Honda / Acura K20a K24a Engine Forum banner

1 - 11 of 11 Posts

·
Premium Member
Joined
·
4,257 Posts
Discussion Starter #1
I'm using k20a/itr cams with eibach evs valvesprings. I know the proper valve lash settings. However I wanted to find out who has played with valve lash settings? I know if you go tighter then you increase valve lift and can squeeze out a hair more power (more lift is the same as having a bigger cam). However if you go too tight, then you can end up with a bad idle and other problems.

I use to go .001" to .002" over on my old d16y8. Has anyone experimented on how far over you can go with the k20 before you have issues?
 

·
Registered
Joined
·
3,120 Posts
If you do that, just make sure that you check your valve lash when the engine is warm.

Unlike the D and B series the K requires the engine to be warm when checking valve lash.

I usually squeeze a couple of thousend more for valve lash on the intake side only. And has worked for me, but I have never dynoed to see if that will increase hp or not.
 

·
Premium Member
Joined
·
1,774 Posts
depends on a number of factors. With stock cams, you could probably run it to 0.000" lash and not run into any interference problems. That's not the case on many aftermarket cams where 0.000" lash would result in V2V or P2V clearances becoming too small.

The best thing to do is to monitor your hot valve lash settings. One of the main reasons to have the lash gap is to permit oil to coat the surfaces between the cam & roller. The minimum lash gap would pretty much be determined by that factor for stock cams. Of course, the tightest lash may not make the most power.

I've gone -0.002" on the lower bound for stock lash, 0.006"/0.008" on stock cams, and it made the engine quieter. I never got a chance to dyno test it, but the engine felt livelier.

With my skunk2 cams, I run the lash at .008" intake and exhaust. I won't go any tighter on the intake b/c I already have issues with 50deg VTC clearance. With 0.008" lash, I can safely run 45deg advance with no V2P. If I went any tighter, I'd probably have to trim my max VTC further.
 

·
Premium Member
Joined
·
4,257 Posts
Discussion Starter #4
If you do that, just make sure that you check your valve lash when the engine is warm.

Unlike the D and B series the K requires the engine to be warm when checking valve lash.
Umm really? Thats good to know because I assumed we did it cold since the other motors were that way. Well, guess I know what I'm working on Sat. morning. Thanks!

I usually squeeze a couple of thousend more for valve lash on the intake side only. And has worked for me, but I have never dynoed to see if that will increase hp or not.
Yeah, I'm not expecting huge gains, but if I can pick up 2-3hp for free, why not :)

So I think I'll follow Chunky's suggestion and just go .002 over.

Anyone know if there is a difference in the valve reliefs on the prc pistons vs the prb ones?
 

·
Registered
Joined
·
103 Posts
The real reason for valve lash is to allow the valve to sit on the valve seat for the designed duration of the manufactor. This allows the heat absorbed by the valves from the combustion process to be transfered to the seats, head, and water. If you run valves too tight you will "burn" them as they cannot remove the heat in the new short seat time. Getting oil between the roller and cam has nothing to do with the cam designed-in clearances.
 

·
Premium Member
Joined
·
4,257 Posts
Discussion Starter #7
Ok, so I just read the helms and it does not say that the engine needs to be warm to do the lash. it just says that the temp needs to be less than 100deg.

I assume that is just a guideline for the tech who has to do the adjustment on a car that was driven into the shop.
 

·
Premium Member
Joined
·
44,696 Posts
I know what you are saying Kommon, but when I recieved my cams from IPS there were specific instructions for the lash. Get it close with the cold (about 4 thous tighter than when warm), but recheck it warm. For reference this was posted by Edo a while back regarding what the K2 profile duration is on the intake and exhaust with different lash
0.008" hot lash - 326.9º and 318.9º

0.009" hot lash - 321.8º and 313.9º

0.010" hot lash - 317.0º and 309.2º

0.011" hot lash - 312.6º and 305.0º

0.012" hot lash - 308.6º and 301.3º

0.013" hot lash - 305.2º and 298.0º

0.014" hot lash - 302.1º and 295.1º
 

·
Registered
Joined
·
191 Posts
I'm using k20a/itr cams with eibach evs valvesprings. I know the proper valve lash settings. However I wanted to find out who has played with valve lash settings? I know if you go tighter then you increase valve lift and can squeeze out a hair more power (more lift is the same as having a bigger cam). However if you go too tight, then you can end up with a bad idle and other problems.

I use to go .001" to .002" over on my old d16y8. Has anyone experimented on how far over you can go with the k20 before you have issues?
Going tighter wont gain you any power and generally will cause a loss over the entire rpm range. Typically the lash grows about .004 inch from stone cold to operating temp. So if you have .008 lash cold it will be .012 hot. Cam profiles are also designed to run at a certian narrow lash range when they are deisgned.

The bigger the cam the more critical the lash becomes.

the lash tightens up over time so starting .001 looser or the top of the factory spec is generally ideal. for example the spec may be .008+-.001 so from .007-.009 of the range recommended by the factory. starting at .009 allows you to go farther between adjustments because the lash will tighten through the specification. if you start at .007 then it gets too tight very quick and hp goes in the toilet.
 

·
Premium Member
Joined
·
4,257 Posts
Discussion Starter #10
The bigger the cam the more critical the lash becomes.
I can definately agree with this.

Omni-Power said:
the lash tightens up over time so starting .001 looser or the top of the factory spec is generally ideal. for example the spec may be .008+-.001 so from .007-.009 of the range recommended by the factory. starting at .009 allows you to go farther between adjustments because the lash will tighten through the specification. if you start at .007 then it gets too tight very quick and hp goes in the toilet.
I'm not following this part. I understand what is being said, but in an application with stock/mild cams, I don't see how these issues could arise unless you go too tight. You are essentially increasing both the lift and duration of the cam. On a stock/mild cam, you still come out smaller than some of the more aggressive and higher performance cams on the market. So tightening up a bit might make your stock cam only as aggressive as a stg 1 cam. Now if you are already running a stg3 cam, then things would be different.

It sounds as though you are actually suggesting running on the loose side of the spec.

I also think that application matters a great deal here as well. My daily driven hpde car with stock internals will behave differently to tweaks like these than a trailored drag car with big cams.
 

·
Premium Member
Joined
·
44,696 Posts
I'm not following this part. I understand what is being said, but in an application with stock/mild cams, I don't see how these issues could arise unless you go too tight. You are essentially increasing both the lift and duration of the cam. On a stock/mild cam, you still come out smaller than some of the more aggressive and higher performance cams on the market. So tightening up a bit might make your stock cam only as aggressive as a stg 1 cam. Now if you are already running a stg3 cam, then things would be different.

It sounds as though you are actually suggesting running on the loose side of the spec.

I also think that application matters a great deal here as well. My daily driven hpde car with stock internals will behave differently to tweaks like these than a trailored drag car with big cams.
I am sure it depends a lot on the type of motor as well. (NA/turbo/n2o)
The valve is the only moving part of the valve train that is subject to the combustion chamber. Increasing lift duration lessons seat duration. There has to be a trade off.
There is a lot of good info in this article
http://www.profblairandassociates.com/pdfs/The Right Lift.zip
 
1 - 11 of 11 Posts
Top