B18/B20 Combustion chamber welding??

[78civic]

After reading on Endynes' site of the filling in (welding) in the chamber to raise compression.

What do you guys think of removing the seats by heating the head enough to loosen them, then welding up, then heat treating back to spec after re-installing the seats.

Just a thought. Probably cheaper to have custom rods/pistons and a block guard to raise comp instead.

E

 

[SlushboxTeggy]

HMT has a tech article about welding up the champers on a D-series. A6 if I'm not mistaken. Welding a head is extremely difficult though. Not only is it aluminum, but it sweats.

 

[78civic]

Yeah, I've welded alum before. But like cast iron on thick sections or large pieces, you should use a heat stick/marker to get it up to temp then you can get to weldin, and it 'flows' alot better. And if you use a MIG, you don't get that much 'glass' to grind off.

I wanted to do this years ago to the EW 12 valve heads but then the D16a1 piston was tons cheaper to raise comp.

Now that I'm thinking of it, there really isn't much room to 'fill in' around the valves anyhow without shrouding them..

Nevermind.. E

 

[K2e2vin]

Most people just weld in quench pads. You don't really want to weld around the valves since it'll just shroud the valves.

Biggest issue with welding the head is the head warping.

 

[78civic]

OK, I just had an kinda obvious Idea.. What about sticking with the B18 head on the B20 block and that would give you about (theoretical)1.5mm extra around the circumference of the c-chamber right? Now that being said, you should be able to do lots of un-shrouding of the chamber and use the B20 head gasket.
I wonder how much you could dig out around the valves??

I'll have to take some pics of the b18 head from the crank end of the cyl and scribe it. I'll ask my son if he can get his little hands in there.

I know that now i'm changing the topic toward increasing the c-chamber but then there would be more room to weld..

E

 

[K2e2vin]

B20 already has the same head as B20A/Bs; the circumference of the B20A head is 81mm.

 

[Controlled Confusion]

you are better off miling the head

 

[78civic]

I'd really not mill the head too much, it retards the cam timing and could lead to premature crackin. Especially if you get too close to those little 'nubs'.

Just last week my machine shop buddy gave me some high domed pistons that someone dropped off and never picked up for months.
They are coated on the skirts but I don't know if it will raise the comp too much with the B18 head.
I took the rings off and it slid in the B18 block nicely, with little resistance.

I need to put them side by side and take a pic. I don't have the barretts or know how to measure the volume of the dome with it pokin out the top of the bore.
I wonder how much could be milled off the crown of the piston??

E

 

[Magana559]

I'd really not mill the head too much, it retards the cam timing and could lead to premature crackin. Especially if you get too close to those little 'nubs'.

Just last week my machine shop buddy gave me some high domed pistons that someone dropped off and never picked up for months.
They are coated on the skirts but I don't know if it will raise the comp too much with the B18 head.
I took the rings off and it slid in the B18 block nicely, with little resistance.

I need to put them side by side and take a pic. I don't have the barretts or know how to measure the volume of the dome with it pokin out the top of the bore.
I wonder how much could be milled off the crown of the piston??

E

Just because they slide in dosent mean they are perfect, your piston to wall clearance should be at OEM specs or of the piston! if not, you will destroy the walls and skirts if they are too tight, if they are too lose you will get way too much blowby and destroy your engine. No good machine shop should bore and hone your block without the pistons your going to use.