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Discussion Starter #1
hey my engine builder told me about a valve adjustment method he's used to get more power. what he does is instead of adjusting both intake valves to .008 and the exhaust valves to .010, he'll adjust one intake valve to .004 and the other to .012. and of coarse the exhaust valves to .006 and .014.
basically +/- .004

on the dyno a b18 gained 5whp and 6wtq.

it's not much power but just seeing if anyone has ever tryed this or any other method to get more power. let me know
 

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Discussion Starter #3
i don't understand how it works exactly but he said it has something to do with the cylinder starts sucking in from one valve 1st which makes it suck in more from that one throughout the intake stroke while pulling in alot more when the 2nd valve opens. but hey 5whp and 6wtq across the entire power band is worth it cause it's free power. i'm gonna try it when my engine is done. will try both ways on the dyno to see how much a single cam will benifit.
 

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Not really a good idea; it'll affect idle and maybe part-throttle driving.

What he's essentially doing is increasing or reducing lift a little by running tighter or loose clearances. They're there for a reason; metal expands when warmed up. If the clearance is too tight then the valves will literally be held open. Too cold and you'll have a lot of valve tick and maybe even premature wear.

Just have it set up where it's not ticking at idle during optimal operating temperature.
 

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Discussion Starter #7 (Edited by Moderator)
when you've dynoed it let us know. im interested!
my car probably wont be ready for the dyno untill march or so but i will keep you guys posted.
Not really a good idea; it'll affect idle and maybe part-throttle driving. What he's essentially doing is increasing or reducing lift a little by running tighter or loose clearances. They're there for a reason; metal expands when warmed up. If the clearance is too tight then the valves will literally be held open. Too cold and you'll have a lot of valve tick and maybe even premature wear. Just have it set up where it's not ticking at idle during optimal operating temperature.
well i could see how it could affect idle and part throttle, but the only cars that they did this to were being dyno tuned so car idled great and had great part throttle. the couple cars that they did this to have been running like that for a couple years. so i don't think there's too much wear that can be caused.
 

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on the dyno a b18 gained 5whp and 6wtq.
ya, most likely vs an engine that hadnt had a valve adjustment in forever. that vs your standard adjustment would achieve roughly the same thing

that was like Zex claiming 5hp increase from their sparkplugs. ya it did make it in a magazine test, but it also held that exact same gain with a just a new set of stock plugs vs the original old ones
 

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Discussion Starter #9
actually it was a newly built engine. just broke in so the valve adjustment was good.
 

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The key question here...does your builder primarily work on small/big blocks or on import motors? Not all Ford/Chevy principles filter down into what we're working with.
 

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this "trick" is just causing the intake charge to "swirl" just like the vtec-e 2 rocker design motors. I cannot see the benifit of ajusting the exhaust valves in this manner.

not to bag on you or your "tuner" but ajusting valve lash too tight is not a good idea. the valves need time seated firmly in the head to transfer heat effectively, being to tight may cause them to burn through especialy the exhaust valves. also may prematurly wear down your cam lobes.

in my experience most "free horsepower mods" are garbage.

make a intake or buy a ebay header and pick up just as many "ponies"
 

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if you've made the gap closer by that much. run the car turn it off after fully warmed up and get feeler gauge and see what it is when its hot... as long as the tappet has no contact with the valve during tdc when hot i don't see premature wear happening.
 

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there is still the cooling issue
 

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I'm really curious how this is going to pan out.

Would you get the same effect, albeit a tad safer, but adjusting one of the intake valves to about 0.012 and leaving the other at stock? I don't think this would help on exhaust, as stated, but it's an interesting theory.
 

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if you have noticed, the race drivers do that. My dad used to work at a shop and professional race drivers always adjusted for a bigger gap.
 

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He's adjusting for a smaller gap on one end; which could possibly mean the valve is being held open when the motor is at operating temp.

As for going with a larger gap, it's just annoying for a street car(ticking).
 

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well just what I do.

If stock (honda specs, cat, stock exhaust) specs is 0.007-0.009 intake and 0.009-0.011 exhaust, by adding headers (no cat, etc.) I go with 0.006-0.008 and 0.008-0.010 etc.

P.S.
I saw this specs for a d17A2 on crower stage 2 some time ago, don't remeber where.
 

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i think im going to do a valve adjustment soon, i have a d15b7 with i/h/e & "high flow cat", head resurfaced twice, cam gear retarded 2 degrees. I was wondering wut to adjust the intake valves and exhaust valves to with a safe outcome and possibly more power with this slight combonation of intake valve clearances you have been talking about.
 
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