WARNING: Howto destroy and engine in 1500km's. Be careful who u trust. [PICS]

[Weq]

So guys, i dont know if u have followed my rebuild or not but last month i something real bad happen to my engine.

Lets play, Spot whats wrong?

http://captanis.members.veritel.com.au/turbo/new_setup2/blown_engine/topview1.JPG
http://captanis.members.veritel.com.au/turbo/new_setup2/blown_engine/topview2.JPG
http://captanis.members.veritel.com.au/turbo/new_setup2/blown_engine/piston2.jpg
http://captanis.members.veritel.com.au/turbo/new_setup2/blown_engine/piston3.JPG
http://captanis.members.veritel.com.au/turbo/new_setup2/blown_engine/piston4.JPG
http://captanis.members.veritel.com.au/turbo/new_setup2/blown_engine/piston5.jpg
http://captanis.members.veritel.com.au/turbo/new_setup2/blown_engine/bore1.JPG

Rebuild consisted of:
CP 9.0:1 pistons
Eagle rods
Cylinders bored and honed to 75.5mm
OEM gaskets, pumps and bearings all around
usual crank linishing etc.

Ok so this engine has 1,500km's on it. Not pretty huh?

First thought would be the tune was off! My reply, i ran a wideband since 0km's. It was street tuned for perfect A/F's from 0km's by a reputable tuner (i'll let him name himself if he wants too).

The backgorund:
About 2yrs ago now i tried installed a cam into my engine. It was all going well until i incorrectly torqued down the cam caps. After this i had to pull the head off to get new cam cams line-honed. While the head was off i deiceded to get 'the works'. New crower valve train, post and polish and ur standard rebuild. New gaskets and seals all around. Everything honed,bored, checked.

After receiving the head back i installed it, standed her up and everything was fine. Well after i replaced the headgasket again because it never sealed properly, it was fine. Well apart from a small amount of smoke on de-accleeration, it was fine...... Fast forward a few weeks and under 200km's done. I go to take the car to the tuner to re-tune her for the new cam and on the way my idle goes funny. Wierd i pull over and notice oil leaking from the exhaust manifold gasket area.. Weirder... Pull the braker cap and dipstick out and notice puffs of white smoke - ringlands gone.

Fast forward to decembder 05. Machinest and mechanic put new bottom end with my 200km old topend. Re-install engine. Few other mods (new turbo kit, injectors, clutch, hondata etc). I broke the engine in for 1000km's. Never over under 3000rpm for the first 200kms. Change oil, never over 3500 till 500km's. Take her onto the highway and it starts overheating after 10minutes. Never overheats around town... Change oil, never over 4000 until 1000km's. NO boost at all during this period. Install a new 70mm dual core radiator. The whole time i still noticed the small amount of white smoke on de-accleration.

After 1k, mechanic readjusted the valve lash because he thought it sounded a little 'loud'. The car hasnt overheated since aven after a small 20minute highway run so i think its all good. Take car to the dyno. Puts down 142kw @ 5500rpm on 9psi - clutch starts to slip. Puts down 167kw @ 5500rpm on 16psi - clutch still slipping. Engine never overheated on dyno or street tune runs. 90c at idle, 93'c in boost.

Get car back with intension of sorting out clutch issues. Take car for a thrash on the weekend, fine all night. Next morning idle bounces a bit and its a bit tempermental. THink nothing off it, we will fix it next time its on the dyno.

So i am thinking sweet, lets take the car home, back to canberra. I prepare everything, hook the laptop up to monitor the engine and head on my way.. After about 1.5hrs of driving at hiway speeds, i notice the engine temp starting to creep. I have had real bad overheating problems before so i know exactly where my temps should and shouldnt be. I pull over in about 10minutes at the next service station. As i slow down the temps rise very quickly. I turn on the heater and its cools down quickly. I check the overflow and its bubbling like mum's hot soup. Radiator is 80% empty. Fill her up and limp it another hr at 100km's/hr. Finally make it to canberra, check the water, hasnt moved. At this point im thinking the thermostat is ****ed since it was sitting for almost 8months.

For the next week i randomly take her out random runs. Im very easy on her. James (BLKCRX) is in town so i take him for a run. Do a few runs on the street and he verifiys the tune is very safe - comments the motor should last for 'years''. Few days later i do a 1-4th run at the track and it overheats by the end of the second run....I get very disapointed and prepare for the worse.

