09/12/13 12:02 PM
Valve Spring Comparison #2

Valve spring comparison #2
Evo VIII, Stock DSM, Manley, Brian Crower

From left to right

Used Stock 4G63
Used Manley
Used BC1100
New BC1100

The EVO springs, set of 16, tested 58-62 lbs @ 1.530

Used stock 4G63 valve spring Appox. 140k miles
56lbs @ 1.530

Used Manley Valve spring, mileage unknown.
78lbs @ 1.530

Used BC1100 valve spring, Appox 5000 miles
85 lbs @ 1.530
There must have been a change in the production of the springs about 2-3 years ago. Since the used springs test stronger than the new ones.

New BC1100, right out of the box
80 lbs @ 1.530

(it's peace of mind at 100 mph plus)
09/12/13 12:31 PM
Re: Valve Spring Comparison #2

Interesting information, Dale!

I've always been curious how the later evo stuff stacked up.

I really like the "beehive" design and the incrediablly light retainer that option brings to the table.

For old guys like me that don;t "zing" their motor north of 7500 much, but run in the 5500-7000 range, (a lot ), they seem like they'd be just the ticket.

Running more spring than you need just stresses the overlovin dogshit out of the valvetrain, and nothing good comes from that.

With the light retainer, I would *think* that the evo spring could have a lower rate and yet still control the valve action as well as (or even better) than a heavier rate spring/heavier retainer combo

What's your take on that?

Got some other questions for ya while you've got the rimac out

What's your take on mileage vs. rpm seen by an engine as it relates to spring "sag"

... Do the springs drop off dramatcically from the get go?
(as in, as soon as they enter service they start to lose some "boing", and it just goes downhill from there)

... Do they sag a scosche and then take a "set"?
(as in, do they drop a certain amount and then plataue at that number)

... does the temperature reached by the engine (overheats) affect the spring tension/sag as much as higher cycle rate a spring "sees" at max rpm's?

Thanks for posting here, I think a lot of us will learn something from your experiences.

09/12/13 01:06 PM
Re: Valve Spring Comparison #2

Well SOP in my shop is in tear down, stock 4g63 are just pitched in the scrap can. They are just not worth the time to clean and test.

This should show why. click

20 odd year old springs that have been hammered on for 100k + plus miles just need replaced (This is also SOP for SBC heads)

Now it seems the turbo head springs are weaker than NA, but for the price of a new set of singles they are still not worth fooling with.

You asked about over heating, I would feel that would also come in as a factor. Just look at how many honda fanboys take a torch to the suspension springs to lower the car????

As far as the EVO beehive retainer, yes it is lighter, but from what I have seen the factory piece is some aluminium alloy. I think back to some of the early small block heads I went through years ago that had the aftermarket aluminium allow retainers and the spring dig marks I would see under them and had to be replaced every season.

The beehive designed spring is a great design. I have no issues with it.

I do tend to set my combos up a tad bit on the stiff side, most spring manufactures suggest a 10% for spring break in. Now add boost to the back side of an intake valve, and you loose that much just to keeping the valve closed to boost pressure, the back side area of a 4g63 intake valve is appox 1.1 sq/inch.

So if stock boost level is 14psi with a new stock spring installed at 66lbs, now subtract 6.6lbs for spring break in, brings us to 59.4 lbs, now subtract 14lbs more for boost, leaves 45.4 to control valve motion.

But not many keep stock boost levels, or factory rev, so that number drops even more.

(my racist jokes aren't actually funny)
09/12/13 02:17 PM
Re: Valve Spring Comparison #2

So an engine pushing 30psi with stock valves and springs would have 30lbs to pull the valve closed? Wouldn't that float before stock redline?

09/13/13 10:12 AM
Re: Valve Spring Comparison #2

Prove it, Yes they should, but some get lucky and get away with it. Same reason some can run K272 cams on stock Evo valve springs.

I know if I set a head up like that, it would fail in short order, sometimes ignorance is bliss.

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