misfit2009

So this'll be the third rebuild of this engine..

First time I think I let the oil level get too low (I know) and too many high g turns and zero g situations and that meant the first rebuild:

0.5mm (20 thou) grind on the mains and there was 1 tiny (I mean tiny) score in one of the bores - since it was open I thought a 0.25 (10 thou) overbore, mahle gold pistons, rods, new diy aluminum flywheel (I'm an engineer) and I made a full set of pulleys and tensioners.

Oil pressure was a little low, and there was a bit of a rattle coming from somewhere (never did find out), but eventually the ring gear fell off my flywheel, so I decided to pull the engine apart to work out the rattling.

Turned out the mahle's had eaten all the bores this time. I decided the slightly low oil pressure could've been the cause so I've had the mains hard chromed and ground to standard size, the bores sleeved and installed 'standard' wiseco pistons

Oil pressure was much better this time, ran it in fine, first time into VTEC rpm and something went funny, oil pressure guage didn't drop (but it's electronic and quite show), it may have actually gone into VTEC and dropped straight back out (presumably the VTEC oil pressure sensor didn't read high enough?) But yeah, engine broken.

Limped it home with low oil pressure, decided to have a look at the VTEC solenoid and it was a bit gritty, cleaned it all out and after starting the oil pressure read much better (although it had had 10 mins to cool off.

So the engine is back on the stand - just one of the big end journals (number 1's) is thoroughly munted, presumably the mains survived because the chrome is much harder than the base metal of the crank. (The mains usually go first because they're a bigger diameter than the rods, which means the surface speed of the mains is higher)

Things I have noticed and have questions about:

The top port on the VTEC solenoid leads to a tapped (threaded) hole in the top of the head - I know this is used as part of Honda's VTEC testing rig, but should it have anything in there? I'm almost tempted to put a restrictor on it to increase idle oil pressure, or a feed tube to the timing chain?

Another thing I found whilst messing around was if I feed air to the VTEC port (where the solenoid should be) air escapes through where the top bolt of the static chain tensioner is (the one on the right as you're looking at the front of the engine), as far as I can tell (the head is still on) that hole runs through to where the head studs are.. Wtf? Why is just 1 of the head studs oil fed?

Edit: should the top bolt of the top chain tensioner have an o-ring or sealent anything on it? I didn't remove it the first time so I don't know


Any ideas? Almost ready to throw this car in the bin.

zeroptzero

The rest of the car is worth keeping, buy a good used replacement motor if you can find one. I would toss that motor out the window., how much pain can one person take.

misfit2009

The rest of the car is also a nail..

fatjoe10

Subscribed! I'm extremely interested in trial and error type things. 1st off, whats the status of the oil pump? what bearing clearancea was this built to? was the block line bored after the sleeve install?

misfit2009

Must say my wallet and I are much less enthusiastic about trial and error.. I'm not sure of the exact operations undertaken (I work on a lathe and our workshop doesn't have the gear to do engine work), the machining on the block itself has been done by a local company (chase engines)

Which side are the rod bearing tangs supposed to be on? I thought I'd copied Honda's orientation but now I'm paranoid that I may have put the OEM rod and piston back together backwards practicing installing snap rings?

I've installed them so the cut outs in the rod are on the exhaust side, is that right?

Edit: oil pump was brand new OEM after first rebuild, all clearances were good but I didn't want to risk it

Edit edit: standard mahle/cp piston ring gaps and standard oil clearances on the crank and rods

windhund116

Sorry, just a quick/simple question --- did you mic all the bearings, after the machining and re-fittings? You use Plastigauge?

Thanks!

e28oo00oo

Misfit2009, thanks for sharing the feedback and sorry about the trails and tribulations. At this point it appears that you are ultimately trying to determine whether to cut your loses or press on. The only experience I have with the intricacies of rebuilding the F20 engine is through this forum and it seems to be well documented that no one other than Honda can really make this engine right. What I can offer is an anecdote as to why that may be.

