a sheet metal intake manifold can be any size and length you want it to beptuomov wrote: ↑Thu Aug 13, 2020 11:37 amWhy? I’d much rather have the turbos spool up at low rpms with the stock intake manifold and then ramp up the boost at high rpms than have the turbos not spool up at low rpms with a short runner intake. And there’s an additional thermal bonus at high rpms when running pump gas.
Here’s how I believe the ramping up of boost at high rpms is going to work in my favor on pump gas. My street car is well intercooled, so it will pull out a ton of heat from the charge, especially when the boost is ramped up at high rpms. Then, importantly, the cooled charge will lose about 25% of the absolute pressure at 8000 rpm because of the intake manifold Helmholtz resonator being out of tune. This will cool the gas that actually makes it in the cylinder, and that's what matter. Even though the compressor outputs horribly hot charge, the cylinder actually gets not too hot, less dense charge after Intercooling and anti-tuned intake. Then one can give the engine more ignition advance on pump gas (compared to engine with a manifold tuned to increase the charge density like in NA engine).
The gain comes from the ability to run very hot charge thru the intercooler and have the inter cooler take out more heat from the whole intake system. Porsche is using this strategy in the four cylinder turbo models now in 2020 also after having switched to this strategy in the 2008 Carrera Turbo.
See what I'm saying?
Only way this "backfires" if the exhaust pressure gets too high and messes up the gas exchange.
can you extrude hone your existing manifold?
create a larger version of your existing manifold?
can you cut your existing manifold apart port it and weld it back togeather? - or acquire a second one for this purpose