Valvetrain

[the_paynter]

Well im getting to the tear down stage of my engine for the twin turbo build.

I have decided to go with two journal bearing T3/T4 57trim Garret turbos with .63AR hot sides. That being said I would like to rev a little higher to give me a most usable power band.

I am thinking about BC stuff as TOM recommended before but what I would like to know if where will this move my available redline too. If it doesnt move it past the 8000rpm mark then I dont think the cost of the valve train upgrade will be worth it considering we can safely rev to 7400rpm stock.

If anyone has any idea if you could shoot it my way that would be awesome!

[TomsSVX]

Camshaft profiles will change where you make your peak power, not valves.

The valves merely allow for more lift and oversized valves will allow for surface area.

Tom

[the_paynter]

Camshaft profiles will change where you make your peak power, not valves.

The valves merely allow for more lift and oversized valves will allow for surface area.

Tom

But I want to also be able to increase my MAX RPM, is this possible?

I know that my WRX valvetrain (valves, sprins, retainers) were only safe till 7000rpm. When I upgraded to supertech dual springs, titainum retainers and nitrate valves, my tuner then raised my redline to 8400rpm

[TomsSVX]

So you are talking about staving off valve float with stiffer springs??

It all depends on the hardware you chose... If it is good for the profile you want on a 4cyl it should be known that the RPM transfers directly. So in short, try to match the hardware you use to the profile you desire

Tom

[the_paynter]

Thats the answer I was looking for :) Thanks Tom

[Seraphinwolf]

Shall we go more indepth about what kind of gains there are from the different Valvetrain upgrades and mods? Poticularly things like the converting to Solid from hydrolic, springs, valves, cams, and porting. :rolleyes: I think my build is currently gonna just lean heavy on the valvetrain mods to carry the increase I'm looking for with the standalone, MAP sensor, and larger injectors to keep up on the rest.

[Cam]

Converting from solid to hydraulic? I am not sure if you meant that the other way around. Our lifters are hydraulic lash adjusters. They fill with oil.

I would highly suggest keeping this set-up because solid lifters must be adjusted extremely often. To adjust them you have to get to them. This means the engine comes out. Big pain in the butt to do every couple months.

The other popular option are roller lifters but there is simply not enough space in our design to accomodate the roller.

[Splinter]

Converting from solid to hydraulic? I am not sure if you meant that the other way around. Our lifters are hydraulic lash adjusters. They fill with oil.

I would highly suggest keeping this set-up because solid lifters must be adjusted extremely often. To adjust them you have to get to them. This means the engine comes out. Big pain in the butt to do every couple months.

The other popular option are roller lifters but there is simply not enough space in our design to accomodate the roller.

He said convert to solid...

My 98 RS cam with solid lifters, as do all modern DOHC subarus. Valve lash adjustment has to be done... pretty much never.

[TomsSVX]

Converting from solid to hydraulic? I am not sure if you meant that the other way around. Our lifters are hydraulic lash adjusters. They fill with oil.

I would highly suggest keeping this set-up because solid lifters must be adjusted extremely often. To adjust them you have to get to them. This means the engine comes out. Big pain in the butt to do every couple months.

The other popular option are roller lifters but there is simply not enough space in our design to accomodate the roller.

Subaru suggests every 100kmiles... When this time comes, even then the clearances are off very little if at all

Converting is a necessity if you want a high RPM engine... The hydroulics bleed out

Tom

[Johnybeas]

what would be the benefit of increasing the rpm limits and going with the solids?

[NeedForSpeed]

Subaru suggests every 100kmiles... When this time comes, even then the clearances are off very little if at all

Converting is a necessity if you want a high RPM engine... The hydroulics bleed out

Tom

Plus, the hydraulic springs allow very little increase in lift, if that is important to you :eek:

[Cam]

Oops, I misread that and thought he said converting FROM solid. Sorry about that. It is what I get for hurriedly checking in and posting on my break at work.

It would still be nice to have room for roller lifters though:rolleyes:...