VWDiesel.net The IDI, TDI, and mTDI source.
Engine Specific Info and Questions => IDI Engine => Topic started by: Jet A on August 19, 2008, 01:24:10 pm
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Got a call from the machine shop, stating two of my pre cups are cracked clear through. Need to find a good source for replacement. problem is, no one seems to make them or have them.
I came up with a solution...i think.
Why not make my own?
While i am at, why not upgrade the design?
Anyone attempted this? I have access to machines and tooling. Even a cnc if i really need it. Can this be done? What is the alloy, is there a better alloy for the job?
Looking for information pertaining to any or all of these questions
Thanks
DP
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Interesting for sure.
I had a link for a supplier, I think it must be on my home computer though.
Someone will post up for ya.
As for the material type, I'm not sure. I wonder if tool steel would be robust enough, stainless maybe? I know back in my Toyota diesel days there was a stainless replacement available for thier IDI engine.
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Interesting for sure.
I had a link for a supplier, I think it must be on my home computer though.
Someone will post up for ya.
As for the material type, I'm not sure. I wonder if tool steel would be robust enough, stainless maybe? I know back in my Toyota diesel days there was a stainless replacement available for thier IDI engine.
a link to a manufacture would rock.
Seems like the two metal expansions rates would seriously seize or cause the precup to fall out.
Regardless, i would rather buy them than make them.
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I know you guys don't have a vw shop around every corner like we do, but why not buy them from VW?
I get everything from them.. rusted bolt? for a buck, I'll have them from VW, no worries.
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Interesting for sure.
I had a link for a supplier, I think it must be on my home computer though.
Someone will post up for ya.
As for the material type, I'm not sure. I wonder if tool steel would be robust enough, stainless maybe? I know back in my Toyota diesel days there was a stainless replacement available for thier IDI engine.
My guess is Inconel
http://en.wikipedia.org/wiki/Inconel
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I know you guys don't have a vw shop around every corner like we do, but why not buy them from VW?
I get everything from them.. rusted bolt? for a buck, I'll have them from VW, no worries.
Cant buy them from VW. If you can...maybe you can get me a part number? Called my dealers, the said they are no longer avaliable. cant buy the head, cam, valves, nothin!
Inconel is good stuff, But i dont believe it does well in heat cycling, constantly being heated from 1400 to 600 would piss it off. This is just from memory...this could be 400 series stainless i am thinking of. Defintaly worth doing some research. Plus not setup to do that type of machining. I know for a fact that it gets work hardend something fierce.
But we will see....
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yea inconel is pretty hard... you'd need special tools to machine that :)
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sorry, too much part searches...
I know I saw them, just didn't remember where
Renault has them available on their parts program.
on the 1.6engine (F8M) there are two measures, 37.5 and 37.7mm (I don't have prices for that)
on the 1.9 engine (F8Q) only 37.5 and it costs 45€ each :O
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Here is the only place that I have found that still has pre-chambers, the only problem is that they are in Germany.
http://www.moto-szlif.pl/wirowe_de.htm
Give it a try.
Herman
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I remember hearing they were Inconel as well. What do you need them for, 1.6, 1.9?
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http://vwdiesel.net/phpBB/viewtopic.php?t=6987
Got that from a canadian wholesale parts supplier distibuter. Big one up there. Tried to get some a while back, they said they had them but would not sell across border.
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Have you looked up Prothe? He might sell them. Or Mike... sorry i don't remember his full screen name for you to look him up someone may pipe up though.
I know they sell ... everything i think between them
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I remember hearing they were Inconel as well. What do you need them for, 1.6, 1.9?
1.6
Here is the only place that I have found that still has pre-chambers, the only problem is that they are in Germany.
http://www.moto-szlif.pl/wirowe_de.htm
Give it a try.
Herman
looks like they have them. But...i dont read, or speak german.
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http://vwdiesel.net/phpBB/viewtopic.php?t=6987
Got that from a canadian wholesale parts supplier distibuter. Big one up there. Tried to get some a while back, they said they had them but would not sell across border.
thanks, I looked it up on ETKA, but the prechambers aren't on the picture.
my outdated soft says they cost about 14€ each from VW
I also searched for the 1.6 ones but no go :(
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I don't sell them either. I have no idea how you'd get them to stay in and trust them once they are out. My machine shop says they epoxy the ford truck ones in, but that's steel in cast iron, not aluminum like our setups.
FYI, many TD PC's I see have hairline cracks from heat, and as long as they aren't cracked all the way to the outside they are generally considered reusable. Though I always have them peened in anymore, just too many horror stories to take a risk.
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When I was going to try to sell an old head(no one bought it so it went for scrap) I had a loose PC on it. Using a press and a socket, I was able to expand it enough for a very tight fit. I did keep 3 of the PC's but they are 1.9 so wouldn't work in a 1.6.
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Mine has substantally cracking.
To much to risk the engine. Going to have the alloy analysed then try to get them turned. Getting test pieces made from 4041 today.
Still looking for a supplier.
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I was unable to find that link last night, The link posted earlier (in German) looks like the one I had as well.
There has to be someone on this board that speaks German so you could communicate with them.
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Actually ended up doing 2 in 4140 and 4 in 304ss. they are gunna be my test pieces. Once i get the hole correctly in place, i am going to have them cast in stellite...which is a chromium cobalt alloy. Havent got a firm price on casting, but sounds like approx $20 per piece
(http://i69.photobucket.com/albums/i44/petermandaniel/precombustor.jpg)
(http://i69.photobucket.com/albums/i44/petermandaniel/precombustor2.jpg)
(http://i69.photobucket.com/albums/i44/petermandaniel/precombustor3.jpg)
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this is a interesting topic, if you can make new inserts, why not make one that goes all the way, like including the roof.
having 3 holes, the stock transfer port, one for the plug, and another for the injector.
that would provide another thermal barrier, increasing the efficiency of the engine, am I right?
