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Discussion Starter · #1 ·
Hi, I've got a JDM K20A that has just lunched itself (con-rod thru block and bent valves). Its fitted to a low-volume kit car. It had a JRSC fitted a couple of weeks before it blew (ran fine for nearly a year before that). I've taken it back to the shop that fitted the JRSC to complain. They say I must have mis-shifted to blow the engine. I didn't. Is it possible to plug into the ECU (hondata - sorry don't know exact model), to check the max revs that the engine had spun to? I've read loads of forums, but haven't managed to get a definitive answer (like directly from a Honda tech).
 

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The short answer is there probably is nothing in the ECU which will help you (it only records an over-rev, not the maximum rpm). The absence of an over-rev indicator will not help you as it can be argued that if the over-rev flag was set it has since been erased.

Anyhow, unless there was a defect with the JRSC or a problem in the installation, the shop which installed the JRSC did nothing wrong. K-Series are known for losing rods.

The next step for you would be to determine exactly what went wrong. You need to look at the rods, especially the rod bearings, including the blown rod.
 

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Discussion Starter · #3 ·
The engine has been stripped. Its a real mess in there, so hard to see what went first. They don't think the big end let go first. The assesment from the guy in the shop is that the piston in pot one hit the values, this mashed the piston and dropped the gudgeon pin. The con-rod then beat the remains of the piston to bits, got bent, and punched a hole in the block :(
So they think the only cause can be valve float, and that can only be due to an over-rev. Does all that stack up? Is it possible if the engine is 'only' revving at, or just below, the 8600 limit on the engine.
 

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Have any rod bearings spun? What do the undamaged rod bearings look like? Are the main bearings good? Have any wrist pins broken into pieces? Are there any heat marks on the crank or rods? Do any other pistons have marks on the top from the valves hitting.

It has been our experience that under race conditions the engine will eventually break at anything above 8600 rpm. The stock pistons, wrist pins and rods are all equally weak. Dropped valves are less common but can occur, especially if the engine has done a lot of miles. Usually if you overrev all 8 exhaust valves will hit the pistons and leave marks. A valve dropped from accumulated fatigue won't do this.

There are a number of different valve spring combinations for the K20A - what do you have? The stock springs start to float at 9200 rpm; but I suspect that the single intake springs (s2000 origin, usually yellow) go higher than this.
 

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Discussion Starter · #5 ·
Haven't looked at the bottom end myself (shop is 100 miles from home, only spoke on the phone). Can't call them now as its 10pm (UK), so can't comment on rod and main bearings yet.
The wrist pin (gudgeon pin in UK speak) did indeed shatter on the piston that failed.
I asked them to look for heat damage, as its the pot furthest from the water pump that went, and I've heard of locallised over-heating if the fuelling map is wrong for the blower. They say there is no sign of heat damage.
Valves have only hit one piston.

The car was not raced, but was mainly used for track-days, and regularly revved to 8k+, often on track for more than 4 hours per day (in 20 min sessions). We belived the myth that honda lumps are unburstable and didn't show it much mercy... The engine only had 6k miles on it when it blew.

Engine is stock JDM K20A, so whatever valve springs that comes with.
 

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Fishtale, that sux mate & I feel for you.

There are a few things that spring to mind reading your posts.
1stly - You say the engine only had 6000K miles on it when it blew right? So thats around 9700klm right?? In my experience, you should never "track" a car (engine) with such low miles on the engine - it hasnt had a chance to properly run or 'bed' in.....
2ndly - if you've had this engine in a 'track car' since new, the engine hasnt had a chance to run at normal running temps & conditions? Therefore, this would be subjecting the (metal components) in the engine to un-natural tempering processes - so you may simply have over-stressed the engine by force feeding it with the SC - maybe the engine was still too tight for the SC......

In my job, I have been running in cars for as long as I can remember - road & track. The engine has to be run-in gradually & evenly.

Also - its strange, i've still never come accross a NA K20 launching itself - stock or modified??

So what kit car is this fitted to?? Atom?? Westfield??
 