Take the car home again to Sydney. Have exactly the same issues. The car would just boil the coolant like the radiator wasnt doing its job. Blows most of the coolant out and i can garentee it formed hot-spots where the temp prob didnt metre. The radiator is now bubbling and frothing like a hooker o.d'ing. Headgasket is gone.......

Leave the car for a week after this. Come back home and start her up - now its sounding like a WRX. I decide to drive it to the mechanics to see if he would warrenty his 1500km old headgasket. 1 minute up the road the car starts to smoke like a MOTHER ****ER. BIG plooms of WHITE, dense WHITE smoke on de-acceleration...

*breath* Thats the first half of the saga - i will post the second part of the saga after dinner... Dont worry, it gets better :) Any guesses on what went wrong !!!

Oh i almost forgot, this is how the head looked after 1500km's.

http://captanis.members.veritel.com.au/turbo/new_setup2/blown_engine/head.jpg




PART 2 (http://www.ozhonda.com/forum/showpost.php?p=587719&postcount=11)

[ProECU]

Thats a tough one to call.
Hard to tell from the photos, but appears cyl 1 sleeve looks cracked.
There is also some coolant residue on those pistins which supports the cracked pistons.

It also "looks" as though the piston to wall clearance is a bit on the excessive side but this might be due to the cylinders going out of round from the crack.

I'm going to go with the Heat generated from power @ 16psi is excessive for stock D-series sleeves.
You hinted in the title to be careful who you trust, I suspect someone you know has taken your car for a nice drive without your concent.
Too much boosting for prolonged periods.

Am i right?

[Weq]

Kinda of the right track, but not quite there :)

This is how the engine looked after the highway trip. I forgot to mention, on the highway i NEVER boosted. -10--25 vac the whole time. The engine temps slowly rising the whole trip, to the maximum of 97'C when i stopped and refilled the coolant. I never heard it knock. Knock was what my mechanic and engine builder blamed.

Sorry if the pics are bad, i should re-do them. Take a close look at the intake valve releifs. Spot the rings?

Also, d-series sleeves are fine at 16psi. They have held 25-30psi before racing, 20psi daily.

Lastly, i spoke to alot of ppl, and showed alot of experienced people. Everyone had a different opinion. Thus, an engineer was enlisted to disassemble and diagnose clearences/build defects.

[todaek9]

omg, the side piece of the piston is cracked and are those valves bend!?...guess Cams were not set right from the start. And definately, it's been over boost...the whole thing was not installed properly as well. PLus, the engine was pretty fried up...i reckon that you should go back to the shop, ask him what happen to it. If you got everything from that shop and installed by them, you should have a fair reason of why. There is also some engineer test report to certify what is wrong with the engine, causes and all. if it's not your fault, you might wanna take some action, If you got your reciept.
still.

but one more thing, did you take out the head yourself and take those pictures???

[todaek9]

and also, what did it smell like???

[Weq]

sorry mechanic took the engine apart because i thought it was a stadnard headgasket replacement... and i wanted it under warrenty. lol

Bottom end, head and engine were built and assembled all by different places. tuned was another place. I didnt want to cut corners everywhere and wanted everything done by the best ppl i new and trusted.

Smell? it smelt of oil. All the time it melt like oil.. oil was being burnt from day 1. I used 3l of oil on the trip up and down to canberra. Also the problem has been determined and cuase found. I will post up later, but i want people to post what they thought happened first :)

Lastly coolant on the pistons was residual from when the head came off. There were no obvious signs the headgasket had been breached - this observation was made by online performance (NOTE: they are an independant 3rd party not involved in any build or problem.)

edit: AS pictured, head still had the CAM inside.

[Bowzer]

What did you use to control your boost? also what was the A/F tuned at up top? im with Evan, pistons running tad bit hot... hot spots causing pre-ignition resulting to detonation... Did you consider sanding the sharp edges on your forged pistons to reduce the chance for hot spots/detonation?

What injectors where you running appears the other cylinders have more carbon deposits and the one with the busted ring landings have less, faulty injector perhaps? Could be misleading as well once water enters into the combustion chamber and mixes up...

