The_Remora

Was the crank for this new 6.5 liter "drilled like a Chevy"?

Vilhuer

It has to be. Check angle those oil holes are pointing in crank pic.

mark kibort

Well Folks, the engine has arrived!

I just saw and touched it for a minute, just before CT automotive closed up shop. It looks great. Nice job on the packaging Tim! very professional, in its own crate and everything.

One of the engine guys at the shop was pushing on the pistons , and they actually moved, top to bottom. I thougth 928 engine tollerances were .001, or is that only on the sides? I guess there is some expansion rate of the pistons that closes up that gap, but how different is that from the stock mahle pistons?

Anyway, I was going to post pictures, but it doesn look any different than it looked when it left Green Bay! But, the crate might be worth posting!

Now, its time to think about when the engine will go in.

Thanks for the offer of help Nor Cal 928'ers! Maybe we can do that when its all together and ready to plug in. Or, if anyone wants to help with the transfer of the parts from the Holbert engine to the new stroker engine, let me know.
Im pretty curious as to what is in that "stock" block.

mk

atb

The .001 (actually .0008?) tolerance is for the oem pistons. Aftermarket domestics (yours are C/A's?) usually run a .0025 min clearance.

Bill Ball

Mark: Let me know when you are ready to start work. I'm kinda booked until after the 18th of May.

mark kibort

I think the top secret game plan is to put the engine in after the 3 race Thunderhill SCCA weekend at the end of May. THEN, i have a month to get the new engine in , dyno check, and broken in before the next race in late June.

hacker-pschorr

Fixed that for yea

How did you like the stickers?

mark kibort

so is this due to the JE piston material used (non forged i imagine)?

I would imagine that the stock piston has an expansion rate that matches the block and thats why they can be so tight, so are the JE's made from aluminum that expands more?

There was some pretty decent movement up and down (kind of a click click up and down when you pushed on the piston ) what is the gap at that part of the piston if the .025" is measured at the side skirt area of the piston and cylinders?

my old question is that i still dont understand why there is a differnce in tollerance with the S4 motors and the 4.7s. (.001 vs .0008")

mk

atb

I believe this is correct, the domestic pistons expand at a higher rate then the OEM's, although I don't think the issue is whether or not they're forged, its just composition. For example aren't the Mahle 968 pistons cast and the KB 968 pistons forged?

I'm not sure what you mean by "up and down" movement, I tend to relate that kind of motion relative to the movement of the piston stroke. Do you mean the piston moves fore and aft in the bore, or maybe side to side against the inboard and outboard cylinder surfaces? Somebody get me a compass.

One thing that I have noticed is that the domestic aftermarket pistons have a significantly smaller diameter around the piston crown where the ring lands are compared to the diameter at the skirt.

On the S4 vs. 4.7L, maybe since the pistons are larger, the gross expansion is more requiring a larger piston/wall clearance. Just a guess.

Bill Ball

OK, right after the end of May is good. We'll have a party. Details later.

mark kibort

up and down meaning if you push on the top and bottom of the pistons. (not the skirt side) i feel the movement. I dont think you could get side to side movement, due to the action of the wrist pin in the piston.

even though the piston tops are slightly smaller diameter, you would think that there would be a tighter tollerance on the tops and bottoms ( not the skirt side)
anyway, I think Tim mentioned that the pistons are forged, and ive heard your explanation before, about the materials expanding more for domestic pistons.

I thought the same thing on the S4 vs 4.7s, but the ratio doesnt match the difference in bore diameters. ie 97mm vs 100mm.

Im sure its ok, but im just curious

any other thoughts there??

mk

svp928

Mark, your pistons are shorter in overall height, so, the piston can rock back and forth over the wristpin more than the stock ones. This is also why the diameter around the ring lands is smaller than stock- they don't want that part of the piston to touch the bore.

mspiegle

Wow! It's awesome to see so much progress on this! I'll be waiting for the videos - especially commentary from the other cars who will be behind you

AO

Mark- Don't forget... there are a lot of us who have a stake in this too!

mark kibort

I could never forget that!

Its pretty exciting! The engine looks great. Just pulled it from the nice box that Tim used. one of the best engine packing jobs ive seen! Ill post some shots tonight. (if you are into that kind of thing) perfect timing too. we have to ship Scots 4.7 to a lucky recipient, and this box will come in handy.

Put a mic on the cylinders and they look to be 103.7mm. the tops of the piston look to be near 1mm narrower, but that's a ball park (ie .039")

Hey, whatever they are supposed to be, Im sure they are. Im just curious as to what the specs are and why the differences from the stock 928 stuff . (and trade offs)

Again, MANY THANKS to the listers that made all this possible. We have to talk about how we get all the names on the car too!!

If i can get this thing together before the summer Laguna race, and not miss a race, it will be interesting to see the reaction of the other guys in ITE as we come off turn 11 at Laguna!

mk