V2Rocket

I like that Honda process - have seen it a few times too.
Wouldn't worry too much about lower cylinder temps but if you wanted, it'd be a good time to add piston squirters and a BF-oil cooler.

Subaru guys "pin" their open-deck blocks to secure the cylinder bores to the outer case walls...seems to work OK for them.

Auto_Werks 3.6

I assume you mean 350 wheel HP? .... asking for a friend

Dave W.

I just used strong dish soap and a wire brush to remove any stains or scale from the walls of the water jacket. It was one of the tips I read on YellowBullet forums.
I wanted the filler to adhere to the walls of the water jacket as much as possible.

blade7

Barry Hart of Hartech has stated that several S2 engines he's stripped have shown evidence of piston pickup at the bottom of the cylinders. With the tight clearances perhaps that's one of the reasons Porsche fitted squirters to the 968 block.

Dave W.

That's why it's recommended to run greater PTW clearance on any half filled block- it'll run hotter.
Basically, heat is the enemy. When a piston gets hot it expands, so you need room between the piston and cylinder wall so the piston runs smoothly in the cylinder. Over expansion will cause galling.

There's a few ways to deal with the extra heat; use greater PTW clearance so the piston remains smaller than the cylinder at hot temps. Oil squirters help keep the piston cooler. On my engine I added ceramic heat barrier coating to the piston top and low friction skirt coating to reduce piston temperature.

steven74

I have my engine apart and the bare block is back from hot tanking. I want to clean up the water passages some more and add the Moroso block filler but want to confirm what to block off from the block filler in the front water passages for a street engine. My understanding is fill the lower hole but leave the center one open. Should I use some rubber hose in the front while the hard block is setting up and remove it once it is formed up or just some paper towels like Shawn did?

Thom

Shawn,

Of all the documentation I can find, all 4G63 rods are quoted to have a big end diameter of 48mm (1.89") instead of the 44.98mm (1.771") you measured. Where is the catch?

gruhsy

I have had this same question from start of the posting of offsets grinds builds.

If I understand correctly after the endless researching:

1.89" is the actual rod measurement if you were to measure the bore of the rod

1.771" is the size of the rod journal if you measure the crank.

The difference being the bearing placement.

Thom

Makes sense, thanks.

How does everyone feel about a "high rev" 16V engine using 156mm 4G63 Gen 2 rods on a 2.5 crankshaft destroked to 71.9mm?

V2Rocket

OUI
better pair it with a dry sump though!

Dave W.

The Gen2 rods are too narrow, the Gen1 (aka 6 bolt) rods nearly match the stock 951 rod width.

You can get aluminum 156mm rods from FFWD Connection and a 1.18" comp height piston from the JE/SRP catalog and build a long rod stroker 2.8 that will handle as much rpm as the oil pump will allow.

Dave W.

Correct, with one small clarification.

Thom

2.7L (104x78.9) with 150mm rods gives a rod ratio of 1.90.
2.8L (100x88.0) with 156mm rods gives a rod ratio of 1.77.
This suggests to me that a stock-ish 2.7 should be a happier 16V engine running higher revs than the usual 2.8 stroker spec.

Destroking a 2.5L crank from 78.9mm to 71.9mm with 156mm rods would give a rod ratio of 2.17, which would be even "better" for high rpm use.
With a 104mm bore the engine would "still" make 2443cc which is arguably not "too" small for a high rpm engine. Add a dry sump with all other supporting mods and how about revving it to 9k+?
(With a 100mm bore the engine would make 2258cc, and by then we would probably want to use a classic 2.3L 5 cyl Audi engine instead).

V2Rocket

Thom,
Rod ratio is nice but it's not everything - the old rule of "run the longest rod you can fit" still applies.

For example, the Ferrari 458 (9000rpm 4.5 V8) has an 81mm stroke and a rod of 144mm...a ratio of 1.77.

Thom

The Ferrari 458 makes a peak torque of 67.5 N.m per cylinder.
I would expect a good 3L 16V 951 engine to make about 175 N.m per cylinder, which is more than 2.5 times as much.
While lateral cylinder load may not be 2.5 times as much, I think we can see where the rod ratio can have some importance on longevity when "too high" the stroke gets.
I know this is some kind of "how long is a piece of string" topic but with no real world feedback that makes many whatnots. I wish Duke did a 24Hr full speed endurance test at Nardo!