Your lucky the chunks from the ring landings didnt destroy the head ... Sleeve the bastard next time

[2MPRSS]

my guess is that it was ur heater that ****ed up everything, hapend to me,it ate up all my radiator fluid and sprayed it all in the interior, closest thing to what has hapened to ur car and mine but u said have a guess so i did :)but CHI came to the rescue with a big bucket of water hehe tell us bro what really hapend,what did online say about it after u droped ur engine off there? it did look preety bad after all that efford u put on that engine

[Weq]

Bowzer: Injectors were RC750CC's. Funnily enough, they were flow tested/cleaned before i put them in because of an unrelated issue. All injectors checked out a lil above 750cc in flow rating :)

On the same note, isnt it interesting how only 1 ring burnt up. ANd the chucks of pistons passed sucessfully out of the head and THROUGH THE F*CKING TURBO without damaging a single thing! All valves were unharmed and so was the turbine! Most of the chucks of pistons were found rattling around just before the cat. My therory is they were liquid at the time they left the engine. Thats one HOT piston.

edit:

The pistons were covered in a carbon/water mix, they look alot worse then they are. All piston tops were unscored and no pitting was observed. Plugs can be seen insude the chambers. No damange was observed.

[todaek9]

I reckon that you should take out the sump and see is there anything lose or not or about to be gone. And also, check your fuel pump as well. a sudden stop of fuel may cause alot of problem as well, esp in high rev.
If i were you, start checking all those really Tiny things that you think is running well. and also, if you don't mind, can you post a picture of the Cilinder head (front where the outlet's are, not close up)

All Turbo honda's, must have a "release pressure" site by drilling a hole in the cilinder head and something fit to it if i'm not mistaken (not too sure how to put it in words), because i've seen afew, and all of them did that. but drill where, i'm not really sure.



Bowzer: Injectors were RC750CC's. Funnily enough, they were flow tested/cleaned before i put them in because of an unrelated issue. All injectors checked out a lil above 750cc in flow rating :)

On the same note, isnt it interesting how only 1 ring burnt up. ANd the chucks of pistons passed sucessfully out of the head and THROUGH THE F*CKING TURBO without damaging a single thing! All valves were unharmed and so was the turbine! Most of the chucks of pistons were found rattling around just before the cat. My therory is they were liquid at the time they left the engine. Thats one HOT piston.

edit:

The pistons were covered in a carbon/water mix, they look alot worse then they are. All piston tops were unscored and no pitting was observed. Plugs can be seen insude the chambers. No damange was observed.

[Weq]

Part 2:

So the mechanic pulls the engine apart and see's all the holes in the pistons. conversation went like this:

Mech: "first thing i did was check the head to see if the valves were touching the pistons. it didnt look like it. So i rang up my engine builder and explained it to him. he said that his seen it before, kids bring engines back a week later with holes like urs. it was detonation. the tune was shit. u cant go running all that boost without premium fuel"
Me: "i always ran BP98. it has a full tank it in now, 98ron."
Mech: "Well what about ur fuel system. sure u had big injectors in there, but a stock fuel pump cant cope with them. it prolly leaned out on high boost"
Me: "Umm it has a brand new pump. flows 255lph, good enough for the power i was making, its good enough to outflow the stock lines"
Mech: "WHat about the timing? did the 'tuner' check the timing"
Me: "Yeh the first thing we did was time the engine."
Mech: "Well it knocked its head off. nothing else too it. My engine builder has been doing this for years, he hasnt messed anything up. THe piston to wall is fine, nothing is out of spec. not OUR fault. Now how much u gonna give me for pulling the head"
Me: "Ur asking me to pay for repairs to my 1500km old engine? lol, sue me"

Anyways so i took the car home, pull the engine out, orded new pistons and shiped it, and my spare engine and EVERYTHING else off to another reputable builder. I left everything assembled so i could could organise the engine to be professional stripped to find the cause of the problem.

Few hours go by and i get a call. "Hey did u realise u had piston to valve contact? Take a look at the pistons. Did the builder check the valve clearance with vtec locked in? This cam is pretty wild compared to stock and with a shaved head and decked block, u should expect it..." ...... Umm no he didnt, he told me many times 'all i did was get the bottom end rebuilt and slapped the head ontop. I didnt even take off the dizzy. i did nothing wrong..." Right..

