[QUOTE=PTAddict;578145]I have no experience with any of the above, although I've researched a lot and plan to add a Harrop system in my car in the next couple of years.
(ITBs present quite different challenges to the ECU in low throttle situations).
Correct. So make sure you get an ECM that will allow you to change cyl to cyl fuel trim at not only idle but other areas of the rpm range. There are only a few that allow you to do that.
Biggest advantage of a true ITB in a streetable application is the ability to use a dramatically larger cam (specifically, larger in the sense of more overlap) while still maintaining idle quality and lower RPM drivability. That's because the close proximity of the throttle blades to the intake valves creates a much smaller total intake volume that is under vacuum, and therefore a smaller volume of exhaust reversion during overlap.
That's not the only reason. You now have no dirty air, all throats are isolated from the exhaust reversion from other cylinders.
Also, an ITB is typically easy to "tune" for optimal effective runner length and thus maximum peak torque RPM.
[QUOTE]
Hope this helps.
__________________
Mark
Engine builder and tuner.
|