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this is a interesting topic, if you can make new inserts, why not make one that goes all the way, like including the roof.
having 3 holes, the stock transfer port, one for the plug, and another for the injector.
that would provide another thermal barrier, increasing the efficiency of the engine, am I right?
You lost me....
3 holes where? one in the top, one in the side and one in the bottom? I cant picture what your thinking.
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exactly, including the top part of the prechamber into the insert, probably the head would have to be machined to make some clearance.
EDIT: now that I visualized it in my mind, a ceramic upper insert would be better, so the air would heat by passing trough the transfer port (inconel would be hot) and there would be less thermal loss to the head material on the upper part (more than 50% of the prechamber surface)
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The prechamber is actually a two piece deal. The sweet graphics you did show the bottom half.
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The prechamber is actually a two piece deal. The sweet graphics you did show the bottom half.
To be honest i havent seen the upper half. Isnt it part of the head, as in not removable?
That is actually the same model i sent to 3d printer and the cnc machine.
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Also you may want to make some that are slightly oversized.
That way if stock size fits loose you can mill the hole slightly bigger and install the oversized chambers.
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To be honest i havent seen the upper half. Isnt it part of the head, as in not removable?
Yes, it is part of the head, I have a head that the pre chamber fell out of, I can get a pic if you want...
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it is in the vw design ;)
take a look at these Renault:
(http://naotefiques.no.sapo.pt/precham1.jpg)
(http://naotefiques.no.sapo.pt/precham2.jpg)
EDIT: just realised that as they are much bigger theres less chance that they fall into the cylinder as the VW ones do.
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Some aircraft engine builders I know use JB weld in an aluminum "head" to hold a stainless steel port tube in the coolant jacket of the combustion chamber (Mazda rotary). Since JB Weld is a thick epoxy, I would think your machine shop's approach is sound.
http://rotaryeng.net/Welded-steel-p-port.html
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Some aircraft engine builders I know use JB weld in an aluminum "head" to hold a stainless steel port tube in the coolant jacket of the combustion chamber (Mazda rotary). Since JB Weld is a thick epoxy, I would think your machine shop's approach is sound.
http://rotaryeng.net/Welded-steel-p-port.html
You lost me with this comment. What does JB weld have to do with a pre chamber?
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I don't sell them either. I have no idea how you'd get them to stay in and trust them once they are out. My machine shop says they epoxy the ford truck ones in, but that's steel in cast iron, not aluminum like our setups.
FYI, many TD PC's I see have hairline cracks from heat, and as long as they aren't cracked all the way to the outside they are generally considered reusable. Though I always have them peened in anymore, just too many horror stories to take a risk.
I guess ARB is quoting this, I guess applying some kind of glue that can whit stand the heat wont hurt.
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JB weld is rated to 600*F. I would not use it for the precup...
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I have built a mazda rotary for aircraft use (never made it to the plane though)...i have seen the jb used in the intake as a guide, but not in the reference u used.
In that case it sounds like it would only be heated to roughly 250 degress F. This is no wear near the 1400- 1800 degrees F that the precup see. I have no idea what these actually see, but i am betting its higher than the egt.
I like a slight interference, and peen them in place. They are not going to fall out when the head is seated. part of the cup rests on the block, its not all free hanging over the chamber.
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They don't have to fall out, only get loose enough to start hitting the piston. Ask me how I know. :cry:
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They don't have to fall out, only get loose enough to start hitting the piston. Ask me how I know. :cry:
After reading through several of the threads on here....i have come across many of your posts that have that last sentence in there. Sounds like you have a lot of life experiances on these motors!! :)
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They don't have to fall out, only get loose enough to start hitting the piston. Ask me how I know. :cry:
I have such a head/block in my yard too. :-/
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I have the opportunity to get one like that real cheap, might get it and try to stick the renault precups in there
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it is in the vw design ;)
take a look at these Renault:
(http://naotefiques.no.sapo.pt/precham1.jpg)
(http://naotefiques.no.sapo.pt/precham2.jpg)
EDIT: just realised that as they are much bigger theres less chance that they fall into the cylinder as the VW ones do.
I got the opportunity to get a Renault head apart so:
(http://naotefiques.no.sapo.pt/DSC01793.JPG)
(http://naotefiques.no.sapo.pt/DSC01794.JPG)
(http://naotefiques.no.sapo.pt/DSC01795.JPG)
these are the second design from the above drawings, they come with two sizes 37,5mm and 37,7mm if I remember correctly
BTW, these came from my 1.6D 55hp Express van, 240K km, the head looks new, no cracks, honing marks on cylinders :O and I can still see the markings on the piston tops, they look new!
but it has 11mm bolts.. so the block is cracked in about 20 places:(
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Actually ended up doing 2 in 4140 and 4 in 304ss. they are gunna be my test pieces. Once i get the hole correctly in place, i am going to have them cast in stellite...which is a chromium cobalt alloy. Havent got a firm price on casting, but sounds like approx $20 per piece
stellite ? I haven't seen that ancient metal for years. $20 each would be a very very good price. Cobalt being a strategic metal ( you can't make a jet engine without it and there are few places in the world to get it)
If you are looking at super alloys, look for something like HMS-1011, Inonel, or a similar Ni-Cr-Co alloy. The nickel and chrome are the bulk ( Ni 70% - 80%, Cr 10% - 15%, Co 5% - 7% as I recall when I was melting then for testing)