Advice On My Head

[D_Stirls]

I'm building a CA18DET and have had a machinist here in SA do all the machining including the head.

The head that i gave them had some Det' damage on the quench pads on the exhaust side. When i gave them the head i asked them to take the damaged area out as there were a lot of sharp point and I though that there was a risk that it could cause Det' had it been left as it was.

When i picked up the head they hadn't removed the area so i left it with them to fix up and came back later. The second time it had been done and collected the head.

I'm just at the point of finishing putting the engine together and i have noticed that when they removed the damaged area thay haven't taken the valves out and they have touched the exhaust valves with the grinder.

I was wondering whether the exhaust valves are coated and or whether the marked exhaust valves will cause a hotspot and the issues that come with that.

P.S. The plans for the engine are ~300kw using a Twin Scroll GTX3071R.

I also supplied the guides and the Valve Stem Seals to go in the head, i was wondering if it was common practise to do the porting after the new guides are installed in the head?

Edited December 13, 2010 by D_Stirls

[luvpsi]

i dont think they are coated as long as the valve is sealing properly on the seats should be fne but i see where you are coming from. i used to be a engine rebuilder and we used to touch up the edges with a special valve grinder so no they are not coated and heat sould be fine

[SimonR32]

That is pretty average workmanship...

PS. Why didn't you just go get a undetonated CA head, someone would have probably paid you to take it away!

[D_Stirls]

The best of the 3 head that I have i kept to use as a solid head if i decide to setup up a solid head down the track.

As for swapping this head for another this head has cost me $1100 for the machining/porting +$250 for parts so that isn't financially an option anymore.

[zebra]

Why did they even have the valve guides in there if they were attacking it with a die?

I would keep those pictures as evidence incase a valve guide fails or a valve burns

[STATUS]

punch your tuner for the DET damage

the head looks fine now, those valves should give you no dramas. will be interesting without the quench pads, some engine det like hell without them others love it, so let me know how you go.

[D_Stirls]

Thanks Trent, reassuring to know.

The doner engine was a standard engine that still had a side mount intercooler and was running a SR T25G. The boost was wound up to 14 PSI (untuned) and the car was flogged (by me, so i should punch myself in the throat). I had a spare engine that was in very good condition where as this engine was well tired (120psi compression) so i flogged it until it did a HG and then put in the good engine. The good engine was the one that i just pulled out (made 217kw) and i pulled it out because i didn't want to push it any further as it's still in good condition.

The SXOC (British 200SX forum) guys quite often take the quench pads out on the CA's just as a matter of course in their big power builds so, i think it will be fine in terms of then being removed. Personally I would leave them in except for the fact that there would have been issues in this case as there were a lot of sharp points in the damage which would have been propagation areas for sure.

I'll will post up the results once the GTX3071R goes on. Initially it'll be run with the current turbo (GT2871R) and some HKS 264x9.0 cams but in March/April i'll put the new turbo on with E85 and i'll be using a Haltech E8 for the ECU.

Edited December 13, 2010 by D_Stirls