Limitations of the hydraulic valvetrain
 

Hello people,

I've been around for a while now, read a lot of threads but I am not much of a poster.

I have a curious question for the mechanical gurus, what do you think is the limitation of the hydraulic system? do you think that with the correct springs, it can hold around 10.5~11mm of valve lift?

awaiting for your replies, thanks.

E.

Re: Limitations of the hydraulic valvetrain
 

no. The valve will bottom out on the guide or the spring will coil-bind before you reach those heights in lift. If you are modifying the valvetrain, HLA's are only going to cause variables and inconsistancies

Tom

Re: Limitations of the hydraulic valvetrain
 

springs coilbind matter resolved.
what do I need to do with the valves? new taller ones?

E.

Re: Limitations of the hydraulic valvetrain
 

How do you have the spring issue resolved, yet still have no idea on valve length?
i only ask this as a person seeking info, not as someone trying to cause problems.

Re: Limitations of the hydraulic valvetrain
 

i have access to many springs sizes, mostly beehive.
i can get the valve length easily no problem. the thing is the svx valvetrain i have no experience in. my original question was to know what you folks think as experts in this car.
i am aiming to a very high valve lift in my turbo setup. i just want to know what to look at inside the valvetrain.
doesn't valve length affect the cam lift? meaning with taller valves, i cannot lengthen the lobes anymore?

wow, too late here, need to sleep, gn!

Re: Limitations of the hydraulic valvetrain
 

The issue with running taller valves is you'll either need to gut the hydraulics and convert to solid followers, or shorten the base circle of the camshafts appreciably. A smaller overall lobe will have greater stresses imparted to it and to the cam followers.

If you are going with much higher lift than stock, then presumably the shape of the lobe is far more aggressive. A more aggressive lobe *may* run into problems with the hydraulic adjusters. There's a lot of mass there for the lobe to toss around, so you may in fact encounter some issues with valve float that you wouldn't see with a stock cam profile. Strictly speculation on my part, but be aware you may be doing a lot of R & D to find out!

Re: Limitations of the hydraulic valvetrain
 

after reading your comments here guys and talking to subaru experts who have previous experience with hydros, i realized that an agressive hydro system might work well in the beginning but later on experience problems. needless to comment about the oil pump issue.

i think i'd better go with the solid system.

thanks

E.

Re: Limitations of the hydraulic valvetrain
 

anyone have info on the solid lifter conversion? is it a matter of fabbing an item the same height as the HLA (w/ correct lash) or is there some drop in parts available?

Re: Limitations of the hydraulic valvetrain
 

search for the word "valvetrain" and you will get there.

Re: Limitations of the hydraulic valvetrain
 

Like RallyBob sez there's a lotta weight moving.
That's the real problem w/ hyd cam parts.
The blessing being not having to check valve clearance occasionally
Which on a street car w/ a EG33 I wouldn't wanna do. Motorcycles can be bad enuff. Or even solid roller small block chevy.
If you're into check valves go solid for more consistent valvetrain action.
Why lots more lift instead of a combo of lift and dur + increasing LSA for the boost be more effective?
I'm guessing you got aftermarket ECU, what ya running?
btw custom length s.s. valves are about $720 for all 24.
which is why I didn't go w/ then for these heads.

Re: Limitations of the hydraulic valvetrain
 

will be running on an MS1 and will upgrade later on to MS2.

what do you intend to do with the heads?

Re: Limitations of the hydraulic valvetrain
 

If you're looking at megasquirt, you may be interested to talk to TomsSVX, as he had the hydra designed, it's like the megasquirt on steroids, it can do all, plus some, and is already designed for the SVX.