2.8SS build on 3.0 turbo engine - questions

[rennzeit]

Lookin at the old pics make you want get back in the track?

[vinyl_tien]

Is there any one build a 2.8SS plus turbo before ??

[rennzeit]

Isn't that what's in a 962?

[Henry Schmidt]

Originally Posted by vinyl_tien

Is there any one build a 2.8SS plus turbo before ??

The 959 is a 2.8 SS sequential, twin turbo . They are 95mm bore and 67mm stroke.

[914/6]

77 turbo may not have a 6 bolt crank ????? Euro ? If not he will need your crank Henry ??

[rennzeit]

That's the magic of the 76 and 77 turbo (and Carrera 3.0) cases: it's the beefy aluminum design of the SC, except it still uses the 6 bolt crank from the 2.4-2.7. So you can "drop-in" a 66mm crank minus various caveats as pointed out by Walt. It has the oil bypass mod, doesn't require timeserts, etc. But there are only ~5000 of these produced worldwide, so...

Henry's crank is definitely the way to go if you already have a 9-bolt case. I was saving my scheckles for one of those eventually, but I lucked into this engine. So I can spend that dough getting the rest of the bits up to snuff to handle the revs this thing will enjoy.

[vinyl_tien]

I have a 3.0 turbo engine, it is going to rebuild, after reading this forum, it really help me and make me thinking, what if I made a 2.8SS with 0.5 bar turbo charge, can I still use CIS fuel system? My goal is made 400 Hps and put on my shorten bell house 930 trans then put into a 73 911.

[Walt Fricke]

Dug

Kevin described the method in more detail than I could. Craig had decided that bushings were going to be better in some way than pins, and came up with his "use an old case as a jig" approach, through which he worked out kinks like sizes, and the all important business of not blocking any oiling holes.

The machinist who had done this to a couple of my motors did so because he distrusted the accuracy of what he called "indicating." I take that to be machinist speak for getting the holes on one side exactly lined up with the holes on the other side. One way of doing this with mating parts like our cases is to bore the holes in one side and insert indicating tools - rods with a sharp pointy end right in the center, which just stick out a little. Then you carefully clamp the halves together, and take them apart. You have nice center punch like marks on the other case half, which you use to drill holes on that side. He thought that wasn't accurate enough, and in any case the slight misalignments were going to make the case halves hard to pry apart when you had to tear such a motor down.

I have no idea how right he was about that, but he knew a lot more than me. Maybe with CNC machines you can get things under a ten thousandth of an inch without any of this old school indicating. Lots of pin type shuffle pinned motors out there. I had one. Wasn't hard to pull apart (though it had blown up and nearly sawed one side in half, which may have made things easier in that regard). I wondered for a long time just how he had been able to go in through a hole which was X wide, and then bore something way down that hole X+Y wide. Then I took a really good look at a damaged case (another rod getting loose) I had kept for no particular reason, and saw the plugs in all the throughbolt holes on one side. Aha.

I think this is an uncommon approach largely because shops which have been doing things one way for a long time, and not having or perceiving problems with it, are not inclined to change. Most of us are kind of that way with at least something.

But I like the idea that this process is exact without anything special in the way of tooling if you are a machine shop with the usual stuff but pre-CNC and electronic digital controls.

And I have no idea about a cost differential. Craig may have no interest in doing traditional shuffle pins. He's got this bushing approach wired. So maybe you'd have to ask your usual machinist suspects. Kevin's description might be all they'd need to come up with a price.

[rennzeit]

Kevin and Walt,

Thank you so much for the extra detail on the machining process. I literally noticed the "blind-hole spotter sets" in the Grizzly catalog last night and wondered if that is how you would mark the case in order to add shuffle pins. Sounds like it is something along those lines. I can see how that wouldn't necessarily be perfect and why a line bore even on an aluminum case might be recommended after installing shuffle-pins. And I can see how the shuffle-sleave method described could eliminate that requirement.

I am a software engineer, but I love machining and obviously anything having to do with understanding my engine more. I'm no where near ready to jig up my own case halves to shuffle-pin or sleave them myself, but I am in the process of machining the first parts of my own design on the CNC mill thanks to the miracle of Techshop. The more machining I do, the deeper my interest gets.

cheers,
dug

[rennzeit]

It's up on the stand now...

[Walt Fricke]

Dug - along the way you can put your design skills to work figuring out how to make inserts which will remove those grooves in the intake port so prominent in your picture. Needed for the CIS injectors, but seldom if ever for aftermarket EFI and never for carbs.

Unless it is purely serendipitous, they pretty much have to disturb the intake air flow in unhelpful ways.

I know some weld them up and rebore the port. Got to be a bit tricky - an interrupted cut? And I don't much like the idea of welding here, though if I knew more maybe I'd realize not a big deal. But overall ought to be better if avoidable.

I'm thinking that you could fasten an insert in place with a small allen bolt, whose head ends up flush with the ID of the port. Could epoxy or otherwise seal in place, and that would make exact match to the cast surface a non-issue pretty much, but the bolt would insure it couldn't fall into the engine no matter what. How inexpensively to make such an insert? Could it be a plastic instead of aluminum?

[914/6]

welding the CIS notch is no big deal, past that welding most anywhere else kills the temper..

[vinyl_tien]

Hi
Can I use 914/6 crank to build 2.8SS with turbo case?

[rennzeit]

I dont think you want to use the non-counterweighted cast crank to rev that high. The E and S crank is forged. I've read some people like the T crank to get the engine to spin up quickly due to the lower rotating mass, but I dont think they are revving as high.

[rennzeit]

After dremmelling off the one stubborn exhaust nut, I was finally able to teardown the top end of this beast.

Type 930/52 - 1977 3.0 turbo - the aluminum case that fits the 66mm 6 bolt cranks
Pistons will be for sale in case anyone is looking for some.
Cylinders are nikasil, I'll keep those for my build.
How do I determine if honing or replating is required?

[rennzeit]

Cams are 4 bearing with 49mm journals, but cam housings have 901 part number.
Cams will be for sale, but there is some pitting in a couple of lobes.

[rennzeit]

Are these heads all the better turbo alloy?
All six have 1926f casting code.

5 are matching:
5/76 date stamp (one 4/76)
930.104.341.2R
Y on upper right

1 has been replaced:
2/78 date stamp
930.104.341.3R
RR350 in upper right

[rennzeit]

I will be selling these heads too since I already found a nice set of built up twin-plug heads. What's a fair price for turbo heads? There's not much in the parts forum to compare to.

Hopefully an update about cracking the case open will not take as long as this last update.

cheers,
dug