944 S2 valves, springs, etc.

[azbanks]

I have the engine out of my 90 S2 cab and I am starting the rebuild process. I have Wossner turbo pistons and forged rods, ARP bolts, etc. I am still deciding on valves and valve springs. I am not planning on running high revs. I've found a supplier for stainless steel valves. I was hoping to find sodium filled exhaust valves but I can't find a supplier that makes them.

Does anyone have recommendations on valve springs and valves?

[wildcat077]

You might want to check out Ferrea's website , they carry a lot of products and i know they make a larger exaust valve for Porsche 2.5 engines.There was also a post in the Rennlist forums where somebody had found springs other than the turbo units that fit our application.

[azbanks]

The 944 S2 has the 3 liter, 16 valve head. Parts for a 944 Turbo will not fit my car.

[walfreyydo]

If you are not planning on running higher revs than OEM I would just run OEM springs and valves. Why not re-use the valves as springs (as long as they measure within spec)?

[azbanks]

Why?

A. 190,000 miles
B. Turbo

https://www.lindseyracing.com/LR/Parts/944VALVESPRINGS.html

[walfreyydo]

Valves and valve springs arent cheap so if it were me I would probably measure them first to see if they actually need to be replaced. But of course if you feel like you want to replace them regardless then I say go for it.

As I understand, upgraded valve springs are only needed for higher revs (raising beyond stock rev limiter) as the clamping force needed to return the valve to its seat in the required amount of time increases (ie: valve float). By the time the cylinder starts to build compression, the valves should be seated and Im not sure how you would need upgraded springs just because you are adding/increasing boost, but maybe I am missing something.

The LR site seems to suggest that boost will force the valve to stay open, but they also mention a redline of 7k rpm, aftermarket cams, which to me is the main reason why you will want upgraded springs.

[azbanks]

If you've ever closed a door in a wind storm, you have experienced the same type of effect a valve experiences working against boost. More wind requires more force to close the door.

The factory S2 valve springs aren't designed to deal with boost. I will be running up to 18 pounds of boost which adds about 40 additional pounds of force to close the valve.

My engine has around 190,000 miles on it now and I don't feel comfortable adding additional stress to springs with that many miles on them.

Building a S2 turbo is not something I would recommend if you want to save money. At least if you want to do it right.

I am already into this for:
new Wossner forged turbo pistons
new Wossner forged rods
bore and nikisil plate the cylinders
turbo
Broadfoot turbo mount with oil lines
Tial BOV
Tial Wastegate
FM Intercooler
new clutch
custom intake( ITB$ with a custom plenum)
custom V-band exhaust
cooper ring head gasket
rebuild the head
Stainless steel valves
DIY PNP Microsquirt engine management system
Custom wiring harness
1000 cc injectors
sequential COP ignition
sequential injection
044 Fuel pump
Radium Engineering fuel lines
Radium Engineering fuel damper
Radium Engineering FPR
Lindsey Fuel rail
new water pump, belts, rollers, etc
new gaskets and seals
new hoses
new vacuum lines
mi$c hardware
and a few other things.

[azbanks]

Does anyone know a good source for 968 intake valve seats?
Per the recommendation of Lindsey racing, I am going to upsize the intake valves to the larger 968 valves so I need to put in 968 intake valve seats.

[kdjones2000]

I have heard that the Microsquirts (at least the old ones, no idea about what you have) have had a tendency to lose their location on the crankshaft angle wheels, which has caused engine failures. This was a loooong time ago, mind you.

Just don't want that with all the $$ being spent on your build that something like that happens to it.

Have you looked at VEMS or ViPEC options already?

[v2rocket_aka944]

Eric,
Take a look on the RL 928 forum.
They found IIRC a Ford Modular 4.6L engine valve spring that fits the DOHC 944/928 heads.

Plenty of OEM turbo stuff comes with plain stainless exh valves. Sodium filled are nice but not necessary...I think if your turbine flows well enough it won't be something to worry about.

[azbanks]

Ferrea has a set of valves for the 2.5 liter 8 valve engine but nothing for the 3 liter 16 valve heads.

I have/had(also a long time ago) heard that microsquirt/megasquirt doesn't work well with the 944 NA and Turbo flywheel due to the number of teeth.
I have not heard of the being an issue with the S2 and 968 flywheels. the S2 and 968 flywheels have fewer teeth. My set up will have a sensor on the crank and a sensor on the cam which is required to run sequential ignition/injection. Having two position sensors should help keep things from grenading my engine.

I have looked at VEMS and used to help Peep with North American distribution of his VEMS PNP systems. He didn't do paypal so I was his middle-man for customers who wanted to use paypal.

I had already built a DIY PNP megasquirt system before I started working with Peep and wanted to keep using my own creation. I am also building a custom wiring harness with concentric twists, a twist-lock motorsports connector at the firewall, and other things to make as clean a harness as possible.