RyanPerrella

WTF are you talking about?

largecar379

Oh it was just a joke........there seems to have been a lawsuit threatened on another site.......(didn't have anything to do with me, but it did have something to do with a fellow Rennlist member....)

Man was that fire-y.....ouch.


back to my paint removal project.......

--Russ

RyanPerrella

So it was supposed to involve me? Why the hell did you quote one of my posts and then suggest lawsuit?

WTF are you getting at exactly? If it was a joke it doesnt make any sense to me, and I cant see how it would be funny? So what is the deal now?

BC

I have a five year old. I know how to handle this:

If there is a continuation in this thread of off-topic conversation, baiting, or general cattiness, I will close it, and only open it when someone personally PMs me about actual pictures of ported 928 heads, or info about them. You will also not get to go to the ice cream parlor after dinner.

cobalt

Didn't read through the entire thread as it got off topic, however it was noted earlier that someone was impressed by the quality of the castings.

From my perspective Porsche castings especially the ones in the pictures are not great.

There is no evidence of porosity or defects and it is good clean metal, however they clearly used old green sand technology (water based sand) vs a petrobond based sand. Surface finish is horrific for a sand casting IMO. There was obviously no time spent cleaning these parts either. A simple cleaning prior to machining would have made sense IMO. The cored passages are incredibly rough and simply shell coating the cores prior to placing them in the mold could have smoothed the surface considerably there was also little time put into cleaning the cores which could have eliminated much of the flash and other parting lines that could have easily been avoided.

I am not talking about new improvements in a 3000 year old process most of what I mentioned has been around since the 30's. I have a number of older Ferrari engine block halves in my metal scrap room. I remelt and use the material on commercial work and the quality is superior to what I see here. If Ferrari new enough to put the extra effort out why didn't Porsche?

I was recently asked to look into manufacturing a replacement intake manifold for a 935. Rather large Magnesium sand casting. The casting is nicely made however it too exhibits horrendous surface roughness that could have easily been reduced or avoided prior to machining.

I guess at some point Porsche decided the cost associated with the little extra work involved was not cost effective however they could have extracted more from their engines if they would have taken it the extra step.

Just my .02.

JEC_31

(Forewarning: thinking-out-loud / blue-sky / wayyyy-out-of-the-the box / thread hijack ideas to follow...)

Has anybody ever asked you to look into the cost of manufacturing custom high-performance heads for the 928? Just to make a short run of them, someone else would tackle the planet-sized amount of R&D and engineering necessary to provide you with a design.

cobalt

Nope.

I actually haven't been taking on any new jobs because I am so busy right now. This is a special favor for a friend. Although I have been thinking about doing more of this type of work because it is more gratifying. I recently made some magnesium steering racks and replacement parts for a friends ALFA TYPO 33/3 the car that won the Targa Florio. However, I only manufacture castings. I can direct you to some competent machine shops and that becomes an entirely different expense. Pics of the housing in yellow is one my parts. I included the 935 pic too. I know most of you guys are not 911 fans but the technology for the time was amazing. Titanium springs, magnesium castings for most parts and every bit of metal on the 911 shell not needed was drilled to reduce weight. What incredible machines these were and from what I am told effortless to drive.

Of course short runs are never cheap and one offs, Ouch, can be devastatingly expensive. The cost of the tooling for the 935 intake could exceed $8k. Casting cost is in the neighborhood of $1500 each including heat treatment, this does not include machining or any inserts etc. although this is a monstrously large intake. I would need to know what material, size, weight and configuration to quote. So I have no idea what it would cost without specifics.

BC

So you are saying it doesn't look like it was on purpose.

cobalt

I am assuming your referring to the surface finish. No. It is a product of the process they chose to use. Whatever foundry Porsche contracted to make the parts did a very nice job however the process yields a rough surface finish. More than likely jobbed out to the lowest bidder. Nothing wrong with it. Auto manufacturers have learned a lot over the years. Just like using SS for exhaust systems and plastic intakes with smoother wall finish for a lot less $$.

BC

Thanks. I guess I should figure out what the proper surface SHOULD be for the intake. I understand the exhaust should be much smoother. There was some info earlier about what sand scrolls to use.

JEC_31

Thanks for the info, and that 935 is one hell of a racing machine. Congrats on being able to say you contributed to it!

Hmmm, $$$$.... perhaps we should stick to Brendan's original topic and concentrate on improving OEM heads.

End thread hijack.

RyanPerrella

There was a great show on the national geographic channel that went inside the Ferrari factory and covered a cars production from the foundry to the finish line.

Some things I found interesting were that they did clean up their sand casting molds before pouring them. The sand casting's are made from a die and when the die seperates it leaves a pretty common ridge around where the two plate halves meet. Ferrari takes this part and uses a die grinder and removes it from the sand mold which is incredibly easy before pouring aluminum into it. Machining the aluminum would be more work so they eliminate the problem at the easiest step, when working with sand.

I have to think that its overlooked by other makes because it seems to be a hand done process. The sand cores are probably too fragile to be handled by robots and there would be so many castings that they couldnt keep up. That and most engine blocks for Porsche , BMW, and so on are made off site by someone else. Ferrari has their own foundry and produces their own blocks and heads. Its also good that they have very good quality control. Something i think you can do when you only make 5000 cars a year.

RyanPerrella

I still think someone should invest in a CNC program and the CFD programing which would no doubt give you huge results if improvements can be made. CFD is far superior to a flow bench as it takes so many more things into account then JUST airflow through the port.

Again its expensive, we need a John Speake who knows CFD and has a 5 axis machine and can write a program because they want to, not just because they want to make money off it. If i ever win the lottery, I think I would invest in the milling machine and the CFD stuff (which is the REAL benefit here) and create a program to get it all taken care of. Good luck though, i dont ever play the lottery.......sorry.

blown 87

What is CFD?

RyanPerrella

Computational Fluid Dynamics

Its a type of computer simulation that can calculate airflow and make adjustments and it can show potential hot spots in a modified head and how to correct them as well. (It does much more then just that) Its pretty commonplace in most autoracing, its pretty much de-rigeor in F1 for EVERYTHING, from head design to brake ducting and everything in between and even Edelbrock is using it now in their head design and manufacturing.