I have never heard of hydraulic lifters bleeding down at higher RPMs. I'm not saying it doesn't occur, but that I have never heard of it. I have heard of hydraulic lifters pumping up at higher RPMs and causing valve float.

I have also personally used special hydraulic lifters that bleed down more quickly. For a very large camshaft, they will bleed down at lower RPMs and give the effect of a shorter duration, lower lift camshaft to give better low and mid RPM torque. At higher RPMs, they do not bleed out enough oil to shorten the duration or decrease lift and therefore give full lift and duration. It is a clever but somewhat crude attempt to give the customer the best of both worlds. The only real downside is a bit of lifter chatter noise at idle and just above idle. See "Rhoads Lifters".

Supposedly the 1.6 lifters collapse at ~8400 rpm and give you reverse vtech, as per a local STS racer who forgot to turn his rev limiter down from 15,000 during ecu setup.

Yes.

They were actually over full and were compressed some before installed so they could re expand to the correct length.

HLA's will pump up if the valves float. Will collapse if there is air suspended in the oil, too much internal leakage or a lack of oil flow to the head. If you hear the infamous tick tick tick, than the plunger in the lifter is bottoming out. I've measured the plunger stroke at .150, if you have .311 of lift at the cam and .150 of plunger compression in the lifter you end up with .161 of valve lift which is a 48% loss.

That being said, I have never had a problem with Kia HLA's.

slmhofy is correct about the lifter weights.


OEM shim-over bucket = 44.7grams

[IMG]https://www.miataturbo.net/attachmen...ine=1364970803[/IMG]

OEM Mazda HLA = 50grams

[IMG]https://www.miataturbo.net/attachmen...ine=1364970803[/IMG]

OEM Kia HLA = 41.2grams

[IMG]https://www.miataturbo.net/attachmen...ine=1364970803[/IMG]

Just for reference a shimless Toyota 1zz-fe = 29.2grams

[IMG]https://www.miataturbo.net/attachmen...ine=1364970803[/IMG]



The Kia lifter is lighter than the Mazda because the plunger assembly is smaller. It also means their is less oil leakage and less capacity for aerated oil, therefore less collapse.


[IMG]https://www.miataturbo.net/attachmen...ine=1364970803[/IMG]


I have contemplated tig welding the plunger assembly together and grinding them to the necessary length to create solid lifter with no shims to fly out (like shim-over buckets) during those accidental mechanical over-revs. But welding and grinding 16 lifters would be a pain in the ass to do correctly, and i'm just not that cheap.

This summer I am gonna order some of these cams and am planning to pursue the zetec shimless lifters.

Hey Matt,

Thanks for verifying. And for reference, I am using the KIA HLAs ordered from partsdinosaur.com.

You seem pretty smart. I've got a question for you if you're interested in trying to figure it out. How did putting HLAs in my head with solid lifter cams change the cam specs. I've got a MSM with the BP5 intake cam and whatever exhaust cam they come with. I know the solid lifter cams have ramps to smooth the lash.

approx.
.007-.008 intake
.009-.011 exhaust

After rebuilding the engine/head with the HLAs, I have noticeably lower idle vacuum (used to be around 18 and now is about 12 in/hg @ 900rpm) and where it used to idle just fine at 14.7, it now very much more likes 14.0. Obviously there's more duration, overlap and a little lift, I'm just not exactly sure how much.

Zetec lifter
 

For weight comparison, here is my contribution to the lifters.
Ford Zetec lifter with 17.325 mm height weighs 32.6 grams, while the stock 2001 lifter weighed 47.1 grams with 3.24 mm shim giving total height of lifter 17.03 mm.

Thanks for the info!

Are you going to be doing some sort of write up on what's involved with someone going to these lifters? I don't think I've ran across anything yet of the forum.

Sorry guys, I can't really find spot on answer searching around. How do I fit 94-98 cam into 2000 miata? Or are they totally different and I am asking stupid questions?

Profiles for HLAs don't have/need intial ramps (to smoothly zero the lash) and don't play nice with solid lifters.
Upgraded Cams for solid lifters would be no different at all between BP and BP4W (the ports flows differently though).

