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Hi,
my accord euro '05 lately has been starting like a diesel engine (the sound of a diesel 4WD startup)..is it because of my 80k service is coming up or is it normal..
Also i have been experiencing some power loss on highways 100k..where going up a slope now it kicks down sometime 2 gears where i recall a few months back, no issue..
possible air filter is dirty?
Fuel injectors.
Try some injector cleaner.
Doubt it is the injectors. I'd put my money on a worn out timing chain tensioner and that the valve clearance needs adjustment.Quote:
Originally Posted by Type R Positive
get your valve clearance done to K20 spec FTW! :thumbsup:Quote:
Originally Posted by aaronng
well looks like the 80k service does include valve clearance. Ok thanks.
If they find that the valve clearance is within spec, then get them to check the timing chain tensioner.Quote:
Originally Posted by revivor
i noticed on the service interval manual, it states they will also check the accessory drive belt. What drive belt is this? Where is this located? Just curious.
Will it cost extra to adjust adjust the timing chain or how much to replace it?
timing chain to replace is damn expensive!! alot of labour! but they shouldnt need to replace te chain, no way! they last for ages... possibly the tensioner, but that easy as to do...Quote:
Originally Posted by revivor
the drive belt is the one that goes around all the pulleys on the driver side of the engine :thumbsup:
Further to and as an enhancement to EURO03act reply, the accessory belt does not drive the cam shafts.
what is required and how much to get it done to K20 spec? :pQuote:
Originally Posted by EUR003act
lol its probably not recomended on the K24 valvetrain (im not sure if itd cause excess wear?) but because i have the K20 valvetrain :p i did all mine to their spec... it didnt cost me anything cause i did it with my friend when we did the head swap...Quote:
Originally Posted by Crapdaz
ive got the spec somewhere if your interested:thumbsup:
Do you feel more powerful?Quote:
Originally Posted by EUR003act
lol dont know, still running stock ecu, stock TB, and hot air intake... :(Quote:
Originally Posted by SPQR
Thanks. I wonder whether such mods work. It's good that someone does the experimentation!Quote:
Originally Posted by EUR003act
What difference is there between "K20 spec" clearance and stock?
My understanding is that you want the minimum cold set valve clearance possible that allows some minimal clearance of the cam lobe base circle when all is at operating temp (with hotter and elongated valves etc...). The smaller the clearance the higher the valve lift and the longer the duration (ever so slightly for both), which should improve breathing just a gnat's whisker.
If this is what the 'K20 spec' is (i.e. a tighter clearance) then it should help power to an infintesimal degree so long as the base circle is not touching the follower. But if the K20 spec is a larger clearance that is not required to provide adequate clearance then it may infintesimally hurt power.
Sounds about right.What difference could there be.:confused:Quote:
Originally Posted by JohnL
the K20 spec is tighter... and yes your right, thatll mean slightly more lift and duration on the cams... which should mean slightly more power...Quote:
Originally Posted by JohnL
the main problem you might face with the tighter settings is that the valve doesnt seat properly with the weaker K24 springs, equalling loss in power :(
Correction - K20 and AUDM K24A3 spec are the same... lol i was looking at the USDM K24A3 spec...
K20 spec:
Intake: 0.21-0.25 mm
Exhaust: 0.25-0.29 mm
K24 spec:
Intake: 0.21-0.25 mm
Exhaust: 0.25-0.29 mm
Why don't you install some ITR springs while you've got everything pulled apart Justin.Quote:
Originally Posted by EUR003act
lol what do you think was in the K20 head i bought?Quote:
Originally Posted by tony1234
lol my entire cylinder head is K20Z1 except for the cams... so my rockers/vlaves/retainers/springs all stock capable of 8500rpm all day long :p
Ah,ok,then get ITR cams then.Quote:
Originally Posted by EUR003act
i have ITR cams... lolQuote:
Originally Posted by tony1234
K24A3 exhaust is better in everything, ITR intake cam is only better for VTEC, its primary and secondary lobes are smaller... :thumbdwn:
hence i stuck my K24 cams back in lol
But probably not the pistons, bearings and crank?Quote:
Originally Posted by EUR003act
talk about hijack!
LOL!
Maybe your car sounds like it is diesel cause it has piston slap, I hope not. Give it a good service and hopefully it runs better.
lol no, probably not lolQuote:
Originally Posted by SPQR
although there is a guy in the states that runs his to 9000rpm for dynos...
