Ok, so I'm planning some engine mods for my blob wagon, I'm only looking for 300bhp for a nice, reliable fast road car.

So here's the question:

For arguments sake, let's say the stock TD04 could push 300bhp.

Am I right in thinking that if I switched to an AFP04 hybrid and instead of pushing that to its max of around 320bhp, keeping it at 300bhp would be more efficient than pushing a stock TD04 to its max as it would keep charge temps down under boost?

TIA.

 

In theory a larger turbo run at the same boost level should create less heat than the smaller turbo. Your mapper would find the optimum level for each turbo.
I changed from a ppp wrx wagon, TD04, running 260 hp to 3"Miltek exhaust and VF34 and couldn't make 300hp but that was 6 years ago.
Trev

 

This is in general, not specifically about the td04 afp hybrid, as i don't know what exh side is.

A larger turbo (with a bigger exhaust housing and turbine wheel) is less of a restriction. A td04 and a VF22 both creating 1bar in the inlet are flowing different amounts of air in volumetric terms. Because the VF22 has a larger exhaust housing and turbine there's less of a restriction so the flow is greater, to produce 1bar of pressure build in the inlet the VF22 is pushing a larger volume of air into the engine despite the pressure being the same.

It's a bit like having a balloon with a pin ***** hole in it (where the hole represents the exhaust side), if you blow it up to 1bar of pressure you can maintain that pressure with the air leaking out by gently blowing extra air in. If you make that hole larger (bigger turbo and exh side) to blow the balloon up to 1bar and maintain that pressure takes a larger volume of air to be blown in.

I know some people just think add a bigger turbo run it at the same boost and it's fine until mapped, but they're forgetting about the lower exhaust side restriction and therefore a larger volume of air to maintain the same pressure.

 

Yeah I'll be ultimately leaving it down to the mapper I'm just thinking 300bhp on a slightly bigger turbo capable of more will be running more efficient and have lower charge temps as the turbo isn't working as hard as a smaller turbo.