Why?

In my experience this is generally done to accept larger lifters to deal with long duration and/or super high lift cams. Is there a Miata-specific reason for this or are you changing cams too?

HLA's FTW.

What do I have in the top end? Nada. Refreshed stock head with about 20,000 miles on it and a dozen or so track days.

I know this doesn't help you what so ever, but I thought I'd point out the lameness of my car one more time.

Do I dare ask? How much are they thru Mazdacomp?

I may do cams at some point (I phrase it this way because my build is as yet unscheduled and unbudgeted), but it's mostly because it's a little awesome and is one more thing that will let me spin a few grand higher more safely.

I just like to do things to do things.

[QUOTE=y8s;431826]I may do cams at some point... but it's mostly because it's a little awesome and is one more thing that will let me spin a few grand higher more safely. [QUOTE]


A fair number of the engines I deal with at work are shim under bucket (Cosworth BD, Cosworth DFV, BMW M12, Lotus Twincam) and they're without exception a PITA and time consuming to adjust shims on. I'd think twice about that mod unless you really need it.

good thing I only plan to do it once! :)

Do HLA's need to be replaced as well? I'm looking at upgrading springs but hardly ever hear of anyone getting new lifters.

The money you'll spend on springs, retainers and seats will get you most of the way to a '99 head swap. Do that instead - the benefit is far greater.

Do the headwork on the 99 head before putting it on an earlier engine...

- L

(The answer to the cry, "more power!" is simply, "more money!")

actually rumor has it that you can take off more material on the early head and it will flow better than the 99. A friend of mine just dropped his head off at Endyne, so we'll know something soon.

Total bullshit. Port height is like 50 degrees on the 94 head, 20-something on the 99 head. I remember seeing flowbench numbers of 175cfm for a stock 94 head, 205cfm for a fully ported 94 head, and 210cfm for a stock 99 head.

Good to know that the ported 95 head in my garage should flow relatively close to a 99 head.

Supposedly Endyn has an NA miata motor that made 240crank ponies. I'll let them tell me what to do, not some kid who lives in his mom's basement.

I'm already in to deep on the 94 head (it's been mildly ported) that I've got. So I think I'll just stick with it.

So as to HLA's anyone know if it's a good idea to replace them?

Alright so it looks like their are a few different strength supertech springs avaliable for the miata. I assume that we would want the stiffest ones, but am unsure.

Any specific springs we should be looking at?

Specifically:
49lbs@36.80mm
74lbs @ 34.20mm
70lbs @ 33.50mm
56lbs @ 34.20mm
58lbs @ 34.10mm

Link:
BELFAB RACING PRODUCTS

Is there any place other than belfab that we can get miata specific supertech springs? I had a pretty bad experience with their rods and all around dealing with them.

You want the lightest spring per rpm/lift range.

Thanks for the response, but why do we want lighter vs heavier?

From what I understand, heavier springs will excessively load the cam lobes and wear down the cams and lifters faster. You want enough spring load to keep the valves from floating at max RPM, with a little margin, and not more than that.

zx-tex speaks the gospel. Put money in the cup!

So lightest is best, but how light?

Anyone know what the length of the 99 springs are?

Thanks guys