Problem #1: Piston to valve clearance. Valves were mashing the pistons during vtec. Maybe the problem was enhanced by his 'tighter valve lashings' he did to quiten the engine down.

So a few days go by and i get another call from the engineer. "Everything else on the bottom end checks out ok. I couldnt really accuratly measure the piston to bore because of the wear."

So the bottom end gets rebuilt. Well actually i trashed most of the bottom end (cylc etc) cause it overheated so many times and the deck has sunk 0.008". So the old bottom end is rebuilt, new bearings and seals all around again.

Few days more go by and i get the low down on the head. Apparently the valve guide clearance was way over spec on 8 valves. 4 valves were not even holding compression properly at all. The engineer was surpirsed it made any power at all. All valves were straight though, and nothing was bent. Head since has been completly rebuilt and all new guides right around.

Problem #2: Valve guide clearance. THis in turn caused the piston to valve clearance to come out of spec and piston to valve contact occour on the vtec cam. Another by product of this was oiling down of the pistons. The guides leaked oil into the chambers. This caused both hot-spots to form at the sharpest and thinnest points (the intake valve releifs), along with overheating the pistons causeing piston to wall contact, which in turn we THINK cause all the overheating issues. It probably also reduced the octane of the fuel down to 86 or lower causeing knock which probably finished off the overheated pistons. Bowzer made a great comment - Yes the new pistons will be modded to reduce hotspots occouring. I have also gone with weicso pistons this time. The reliefs are a little thicker and they come coated for less expansion.

http://captanis.members.veritel.com.au/turbo/new_setup2/pistons1.JPG

This is how the car sits atm. Just waiting on a few parts from the US.

http://captanis.members.veritel.com.au/turbo/new_setup2/car_sitting.JPG

[SKREMN]

sorry to hijack
This is my engine fully rebuilt and this happend after 3500 with no boost and no tune
it had ctr pistons and cams
i had overheating problems also and got the head gasket redone after only 100k's coz it blew and mixed water and oil all up
this lasted for a short while and then boom all finnished
the car allways used up water
http://i19.photobucket.com/albums/b164/skremnLS/head.jpg

http://i19.photobucket.com/albums/b164/skremnLS/block.jpg

[Weq]

SKREMEN: It isnt a hi-jack. We have MORE in common then u actually think. As far as i can tell, id say u had the same problem as me.... i wonder who built both our heads?

PS. Ur damage is usually associated with a snapped timing belt or a jumped belt or keyway. But only because i know the history i think otherwise...

[michael_antoi]

so the mech's at fault...did u go back to him?

[ECU-MAN]

weq,

after reading your entire posts, you mentioned piston to valve contact, but thats what I 1st thought after seeing them pics. notice how the pistons broke in the valve recesses only.

I suggest you have your head leak tested and I dont think thoes valves will seal as well as they once did,

from looking at the pics of the piston crowns and chamber in the head, there is no sign of lean mixtures or detonation.

[Weq]

weq,

after reading your entire posts, you mentioned piston to valve contact, but thats what I 1st thought after seeing them pics. notice how the pistons broke in the valve recesses only.

I suggest you have your head leak tested and I dont think thoes valves will seal as well as they once did,

from looking at the pics of the piston crowns and chamber in the head, there is no sign of lean mixtures or detonation.

Yeh everything is being checked and replaced if needed (i have a doner head). Thanks for the advice :)

Re lean: Everyone keeps telling me it was knocking. I cant see it, i didnt hear it (always boosted with windows down cause of the heat) alot of ppl cant show me it, but everyone keeps saying it happened.. Like i said, i had a wideband on it the whole time, A/F was tuned to 10.9 in boost and it held strong throughout the rev range..

Cheers for taking the time to look :)

micheal: He was at fault in a sense, but the engineer said my case would be very weak. He does this for a living (professional witness) and said its not a 'compulsary' part of building and engine, its rather an optional extra which is worth while - in the sense of the law.

My big case would of been against the builder of the head. Alas due to the timeframes involved (the reason why i have told the entire story, it spans over a year) there is no way i could really prove that he was souly at fault.

[ProECU]

Weq

how do you then explain the cylinders cracking?

[todaek9]

Did you say you SHAVE your Cilinder HEAD??? by how many mm?