(running K20 oil pump)
lol i think ill stick to 8000rpm however :thumbsup:
sorry to hijack, im ashamed :(
I'm having trouble seeing why that would be the case (with any springs if the only variable were the clearance), unless the clearance was so tight it wasn't really a clearance at operating temp...Quote:
Originally Posted by EUR003act
The problem with weaker springs usually occurs at full lift as the valve train 'overshoots' the cam profile due to mass intertia, and perhaps a slight bounce as the valve seats, if it seats harshly (which should I think be more gentle with a lesser clearance).
you said it right there yourself, with a weaker spring on a very tight clearance, the spring may not have enough pressure to push the valve all the way home...Quote:
Originally Posted by JohnL
its not going to be an issue as the AUDM K24A3 has the same spec as the K20 anyway... but if it were the K20A3 or the USDM K24A3, then yeah it might cause problems...
Then is that a problem with low spring stiffness or with inadequate spring pre-load. I'd suggest it's an issue with preload and the spring needs to either be longer or shimmed at it's base (so long as you could shim it without risking coil bind).Quote:
Originally Posted by EUR003act
I'm all for using the weakest springs reasonably possible for the red-line the engine sees (+ a bit for safety), stiffer springs use power and cause greater cam wear etc.
It seems to me that so long as any clearance exists then the spring will be pushing (or pulling) the valve shut just as hard no matter what the clearance might be.
you may be right, it was just interesting to me that the engines which have the lower redlines/weaker springs all have slightly looser clearances...Quote:
Originally Posted by JohnL
and true, hard spings to use up valuable power
I suspect it might allow more time to safely ignore the valve clearance?Quote:
Originally Posted by EUR003act
Sometimes valve clearances open up with wear, sometimes they close up with wear, depending on what surface is wearing the most quickly (i.e. wear on lobes / followers / valve stem tips causes clearances to open up, wear on valve seats causes them to close up).
My gut feeling is that it's probably safer to allow the clearances to get too big than too small, hence a larger clearance on a lower perfomance engine with a longer clearance service interval(???).
Or, maybe one engine model wears the lobes / followers etc faster (than the seats) and can tolerate smaller spec clearances because they tend to get bigger in service, but the other engine model tends to wear seats more so the clearance tends to get smaller in service, thus requiring a larger spec gap...???
Dunno, just thinking out loud..
Nah, you can create too much force smacking the valve cap.Quote:
Originally Posted by JohnL
One of my good mates lunched the head on his 450 dirtbike, as valve clearance was out of spec (too large) on one valve. I used to help him with all that stuff, as there is nothing to doing cam swaps and valve clearancesw in these things.
He never got around to replacing the shim that was out of spec, and guess which cap smashed to pieces, in turn dropping the valve into the cylinder and making a mess of things?
My theory is you could throw the valve open, insted of just pushing it open with loose clearances.
I guess that's why they have a lower and upper limit to valve clearance specs.
Yes, it's bad thing to run with an excessive clearance for an extended period (and if you do you may end up wrecking the surfaces etc), but if the clearance tightens so much that at operating temp there is a negative clearance then the valve will be held just slightly open.
Keep in mind that the hot clearance will be significantly less than the cold clearance due to the valve expanding and getting longer as it heats up, which is why the clearances are more like 0.3mm than 0.001mm (and the hotter exhaust valves typically run a larger clearance than the cooler inlet valves).
Losing all clearance would obviously cause some compression loss, but more seriously may also cause the valve head (particularly an exhaust valve) to overheat and burn the lip of the valve head (causing more compression loss and a need to replace the valve).
This is because the hot valve head needs to seat home for a significant duration in order for heat to conduct from the valve head (through the lip) into the much cooler cylinder head. If this doesn't occur then the valve may just get hotter and hotter, and hotter.
Some heat usefully transfers through the valve stem into the head via the valve guides, but this isn't as good or direct a heat transfer pathway as the valve seat.
This is also a reason why it's a bad idea to narrow the width of the seat on exhaust valves, i.e. narrowing the seating width reduces the area of contact between the valve and the valve seat, causing a reduction in heat transfer from the valve head to the cylinder head and can cause the valve to overheat (leave it at stock width is usually the best thing).
I don't understand your theory...?Quote:
Originally Posted by Type R Positive
Like this: http://www.yucs.org/~rweiser/pics/balls.gif