rjudgey
04-20-2013, 04:16 AM
Right had some bad news my A18/A20 hybrid is toast, it was smoking quite badly thought it was something not too serious so left it a bit haven't really used it apart from running it once a week to charge the battery and clean the brakes up, finaly weather got better so I did a compression test piston 4 is toast. Stripped head off and all looked new apart from piston and chamber soaked in oil, thought hmmm not good bottom end problem maybe ring has cracked. So I stripped the sump off and pulled some of the main bearing caps off and big ends off only to discover alluminium embedded in them, as it's ally it's not damaged the crank the oil has been doing it's job and iron is stronger than ally so it's basically squashed the ally into the soft surface of the bearings. Only down side is can only get to the lower half of the mains so can't check the condition and state of the top half unless I take the gearbox out. My feeling is if I replace the big ends and gently smooth out the main bearings that I can get to I could bodge it back together again. what do you guy's think I only won't it to last out the summer to get a couple of drag races and track days done.
So after seeing this was a bit cheesed off so thought well got to be something melting on the pistons so pulled all 4 out first 3 all like new very annoying as they are nearly new only 1000k miles on them at most, got to piston 4 which is allways the one that runs the hottest and as it comes out I can see all the ring landings have broken off and are falling out!!! Ouch how the F did that happen I've never had a piston fail like that before normally the ring landings compress pinching the rings and leads to a crack which blows a hole through the crown. This is new and never so soon after new parts being fitted! hmmm then I remembered when I first rebuilt the engine just before being tested for road worthiness the stupid mechanic left engine running for ages with the rad fan off even though I said to switch on and leave on, found engine totally over heated and had blown the coolant out the reservoir tank. So now I'm thinking/hoping that the Honda pistons are fine but as it's number 4 would have got the hottest it's led to metal fatigue which has caused the thinest parts of the pistons to break away?? You think I'm on the right track or could be that I'm just unlucky and have a bad piston or there could be a flaw with Honda oem pistons? The cheap as shit Sealed power ones I used to use had a lower CR ratio but allways lasted at least 10-12k miles before cracking on me.
Anyway so now I'm left with a few options, go back to using crappy sealed power low CR ratio pistons, use JIS ones with higher CR ratio possibly better made nice and cheap, or go full monty and swap out pistons for forged units, I have the bore clearance as I added .05mm clearance on this block to prevent the cast ones from expanding and causing failure as they would from running 200bhp. I haven't seen any forged pistons that are off the shelf but I know a few peeps have had diamond ones made up and possiblyk JE but looking for some ref: numbers I can give to Either one preferably JE as I have a mate who works next to their UK factory so would be very easy. Either that or I post em a piston to copy.
I would like to use aftermarket rods but the lightest I've seen are Brian Crower LS B18a/b rods at 440grams at a sensible price but still way heavier than Honda stock rods, and as I haven't had any issues with these and they are so nice and light I'm in two minds to change or to keep what do you guy's reckon? There is the Eagle Titanium rod option which would be uber cool but then I'd have to use B18A/B pistons which would mean a rebore as only size I can get that is close is 83mm and I'd have to possibly get the pistons valve reliefs remachined to suit my much larger valves but not the end of the world I guess. I think the main thing is to do this on smallest budget (although there is no budget) but with best parts/per dollar and keeping the whole rotating mass the lightest. Maybe put some titanium wrist pins in is another idea I've been toying with? what do you think?
The head is pretty much new still although I need to strip down clean the old oil off the chambers and backs of valves, plus check the bearings but all the valves and everything else looks all good hopefully the bearings are good or just need some TLC with wet and dry paper to re polish.
Bit of a pain really as just had the engine running sweet and was looking forward to have a header made up finally, I know having 200bhp and 160lbft isn't easy on these engines but it should have lasted longer than 1000k miles :( Most my engines last 12-15k miles before needing new pistons and rings which I put in with new Big ends, do this couple of times before pulling out and doing full on rebuild.
Other throw it out there option is to put one of my working B20A's into the car I'm thinking with a bit of work on where the rear engine mount sits, and using the original shafts from my A20 it should go in if I whack my carbs on and then just need to figure out how to get the ignition working. Possibly pull head off and do some quick P&P work maybe drop in some larger valves I have, then find some cams from B18 should give me a pretty potent setup although not sure how long the rods and pistons would last! lol!
So after seeing this was a bit cheesed off so thought well got to be something melting on the pistons so pulled all 4 out first 3 all like new very annoying as they are nearly new only 1000k miles on them at most, got to piston 4 which is allways the one that runs the hottest and as it comes out I can see all the ring landings have broken off and are falling out!!! Ouch how the F did that happen I've never had a piston fail like that before normally the ring landings compress pinching the rings and leads to a crack which blows a hole through the crown. This is new and never so soon after new parts being fitted! hmmm then I remembered when I first rebuilt the engine just before being tested for road worthiness the stupid mechanic left engine running for ages with the rad fan off even though I said to switch on and leave on, found engine totally over heated and had blown the coolant out the reservoir tank. So now I'm thinking/hoping that the Honda pistons are fine but as it's number 4 would have got the hottest it's led to metal fatigue which has caused the thinest parts of the pistons to break away?? You think I'm on the right track or could be that I'm just unlucky and have a bad piston or there could be a flaw with Honda oem pistons? The cheap as shit Sealed power ones I used to use had a lower CR ratio but allways lasted at least 10-12k miles before cracking on me.
Anyway so now I'm left with a few options, go back to using crappy sealed power low CR ratio pistons, use JIS ones with higher CR ratio possibly better made nice and cheap, or go full monty and swap out pistons for forged units, I have the bore clearance as I added .05mm clearance on this block to prevent the cast ones from expanding and causing failure as they would from running 200bhp. I haven't seen any forged pistons that are off the shelf but I know a few peeps have had diamond ones made up and possiblyk JE but looking for some ref: numbers I can give to Either one preferably JE as I have a mate who works next to their UK factory so would be very easy. Either that or I post em a piston to copy.
I would like to use aftermarket rods but the lightest I've seen are Brian Crower LS B18a/b rods at 440grams at a sensible price but still way heavier than Honda stock rods, and as I haven't had any issues with these and they are so nice and light I'm in two minds to change or to keep what do you guy's reckon? There is the Eagle Titanium rod option which would be uber cool but then I'd have to use B18A/B pistons which would mean a rebore as only size I can get that is close is 83mm and I'd have to possibly get the pistons valve reliefs remachined to suit my much larger valves but not the end of the world I guess. I think the main thing is to do this on smallest budget (although there is no budget) but with best parts/per dollar and keeping the whole rotating mass the lightest. Maybe put some titanium wrist pins in is another idea I've been toying with? what do you think?
The head is pretty much new still although I need to strip down clean the old oil off the chambers and backs of valves, plus check the bearings but all the valves and everything else looks all good hopefully the bearings are good or just need some TLC with wet and dry paper to re polish.
Bit of a pain really as just had the engine running sweet and was looking forward to have a header made up finally, I know having 200bhp and 160lbft isn't easy on these engines but it should have lasted longer than 1000k miles :( Most my engines last 12-15k miles before needing new pistons and rings which I put in with new Big ends, do this couple of times before pulling out and doing full on rebuild.
Other throw it out there option is to put one of my working B20A's into the car I'm thinking with a bit of work on where the rear engine mount sits, and using the original shafts from my A20 it should go in if I whack my carbs on and then just need to figure out how to get the ignition working. Possibly pull head off and do some quick P&P work maybe drop in some larger valves I have, then find some cams from B18 should give me a pretty potent setup although not sure how long the rods and pistons would last! lol!