550 Spyder "4 cam"-like engine build up **NEW UPDA

[AirBus]

Hi great project.

Have you see this site?

http://www.apfelbeck.nl/

Regards, Udo
_________________
VW T1 1964 - Mouse Grey - Pearl White

Bagged, Porsche steeringrack/brakes..IRS, T1 1915cc

[M-Owen]

Hey Turk are you out there still???

[marzano]

[M-Owen]

I have never seen an operating engine with the Apfelback heads but I have seen several engines with porsche 911 heads and cams such as the one I am building as well as the Russ Fellows Drag Car.

[TurkTurk]

Hello all, after a long hiadus from this project, I have returned to continue work on it. I imagine that you all thought it went the way of the dodo bird. I have been very busy, moving into a new place, purchasing a new car (99' Porsche 911!) and settling in. Here is an update:

I have contacted a custom camshaft manufacteur who will design the intake and exhaust profiles for me. Their process is OEM quality, I'll have to ship them a completed cylinder head, the power curve that I would like (which I conveintly have from my 1500 GS manual) the cfm of the heads ect. This is a huge step that I am more than happy to pay the money for to have completed. I've chosen to use hydraulic tappets so that the camshaft can run directly on top with zero valve clearance. Designing to this specification will be much easier than designing with a push-rocker in between the cam lobe and valve spring as in the original engine.

Anybody think this isn't a good idea? The most difficult part of using hydraulic lifters is oiling them. There are a ton of oiling requirments in these heads as there's three shafts anyway.

[Jake Raby]

[TurkTurk]

Haha, yeah seriously. I've got a fair feeling that I'll be alright for a while. While not the pinnacle of Porsche engine design, you have to admit, its a sweet little engine especially listening to it wail at 6500 rpm out of a turn.

[M-Owen]

Hey Turk, What a pleasant suprise to see a post of your project. I was wondering if you were still working on it. I started the machining on my engine but since it's not top priorty things happen slowly. Congrats on th new 911, I have a 2000 996 Cab and I love it for everyday use however I would never trade any of my aircooled 911's for it. Please enjoy it, for the most part you should not have many problems just keep an eye on the heads for leaks. This is why I got rid of my 99, but it does go like the dickens and it's hard to break loose. I will attempt to post pics of my cam towers they were done yesterday

[TurkTurk]

Yeah, I love the car. I purchased it in the suggested range 50-60,000 miles for a bargain. Just had the 60K done and my mechanic says everything looks good. It is an absolute blast to drive.
Glad to hear you're moving along with your project, definitely post pictures of the pieces.
I actually just bought some Pauter type 4 rods from Jake for a great price, looking forward to getting those. Right now, I'm focusing on building the mock up of the short block so that includes: case, case machining for relocated cylinder studs, crank, bearings, rods, pistons, cylinders. I'm sending my cylinders to LN engineering to have them overbored to 85mm from 84mm. Also, I'll be purchasing custom JE pistons with dome tops, valve reliefs, relocated pin height ect. Once this is all assembled, I'll be able to work on the valve train from the case outward and from the heads inward simultaneously.
I'll post pictures soon.

[M-Owen]

I forgot to tell you that I went with a water cooled case and cut the water jackets off, this allowed me to maintain the 118 Center to Center 911 Cam tower. I am having plates made to take advantage of the 3mm offset of the type 1 rod. I am getting my cylinders to Charles one day to have bored and plated, Like I said slow motion these days.

[TurkTurk]

That's a pretty good idea actually. I remember reading an article in hot vws I beleive about utilizing a water-cooled case, cutting off the jackets, and using it as an air cooled one. Post some pictures! I had thought about working with Charles on some custom cylinders, that way I didn't have to make spacers, deal with head stud location issues ect. Plus I'd have all-alloy/nickasil cylinders. I just couldn't justify the nearly $2000 additional cost on an "experimental" engine.

[TurkTurk]

Jake,

How did the original engines get oil pressurized into the heads for the camshafts?

[M-Owen]

Hey Turk,

I am pretty sure the cams on the furman engine recieved their oil via internal ports. If you are still using 911 heads with a custom cam towers you might want to consider external oiling like porsche did with the 908.

