2375 Water Boxer Tear Down

[jberger]

Volks,
I posted this on thesamba as a follow up to my initial review\build thread. I am trying to identify an oil consumption issue before revising this build and starting again. The first part is my initial review from 2012, then the follow up.

"Thought I'd throw my info into the mix. It all started about a year ago when I noticed a dpr 82mm crank sitting on a back shelf of my local shop. I thought what can I do with this??! I ended up using 96mm QSC shaved top pistons with stock length Scatt rods, stock style AMC heads with TRW valves, CB 2252 Cam (which I have already run in a bone stock 2.1 build using OE pistons and liners).

This combo was headed for sky high compression numbers... not much I could do. With a step cut in the head I was able to keep the static and dynamic ratio just below that of a stock DJ code lump. As such I thought I would give the porsche 1mm piston squirters a try at keeping the pistons cool, so adapted them to the case.

Other details- Deves rings, Stock cylinders bored to 96.05mm, schadek 30mm pump, pick up tube mod similar to 10C but with interference fit instead of o-ring, .040" copper head gaskets (annealed prior to install), 1.25/1 ratio rockers, stock hydro lifters

I have built dozens of stock air and water cooled engines and this one has given me an ulser.. worrying about every little thing. That said, I now have 100 miles on it and am beyond impressed. She sits in my wife's '86 syncro westy with 215 15 tires and stock gearing. I had an AA 2.2 stock compression top end in the previous power plant and this feels worlds different. Infact, I built a GW 2.3 "kit" for a friend a couple years ago that feels like a 1.9 compared to this. I live in an area that has hills that are over 12% gradient and i'm cresting hills in 3rd with partial throttle that I previously crawled up in 2nd mashed to the floor.

Now I know this may be very short lived due to the high compression. If it grenades in the next few hundred or thousand miles I'll build the same thing again only with some JE blanks with higher pin heights for a BIT lower compression. So far it has no perseivable ping, and I'm not the kind to drive around with my fingers stuffed in my ears."

"I built a temp replacement powerplant to swap out and inspect the 2.4. It has run beautifully from day one, except an oil consumption issue (more on that later). The temp engine is loosely based on a 10c 2.2. This one is actually a 2178 with AA 95.5mm jugs, longer rods, trimmed pistons, a 2280 Eagle cam and some mild head work. The idle is a bit lumpy.... but What a GREAT little engine. It rev's out more freely then my 2.4 did and holds Almost as well up the hills. I have a test hill in my hood that is used to determine performance. Always in 3rd, I roll on the throttle from 30mph at the very bottom and see how it crests. The 2.4 would pull out to about 3800rpm and drop to about 3200 at the VERY steep top. This little guy will bust out to 4000rpm but is just a bit under 3k at the top. For comparison, an empty tintop syncro that I converted to EJ22 subie will only rev out to 3500 and is below 3k at the top.

Back to the 2.4..
I pulled the heads, cyls and pistons. Thinks look ok, just carbon'd up. I thought I would see some damage on the pistons from the abuse I've put it through.. but not even a mark. This thing has been going through oil pretty bad, 1/2 a quart every 200miles.. Less if I baby it, more if I don't.

I mic'd the cylinders and they are all still within .0001" (one tenth of one 1000th) of each other, in taper and round.
I also checked the ring gaps.. Interestingly, when new the top and scraper rings had .012" gaps, now they are all .018", some middle rings a bit bigger.
These were Deves rings and interestingly enough at the last moment I swapped in the QSC oil control rings (hastings single piece type with expander spring) due to fit issues with the Deves set, twice. The oil control rings have .025"+ gaps, they were not checked at install.

#4's rings looked to be aligned on the bottom of the cylinder... all others were still staggered.

I am planning to put it back together with the 2280 cam instead of the 2252 and the same head work that I did to the 2178.. but need to sort out if I actually have a ring issue, or....."

[Piledriver]

My sons motor started sucking oil like fuel after ~50K, low compression... oiled up the plug ~instantly.

It was all due to aligned ring gaps on one cylinder.(they apparently do rotate)

Realigned, reassembled, compression and oil consumption both fine again.
(did NOT install new rings)

[Steve Arndt]

So do you think the oil squirters are causing the excess oil consumption?

