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What's Needed To Run 35Psi? Rb26-25

GD51LA

By GD51LA,
in Engines & Forced Induction

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XKLABA Grand Master

XKLABA

Posted
Posted

The pressure on the valves is both sides, in and out, the exhaust manifold usually has more pressure then the inlet

Then that also has to do with how old and tired the springs are and what there seat pressure is

Who ever said there was no such thing as a dumb question is a dumbarse :yes:

discopotato03 Grand Master

discopotato03

Posted
Posted

Yes higher poundage inlet valve springs because you have boost pressure behind the inlet valves acting on the whole area of the backs of the valves . You don't have combustion pressure on the chamber side of them as soon as they close .

More boost means greater heat and pressure and the hot/exhaust side is the half to worry about to avoid reversions and detonation . A dedicated turbocharged race engine has to be reliable when running in a supercharged state for long periods of time . OE road turbo engines are designed to use the "power boost" to get up to speed or climb the odd hill for short periods of time .

Interesting actually , restricted rally engines are often thought to have small compressor sides compared to the turbine side . This is because they are rev limited by the restrictor so have no use for large compressor wheels . The turbines are big in relation to the compressor because they have to have a survivable pressure and heat balance across the engine ie hot side vs cold side .

To make any engine survive a lot of boost for any significant length of time you need to increase the flow capacity of the hot side . Things like porting/exhaust valve size/manifolds/turbos with larger hot sides eg GT3576R/very low restriction hot side .

Actual engine cooling is important because you have to reject more heat developed by higher power outputs . Effective oil cooling / charge cooling / water cooling would be a real good idea .

The burning question is how long do you expect to be using high boost performance ?

A .

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scotty nm35 Grand Master

scotty nm35

Posted
Posted

Actual engine cooling is important because you have to reject more heat developed by higher power outputs . Effective oil cooling / charge cooling / water cooling would be a real good idea .

The burning question is how long do you expect to be using high boost performance ?

A .

^^ This.

Bolt that head down hard with some 625+ or L19's. And don't come crying if something lets go, it's bound to happen eventually. Even a popped cooler pipe makes a great mess at that pressure. :P

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