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Discussion Starter · #7 ·
SMB, thanks for the info. Yeah, the car was used on track pretty much from day one. The factory told us that running in isn't really necessary on modern engines (run in on the bench etc), but to take it easy for the 1st 500 miles or so - which we did. The car is road legal, so we ran in on the road, avoiding high/constant revs etc. Some sources suggest revving the nuts of the engine from day one to avoid polishing the bores, not yet convinced myself. In hindsight, following your advice of a longer run-in period may have been wise... However, it hasn't spent its entire life on track, about 50/50 normal(ish) road driving and track driving. Track driving was only track days, not real racing, so not totally brutal.
Tempering the engine prior to adding the blower does sound plausible, but unfortunately everyone I ask (I have mates in touring car and F3 in the UK) has a different theory.
Having searched the web, there are a few stories of K20A blowing, mostly user error - lack of oil killing the big ends, or missing a cog and buzzing it. One race series in the US has had reports of 'soft' con-rods causing failures (I think that may be rubber chicken's background).
The factory line seems to be that K20A's can only be killed by over-revving, so we must have done. Unsurprizingly, I'm not convinced.
I've now had a propper spanner-man have a look at the wreckage. The bottom end of the engine is absolutely fine - no spun bearings, crank journals all fine, no evidence of heat damage. The con-rod that hit the block is only bent, not snapped. The gudgeon (wrist) pin, is still in one piece (my earlier post was incorrect on this). The piston has completely disintegrated and destroyed/split the bore wall, and mashed all 4 valves. All other pistons/valves and the valve train itself has little or no damage. There is a tiny amount of scoring in the other bores, but this was probably caused by the schrapnel after the failure.
In the view of the mechanic (experienced, but not an engine builder), the piston let go before it hit the valves. Over-revving is still a possible cause, but not the only one? He thinks other possibilities may be detonation causing piston failure, or localized over-heating in pot one causing the piston to seize, and the con-rod to tear itself out. There is so little of the piston and bore wall left that its hard to check for heat damage. May need to send bits away for analysis.
You're on the right line with the type of kit-car, I'd rather not say which at this point to avoid unfairly harming the reputation of the garage with my whinging and conjecture. Will post details once our little dissagreement is resolved.
 

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To me it sounds like your analysis and conclusion are correct.

On the West Coast of the US there have been 7 K20A powered road race cars. 6 of those lost engines, usually in the first couple of months of use.

My engine let go after travelling all the way to Mid Ohio last August. It died in a similar fashion to yours - the piston let go. The rod and wrist pin were intact (still in the bore), but the piston had exploded into small pieces. The engine was fairly new and I am 100% sure it was not over-revved, the oiling and everything else looked good. Our conclusion initially for the other engines was the rod bearings were spinning, then it looked like the wrist pins were breaking, but after my engine died I concluded that the top of the piston falls off.

Road cars seem fine revving to 9000 rpm or so (I took mine up to 8800 rpm countless times, on the dyno and on the street). Circuit racing seems to be much harder on the engine than the street (people who don't race probably don't see why this is so). We have successfully got 3 K20A engines to last 6 months+ by limiting the engine speed to around 8000 rpm. The one surviving engine from the 7 race cars above was shifted at 8000 - 8200 rpm for it's whole life.

The conclusion is to limit the rpm on circuit engines, or replace the pistons and rods if you can. In our case the rules did not allow us to replace the rods or pistons, but for any track car I would say it is a good idea.

BTW the way to break the engine in is to put it under high load straight away, but limit the rpm. I break engines in by cylcing them from 2000 - 4000 rpm at about 5 inches vacuum (approx 1/3 throttle) for 10 minutes, then 2000 - 5000 rpm at almost full load (2/3 throttle) for another 10 minutes. Don't let the engine idle any more than necessary from the first startup. Dump the oil and filter, replace with synthetic, and you're done. This method gives a leakdowns of half a percent or less, and gave me almost 6 hp more than engines that other people had broken in. If you are using non-Honda rings then the break in will take much longer (perhaps 5-10 times as long) and you'll only get down to 2% leakdown at first. Then the engine will slowly come down to around 1% leakdown after a thousand miles or so.
 

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In Australia, we have the K20A2 - 8000rpm limit, 11:1 comp (not 11.5:1) different cams (same lift but less duration) heavy ass flywheel, smaller inlet manifold ect.
They're rated @ 147Kw & 193Nm. Not bragging or anything, but out of all the guys in QLD & probably Australia (not race cars but there's only 2 or 3 max) I've had my car on the track (probably) more times that anyone else - my car gets the absolute shit reved out of it & I push it as hard as it will possibly go. I 've never been back to Honda since buying new in 9/03.....just used Redline 5W30 from 10K onwards & changing that oil only 3 times since then - its now done 24,988klms ........20+ track days would be an understatement.

Since Hondata, Toda Headers, JDM Intake Manifold, InjenCAI & the (proper) 2.5" mandrel bent exhaust, the power increase is huge, bloody massive - I know the engine is under a whole new lot of stresses now, & its driving characteristic is completely different - I am blown away by the difference it has made, but at the same time, respectful of the engines' requirements. I do a number of warn up laps before going full bore, & once finished, I always (without fail) slow down to about 55-60kph, reach down & pop the bonnet whilst driving back to the pits. This gives the engine bay a massive dose of cold air, & by the time I get back to pits, the engine/oil temps are back to road-regular.......its not good coming in & having a stinkin' hot engine, that's asking for trouble if you ask me.....

