333pg333

Block looks a little different to when we last saw it!

blown 944

Looking forward to this.

I especially like the crank and rod selection... Lol.

I hope it is all you want from it.

Are those flanged sleeves? I'm guessing yes.

refresh951

Those parts are absolutely stunning!

A few questions:

1) Will the build be non-interference?
2) What was the final max run-out on the crank? Did the crank have to be straightened again after nitride?
3) Did you coat the ACL Race bearings?
4) Will the build have a deck plate?

Duke

Not a bad kombination of crank/rod sizes that you came up with We took a look at the full Carrillo range and came up with a few suitable setups and finally decided on the Evo combo. For an N/A build there is some suitable Honda rods.

Yes flanged sleeves.

As we've discussed on FB this setup is what I feel is the best compromise between displacement and ability for high rpms and thick enough cylinders not to worry at high hp. Especially now with the dry sump. Who knows, I might go crazy and do solid lifters and 8000 rpm sometimes in the future...!

Duke

Thanks Shawn!

1. We have not designed the pistons with this in mind. Similar valve pockets as stock.
2. I don't have this spec written down. The shop assembled the crank and did some measurements after the crank was done and concluded it was fine. It was then balanced as the final touch.
3. No. I had the bearings coated in my last 3.0l 16v turbo and that damn 2nd rod bearing went south anyway
These bearings should be much better than the stock ones and being a race engine it won't see many miles in 1 season. Will most likely replace the bearings every season just to be sure.
4. No deckplate. The siameseed block, the large head studs and the pinned girdle should be plenty stable. Had no issues at 514 rwhp with this setup in the past. (But a deckplate wouldn't hurt though!)

Duke

So folks! I got handy with the scale yesterday for your technical viewing pleasure

Pistons:
* stock 968
* Wössner 104.5 mm 9.5:1 CR 16 turbo
* JE 104.15 mm 8.9:1 CR 16 turbo

Rods:
* stock 968
* Pauter
* Carrillo for Mitsu Evo






Wössner VS heavy duty JE piston pin



Stock


Wössner


JE (minus rings)




Stock 968 rod minus 1 rod bolt


Pauter 944/968


Carrillo Mitsu Evo

Duke

My conclusions regarding the weights.

* Stock is heavy stuff and should be replaced in any build regardless of turbo or N/A.
* The JE piston have less skirt than the Wössner than in turn have less skirt than stock = less friction. (As long as it is enough)
* The JE piston is the lightest of the bunch but with a heavier more robust piston pin.
* The Carrillo rods are surprisingly light, partly is probably due to the smaller big end.

All in all the new combination of JE piston and Carrillo rod is about 35% lighter than the stock combination.

Thom

What difference should using (slightly) smaller big end and piston pin diameters make, if any significant one?

Did you go for std length 150mm EVO rods or rather 156mm rods in order to maintain a smilar rod ratio as before?

Duke

I also measured my crank and compared to a stock S2 crank I have.
Turns out the information in the wind that the 968 crank is lighter is incorrect.
My worked crank was 23.5 kg.
The stock S2 was 25.1 kg.

Considering the turned journals and the minor lightening I'd say the cranks are about the same weight.

Duke

Difference compard to stock or to this setup?

Standard 150 mm. Not sure as long as 156 mm would have been possible with the pistons. A high CR N/A pistons would probably work fine.

Thom

Yes, difference compared with stock.
Rod ratio on a 3L using stock parts is 1.70, will be 1.65 here. You would have got 1.71 with 156mm rods and 91mm of stroke.
It wasn't clear to me if your new pistons were custom to the point of featuring a slightly higher pin bore.

Duke

The pistons are custom. Just looking at my own pics I can't see how the piston pin could sit 6 mm higher. But with less dome and another ring config it should be possible to spec out an N/A pistons for this.
A few mm's higher rod would have worked but that would have meant custom rods too. I don't think this is a path that would have given any real life benfitis to persue.

Duke

The 104 blocks are siamesed this way from the factory. The floor is also higher up so there is less of the pistons that are free standing compared to a 100 mm block.

333pg333

That's a big reduction in the reciprocating mass. Should just zing through the gears.

Ernie J

How come you didnt go to 106mm?