
if T.O.O. could figure out a way to make the process work, even if his
additional process cost 1-3mill. he'd own those machines tomorrow. After
all we charge the same for heads that we never touch, as for the hand done
specials. So time would be the factor, and if the time was less and the
quality as good, we'd be using it, and our profits would be considerably
greater.
Posted by Padreic (pooh-fighter@bruce-lee.com)
on September 27, 1998 at 20:19:35:
In Reply to: Re: But I thought.....Yea, Sure.
posted by body on September 27, 1998 at 18:32:01:
Luckily I didn't do anything hasty and send the head off to have it extruded...
so what about the headers? we picked up a used DC SS header and had it "bathed" most of the carbon buildup is now gone on the inside....well...where we can see anyway....and we noticed how rough it is where it bolts up to the head....do headers follow the same rule of being smooth and shiny like exhaust ports? If so....would extruding the header be advisable? Thanks!
Posted by NITRO on September 27, 1998 at 23:18:25:
In Reply to: Thanks again Nitro!...but what
about this now? posted by body on September 27, 1998 at 20:19:35:
Regardless of application, grind the port in the header flange slightly larger than the ehhaust port exiting the head. On the intake side, always make sure that the inlet port in the head is slightly larger than the port exit of the intake manifold. We're not talking much, but assuming that flow will be traveling backwards on each side of the engine, the small step you create with the mismatch will prevent the reverse flow from having such an easy time, because it ain't worth shit for power...little things (T.O.O.). If you have the money take the headers (or ship them)to either JetHot or HTP and have them coated inside and out. Not only will they clean the crap out of the headers, but the coating will retain heat, resulting in better flow. That's simply one reason we like mild steel with coatings over stainless. Applications where we MUST use stainless, we coat them inside and out as well.