what power levels can the standard valve springs handle?

[K7ERG]

as the heading. What is the power level standard valve springs can handle? Before having to change them for different ones. Also where to buy new standard valve springs?

[aelred]

I am in the process of getting some from Schrick, I can give you some info later once I speak to them

[MrVain]

Hmm

The standards spring dont like revs above 7500rpm. But they can handle alot of power. Theres been alot of cars in sweden with more than 700hp with original springs.

[Graham]

The spring has is not effected by power--heat and speed are what kill springs the springs only close the valve, the cam would take all the load of opening a valve under pressure, the spring is just there to shut it again

[EspenW]

Lighter lifters and lighter retainers can extend the possible rev range of the springs.
Using stiffer springs with stock rev limit (and not too radical cams) is a complete waste of money that will cost horsepower and accelerate cam wear.
You want the softest spring that will not float the valve at redline. Anything stiffer will cost horsepower at all rpms.

[Jamo]

Lighter lifters and lighter retainers can extend the possible rev range of the springs.
Using stiffer springs with stock rev limit (and not too radical cams) is a complete waste of money that will cost horsepower and accelerate cam wear.
You want the softest spring that will not float the valve at redline. Anything stiffer will cost horsepower at all rpms.

Exactly

Springs are more of a concern with higher lift cams as the higher the lift the more of a pounding they take.

[S2central.net]

Agreed also... Nicely worded by Espen there

[javispa]

I know it may be better to ask this somewhere else but, as it all has relationship with head specs, I have decided to ask it here. I was wondering how much output can the standard valves handdle, and also how much power could be obtained using the stock head, without having to modify / polish ports and valve guides.
Thanks very much .
Cheers!

[Taagom]

... how much power could be obtained using the stock head, without having to modify / polish ports and valve guides.
Thanks very much .
Cheers!

I have the same question.
My car :
7a cams and stock head
GT35r 1.06 @ 2bar
wagner turbular exhaust manifold
costum intake manifold, 82mm throttlebody, 3'' piping
3.5'' downpipe
Power at the wheels : 386nm & 365hp


.. so are the stock ports the biggest thing holding my power down ?

[MrVain]

I have the same question.
My car :
7a cams and stock head
GT35r 1.06 @ 2bar
wagner turbular exhaust manifold
costum intake manifold, 82mm throttlebody, 3'' piping
3.5'' downpipe
Power at the wheels : 386nm & 365hp


.. so are the stock ports the biggest thing holding my power down ?

This car has a stock head and 7A cams. Only harder valve springs.

http://www.garaget.org/?car=71679

It was on the PPF dyno last week and got 590 whp...

[Taagom]

Thank you very much for the info.
Do you know where i could find the dyno chart for this 590whp pull ?

[MrVain]

Thank you very much for the info.
Do you know where i could find the dyno chart for this 590whp pull ?

Sorry.. no
Dont think he have posted it..

[Bram]

I have the same question.
My car :
7a cams and stock head
GT35r 1.06 @ 2bar
wagner turbular exhaust manifold
costum intake manifold, 82mm throttlebody, 3'' piping
3.5'' downpipe
Power at the wheels : 386nm & 365hp


.. so are the stock ports the biggest thing holding my power down ?

Did you check your cam timing already? Your RR graph looks a bit different from what I would expect from a 7A cam setup with a GT35. Especially that dip just before the line starts climbing.

[Taagom]

The cams have stock timing.

[EspenW]

I have the same question.
My car :
7a cams and stock head
GT35r 1.06 @ 2bar
wagner turbular exhaust manifold
costum intake manifold, 82mm throttlebody, 3'' piping
3.5'' downpipe
Power at the wheels : 386nm & 365hp


.. so are the stock ports the biggest thing holding my power down ?

Can you post the AFR graph too. I had the same sort of dip when running too rich. Superflow is a strict dyno, so 395whp isn't that bad, but 386nm is low for that setup.