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Rebuilding 531 head

2farty2

2farty2

New member
Joined
Nov 8, 2012
Location
Tidewater, Virginia
I'm looking at buying a 531 head and rebuilding it before I put it in my turbo build.

The goal is to get as close to 300hp as I can on a 15g. Obviously, this necessitates bigger valves, better cam, and all of that.

My questions are:

1) With an IPD turbo cam, will the stock 531 valves do it?

2) If the stock valves will flow enough, will the materials hold up?

3) If I have to upgrade the material, I'll buy larger valves. Am I correct in thinking that 38mm Exhaust / 46mm Intake valves are the largest I can go on stock seats?

4) RSI Economy Valvetrain, or OEM Volvo for springs and retainers?
 
That was my question: Which one is better? I have heard that the stock valvetrain can safely hit 7,000RPM, but then again RSI guarantees that their springs and retainers can do it.
 
What fuel system are you planning on? You don't need 7000rpm to make 300hp. That being said, are you targeting 300 at the crank or the wheels?
Either way, there are a myriad of threads on the 300hp recipe...
 
Also, though I'm shooting for 300wheel now, I know how addicting boost can be. That's why I want to put my money into supporting mods and overbuild a 300hp car. The 531 may sit in my garage until I build a bottom end to match. Not sure yet.
 
The stock valve springs are soft. You can see signs of valve float on a stock cam. There will be smooth shiny areas and then a light golden color, then another shiny section. That golden section on the cam lobe is where the tappet is floating off the lobe. You can see this on almost any Volvo cam.
For higher revs I would highly recommend some better springs.
 
If they are stiffer than stock, and don't hit crazy harmonics at 7k, then yes they are better.

I started using modified air-cooled VW race springs, but they require machine work to fit properly. CB Performance makes them, about $70-$120 depending on model.
 
culberro said:
If they are stiffer than stock, and don't hit crazy harmonics at 7k, then yes they are better.

I started using modified air-cooled VW race springs, but they require machine work to fit properly. CB Performance makes them, about $70-$120 depending on model.
Click to expand...

Yeah the VW Bug-pack derived stuff everybody sells is fine.............if you want to DOUBLE the recommended seat pressure....

In before "I never saw a problem!!! I LIKE my springs!!!"
lotto-gifs7.gif
 
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