[Piledriver]

So do you think the oil squirters are causing the excess oil consumption?

Not unless they are pointed wrong.
I know aligned gaps can suck oil badly from personal experience.

I am personally highly dubious a boxer motor needs squirters.
There is already a s###storm of oil flying around off the crank.
(maybe on 1/2 side or if running DS with case vacuum)
I suspect that's why the pistons stay together at all on ACVWs.

Notched rods don't hurt.

[jberger]

The thing is, my compression was very good... near 220 on all cylinders. Leak down was perfect also, prob due to the oil in the cylinders..

Intake guides and ports were bone dry (I posted about my crank case vent\filter system on TS also).

At idle it did have a slight positive case pressure, like .5 inches of mercury, but I have seen plenty of air cooled's that would almost blow your hand off the oil fill

Stock Digifant with rock solid idle as well, so not too much case pressure at idle..

[Piledriver]

The thing is, my compression was very good... near 220 on all cylinders. Leak down was perfect also, prob due to the oil in the cylinders..

Intake guides and ports were bone dry (I posted about my crank case vent\filter system on TS also).

At idle it did have a slight positive case pressure, like .5 inches of mercury, but I have seen plenty of air cooled's that would almost blow your hand off the oil fill

Stock Digifant with rock solid idle as well, so not too much case pressure at idle..

As long as you are not sucking/venting on the 3/4 rocker box, it should not have a serious problem.
I run a restricted purge to 3/4 via a check valve, so it can only suck.
This at least theoretically keep the 3/4 rocker box clear.

I suppose worst case it could be an issue with the sprayers: I don't have any direct experience with them.
I have seen the dual rail chrome 3 pc type rings not seat on used jugs (std iron seats better).

[syncrogreg]

That 2280 is going to raise your dynamic a fair bit. The inlet closes at 36degrees on the 2280. I don't know why CB called it a cheater cam but in my books it is because you are cheating a low compression build into a higher one. I also built a 2.4 with qsc pistons 82mm dpr and a 2280. I would suggest you rethink using a 2280, not only because of the risk of detonation (you can do the numbers on that and mitigate error) but because the 2280 runs out of legs too early. Its a stump puller at low revs but lack lustre between 3800 and 5800. Try Rocky/Chris's cam its a cracker. Greg

[jberger]

That 2280 is going to raise your dynamic a fair bit. The inlet closes at 36degrees on the 2280. I don't know why CB called it a cheater cam but in my books it is because you are cheating a low compression build into a higher one. I also built a 2.4 with qsc pistons 82mm dpr and a 2280. I would suggest you rethink using a 2280, not only because of the risk of detonation (you can do the numbers on that and mitigate error) but because the 2280 runs out of legs too early. Its a stump puller at low revs but lack lustre between 3800 and 5800. Try Rocky/Chris's cam its a cracker. Greg

I have been running a 2252 which I believe closes the intake sooner than the 2280. I had figured 10.0:1 dynamic with that cam. Should be less with the 2280.

I am concerned with the loping idle though. I would think that the increased compression and displacement of the 2375 over my 2178 will make the idle even more rough. How did yours act?

[Piledriver]

You do realise a GM LS motor runs a DCR around 8-8.5:1, right?

10:1 dynamic is in E85 or propane fuel land, wher 110-120 octane and charge cooling is normal...
(Endyn squishies might allow it, Heron head is pretty good too but not THAT good)

KB-silvolite has renamed itself again so their DCR calculator moved here:
https://www.uempistons.com/index.php?ma ... 525fa02016

[syncrogreg]

Ahhh I was thinking 2254. I don't have a cam card for a 2252. Idle was rough with the 2280. Acceptable for a bush bashing tin top Syncro, not or a highway/traffic handling westy. I understand the passion for the 2280, its a great cam to bring a sedate MV to life. I just don't think it is the right cam for this build, in this van.
Re the oil usage. I used a set of chrome b 23 Volvo rings. The top comp ring and the oil ring fit, the qsc 2nd comp was used.

[jberger]

You do realise a GM LS motor runs a DCR around 8-8.5:1, right?

