Quote:
Originally Posted by BabyDiesel
Welcome!
I am not familiar with Toyota engine by any means, but can Prius pistons be used in your 1.5? I believe I read they give a higher compression ratio and more efficiency. I know Echofrancis is putting them in the Echo-Troll.
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Excellent question! Up until recent MY the Yaris/Prius/Scion Xa and Xb shared the same basic long block engine, except the engine was called the 1NZ-FXE in the Prius to denote the Atkinson cycle and the longer rods for the 13.1 to 1 compression ratio versus the 10.1 ratio of the 1NZ-FE. I think the piston were actually the same size, under two different part numbers, but the rods were different. Also note the exhaust manifold was a true 2 into 1 design versus the 4 into 1 design for the Yaris, Xa, and Xb. Increasing the compression ratio might present some issues to the ECU which means recalibration and lower torque at low and midrange rpms. As torque get the vehicle moving and the small 1.5 liter displacement can be a little hairy in highway onramp situations, I'm actually going the other direction in my design.
I want to lower the rpms for maximum torque, so the standing start to freeway speed time interval decreases.
I'll use a two inch spacer between the intake manifold and the head. This should have an effect similar to running extra long headers on the exhaust side of the head. Since there aren't long tube headers manufactured for the 1NZ-FE engine which would fit the system, creating the spacing on the intake side seemed the more logical choice.
Throttle body spacers and long rise intakes are a mainstay of the hotrod/ performance oriented community for decades.
It has taken me several hours of research to find a manufacturer. As I said in my original post vendor support, for the Yaris in falling off, but I found a 2" spacer which should do the job and hide well under the engine cover.
This is a daily driver need to pass smog or emission testing every two years. They don't actually dyno cars anymore in California for MY 2000 or newer. They do the physical inspection and hock up to the OBDII connector looking for codes and modifactions.