Re-reading the last 2 posts, it does sound like that single piston let go all by itself, but that's strange, I'd even go so far as to say it was manufacturing fault (metal fatigue) but theres' no way warranty would touch you as the engine had a Blower on it.
 

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Up until a few weeks ago I probably had the same attitude as you. But since my JDM lost the bottom end I no longer have the K20 on such a high pedestal. My engine was used in a similar manner to yours, mostly track days. Never caned till the oil was up to temp and it always got a cool down lap. These engines are not indestructible and boasting about a lack of oil changes may come back to haunt you... Not having a go at you, just want you to be aware that these engines are not as tough as some make them out to be.

Video of it letting go here
 

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OH MY GOD !!!!! I WILSON!!

how freaky is this - I was just watching a massive downloaded vid of that exact same clip, but it finished after the straight. So if effect, you just showed me the remainder of that whole clip!!!! FREAKY!!!!!

Mate, you were going EXTREMELY HARD, & that track is a continously high revving maxxing out sort of a track, well, for an Elise anyway...:)

Was that big-end failure??, it sounded like a real gradual whirring, then turned into that severly nasty daka daka noise.
 

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Something else I just thought of.....

When the K20's sitting in an elise, its behind the driver right? So theres no way its getting the same amount of general air flow around it as it was designed & intended for. I know you can get oil coolers ect, but a constant cool airflow, going under & over the engine is just as important as cooling the oil.
 

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Bloody IE just lunched itself as I was about to post a reply aahhh :hammer:

Yes the engine is mid-mounted, but there are two naca ducts on the undertray, two side intakes, plus the engine cover is mostly mesh. The temps were all OK. Engine is in the UK now waiting to be examined, but a big end is as good a guess as any. Seems to be a bit of a weak link with the K.

Having read what Mr. Chicken has had to say I'll probably reduce the cut-off to around 8,200 from 8,600.

Just out of curousity what Forum has the link to the video you were downloading? I though I'd taken it down from my site to make room for other stuff.
 

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It was UK based, a guy I know Trung (EP3CTR) post it up on CRSX.

So what are you going to do now?? Have you seen inside the motor itself to see where the damage is?? Pls try & post up some pics, this would be really helpfull.

When I had the Hondata tuned, the tuner & I discussed a few options regarding rev limiter ect....I left it at 8500rpm after much deliberation, I was going to go higher to 8800, but its strange, you get a small sinking feeling during the install thinking "What if it blows up whilst at 8500+" !! OMG !!! so we left it at 8500.
After 3 days of road tuning, we went to the dyno where it was all black & white. We only needed an hour on the dyno to finalise the tune. The car couldnt make any more power after 8250rpm - the cams have the lift, but not the duration. The Toda headers worked their magic tho....providing a massive mid range gains.
So needless to say, I dont rev it past 8300 on the track unless I wasnt watching what I was doing - there's no point - if fact the power drops away after 8250.....doesnt even flatten out?

Here's a clip of me at the Track. you'll see because of the track, we dont hold the rpm's you guys do, so i'm sure that helps the engine!!
This is pre-Hondata, but with Toda Headers, oh yeah, and a boring 8000rpm redline, that's why it doesnt sound as if its going that hard!! lol
BTW - heading down the straight past that 13B RX7, I was in 5th gear flat bikee....... :D
http://members.iinet.net.au/~joannepulis/sparefiles/Hot lap with Stu QR.wmv
 

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I had done about 20K miles on mine when it went. It was perfect until it popped. Engine will be cracked open next week - photos will go up shortly after. New JDM is in already, but I'm fitting an extra oil cooler and tidying up the wiring etc while I have the rear clamshell off. Also connected the VTEC oil pressure sensor that is missing for some reason on the JDM K20A. This is useful since it can give an early warning of oil stravation since it triggers at something like 35psi and drops the engine out of VTEC. The engine had a baffled sump so it shouldn't have run out of oil. But Spa (where the video was shot) has some nasty high speed, high G corners that can cause oil stravation. Funny thing is I was taking it relatively easy - only my 4th lap of the day and I was on road tyres, instead of my normal R compound. If the budget can handle it I'd like to dry sump the engine at some point.

Got a mate living in Byron Bay that's Honda mad, he going through the process now of trying to import his K20 powered Elise into Aus. I'm sure he'd like to get a pax ride in yours on track.