10:1 dynamic is in E85 or propane fuel land, wher 110-120 octane and charge cooling is normal...
(Endyn squishies might allow it, Heron head is pretty good too but not THAT good)

KB-silvolite has renamed itself again so their DCR calculator moved here:
https://www.uempistons.com/index.php?ma ... 525fa02016

I am quite sure of what my engine was turning. I cc'd my parts prior to and after I machined them. I even added a small step cut in the head to reduce the compression as much as possible without having huge deck\squish height. My static Compression was 10.5:1. And As I mentioned above, compression test results were close to 220psi.

I ran this engine for over a year in my Wife's daily driver Syncro Westy. I was not nice to this engine... ever... 5500rpm shift points... trying to blow it up. Pulling trailers, 5 dirt bikes, 4 kids, 100lb dog, gear.....Camping all over California, mountains, deathvalley...

Even though it had zero pinging timed at 40deg btdc at first.... due to the oil consumption and contaminated cylinders it developed a tendency to ping (I think all on number 4 which had rings aligned) after a number of months of running. I have documented my install of a J&S safeguard knock control system on thesamba. Once installed I ran it timed at 45deg BTDC for months. I only pulled it, to tear down and inspect, improve, rebuild and reinstall. Plus I wanted to toy with the other engine configuration.

[jberger]

Ahhh I was thinking 2254. I don't have a cam card for a 2252. Idle was rough with the 2280. Acceptable for a bush bashing tin top Syncro, not or a highway/traffic handling westy. I understand the passion for the 2280, its a great cam to bring a sedate MV to life. I just don't think it is the right cam for this build, in this van.
Re the oil usage. I used a set of chrome b 23 Volvo rings. The top comp ring and the oil ring fit, the qsc 2nd comp was used.

What brand of ring set did you use for the B23? I have not had issues with many sets of AA rings (Hastings I believe?).. their top ring is bright silver in color.. but those are for 95.5 cylinders.

You mentioned Chris and Rocky's cam is really nice... Did you end up shaving your piston tops again after your initial build? I thought you had set a positive deck height. It sounds like you didn't get much run time with the 2280 in your 2375cc... could you elaborate on the characteristics of the rocket cam? Idle vacuum, loping, mileage in differing conditions? We may not be able to compare as my van is quite HEAVY all the time, sounds like yours is not.

[syncrogreg]

I did about 2,000kms on the 2280. Mostly I babied it because I knew it was detonating. When I pulled it down I was expecting to find piston damage, but not a single mark. So I figured I must have been right on the edge and only swapped the cam to get the dynamic down. I took 1.8mm off the top which gave me .05 above deck from memory. Piston dish ended up at 39cc and I got 17cc on the gen heads (have heard some say they are 15cc?). Been a while since I put a vac gauge on it but it has plenty of vacuum and a rock solid idle. Best of all it pulls hard. Weird lobe profile, kind of pointy. Mine is a full camper too, we didn't get Westies here in Oz, just a local fit up with a fiberglass pop. Rings are hastings - rs1651000cr4h b23t.

[Piledriver]

Sounds like your STATIC compression ratio was 10.5:1.

Your DYNAMIC CR (what you spec'd at 10.5:1) will be considerably lower, depending on cam and rod length to a lesser extent.

Link to easy+good+free dynamic CR calculator provided earlier.

[jberger]

Sounds like your STATIC compression ratio was 10.5:1.

Your DYNAMIC CR (what you spec'd at 10.5:1) will be considerably lower, depending on cam and rod length to a lesser extent.

Link to easy+good+free dynamic CR calculator provided earlier.

I stated many times that my dynamic compression as I calculated was 10.0:1 using the 2252 cam. Not 10.5:1. This was calc'd using a degree wheel on the lifter with the case mocked up. Iirc the intake close event was at 34deg abdc, but I would need to confirm off my build notes. I think the cam cards do not match reality when using type IV hydro lifters. But I haven't checked the same cams in a bug case with large dia lifter faces.

Theoretically the dj code engine runs these same numbers (compression wise) so I figured I'd be safe.

Has anyone with a dj recorded compression psi with a know good leak down top end for comparison?