Back in 2007 and 2008 I was an undergrad studying mechanical engineering and was lucky enough to land a co-op (3 semester internship) position with Honda Manufacturing of Alabama. This facility is located near Talladega and is a full manufacturing and assembly facility that at the time employed about 4,000 people and built every Pilot and Odyssey in the world. I alternated between school full time and work full time each semester for three rotations with one semester spent in engine die cast, engine machining, and engine assembly. Got to see the J35A6/7 3.5L V6 from ingot to running engine. In short, they make the entire engine from scratch onsite. They cast, machine, and assemble the block and heads onsite while cranks and connecting rods come in as rough casts with the finishing machining done onsite to maintain bearing and other tolerances. The engineering and quality control is truly amazing. To share all I saw would take too much time but I can tell you that while die cast and assembly is sweet, the machining department is nuts. They probably have 2 million dollars of replacement carbide inserts alone on hand at any given time, the department probably has 150 people in it alone, and most of the actual machines that do the machining are custom units designed and manufactured by Honda Engineering North America (a whole separate company that simply designs and builds the machines that build the cars so that no other OEM can exactly duplicate how they do it). One of the more impressive machines was the unit that machined the cylinder head camshaft journals. The boring bar alone was about an $18k piece that was replaced regularly and if memory serves the design tolerance was -0, + 0.0003'' (8 microns). This was effectively within measurement error for even the Ziess CMM machine and was basically as good as you could repeatably achieve with that type of manufacturing throughput. Cylinder dimensions were equally nuts though I cannot recall specifics.

Now its manufacturing so six sigma only goes so far and eventually everyone makes mistakes. What matters is what you do about it. So one day the piece of tooling that machines the face of spark plug seat in the cylinder head breaks an insert and it somehow isn't caught immediately. They stop production, replace the tooling, and identify every potentially effected cylinder head in the system. These units are flagged and since it happened same day the cars were still in the holding lot out back (holds several thousand vehicles prior to shipping). I was then part of a team of about 100 folks that went out into the holding lot, popped the hood, pulled the engine covers, coils, plugs, etc. and manually inspected every rear cylinder head. Out of several thousand potentially effected we found.....five. Yes only five. Then I sat there for 6 hours per car and documented the entire head replacement process per vehicle, hopped in the car, took an Odyssey up to 115 mph on the test track out back, and then signed off on a job well done.

The point is that this was the care that Honda gave to its Pilot and Odyssey. It stands to reason that the S2000 was given even more scrutiny and damn if those Japanese don't know how to design,engineer, and QC the shit out of an engine. The fact of the matter is that Honda is not any old OEM it is unlikely that even reputable engine builders have the machining or measurement technology to repeatably create what the factory did every day. My recommendation is to swallow your pride and get another OEM engine or swap something else in (K series, LS, etc.), but I'm just a guy on the internet.

Charper732

The thing with hard chroming journals is that there is a possibly of it failing. That's why its pretty rare to see it done these days. Find a used crank or turn it into a F24. K24 crankshafts are cheap as hell new.

As for the oiling. The #1 head stud closest to the vtec solenoid side is the oil feed to the head from the oil pump. There is a hole at the top of the head that goes to no where that bleeds off oil pressure. I have honestly thought plugging it as well. I've talked to 4piston and inline pro about it, neither of them have ever plugged that hole, even on their race cars. The consensus is that it's a left over design from the K series as that hole would directly hit onto the timing chain giving it lubrication...same purpose on the F, it just sprays straight onto the valve cover though and falls down.

Also, bearing tangs..best practice is exhaust side, but it really doesnt matter if there are 2 oiling holes on either side of the piston pin.
If you went standard bearing clearances, I hope you went on the loose side. I personally never go tighter than .0015"

misfit2009

Sorry for the delay in response to everyone - I checked all the clearances on the previous build - all were towards the loose end of the manuals 'new' spec, and iirc one or 2 of the mains were on the borderline of being at the "service limit " (ie the close side of the the service limit). So probably all between 0.02 and 0.04mm for the mains and the rods were all perfect at roughly 0.03mm, but I didn't write any down sorry.

I mic'd the mains and they were all 54.99, but I don't have any bore clocks at home so I couldn't check the mains in the block.


One thing that had crossed my mind since I last posted is since the first engine build I've run a tegiwa sump baffle plate (think it's a copy of someone else's, not sure), and looking at it when the sump is installed and the oil pump is also in the way I could've starved the engine that way? I know at ~6k rpm the pump flows about 1.5 litres of oil a second (!!!)

I've read about the VTEC mechanism leaking like a sieve (never seen it myself) but could it be that between the sump baffle and the change in flow around the engine I starved it of oil?

It wouldn't take long to drain the sump underneath the baffle, and with all the extra oil retuning to the sump from the head (rather than the mains/rods) it could (hopefully) be possible the oil was sitting on top of the baffle and not getting to the pick up.

That's what I'm hoping anyway..

Charper732

do NOT assemble an engine at .02mm of bearing clearance that leaves such little room the chance of having journal to bearing contact is quite high. Pair that with the fact that many people don't assemble motors in a clean room and you have a motor with trashed bearings real fast. I usually do all my builds between .04-.05.