Low RPMs

[Racing Mind]

Why are the RPMs limited so low on the Ford direct injected engines (both Duratec and Ecoboost)? Is it a fuel system limitation?

Thanks,
Joe

[Sponsor]

[zetecDon]

Moved to "General Technical Chat".

[Racing Mind]

Don, I don't think the "general" area is the appropriate place for this question as it is directed specifically to the new focus ST, being direct injected. Can you please move this back to the ST forum, please?

[swansong]

The engines are simply designed to provide more power and torque at the lower RPMs, especially the 2.0L Ecoboost. The low end torque is more useful in everyday driving situations, versus having to rev up to 9k to get any power.

The dyno of the ST says it all, it doesn't make power past 5500, so no need to rev it past that. All the power to be had is in the midrange, by design.

[Racing Mind]

Thanks, Swansong. Have you gleaned any reason why the engine might be prohibited from revving higher? I'm looking to build a light-duty racing motor. The cams will push the powerband to the right.

[swansong]

I don't think it's prohibit as much as it's just designed with a specific powerband in mind. Whether or not the stock internals are capable of spinning much faster, with a different cam setup, I have no idea. Beyond my expertise

[amc49]

X2 swansong...............

'Light duty' and 'racing motor' to me would seem to be two diametrically opposed things.................the rpms are no lower than other over the counter engines intended to provide hi-perf while staying together for longer than 2 hours. The dyno shows the over run to go easily to 6000+ without dropping like a rock. Once ANY mass produced auto engine goes over around that rpm you can expect reliability to start dropping faster, hence the question of 'light duty'...........it's not a 12000 rpm bike motor, and surprise, start keeping them over 7000 all the time and they wear out just as fast.