I can only see the first 40 sec of your vid, I get an error after that??? I like what I see though :up: Another vid of my car is here at a Dutch Sprint/AutoX http://www.planet.nl/~iwilson/Lelystad_combined.wmv
 

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OK just caught the thread on CRSX. Bit of background on that vid. The other car in the vid is a racing K20 powered Elise on full slicks. I did the video to show the difference between road tyres and slicks. The lap of my car is actually my first lap out - which is why it starts at the end of the straight since I was warming the engine up prior to that - didn't need much since I'd just done two laps before someone crashed closing the circuit for 15mins.
 

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Discussion Starter · #17 ·
Rubber chicken - thanks, very interesting. So few K20As fail its been hard to find details of any similar failures to ours. I was starting to be brainwashed into thinking I simply must have given it too many revs at some point.
When the car is re-built we'll definately reset the rev limit to 8200 - especially as we're force feeding it. As we don't race (yet) we have the option to uprate the rod/pistons and have been getting quotes for doing exactly that. May well go this route if the prices aren't too silly (like more than a 2nd hand replacement engine).
The run-in info backs up what I've been told by others, will follow this advice with the new engine.

SMB20 - we religiously follow the warm up/down for the car too, just don't open the bonnent, cos there isn't one.
How long have you had the hondata and higher rev limit? Have most of the track days been with the 8000 limit?
I realize that Honda are never gonna take the engine as a warantee case, our question is about the amount of R&D done by company that engineered the car and blower conversion. The peak power moves further up the rev-range with the blower, so you do get more power for revving past 8200 - if it stays in one piece...

iwilson - I've read your comments on possible oil starvation elsewhere. Sounds plausible to me, given the number of road cars that have lost a K20A because the owner simply didn't realise the consuption of the lump and let it run dry. I fully understand that you were NOT low on oil, but experiencing big G's - I guess that the results of starvation are the same in either case. It will be interesting to see the state of your pistons when the engine is opened up, but certainly sounds like the bottom end on the clip. Good tip on the VTEC sensor, I'll check it out on ours.
 

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I can imagine which thread that was... The thing with the VTEC oil pressure sensor is if you notice the engine drop out of VTEC when it shouldn't you know you have an oil pressure problem. Whereas with a gauge it's very easy to miss a quick drop in pressure unless it has an alarm like the SPA gauge for e.g. I presume your's had a baffled sump?

What are your plans? May be cheaper to salvage the head and flywheel and get hold of a Euro CTR block. The slighter lower compression won't matter since you're S/C. I may be able to help out.

Dunno who you do your trackdays with but I can recomend Lotus on Track (it's not only Lotus). Non-profit so cheaper, plus very high standard of driving. 30 pound membership fee, which you'll get back in money saved on your first event. http://www.lotus-on-track.com/
 

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Discussion Starter · #19 ·
We have no pressure guage (yet), so dropping out of vtec is much better than waiting for the oil pressure light of death.
Yes we've got a baffled sump. Also ran formula R, so pretty high cornering loads, but neither of us are that much of a hot-foot so certainly not as much as the tyres could have managed if we had the talent.
Considering a UK lump if we can't come to an arragement with the factory for sharing the cost of a replacement JDM. Our man thinks the head may not be save-able as valves have been mashed into it pretty hard. Same thoughts as you on swapping fly wheel (unless its a really recent UK K20A), and on lower CR probably being better for force feeding anyway. Only downer will be slightly less lumpy cams if the head cannot be saved. Best offer so far for 2nd hand UK engine is 1500 quid for cash, but no provenance. Also found JDM lump (with g'box) for 5500+VAT, certified 15k kms. This isn't far off new price for engine only, and we don't need a new g'box, but seller doesn't want to split. Any better offers you know of?
So far all UK trackdays, mostly midlands-ish - Donny, Oulton, Bedford, S'stone, Brunters etc. Interested in the organiser you mention, will check it out. In a similar vain, we've done lancer register and scooby club days before - both the right price and don't mind if you don't have the 'right' car so long as its interesting and you don't drive like an arse. Goldtrack/RMA seem to run days well, but you pay for it. Sleazytrack are getting better. Tracksport really well run and cheap, especially for Oulton.
 

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I'll see if I can sort something out. My old JDM is back in the UK now - it's probably only spun a bearing... Not sure what the plans for it are. Pretty sure a low miler Euro Type R could be arranged. Drop me a mail to [email protected] if you don't get a result with "the factory" :)

LOT do quite a few days at Bedford, Brands, Donny etc. Occasionally they'll share with Easytrack or RMA. Also do quite a few European events. I'll definately be at Zandvoort in August - very nice track, well worth a visit :up: Mostly Elises/Exiges from Standard to 300hp+ but also Porkers etc. Be nice to see an **** in action.
 
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