[Jake Raby]

I'd feed the oil via a -4 AN hose from the main oil galley... I do this on my engines in some instances.
_________________
Jake Raby
Raby Engine Development
www.rabyenginedevelopment.com
"I've never given anyone Hell, I just told them the truth and they thought it was Hell"

[TurkTurk]

Yeah, that's what I was planning on doing, running an An line through a pushrod tube into the cylinder head. Not only will this protect the line, but it'll look more "factory" and less "race-car". Also, Im currently working on getting data for the buck I'll be building for the aluminum body. A fellow here in Atlanta has original body panels form a 550 (most important being the rear clam shell) as well as fiberglass molds from an original car. I'll use a contour gauge and a hell of a lot of time to build an accurate buck from which to make the body. Bought another Carrera assembly manual, this one being more detailed with lots of info on bearings retainers, checking and adjusting backlash ect. Moving along..

[TurkTurk]

An update to the project:

I've acquired more engine components. My first major priority is to mock up the short-block minus the layshaft and internal bevel gears. I beleive I've finally settled on the supplier for the spiral bevel gears, its hard to come by a company that keeps the correct size in stock. I've purchased a set of really nice stock length (5.000) in. Pauter connecting rods from Jake. Those will be sent promptly to Pauter to be re-bushed for use with 85mm JE 911 pistons that are set up to run 10:1, perfect for dual plug.
On an interesting note, I've decided to use Hydraulic tappets from a Ford 4L DOHC cam engine. I've done a basic mock-up of it below. I'm doing this for several reasons: the hydraulic lifter will allow me to design for zero tolerance between the lifter and cam. It makes things simpler when designing the cylinder head camshaft retainers. Furthermore, and more importantly, the camshafts will not be asymmetrical and wont have to have those funny flywheels on their ends.

What is an asymmetric cam and why did Porsche use them? An asymmetric cam, as described below in Porsche's own literature ( a Carrera Engine manual), is a camshaft where the shape of intake curve is not the same as the shape of the exhaust curve, they are "asymmetrical". This was specifically employed because of the use of theactuators used between the valve and cam lobe. As you can see, and as it is described in the manual, the cam lobe does not run on a constant surface relative to the lobe surface and therefore the timing must be different for each part of the cycle. This isnt' an issue on flat-tappet systems like those seen on most cars because the cam lobe is faced with a flat and therefore constant-curved surface throughout a full rotation. Anyway, using a hydraulic lifter does away with that and all I have to worry about is getting oil too it, which is already a design parameter stimulated by camshafts,bearings, and gears in the head.

Lastly, I was reading some literature on the Porsche 959's engine today. The 959 engine used an aircooled block and cylinders and watercooled heads so that 4-valves per cylinder could be employed (the whole reason for watercooling in the 996-forward 911 iterations). That got me thinking how cool it would be to use a 993 block with 996 heads, twin kk turbos, ect to create a "replica 959 engine" in the same spirit as this one. Anyone want to see THAT tackled after this? Interesting note: the 996 turbo/GT3/GT2 actually use a similar configuration. Their internals are essentially 993 items with water-cooled cylinder jackets and 996 watercooled heads. Once I get a little time off this upcoming holiday, I'll be able to start posting pictures of hardware mock-up. That's when it will get exciting.

[M-Owen]

If I haven't told you how impessive your project is ...

[Stuggi]

This is just insane, just the hobby I want to be doing after my engineering exam (I'm enrolled onto Finlands best mechanical engineer program). Keep up the good work!
_________________
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1969 Panelvan

Orange VW Fest!
Pulled out of a Lake Fest!

[TurkTurk]

I appreciate the compliments, here are a few pictures of my newly designed camshaft retainer. Im having the cylinder spacers machined this weekend, I'll post pictures of having those machined and inserted/bonded in. One of the retainers is "cleared" to see the spring-lifter assembly. A design choice that I made was the split the two retainers. I did this for a specific reason and it relates to an engineering concept known as constrain-theory. It is obvious that under-constraining a component means that it will move where ever it wants under load. For instance, if your crankshaft only had one half of the crankcase to sit in, it would be under constrained and would simply fall out of the case. Just as poor a design is known as over-constrained. This is when too many constraints are put on a component and two many variables effect accuracy of alignment ect. If I had designed the retainers as one unit that held both lifters and both camshafts, the accuracy and precision of the lifter bores would be affected by the forces on the camshaft and vice versa. By separating the whole assembly into four distinct units, the precision of the lifter bore is not affected by the camshaft and the camshaft concentric to its bearing wont be dependent on extenuating forces of the lifter,springs, expansion, bolts ect. Because the camshaft and gear assembly isnt connected to the lifter, neither should their mountings. However, the parts will have several "alignment" slots or pins that keep them true in relation to each other, they just wont be a singular piece. So, the camshafts and gears will be a single unit on each head and each lifter-retainer pair will be one unit, the two bolted together on the cylinder heads.

[M-Owen]

That looks like it will work. What did you decide to do about oiling?