That is not entirely true. Myself as well a many others have converted from HLAs to SUBs using the stock cam.

However, I think it is more or less a longevity issue. For racers it is A OK, not so much for a motor attempting to go 300,000 miles.

There are many things wrong that can "work" for a period of time.
With low loads and rpms the increased wear might not be noticeable during a enthusiast life (lash service time down to a third, maybe), with bigger cams/springs and rpms it might reduce the service life to a couple of hours (down from 10 or so).
The BP is not immune from physics.

It's possible to build race engines with OEM damper and worn OEM pump gears too, but you better keep track of what you could have done better (and don't blame others for your choices).

Running OEM damper and pump is far from an apples to apples comparison with running SUBs on a Stock hydraulic cam. The use of SUBs makes proven power.

I was under the impression that it was pretty common to use SUBs on stock cams in competition use. I was given this advice when I first started to mod my motor internally by Mazda Motorsports. The only way you can do business with them is if you are a racer with a competition license and have proof you are competing in a sanctioned event. I think this is a pretty reliable source as to what is best for race applications.

That was a few years back when I got this advice, but I am still unaware of any valvetrain problems resulting from the use of SUBs with a stock HLA based cam and mild springs, or if they still give this advice. If anyone knows of problems that I am unaware of, please chime in.

You mentioned big cam and springs. The miata cam is really mild, and you do not need big springs if you are running a stock cam with SUBs because you have lightened the valvetrain significantly, and are unlikely to increase rpm range.

Stock cam with free lifters could of course be a sanctioning restriction, and on the limit you will find some power (but you have to take care of your wear, as with everything in competition).
With some freedom (as in the Topic of this tread), I see few reasons for selecting a HLA cam and use it with solid lifters, even with mild springs.

I have noticed some wear on my SUBs, but have not seen any wear to the camshaft. I ran the car for years with an eventual camshaft change during that time. I will need to replace 2 or 3 lifters soon.

I think the mod is usually done in classing that allows only minor mods to valvetrain and must retain the stock cam.

I'm not sure, but I think you could use the 94-98 cam in the 99-00 head as long as you used HLAs.

Like was also mentioned, the HLA cams "supposedly" don't work that well with solid lifters as the ramp rates are faster.

Though they do work fine the other way. HLAs with solid lifter cams. I'm running that setup now.

Sorry for not responding sooner.

I don't have any specs on the BP5 intake cam, but based on your intake manifold vacuum and fuel enrichment I would say the valve overlap and/or the IVC point have been increased.

Increasing valve overlap will increase Internal EGR (especially at idle when manifold vacuum is at its highest). The nonreactive and hot exhaust gases remaining in the cylinder will cause unstable combustion which will lower power output, because idle is the speed where, engine output = friction and pumping losses, it will be necessary to increase idle air and fuel flow to stabilize combustion, which is why bigger cams idle at higher engine speeds.

Does any of that make sense?

My suggestion would be to advance the exhaust cam (rotate it clockwise), this will decrease the valve overlap and begin the exhaust blowdown stage earlier. Early EVO (Exhaust Valve Opening) will put more energy into the turbo and reduce pumping loses.

If you have a CAS and move exhaust cam, don't forget to reset your timing...

You can also retard the intake cam, which will reduce overlap and move the powerband up. The down side to moving intake cam is that, it is much more sensitive to changes than the exhaust cam.

Note: In my experience if you reduce the overlap too much the engine feels lazy.


I'm working on putting together a comprehensive post on cam design and selection but it could take some time.

For those that don't know, CAT Cams is a good cam manufacturer and have a CNC grinder capable of making some amazing inverted radius profiles.

Under most conditions I see no problem with using a hydraulic cam with solid lifters.

The profile properties such as ramp rate (velocity, acceleration, jerk) and the lash ramps (or lack there of) on an OEM hydraulic or solid cam are tame compared to performance profiles found on aftermarket cams.

You may experience accelerated wear when using part combinations that were not engineered together, but that should be expected to some degree.

Just remember Mazda or any OEM company's primary concern is NVH and longevity.