Redneck budget wastegate

[Eric Deslauriers]

So when you're cruising down the highway at 62mph boosting 12psi for about 23 hours, you think of a lot of ways to make your rig go faster for cheap.

Does anyone have thoughts on welding a flange onto the presurized intake tube and using a 13psi radiator cap as a pressure-relief valve?

Just a thought I had in one of my less lucid moments... ;)

[britannic]

It would probably work in principle, although I'm not sure if a radiator cap can handle the air volume. Oil mist will vent with the compressed air, the turbo will speed up as the compressor load lightens and there may be some high pitched whistling.

The only real reason to limit boost is to prevent the air overheating (when there isn't an intercooler) and to limit backpressure to an optimum level. The compression ratio and combustion pressures are such, that the real enemy is exhaust gas heat, not too much boost.

The best way to limit the boost pressure is at the exhaust turbine side, either via an exhaust blow off valve or a wastegate governed by the boost side.

[Larry Andrews]

Speaking of less-than-lucid moments...

http://www.takakaira.com/accessories/nightpager/nightpager.html

How's that for a budget wastegate?

[D-max Man]

What purpose does that thing serve?

[Larry Andrews]

Originally posted by D-max Man:
What purpose does that thing serve? My thoughts exactly! :cool: Had I not heard a couple of the local spiky haired youth talking about how cool it would be to have one...

[grape]

wastegates and blow offs serve two totally separate purposes. wastegate obviously controls total boost on the exhaust side. blow off keeps the throttle plate from looking like a taco on gas engines between shifts, not a problem we are faced with.

[Eric Deslauriers]

So what's too hot for an intake charge?

Remember, I'm only pushing around 650 EGTs on major uphills, usually in the 400 range. Yes, I can probably very safely add more fuel, but I'd rather keep the nice safety margin I have for now. smile.gif

TIA,

[britannic]

Originally posted by Eric Deslauriers:
So what's too hot for an intake charge?

Remember, I'm only pushing around 650 EGTs on major uphills, usually in the 400 range. Yes, I can probably very safely add more fuel, but I'd rather keep the nice safety margin I have for now. smile.gif

TIA, The intake charge density decreases with heat, until eventually there's not enough oxygen to completely combust the injected fuel. Boost pressure also goes up as the air heats up and expands more, but it's no longer effective for the above reason.

An IC and/or water mist injection are both effective at cooling the intake charge. For example, in the 6.5LTD, the intake air temp. at 12-14psi boost can be as high as 320F. A properly matched intercooler can readily reduce that temperature by 200F or more, resulting in more fuel being burnt, cooler EGTs and of course more power.