Acid porting

[longarm]

I've been reading alot about acid porting.
Does anyone on the board have experience with this
technique of porting.
I've read about everything available, I'm sure it could possibly be done, but I would like to hear first hand accounts of its use and success or failures.

 

[Locomotion]

"Acid porting" is somewhat of a blanket term to describe porting that's been covered up - ground areas doctored to appear as having the originally cast texture. Lots of stories about different ways to achieve it, including battery acid or something similar, natural or salt-enhanced rust, regular porting then using some of the aforementioned methods...there are probably other creative methods. Regarless of how it's done, it is time-consuming and expensive if someone else does it. I've heard a lot about it because of the class rules I race under.

 

[moper]

Yeah, it's not doen for any reason other than to hide porting work in classes that must be unmodified ports. It is only done to get the surface back to looking sort of like cast iron. The port work is not done by acid, but by hand. Then the acid is used to create the texture. Then the port's sealing flange areas are milled and/or the valves are sunk to reduce the port's measured cc back near stock.

 

[longarm]

I know its orignal intent.
Its been a round for a while.
I was reading some updated information, and
some claim by multipal applications and short term
exposures they are getting good results in flow numbers.
Most of this info is coming from dirt racers and tuners.
Does anybody have any provable flow data or sites
that might be more trustworthy, it gives the appearence
of a black art that's not credible.
Is this possible or is it just table racing.
I'm most interested in how the metal removal could be controlled
in key areas.
This site has a decent desciption for its use as a coverup.

http://www.rlengines.com/Web_Pages/acidporting.html


What i'm finding mostly on the blogs is they are using wax to partially exclude
the bowl area and manifold surface then finishing those by hand.

 

[Petzschler]

how would one maintain consistancy from port to port? you'll still have to go in a hand grind it to
even everything out. Like the others said here.. its to "cover up" cheating in some classes. personally,
i wouldn't believe everything you read on the net. especially when $$$ are involved.

 

[longarm]

How would one maintain consistancy from port to port?

That's exactly the info I'm interested in 360Z28! :read2:
What i'm finding mostly on the blogs is they are using wax to partially exclude
the bowl area and manifold surface then finishing those by hand.

 

[Petzschler]

sand content in the iron, thickness of the iron, too many variables involved to give it the ole' acid trip. I'm sure it could be done, but to do all 16 ports would be very labour intensive and if you had to send it out to do.. huge $$$'s. IMO get out the grinder and git it done. btw, petrolium jelly does alot better job of protecting areas of the port then wax does. but I have to ask, is there any particular reason you wanna go the acid route? back in the day alot of NHRA stocker guys where doing that, but they quickly found out that it was a unreliable way to gain et/mph. durability would also be a big problem for street use. just my drug induced opinion.
cheers

 

[moper]

Long, think of the acid as simply the paint on the engine.... It only makes it LOOK right. They are still hand ported first.

 

[mod38-1]

Acid porting is used a lot in racing where rules state no porting or head work other than that I do not know of any advantages

 

[longarm]

Moper,
I fully understand that the heads are ported by hand
and then acid solution used to cover the work to make
them look as untouched to pass visual inspections.
As I read the blogs and websites, some claim to have
new technics to control metal removal without hand grinding
execpt in the bowl and intake flange areas.

I can't see how it could be controled to this level so
I'm going to call BS.