IF you say that is so called a "reputational" tuner or builder, i think, yea, reputational, Good in talking SxxT...bad luck dude...is either you fried the thing yourself, or they fried it for you...and i guess, you can't have any claim from them for sure. and surely, they would not be responsible for the thing, if they do, i think you're lucky..but i doubt that...

one more thing, go and get yourself a set of Darton's Dry sleeves, and changed the cilinder head if i were you...a shaved head will never be good...

What compression are you running at the moment? 10.2:1? 10:1? 9.5:1? 9.0:1?

IF you want a good builder, find someone that does over 50 Vtec turbo's..or really good in Vtec..does like over 100 mods internally on vtec. Reputation doesn't really count if they have only ONE CAR to promote their name, if you get what i mean.

[LVNIT]

Ive been in his car, seen it go nearly right thru the rev range, the a/f was always a nice and consistent figure.

[Slow96GSR]

Let me recommend some reading for you and your builders... here! (http://www.strathlan.com/TEK/docs/ThermalConsiderations.pdf) If you we're running the CP 85mm pistons you should have bored to about 85.09mm-85.1154mm (.004”-.005” over). They aren't a perfect circle piston. See aluminum has a pattern. It expands more in one direction than the other, all metals do, just aluminum does it more. So you have to take that in to consideration. That's why the piston it out of round, once it heats up it comes to a perfect circle, or close to one. I don’t know if the builder took that in to consideration but thought I’d mention it. Once you deck the head and block you have to make sure you get the proper stroke and gasket. The rod, crank and piston makers don't know what you are decking to so they make it for a stock height, then you have to get the proper gasket thickness. Now factory deck height is high enough to deck it a few times to make it flat but if there was significant warpage or nicks you might only get one or two passes. The head also needs reliefs put in to the valve seats so they don’t hit. Make sure you got the right size valves, Crower does have over sized valves and it’s easy to order the wrong set, I have before.

[ProECU]

I know who tuned the car and have absolute faith in his ability.


Ive been in his car, seen it go nearly right thru the rev range,
the a/f was always a nice and consistent figure.

But at what PSI what this demonstation.
I have an inclination it was overboosted. Weq trying to sell a stock radiator in the FS section.. it appears he's bought something more up to the task.
I am of the opinion it was also overboosted.

[tinkerbell]

the fact that 3 different builders were used leads to:

block was decked
+
head was shaved
+
piston to valve was not checked in VTEC

pretty simple equation = likely hood of piston to valve contact very high

but i ask why this did not show up on the dyno/driving?

plus - was overheating from too tight piston to cyl. wall clearance?

[michael_antoi]

pretty simple equation = likely hood of piston to valve contact very high

but i ask why this did not show up on the dyno/driving?



very good point - wouldn't the pistons and valves have hit each other the FIRST time u hit vtec?

[STOCK]

Time to ditch the d and swop in a b then turbo it!

[Slow96GSR]

... plus - was overheating from too tight piston to cyl. wall clearance?

Actually If it was too tight it would have seized. Being too big would explain the white smoke in the oil's dipstick tube with the cracked sleeve and bad gasket, if there was a bad gasket, don't want to read it all again! Also would have had a lot of blow by until the pistons warmed up. Then it wouldn't be too bad but still a little too much.

[Weq]

the fact that 3 different builders were used leads to:

block was decked
+
head was shaved
+
piston to valve was not checked in VTEC

pretty simple equation = likely hood of piston to valve contact very high

but i ask why this did not show up on the dyno/driving?

plus - was overheating from too tight piston to cyl. wall clearance?

Well this is the question. THe water was being boiled, and the whole cooling system was brand new - everything.

We think the pistons were being overheated, to the point where they were rubbing. THe overheating was caused by the oil that was comming through the guides and causeing hotspots on the pistons. Thats my understanding from talking with the piston company on how something like this can happen. The valves basically finished off the problem. Like i said, im pretty sure the metal was almost liquid because it did no damage to vales/turbines etc - that of im the luckiest man around.

The reason everything was built by different shops, was just a matter of conincidence. At the time of the pistons being installed, the mechanic had EVERYTHING he needed. He had the head and he had the bottom end. I gave everything to him at once and said 'make it work' basically.

Lastly, Pro ECU, the damage you see was what was left AFTER at 3hr high-way trip. During the time, there was NOOOO boost at all. I pulled the plugs before and after i left, and after i got home there was a very different picture. Lastly, it defaintly didnt overboost either way. I guess u'll have to trust me on this one.

