Standard 4AGE Valve Springs and 18+psi???

[ap7]

I'd say if you don't go over 6.5k rpm in a turbo engine you might get away with it.

But you will end up revving it out more than that and I can guarantee you that!

These engines don't get happy till it is over 4k rpm and like it all the way to 9k if not more rpm.

For $220, I can't see why one would not invest in something like the HKS springs that I have for peace of mind.

I am revving mine out to 9.2k and it can still go further and my 4agze is turboed too!

I don't even run a rev cut out....why...cos I like to rev it out a little when it is needed! lol

[jeffro ra28]

Id just like to pipe in and say that heavier springs wont affect your power by any measurable amount.

Remember the extra energy required to open the valve is returned to the the valve train when the valve closes.

[oldcorollas]

some will be dissipated as heat too, but again, as you say it is not as simple as saying X increase in spring force = X more power required

[dangdang]

ohc engines valve train is pretty darn efficient compared to either a rocker or pushrod and rocker design. Billzilla wrote a great article on his site outlining this. It would however have to use at least a little more power with a heavier spring.

[dangdang]

Its all here..

Friction in the valve system(s).
The differences in the requirements for the valve springs, etc...

http://www.billzilla.org/2v4v.htm#friction

[oldcorollas]

at end of the day, friction = power loss, higher force = more friction = more power loss, but ti comes down to what % of what loss

[hosking1991]

im running performance branded springs on my 7mge build (they are the same part no for 4ag and pretty well priced) , they are about 10-15 pounds more in seat pressure compared to stock springs and i think @35mm installed height they were 55-60 pound, compared to factory springs which were a tad under 40 pound @ 35 mm

(and yes i know i work with both imperial and metric im a freak )

[dangdang]

Same p/n interesting. I went with the performance on a friends recommendation, he owns a machine shop and has had a lot of success using them in his customers builds. Also they were a hell of a lot cheaper than HKS.