[Weq]

Actually If it was too tight it would have seized. Being too big would explain the white smoke in the oil's dipstick tube with the cracked sleeve and bad gasket, if there was a bad gasket, don't want to read it all again! Also would have had a lot of blow by until the pistons warmed up. Then it wouldn't be too bad but still a little too much.

Sorry this is ALLL wrong. I had NO blow by. I blew ringlands on my stock engine and i know exctly what blowby is like. I had no smoke comming from the engine - you are confusing my stock engine with the rebuilt one.

Secondly, the sleeve was NOT cracked. Please beleive me, it is an optical illusion/dirt/grime.

The symptoms i got when the built engine was done, was after it had warmed up i got gushes of white smoke on the slightest bit of de-acceleration (ie if i revved the engine, it would gush out).

[ECU-MAN]

self destruct begun after valve lash adjustment. another thing to consider.

that a posibility why is did not show up on dyno/driving power run's



the fact that 3 different builders were used leads to:

block was decked
+
head was shaved
+
piston to valve was not checked in VTEC

pretty simple equation = likely hood of piston to valve contact very high

but i ask why this did not show up on the dyno/driving?

plus - was overheating from too tight piston to cyl. wall clearance?

[bigteethygrin]

ummm.. really bad at engine advise.. but you sure the detontation didnt lead to burning a hole in your head gasket leading to the overheating??

[jimmeh]

i took my head to the same place to get it serviced. and i had a chat with dyno dave and he kinda told me how they messed up my head.

1. they cut the valve seats too deep so they shaved a little off the top of each valve stem to compensate

2. they also mixed up my valves- dyno dave told me that each valve guide is honed to each valve. and this causes the motor to burn oil

this is what dave told me over the phone. dave has the head now and i will tell u what else is wrong with the head once i have a chat with him

[Weq]

White smoke normally indicates water in the combustion chamber, have you checked the head surface for warping? If I read it correctly you were adding water to a hot engine and that sometimes causes slight warping of the head around the water passage hole area.

thanks for the comments. yeh the head has undergone a full service, crack check etc etc. The head defaintly warped after the fact though. the deck sunk also. all this with my temp gauge never going over 97'C

[SKREMN]

My blown motor used to use up oil as well
but my new one doesnt and both by the same builder
maybe he did it properly this time

[Weq]

self destruct begun after valve lash adjustment. another thing to consider.

that a posibility why is did not show up on dyno/driving power run's

valve adjustment was done JUST before the dyno, unfortunatly. so engine was dead within 400km's of the valve adjustment.

[spanks]

First engine has detonated itself to death.....Second engine...OUCH

[Weq]

First engine has detonated itself to death.....Second engine...OUCH

care to elaborate?

[superR]

fark.....i hope mine does not play that shit with me!
oh well live and learn......Always check the clearence from the vtec lobe!
anyways how is it all going now man....ready to come to the creek with me?

[spanks]

care to elaborate?

FIRST ENGINE
The colouring of the pistons and the fact that ringlands on all pistons a fair giveaway..too much comp,too much timing,using wrong fuel..not sure without knowing specifics...

SECOND ENGINE
Have seen a few K20 engine do this from over-revving..

[h22a accord]

fark man, thats crap. get a lawyer.

[Weq]

FIRST ENGINE
The colouring of the pistons and the fact that ringlands on all pistons a fair giveaway..too much comp,too much timing,using wrong fuel..not sure without knowing specifics...

SECOND ENGINE
Have seen a few K20 engine do this from over-revving..

see ppl stop at the 'it detonated' part and shrug it off. There are many more reasons why a 2k old engine will detonate itself to death, other then bad fuel, timing or not enough. all of these were spot on ;)

[spardikis]

This whole thing is just a huge shiv storm.....:mad: i prob would have taken to it with a hammer by now, like "screw this F(*)#(n thing, take that! and that! and that! and that u bllody thing haha i sorted u (kicks engine) :Dhaha

then 10 minutes later :eek: what have i done...
then :(

oh that link u posted slowgsr was really interesting. I will take that into account when doing my next one - b16a with wiseco forgies, eagle rods apr bolts? You really have to make sure ur clearances are spot on! Best to take it to an engineerin shop 4 bore/hone. top post